Area-controllable synthesis of (001), (101) and (011) planes in ZSM-5

Subscriber access provided by Kaohsiung Medical University

Article

Area-controllable synthesis of (001), (101) and (011) planes in ZSM-5 zeolites Kai Wang, Mei Dong, Xianjun Niu, Junfen Li, Zhangfeng Qin, Weibin Fan, and Jianguo Wang Cryst. Growth Des., Just Accepted Manuscript • DOI: 10.1021/acs.cgd.8b01354 • Publication Date (Web): 13 Nov 2018 Downloaded from http://pubs.acs.org on November 19, 2018

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 45 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Crystal Growth & Design

Area-controllable synthesis of (001), (101) and (011) planes in ZSM-5 zeolites Kai Wang,a,b,c Mei Dong,*,b Xianjun Niu,b,c Junfen Li,b Zhangfeng Qin,b Weibin Fan,b Jianguo Wang*,b a

College of Chemical and Environmental Engineering, Anyang Institute of Technology,

Anyang 455000, PR China b State

Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of

Sciences, P. O. Box 165, Taiyuan, Shanxi 030001, PR China. c University

of Chinese Academy of Sciences, Beijing 100049, PR China.

Corresponding authors. Tel.: +86-351-4046092; Fax: +86-351-4041153. E-mail address: [email protected] (M. Dong); [email protected] (J. Wang). Postal Address: Prof. Jianguo Wang, State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, P. O. Box 165, Taiyuan, Shanxi 030001, PR China.

1

ACS Paragon Plus Environment

Crystal Growth & Design 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Abstract A comprehensive survey into the effect of synthesis factors, such as n-butylamine (NBA) amount, alkalinity and H2O amount, on the crystallization process and the morphology of ZSM-5 products was performed. The results showed that a moderate NBA amount ([NBA]/[SiO2] = 0.08–0.12) may endow the growth process with the earlier “NBA-contained stage” and the later “NBA-free stage”. With the transformation of “NBA-contained stage” into “NBA-free stage”, because of the different growth trends induced by NBA+ and Na+, (101) planes appear first and then increase gradually at the expense of (001) planes; their area depends on the relative time span of two growth stages. Moreover, there is a decrease in Si concentration at the later stage of crystallization process. With the decrease of Si component in the range of C < Co (the critical concentration), thermodynamic morphology is maintained and no (011) planes are observed. In contrast, a higher Si concentration with C ≥ Co can generate the “shielding effect” and lead to the deviation of the kinetic morphology from the thermodynamic one, giving rise to the appearance of (011) planes; moreover, the area of (011) planes increases with the Si concentration. Therefore, by adjusting the crystallization conditions, area-controllable synthesis of (101), (001) and (011) planes in ZSM-5 zeolites was achieved in this work. Key words: Synthesis conditions; NBA amount; Alkalinity; H2O amount; (001), (101) and (011) planes; ZSM-5 zeolites.

2


Page 2 of 45

Page 3 of 45 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


1. Introduction MFI-type ZSM-5 zeolites are crystalline microporous aluminosilicate materials with anisotropic framework, which contains two categories of intersected 10-membered ring channels, the straight channel along b-axis (5.6 × 5.3 Å2) and the zigzag one along a-axis (5.5 × 5.1 Å2). Due to defined pore structure and high thermal stability,1-4 ZSM-5 zeolites grown into membranes have wide applications in the field of adsorbents, separation and the shape-selective catalysts.5-7 Through the oriented stacking of isolated ZSM-5 zeolites along b-orientation, the resultant chainlike ZSM-5 zeolites increased the tortuosity of pore channels, thus raising the ratio of diffusion coefficient of p-xylene to that of o-xylene from 1.09 to 3.17, as comparing with the isolated ZSM-5 zeolites.8,9 Similarly, enclosed by the ZSM-5 filme with the oriented assembly of coffin-shaped crystals along c axis, hollow ZSM-5 capsule not only facilitated the formation and the uniformly distribution of Metal-acid sites, but also increased the contact time as the unreacted reactants and primary products diffused outward through shell from the inside cavity, thus obtaining the better synergistic effect and the enhaned catalytic performance.10,11 Besides, with the orientations of (101)/(011) and (002) planes paralleling the substrate, B-Al-ZSM-5 zeolite membranes prevented the pass through of CO and SO2 in the mixed gases with O2, thus exhibiting the ideal selectivity for O2 over CO and SO2.12 So the catalysis or separating performance of ZSM-5 zeolite films was determined by the features of the surrounding pore, which is closely relative with the grain morphology and orienrtation.

13-15

With the exposure of

different crystal faces, molecules diffused through the zeolite membrane following different channels and mechanisms.

16,17

It indicates that a few novel-shaped ZSM-5 zeolite crystals

with the exposure of some area-controllable crystal planes have many potential applications in membrane separation and catalysis. To synthesis of ZSM-5 zeolites with different morphologies, the influence of crystallization parameters on the the final morphology of products was investigated widely

3



Page 4 of 45

in recent decades.18,19 Due to the difference in the charge, size and geometric shape, the category of template agent was believed to have a big impact on the morphology of products. The

utilization

of

quaternary

ammonium

TBA+ and

di-quaternary

ammonium

C22H45-N+(CH3)2-C6H12-N+(CH3)2-C6H13 led to the formation of the rectangular and multilamellar ZSM-5 crystals,20,21 whereas the coffin-, octagon- and leaf-shaped ZSM-5 crystals appeared with the employ of monomer, dimers and trimers of TPA+ as template respectively.16,22 The amount of template agent was another important factor to affect the morphology of products. The decrease of TPAOH amount resulted in the elimination of (001) and (011) planes but still recognization of (101) planes with the transformation of octahedron into coffin in the morphology of ZSM-5 zeolites.23 In addition, various morphologies were obtained by adjusting the compositions of initial reaction gels. For instance, a series of variations in the morphology of products were observed with the increase of Si/Al ratios in the initial gel, that was, nanorod aggregate first changed to microspindle and then to single or twinned hexagonal crystals; Length/width ratio of crystals was shortened as the result of increasing Na+ and OH− concentrations.24,25 Nevertheless, there was not yet clear on the control mechanism of crystal planes, especially the area-controllable synthesis of crystal planes in ZSM-5 zeolites.

Figure 1 Different from usual encountered morphologies of twinned boat and twinned coffin (Figure 1a-1b), a novel octahedron-shaped ZSM-5 zeolites appeared in this work, which exposed

(001),

(101)

and

(011)

planes

simultaneously

(Figure

1d).

Through

multi-technologies, the influence mechanism of synthesis factors, such as n-butylamine (NBA) amount, alkalinity and H2O amount, on the crystallization process and the morphology of products was demonstrated in detail and in depth. Based on obtained conclusions, by adjusting these synthesis conditions selectively, area-controllable synthesis of (001), (101) and (011) planes in ZSM-5 zeolites was achieved.

4


Page 5 of 45 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


2. Experimental 2.1 Synthesis of ZSM-5 zeolite catalysts The synthesis of ZSM-5 zeolite catalysts was carried out following the typical hydrothermal procedure with the molar composition of SiO2: 0.14 Al2O3: Y Na2O: X NBA: Z H2O. Sodium hydroxide (NaOH, AR, Tianjingshengtai Chemical Co., China), sodium aluminate (NaAlO2, CP, Shanghai Chemical Co., China) and template agent n-butylamine (NBA, CP, Shanghai Chemical Co., China) were successively added into the deionized water under stirring at room temperature. Then, the addition of colloidal silica (40 wt.% of amorphous SiO2) into above mixture was proceeded drop by drop, and the synthesis gel was obtained with the stirring for 60 min. In the next step, the synthesis gel was transferred into a Teflon-lined reaction caldron with the volume of 120 mL, and then hydrothermal crystallized under the agitation of 15 r/min at 443K. Though cooling the reaction caldron in ice water, washing until the pH of the supernatent to neutral, and calcination at 833 K for 12h, the final product was obtained for further characterization, which was denoted as Z-X-Y-Z (X = [NBA]/[SiO2], Y = [Na2O]/[SiO2] and Z = [H2O]/[SiO2]). 2.2 Characterizations of ZSM-5 zeolite catalysts X-ray powder diffraction (XRD) patterns of resultant ZSM-5 samples were taken on a Rigaku MiniFlex II desktop X-ray diffractometer with Cu K radiation. The relative crystalinity of ZSM-5 samples was calculated by comparing the total area of the peaks locating at 2θ = 22.5–25° with the reference Z-0.27-0.09-31 sample, which has the highest crystallinity of 100%. Scanning electron microscopy (SEM) images were used to characterize the morphologies and exposed crystal surface of resultant ZSM-5 samples over a field emission scanning electron microscope (JSM 7001-F, JEOL, Japan), and tested samples were covered with a thin gold layer by sputtering prior to SEM detection. The concentration of silicon and NBA amount in mother liquid along the whole crystallization process of ZSM-5 zeolites were determined by the inductively coupled plasma atomic

5



emission spectroscopy (ICP-AES, Autoscan16, TJA) and elemental analyzer (EA, Vario, EL, CUBE), respectively. 3. Results and discussion 3.1 Area-controllable synthesis of (001) and (101) planes

Figure 2 and Figure 3 Figure 2 shows the XRD patterns of Z-X-0.09-31 samples (X = [NBA]/[SiO2) with the increase of X from 0.002 to 0.27. All Z-X-0.09-31 samples showed the strong characteristic peaks of MFI structure at 2θ = 7.88°, 8.76°, 23.0°, 23.84° and 24.3° without presence of any amorphous and other crystalline phases, indicating that the resultant products were pure ZSM-5 crystals with high crystallinity. Besieds, as shown in Figure 3, with the increase of the NBA amount, the morphology of the ZSM-5 samples varied extensively, which can be categorized into three groups: The particles with shape of twinned coffin can be obtained at the NBA amount range of 0.002 ≤ X ≤ 0.05 (Figure 3a & 3b); Increasing X from 0.08 to 0.12, pro-twinned coffin appeared (Figure 3c & 3d); When X value further increased from 0.15 to 0.27, the twinned boat morphology was observed (Figure 3e & 3f). This means that the amount of template agent NBA played an important role in adjusting the morphology of ZSM-5 zeolites. The relationships among NBA amount, crystallization process and morphology of product were researched in following part. 3.1.1 The effect of NBA amount on the crystallization process

Figure 4 As shown in Figure 4a-4c, there is a obvious difference in the induction period of the synthesis systems with the different amount of template NBA. During the induction period, the silicoaluminate species condensed into the primary structure building unites around Na+ through the electrostatic interaction; Subsequently, the further rearrangement and connection

6


Page 6 of 45

Page 7 of 45 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


of primary structure building unites around template NBA+ generated the large amount of nuclei in synthesis system.26,27 So Na+ and NBA+ were both incorporated into the ZSM-5 crystal nuclei in this stage, and their effect presented in a synergistic way: Na+ played the role of charge balancing agent, which neutralized the negative charged framework of molecular sieve, meanwhile, the effect of NBA+ was attributed to structure directing function, filling and stabilizing of the zeolitic channel.28 As shown in Figure 4a-4c, the induction period of synthesis systems with [NBA]/[SiO2] = 0.03, 0.08 and 0.27 were 14.0, 13.7 and 13.0 h, respectively. The remarkable reduction of the induction period with the increase of template NBA amount suggested that the template NBA effectively promoted the primary structural units in the gel system to connect, rearrange, and nucleate, thus shortening the induction time. When it comes to the stage of crystals growth, the primary structural units formed by Na+ were as building blocks, which migrated to and piled up on the surface of crystal nuclei by attaching to the surface terminal TOH, thereby forming new zeolitic layers. Depending on the amount of NBA, the variation of NBA concentration in mother liquid and the apparent rate constant (K) both had a remarkable difference (Figure 4a–4c). The crystallization of ZSM-5 zeolite started at 14 h in the system of Z-0.03-0.09-31, and the concentration of the template NBA in the mother liquid maintained at 0.056 mol/L before 14 h; The increase of crystallinity and the incorporation of template NBA into the ZSM-5 framework resulted in the gradual decrease in the concentration of template NBA in liquid; As the increase of crystallinity to 3.1% at 15 h, the concentration of NBA in liquid decreased to the lowest detectable limit of EA detector, which indicated the wholly disappearance of NBA in liquid; Subsequently, when the crystallization was further carried out to 24 h, the crystallinity of ZSM-5 zeolite gradually increased to 100% with maintenance of NBA concentration bellowing the lowest limit of EA detector, suggesting that template NBA was absence in the crystals growth of Z-0.03-0.09-31, and this process was defined as “NBA-free process”. When it comes to the system of Z-0.27-0.09-31, the initial concentration of NBA in liquid increased to 0.44 mol/L, the start of crystallization further

7



shifted to 13h; prolonging the time to 20 h, the crystallinity of products grudually increased to 100% with the gradual decrease of NBA concentration to 0.25 mol/L in liquid. The existence of abundant NBA in liquid at the end of crystallization illustrated template NBA was participated in the whole process of crystals growth of Z-0.27-0.09-31, which was “NBA-contained process”. According to the survey of Speybroeck28,29, in the “template-free process”, the primary structure building unites were formed by Na+; The high concentration of primary structure building unites promoted the self-condensation or self-rearrangement around Na+ on the surface of crystals to generate the new zeolitic layers. On contrary, with the presence of template agent (NBA), the primary structure building unites formed by Na+ would be apt to condense or rearrange around NBA+ for the formation of the new zeolitic layers. As shown in Fig4a-4c, the increase of [NBA]/[SiO2] from 0.03 to 0.27 raised the apparent rate constant (K) from 23.6 to 29.4. This means that the primary structure building unites would assemble preferentially around NBA+ than that around Na+ to form the new zeolitic layers, the increase of NBA amount accelerated crystallization rate. As for the system of Z-0.08-0.09-31, the initial concentration of NBA in liquid was 0.14 mol/L, and the start of crystallization shifted to 13.7 h; With the extension of time to 19 h, the crystallinity of products achieved to 78.6%, the concentration of NBA in liquid gradually decreased and disappeared; Further increasing the time to 22 h, the crystallinity of products increased to 100% with absence of NBA in liquid. These variations indicated the process of crystals growth with [NBA]/[SiO2] = 0.08 was consisted of the earlier “NBA-contained process” and later “NBA-free process”. Compared with the system of Z-0.03-0.09-31, because of the induction effect, slight increase of NBA caused the apparent rate constant (K) increasing from 23.6 to 28.7 in Z-0.08-0.09-31. However, only the small gap of the apparent rate constant (K) between the system of [NBA]/[SiO2] = 0.08 and 0.27 was observed (28.7 & 29.4). This was attributed to that a large number of crystals (crystallinity is 78.6%) formed with the depletion of NBA in liquid of Z-0.08-0.09-31, and the abundant terminal TOH units on the surface of these crystals significantly accelerated the crystallization process, therefore, no obvious drop in crystallization rate was observed.30

8


Page 8 of 45

Page 9 of 45 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


3.1.2 The effect of NBA amount on (001) and (101) planes From above, according to the amount of NBA in system, there exists two growth modes during the growth process of crystals, they were “NBA+-induced growth” and “Na+-induced growth” respectively, and the former was more competitive than the later. Figure S1 showed the variation of morphologies during “NBA+-induced growth” process in Z-0.27-0.09-31. The initial crystals Z-0.27-0.09-31 (14) (Here, the number locating in bracket denotes the crystallization time.) were observed for the first time, which existed in the form of boat (Figure S1a). After crystallization for 16 h, a few fine crystals grew in the (010) planes of boat-shaped crystals (Figure S1b). Increasing the crystallization time to 18h, Z-0.27-0.09-31 (18) appeared as twinned boat with the growth of these fine crystals in (010) of boat (Figure S1c). When the crystallization was further carried out for 20 h, Z-0.27-0.09-31 (20) showed the similar morphology with Z-0.27-0.09-31 (18) but with the increase of grain size (Figure S1d). Besides, the distinct variation of morphologies of “Na+-induced growth” process in Z-0-0.09-31 was displayed in Figure S2. The initial crystals Z-0-0.09-31 (27.5) presented as coffin (Figure S2a). Prolonging the crystallization time to 38 h caused the appearance of a few fine crystals in (010) planes of coffin-shaped crystals (Figure S2b). With the further increase of time to 48 h, perfect twinned coffin crystals were obtained as result of the grow up of these fine crystals in (010) planes of coffin (Figure S2c). So we can concluded that the growth trends of ZSM-5 zeolite crystals depended on the synthetic environments:31–34 NBA+ induced crystals to grow toward boat firstly, and then to twinned boat in “NBA+-induced growth” or “NBA-contained process”; Contrarily, with the induction effect of Na+, the crystals grew into coffin and twinned coffin successively during “Na+-induced growth” or “NBA-free process”. When it comes to system of Z-0.03-0.09-31, the boat-shaped Z-0.03-0.09-31 (15) had formed (Figure S3a) under the synergistic effect of Na+ and NBA+ at the end of the induction period, meanwhile, “Na+-induced growth” process started with the depletion of NBA in liquid. As crystallization further proceeded to 18h, by way of pro-coffined crystals, the morphology of crystals gradually transformed from boat into coffin (Figure S3a-S3c).

9



Further increasing the crystallization time to 20 h caused the formation of twinned coffin as a result of the appearance and growth of fine crystals in the (010) plane of coffin (Figure S3d). Coffin and twinned coffin were successively obtained as the crystallization entered into “NBA-free stage”, which was the typical trend of “Na+-induced growth”.

Figure 5 Figure 5 showed the morphologies of samples with different crystallization time in system of Z-0.08-0.09-31. Boat-shaped and twinned boat-shaped crystals were successively obtained with the assistance of NBA+ before 19 h (Figure 5a-5e), which was similar to that of the “NBA-contained process” in Figure S1. Afterward, the growth process of crystals entered into “NBA-free stage”, and the morphology of products varied remarkably with the extension of crystallization time: twinned boat first transformed into octahedron (Figure 5f-5g) and then to pro-twinned coffin (Figure 5h-5i), which was the typical trend of “Na+-induced growth”. It was worth noting that the crystal faces also changed considerably during above variation in morphologies: (001) planes reduced to disappearance little by little, meanwhile, (101) planes grew out of nothing and became larger gradually. The above results proved that the moderate NBA amount endowed the growth process of [NBA]/[SiO2] = 0.08 with the earlier “NBA-contained process” and later “NBA-free process”. So we conferred that this variation of the crystal planes or morphologies of crystals was ascribed to the different growth trends induced by NBA+ and Na+ with the transformation from the earlier “NBA-contained growth process” to the later “NBA-free growth process”. Furthermore, a verifying test was designed here, the crystal with the shape of twinned boat in Figure S1d as the seed (10 wt.%) was added into the template-free system (Z-0-0.09-31), and the variation in the morphologies of samples were also monitored by SEM images. As shown in Figure S4, a series of variations in shape were observed, that was twinned boat (Figure S4a) → Octahedron (Figure S4b-4c) →Pro-twinned coffin (Figure S4d). At the same time, the similarity between the variation of (001) and (101) planes in verifying test and that in Z-0.08-0.09-31 indicated the reasonableness of our conjecture. The time point of the growth process transforming from “NBA-contained stage” into

10


Page 10 of 45

Page 11 of 45 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


“NBA-free stage” was denoted as T0. As revealed in Figure 4d, the whole crystallization process of [NBA]/[SiO2]≥0.15 was “NBA-contained process”, the products presentes as twinned boat as a result of T0 =38 h; The decrease of [NBA]/[SiO2] to 0.08~0.12 gave rise to the appearacne of “NBA-free process” in the later growth stage of crystals and the formation of pro-twinned boat in products with the shift of T0 from 38 to 24 h in [NBA]/[SiO2] = 0.12 and 195 h in [NBA]/[SiO2] = 0.08. Further reducing [NBA]/[SiO2] to 0.03, “NBA-contained process” disappeared from the growth stage of crystals, which made T0 moved forward to 15h, and the morphology of twinned boat was obtained. In summary, the amount of template NBA changed the time point (T0) or the relative time span of “NBA-contained process” and “NBA-free process”, thus influencing the morphology or the crystal planes of products, owing to the different growth trends induced by NBA+ and Na+. What's more important is that by adjusting the crystallization time in the system with the amount of [NBA]/[SiO2] = 0.08–0.12, the objective of controlling the relative area of (001) and (101) planes in ZSM-5 zeolites can be achieved. 3.2 Area-controllable synthesis of (011) planes 3.2.1 The effect of H2O amount and alkalinity on (011) planes

Figure 6, Figure 7 and Figure 8 Figure 6a and Figuer 6b showed XRD patterns of Z-0.03-0.09-Z and Z-0.03-Y-31 samples with Z = 15~31 and Y = 0.09~0.18, respectively. Accompany with the absence of any amorphous and other crystalline phases, the characteristic MFI structure peaks of these products with strong intensity illustrated that the synthesized samples were pure ZSM-5 crystals with high crystallinity. As the influence of H2O amount on the morphology of products shown in Figure 7, ZSM-5 crystals with twinned coffin were observed with [H2O]/[SiO2] = 31 and 26 (Figure 3b and Figure 7a); With the decrease of [H2O]/[SiO2] to 20, (011) planes began to appear in the twinned coffin but with the embryonic-stage (Figure 7b); Continue to decrease the ratio of [H2O]/[SiO2], the area of (011) planes in twinned

11



coffin increased gradually (Figure 7c-7d). Besides, the alkalinity was another important parameter affecting the morphology of ZSM-5 zeolites. As shown in Figure 3b, the products synthesized from the system with [Na2O]/[SiO2] = 0.09 existed as twinned coffin; Increasing [Na2O]/[SiO2] to 0.12, minimal (011) planes was observed in twinned coffin (Figure 8a); Further increasing [Na2O]/[SiO2] gave rise to the increase of (011) planes in twinned coffin little by little (Figure 8b-8c). Although the similarity of the variations in (011) plane by decreasing H2O amount and by increasing alkalinity was observed, the influece of the later was more while that of the former was less. 3.2.2 The formation mechanism of (011) planes After mixing the raw materials, the rapidly reaction of the aluminum species with silica gel generated the initial synthesis gel, which balanced with the silicate and silicoaluminate species in liquid. When the temperature rised to the crystallization temperature, the new dissolution equilibrium was established, which promoted the increase in the concentration of silicate and silicoaluminate species in liquid, giving rise to the occurrence of nucleation.10,11 Supplying the nutritions for the nucleation and the growth of crystals, the comsume of silicate and silicoaluminate species in liquid caused the gradual dissolution of active solid gel, due to the dissolution equilibrium. Because the solubility of the ZSM-5 zeolites was less than that of the active solid gel,35 the active solid gel was depleted and disappeared, leading to the decrease in the concentration of silicate and silicoaluminate species in liquid at the later stage of crystallization process. What is the most interesting that the appearance of (011) planes also happened at the later stage of crystallization (Figure 5 and Figure S4), which suggested the decrease in the concentration of silicate and silicoaluminate species in liquid was particularly important for exploring the formation mechanism of (011) planes. According to the previous reports, the variation in the concentration of active components caused the change of the relative growth rate of the crystal, thus affecting the product morphology during the synthetic system.36,37 Further study revealed that when the change happened in the concentration of active components, the growth 12


Page 12 of 45

Page 13 of 45 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


history of crystals had a significant effect on the growth rate in the future.38 As shown in Figure S5, with a history of slow crystal growth under low concentration, increasing the concentration caused the instantly strengthening of the growth rate of crystal to the corresponding thermodynamic growth rate; However, with a history of rapid crystal growth under high concentration, the growth rate of crystal first dropped to zero and then slowly increase back to the thermodynamic growth rate as the result of decreasing the concentration. Therefore, the kinetic growth rate of the crystal was lower than thermodynamic growth rate of the crystal during this period, and this phenomenon was “shielding effect”.39,40,41 Besides, there existed a critical concentration (Co), and only the decrease in the concentration of active components in the range of C ≥ Co led to the appearance of “shielding effect”.

Scheme 1 In addition, nucleation at high concentration occured anywhere on the crystal surfaces following the Birth and Spread mechanism.40,42 After nucleation, active components in liquid further absorbed and grew on the surface of the crystals, then integrated with the original nucleating sites, thus enabling it to spread over the surface to form a perfect monolayer. Subsequently, repeating the nucleation and growth of the first layer, the formation of the second layers occured with “layer-by-layer” growth (Scheme 1c and 1d). According to the Bravais-Friedel-Donnay-Harker law and Hartman-Perdok law,43 the shape of new forming layer also depended on the growth rates, the crystal edge with a fast growth rate reduced to disappearance little by little, while that with a slow growth rate would be retained and increased in length gradually. As shown in Scheme 1b, BC edge gradually moved toward O point with the increase of growth rate along c axis until it vanished during the growth process; On the contrary, the decrease of growth rate along c axis promoted the move of BC edge away from O point, thus causing the appearance and the increase of BC edge. When Si component in liquid nucleated and grew on the (010) planes of twinned coffin, the shape of twinned coffin kept unchanged with the increase in the number of layers

13



(Scheme S1a) during the constant stage of Si concentration. However, when it comes to the decreased stage of Si component, the morphology of product has a lot to do with the “shielding effect”. With the disappearance of “shielding effect”, the decrease of Si component (C < Co) reduced the growth rates of all directions in the same proportion, and the kinetic growth rates stay in step with the thermodynamic growth rates.38,39,41 In this condition, the new forming layer maintained the original thermodynamics shape but with the longer time to construct a perfect layer (Scheme S1a and S1b). On the contrarily, the decrease of Si component with C ≥ Co not only decreased the growth rates along all directions in the same proportion, but also caused the appearance of “shielding effect” in one or some certain direction. The shortening in the migration distance from OO’ to OO’’ and the emergence of BC edge in Scheme S1c indicated the “shielding effect” occured at OO’’ direction, resulting in the further decrease of the growth rate along c axis. So owing to the the deviation of the kinetic growth rate with thermodynamic growth rate along c axis, BC line would move away from O point toward AD line (Scheme 1b). As shown in Scheme 1c, when the new layer grew on (010) planes of twinned coffin by Birth and Spread mechanism, the (011) planes began to appear; With the further increase of “shielding effect”, BC line increased in length and continued to shift from O point to AD line gradually. Following “layer-by-layer” growth mode, the increase in the number of layers resulted in the increase of (011) planes in twinned coffin.

Figure 9 On the whole, as for the systems of Z-0.03-0.09-Z and Z-0.03-Y-31 with Z = 31–26 and Y = 0.09, the concentration of Si component was relative low (Figure 9a and 9b). At the early stage of constant concentration of Si component, the thermodynamics morphology presented as twinned coffin (Scheme 1a); Due to the disappearance of “shielding effect”, the thermodynamics morphology maintained with the decrease of Si component at the later stage of crystallization. The embryonic-stage of (011) planes in twinned coffin with system of Z = 20 and Y = 0.12 indicated the critical concentration (Co) in Z-0.03-0.09-Z and Z-0.03-Y-31 for the appearance of “shielding effect” were 0.47 mol/L and 0.38 mol/L,

14


Page 14 of 45

Page 15 of 45 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


respectively. Increasing Si concentration more than the critical concentration for Z < 20 and Y > 0.12, due to the decrease of Si concentration, the appearance of “shielding effect” caused the deviation of the kinetic growth rate with thermodynamic growth rate, thus changing the thermodynamic morphology of product to the kinetic morphology (Scheme 1a). As shown in Figure 7-9, enclosed by the critical concentration (Co) and the decrease curves of Si component, the shaded area showed a good correspondence with the area of (011) plane in twinned coffin: No shadow appeared in the range of C < Co; The shadow began to appear for C = Co, and the area of shadow increased with the increase of Si concentration (C > Co). So through controlling the concentration of active Si component by adjusting H2O amount or alkalinity of systems, the exposure of (011) planes and these area were both regulated precisely. 3.3 Area-controllable synthesis of (001), (101) and (011) planes 3.3.1 The exposure of (001), (101) and (011) planes

Figure 10 and Figure 11 As XRD patterns of resultant samples disaplyed in Figure 6c and Figuer 6d, the characteristic MFI structure peaks appeared in high strength but with no observation of any amorphous and other crystalline phases, indicating that Z-0.08-0.09-Z and Z-0.08-Y-31 samples with Z = 20–36 and Y = 0.09–0.13 were all pure ZSM-5 zeolites with high crystallinity. Figure 10 displayed SEM images of Z-0.08-0.09-Z products with different [H2O]/[SiO2] ratio, it was found that (011) crystals planes were absence from pro-concex coffin with [H2O]/[SiO2] = 36 (Figure 10a); With the decrease of [H2O]/[SiO2] to 20, (011) crystals planes in pro-twinned coffin grew from nothing and increased gradually in area (Figure 10b-10d). SEM images of Z-0.08-Y-36 products indicated that the products with [Na2O]/[SiO2] = 0.09 presented as pro-twinned coffin, and no (011) planes was observed (Figure 10a); Increasing [Na2O]/[SiO2] to 0.13 gave rise to the emergence and the gradual increase of (011) planes in pro-twinned coffin (Figure 11). Furthermore, by comparing the

15



area of (011) planes in pro-twinned coffin shown in Figure 10 and Figure 11, it was clear to know that the influece of increasing alkalinity on (011) planes was more than that of decreasing H2O amount. According to the formation mechanism of (011) planes investigated in 3.2, we can conclude that due to the relative low concentration of Si component for Z-0.08-Y-Z systems with Z = 36 and Y = 0.09, the decrease of these concentrations at the later stage of crystallization were not serious enough to cause “shielding effect”, therefore the thermodynamics pro-twinned coffin kept unchanged. Decreasing Y to 31 or increasing Z to 0.1, the observation of (011) planes but with small area suggested the critical concentration (Co) for the appearance of “shielding effect” were close to 0.29 and 0.26 mol/L in Z-0.08-0.09-Z and Z-0.08-Y-36, respectively. Going to increase Si concentation more than the critical concentration for Z = 26~20 and Y = 0.12~0.13, the decrease of Si concentration engendered “shielding effect” and the gradual increase of (011) planes in pro-twinned coffin. As shown in Figure 9-11, well correspondence between the shaded area (enclosed by the critical concentration Co and the decrease curves of Si component) and the area of (011) plane was also observed: No shadow was observed for C < Co; The shadow appeared and increased in the area gradually as the increase of Si concentration in the range of C ≥ Co. In addition, increasing alkalinity and decreasing H2O amount both caused the transformation from pro-twinned coffin to octahedron, meanwhile, (001) planes grew out of nothing and became larger gradually but with the reduce of (101) planes (Figure 10-11), which was the inverse process of “Octahedron→Pro-twinned coffin” observed in Figure 5f-5h. Based on the obtained results in Section 3.1, the growth process of Z-0.08-Y-Z was consisted of the earlier “NBA-contained process” and later “NBA-free process”, the morphology of products depended on the relative time span of these two processes (For the convenience of investigation, the time spans of “NBA-contained process” and “NBA-free process” were denoted as “T1” and “T2”, respectively). According to the previous report, the crystallization process of seed-induction systems was described by a cubic function,44,45

16


Page 16 of 45

Page 17 of 45 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


  

M t  M 0 1

K a   Kb   Kc  t  1 t  1 t  d0   d0   d0 

(1)

Where, d0 and M0 represent the size and the mass of the crystal nucleus; Mt represents the mass of crystallized zeolite at time t; Ka, Kb, and Kc are the growth rate constant along a, b and c axis, respectively. As displayed in Figure 1, the size of ZSM-5 zeolite crystal in width, height and length were marked as La, Lb and Lc respectively, which was proportional to the crystal average growth rates along a, b and c axis directly.23 So the crystal size along a, b and c axis, La, Lb and Lc, at crystallization time t, could be expressed as below:44

Lta  d o  K at

(2)

Ltb  d o  K bt

(3)

Ltc  d o  K ct

(4)

As the crystallization times prolonged to T1 (the time of NBA-contained process) with the crystal nucleus of M0 (Figure S6), the Eq.(1) can be expressed by

  

M 0  M T 1  M 0 1

K a   Kb   Kc  T1  1 T1  1 T1  d 0   d 0   d 0 

(5)

As the crystallization times prolonged to T2 (the time of NBA-free process) with the crystal nucleus of (M0 + MT1) (Figure S6), the Eq. (1) can be expressed by

  

M 0  M T 1  M T 2  M 0  M T 1 1

K a   Kb   Kc  T  1 T1 T2  1 T1 T2  T1 2   La   Lb   Lc 

(6)

The mass (M0) and the size (d0) of the crystal nucleus can be ignored, so the Eq. (5) and Eq. (6) can be translated into:

M T 1 d 03  (d o  K aT1 )(d o  K bT1 )(d o  K cT1 )  K a K b K cT13 M0

(7)

M T 1  M T 2 LTa1LTb1LTc 1  LT 1  K T LT 1  K T LT 1  K T 



M T1

a



a 2

b

b 2



c

c 2



 d o  K aT 1 K aT 2 d o  K bT 1 K bT 2 d o  K cT 1 K cT 2  K a K b K c T 1T 2  17


3

(8)


Here, the ratio of

Page 18 of 45

T2 ( Before) can be obtained by solving the Eq. (7) and Eq. (8). T1

3 LT 1 LT 1 LT 1 T2 Before  a b c T1 d0

3

M T 1  M T 2 M 0 M T21

1

(9)

With the increase of alkalinity or the decrease of H2O amount, the supersaturation increased, which further increased the number of crystal nucleus in synthetic system. As the number of crystal nucleus increased by n times (Figure S6), d0 and M0 of the crystal nucleus kept unchanged, while the grain size of MT1 crystals shortened from LaT1, LbT1 and LcT1 into La'T1, Lb'T1 and Lc'T1 (LaT1 ≥ La'T1, LbT1 ≥ Lb'T1 and LcT1 ≥ Lc'T1), the mass of “NBA-contained process” and “NBA-free process” changed into M T1 and M T 2 , respectively, depended on

n

the conservation of mass. Then

T2  After   T1 

3

3

L,aT 1L,bT 1L,cT 1 d0

L,aT 1L,bT 1L,cT 1 d0 3

3

T2  After  can be expressed by T1

M T 1  M T 2 nM 0   1 M T21

M T 1  M T 2 M 0 M T21

n

(10)

1

According to the Eq.(10), with the increase of the number of crystal nucleus,

T2 Before ≥ T 2  After  as the result of LaT1 ≥ La'T1, LbT1 ≥ Lb'T1 and LcT1 ≥ Lc'T1, T1 T1 suggesting that the increase of supersaturation increased the relative time span of “NBA-contained process” (T1), compared to that of “NBA-free process” (T2). Based on the conclusion obtained in Section 3.1, this variation of these two relative time spans gave rise to the reduce of (101) planes, the appearance and increase of (001) planes with the transformation of pro-twinned coffin to octahedron (Figur 10-11). So through the above investigations into the influence of alkalinity and H2O amount on the crystallization process and the morphology of Z-0.08-Y-Z products, area-controllable synthesis of (001), (101) and (011) planes in ZSM-5 zeolites can be achieved.

18


Page 19 of 45 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


3.3.2 The effect of alkalinity and H2O amount on Lb

Figure 12 The above results revealed that not only in systems of Z-0.03-Y-Z but also in systems of Z-0.08-Y-Z, although the similar variations of (011) planes were observed with the increase of Si concentration by decreasing H2O amount or increasing alkalinity, the area of (011) planes obtained by the later is obvious greater than that produced by the former. Therefore, it was necessary to explore the differences between the effect of these two measures. As dispalyed in Figure 1, the size of ZSM-5 zeolite crystal in width, height and length were marked as La, Lb and Lc respectively, which was proportional to the crystal average growth rates along a, b and c axis directly.23 Accoding to SEM images of Z-0.03-Y-Z

L

Z 0.030.09 Z a  fact

shown

in

.030.09 Z , LZb0fact

Figure



7-8,

we

measured



the

Z 0.03Y 31

(Z = 31, 26, 20, 17.5, 15) and La  fact

factual

sizes



.03Y 31 , LZb0fact (Y =

0.09, 0.12, 0.15, 0.18), respectively. Adjusting Z = [H2O]/[Si] in systems of Z-0.03-0.09-Z: .030.09  Z 31 LZa 0fact .030.09  Z 31 LZb0fact

0.030.09  Z Z  LZa theory



0.030.09  Z Z  LZbtheory

, Z  26, 20, 17.5, 15

0.030.09  Z Z   LZa0fact.030.09Z Z , Z  26, 20, 17.6, 15 LZa theory

.030.09  Z Z  LZb0fact 0.030.09  Z Z  LZbtheory



.030.09  Z Z  LZa0fact.030.09Z 31 LZb0fact .030.09  Z Z  LZb0fact.030.09Z 31 LZa 0fact

, Z  26, 20, 17.5, 15

(11) (12) (13)

Adjusting Y = [Na2O]/[Si] in systems of Z-0.03-Y-31: .03Y 31 0.09 LZa 0fact .03Y 31 0.09 LZb0fact



0.03Y 31 Y  LZa theory 0.03Y 31 Y  LZbtheory

, Y  0.12, 0.15, 0.18

0.03Y 31 Z   LZa0fact.03Y 31 Z , Y  0.09, 0.12, 0.15, 0.18 LZa theory .03Y 31 Y  LZb0fact 0.03Y 31 Y  LZbtheory



.03Y 31 Y  LZa0fact.03Y 31 0.09 LZb0fact .03Y 31 Y  LZb0fact.03Y 31 0.09 LZa 0fact

, Y  0.12, 0.15, 0.18

19


of

(14) (15) (16)


Page 20 of 45

Decreasing H2O amount or increasing alkalinity in the systems of Z-0.03-Y-Z, average growth rates along a, b and c axis increased theoretically in the same proportion with the increase of Si concentration, the Eq. (11) and the Eq. (14) were set up as the result of the lowest concentration Z-0.03-Y-Z with Y=31 and Z=0.09 as a starting point. Besides, from 3.2, different from the appearance of “shielding effect” along c axis with C ≥ Co, the kinetic growth rate was equal to the thermodynamic growth rate along a axis in each concentration system due to the non-existence of “shielding effect”. So the growth rate along a axis were took as a reference, the Eq. (12) in systems of Z-0.03-0.09-Z and the Eq. (15) in systems of Z-0.03-Y-31 can be obtained. Then,

and

.03Y 31 Z  LZb0fact 0.03Y 31 Z  LZbtheory

.030.09  Z Z  LZb0fact 0.030.09  Z Z  LZbtheory

(Z = 26, 20, 17.5, 15)

(Y = 0.12, 0.15, 0.18) can be easily caculated from the Eq. (13) and the

Eq. (16) respectively. Meanwhile, on basis of

L

Z 0.08Y 36 a  fact

.08Y 36 , LZb0fact



L

Z 0.080.09  Z a  fact

.080.09  Z , LZb0fact



(Z = 36, 31, 26, 20) and

(Y = 0.09, 0.10, 0.12, 0.125, 013) measured from Figure 10-11,

through the same processing method with the system of Z-0.03-Y-Z,

31, 26, 20) and

.08 Y 36 Y  LZb 0fact 0.08 Y 36 Y  LZb theory

.08 0.09  Z Z  LZb0fact 0.08 0.09  Z Z  LZbtheory

(Z =

(Y = 0.10, 0.12, 0.125, 013) in system of Z-0.08-Y-Z also can

be obtained from the Eq. (S1)-(S3) and the Eq. (S4)-(S6) respectively.

As plotted in Figure 12, whether in systems of Z-0.03-Y-Z or Z-0.08-Y-Z,

ratio was greater than 1 but with

Lb  fact Z 

Lb  theory Z 

Lb  fact Y 

Lb  theory Y 

< 1, indicating that Lb increased by

increasing alkalinity but decreased by decreasing the H2O amount, and these variations were intensified with the increase of Si concentration. Based on the above results, whatever by increasing alkalinity or decreasing H2O amount, the effect of increasing Si concentration on the synthetic system was two-fold. When the concentration of Si was in the range of C < Co,

20


Page 21 of 45 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


duo to the non-existence of “shielding effect”, the thermodynamics morphology maintained in each concentration system. However, the average growth rate along b axis was enhanced by increasing alkalinity while that was restricted by decreasing H2O amount. When it comes to Si component with C ≥ Co, “shielding effect” caused the appearance of (011) planes in products of each concentration systems. Meanwhile, the variations of Lb along the increase of alkalinity and the decrease of H2O amount were also occured but with more intensity. So compared with the shorter Lb in systems of Z-0.03-0.09-Z and Z-0.08-0.09-Z by increasing H2O amount, the longer Lb granted the products with the larger (011) planes by increasing alkalinity in systems of Z-0.03-Y-31 and Z-0.08-Y-36. In addition, accompany with the positive “shielding effect”, Lb or the average growth rate along b axis also had a big impact on the appearance of (011) planes: the reduced average growth rate along b axis by decreasing H2O amount counteracted the positive effect of “shielding effect”, while the enhanced one by increasing alkalinity played a synergy role with “shielding effect”. So with the appearance of “shielding effect”, the longer Lb by increasing alkalinity than that by decreasing H2O amount gave rise to that C0 for the appearance of (011) planes by decreasing H2O amount is greater than that by decreasing alkalinity (Figure 9). In particular, as shown in Figure 9 and Figure 12, the gap of C0 between by decreasing H2O amount and by increasing alkalinity for the appearance of (011) planes became more significant (0.29 mol/L & 0.26 mol/L in Z-0.08-Y-Z, and 0.47 mol/L & 0.38 mol/L in Z-0.03-Y-Z) with the increased difference between Lb-fact/Lb-fact (Y) and Lb-fact/Lb-fact (Z) from Z-0.08-Y-Z system to Z-0.03-Y-Z system. 4. Conclusion The synthesis factors, such as template NBA amount, alkalinity and H2O amount, have significant influence on the crystallization process and morphology of products. On one hand, according to NBA amount, the crystallization procss has a big difference: the growth processes of crystals with [NBA]/[SiO2] ≥ 0.15 and [NBA]/[SiO2] = 0.03 were “NBA-contained process” and “NBA-free process” respectively, while that of [NBA]/[SiO2] = 0.08–0.12 consisted of the earlier “NBA-contained process” and later “NBA-free process”.

21



With the transformation of “NBA-contained process” into “NBA-free process” in system with [NBA]/[SiO2] = 0.08–0.12, (101) planes grew out of nothing and became larger gradually but with the reduce of (001) planes, owing to the different growth trends induced by NBA+ and Na+. For another, the increase of supersaturation raised the number of crystal nucleus and the ratio of the relative time span of “NBA-contained process” to that of “NBA-free process”. So by adjusting the crystallization time or the supersaturation, the relative time span of these two stages were effectively controlled, thus changing the relative area of (001) and (101) planes in ZSM-5 zeolites. In addition, through mintoring Si concentration, the crystallization process was divided into the previous constant stage and the later decreased stage. The morphology of products all existed as thermodynamics shape at the early stage, and great variations in morphology occurred at later stage, depending on Si component. With the decrease of Si component (C < Co), the kinetic growth rates stay in step with the thermodynamic ones, the thermodynamics morphology maintained, and no (011) planes was observed. Increasing Si concentration with C ≥ Co, the decrease of Si concentration generated “shielding effect”, thus causing the deviation of the kinetic growth rate with thermodynamic one along c axis. As a result, (011) planes appeared, and their area increased with Si concentration. Meanwhile, Lb increased by increasing alkalinity but decreased by decreasing H2O amount, and this difference was intensified with Si concentration. With the appearance of “shielding effect”, the area of (011) planes caused by increasing alkalinity is greater distinctly than that produced by decreasing H2O amount. So by adjusting the alkalinity and H2O amount selectively, the area of (011) planes in ZSM-5 zeolites was controlled precisely. What's more interesting, as shown Figure S7, with other organic amines as template agents, the partly or wholly similarities in variations of (001), (101) and (011) planes were observed, which indicated the area-controlling measures in this paper were also suitable for other template agent systems, thus laying the foundation for developing the potential applications in membrane separation and catalysis.

22


Page 22 of 45

Page 23 of 45 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Supporting Information The Supporting Information is available free of charge on the ACS Publications website at DOI: xxxxxxxxxxx. SEM images of Z-0.27-0.09-31, Z-0-0.09-31 and Z-0.03-0.09-31 samples with different crystallization times; SEM images of the samples obtained at different crystallization times in the system of Z-0-0.09-31 with the addition of boat-shaped crystal seeds (10 wt.%); Crystal growth behavior under varying conditions; Crystal growth model of seed-inducted system; Variations of (001), (101) and (011) planes in the system with Na+, N-propylamine, Triethylamine, and Tripropylamine as template under the similar conditions; Layer growth with constant growth rates along all directions, decreased growth rates of all directions in the same proportion, and decreased growth rates of all directions in the same proportion but with appearance of “shielding effect” along OO’ direction; Relative calculation formulas in the system of Z-0.08-Y-Z. Acknowledgments The authors are grateful for the financial support of the National Key R&D Program of China (2018YFB0604802), the Strategic Priority Research Program of the Chinese Academy of Sciences (XDA21020500), the National Natural Science Foundation of China (21573270, U1510104, and 21773281), the Natural Science Foundation of Shanxi Province of China (2015021003), the Innovative Talent Program of Shanxi Province (201605D211001), the CAS/SAFEA International Partnership Program for Creative Research Teams, the Youth Innovation Promotion Association, CAS (2016161), and the School foundation of Anyang Institute of Technology.

Notes and References

[1] Khatamian, M.; Khandar, A. A.; Haghighi, M.; Ghadiri, M.; Darbandi, M. Synthesis,

23



characterization and acidic properties of nanopowder ZSM-5 type ferrisilicates in the Na+/K+ alkali system. Powder Technol. 2010, 203, 503-509. [2] Mentzen, B. F.; Tuel, A.; Bayard, F. Location of the tripropylbenzylammonium ion (P3BZY) in the as-synthesized zeolite ZSM-5 (Si/Al=28): A study by solid-state NMR, computer simulations and X-ray synchrotron powder diffraction. Micropor. Mesopor. Mater. 2006, 93, 171-179. [3] Holm, M. S.; Svelle, S.; Joensen, F.; Beato, P.; Christensen, C. H.; Bordiga, S.; Bjørgen, M. Assessing the acid properties of desilicated ZSM-5 by FTIR using CO and 2,4,6-trimethylpyridine (collidine) as molecular probes. Appl. Catal. A: Gen. 2009, 356, 23-30. [4] Sazama, P.; Wichterlova, B.; Dedecek, J.; Tvaruzkova, Z.; Musilova, Z.; Palumbo, L.; Sklenak, S.; Gonsiorova, O. FTIR and

27Al

MAS NMR analysis of the effect of

framework Al- and Si-defects in micro- and micro-mesoporous H-ZSM-5 on conversion of methanol to hydrocarbons. Micropor. Mesopor. Mater. 2011, 143, 87-96. [5] Huang, L.; Qin, F.; Huang, Z.; Zhuang, Y.; Ma, J. X.; Xu, H. L.; Shen, W. Hierarchical ZSM-5 Zeolite Synthesized by an Ultrasound-Assisted Method as a Long-Life Catalyst for Dehydration of Glycerol to Acrolein. Ind. Eng. Chem. Res. 2016, 55, 7318-7327. [6] Zhang, Y. W.; Yu, J. Y.; Yeh, Y. H.; Gorte, R. J.; Rangarajan, S.; Mavrikakis, M. An Adsorption Study of CH4 on ZSM-5, MOR, and ZSM-12 Zeolites. J. Phys. Chem. C. 2015, 119, 28970-28978. [7] Zhang, J. G.; Qian, W. Z.; Kong, C. Y.; Wei, F. Increasing para-Xylene Selectivity in Making Aromatics from Methanol with a Surface-Modified Zn/P/ZSM-5 Catalyst. ACS Catal. 2015, 5, 2982-2988. [8] Quan, Y. H.; Li, S. Y.; Wang, S.; Li, Z. K.; Dong, M.; Qin, Z. F.; Chen, G.; Wei, Z. H.; Fan, W. B.; Wang, J. G. Synthesis of Chainlike ZSM-5 Zeolites: Determination of Synthesis Parameters, Mechanism of Chainlike Morphology Formation, and Their Performance in Selective Adsorption of Xylene Isomers. ACS Appl. Mater. Interfaces. 2017, 9, 14899-14910.

24


Page 24 of 45

Page 25 of 45 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


[9] Jin, L. J.; Xie, T.; Liu, S. B.;Li, Y. X.; Hu, H. Q. Controllable Synthesis of Chainlike Hierarchical ZSM-5 Templated by Sucrose and Its Catalytic Performance. Catal. Commun. 2016, 75, 32-36. [10] Wang, K.; Dong, M., Li, J. F.; Liu, P.; Zhang, K.; Wang, J. G.; Fan, W. B. Facile Fabrication of ZSM-5 Zeolite Hollow Spheres for Catalytic Conversion of Methanol to Aromatics. Catal. Sci. Technol. 2017, 7, 560-564. [11] Wang, K.; Huang, X.; Debao Li, D. B. Hollow ZSM-5 zeolite grass ball catalyst in methane dehydroaromatization: One-step synthesis and the exceptional catalytic performance. Appl. Catal. A: Gen. 2018, 556, 10-19. [12] Dong, W. Y.; Long, Y. C. Preparation and characterization of preferentially oriented continuous MFI-type zeolite membranes from porous glass. Micropor. Mesopor. Mater. 2004, 76, 9-15. [13] Reddy, J. K.; Motokura, K.; Koyama, T. R.; Miyaji, A.; Baba, T. Effect of morphology and particle size of ZSM-5 on catalytic performance for ethylene conversion and heptane cracking. J. Catal. 2012, 289, 53-61. [14] Au, L.T.Y.; Yeung, K.L. An Investigation of the Relationship between Microstructure and Permeation Properties of ZSM-5 Membranes. J. Membr. Sci. 2001, 194, 33-35. [15] Lee, J. S.; Lee, Y. J.; Tae, E. L.; Park, Y. S.; Yoon, K. B. Synthesis of Zeolite As Ordered Multicrystal Arrays. Science. 2003, 301, 818-821. [16] Lai, Z. P.; Tsapatsis, M.; Nicolich, J. P. Siliceous ZSM-5 Membranes by Secondary Growth of b-Orienten Seed Layers. Adv. Funct. Mater. 2004, 14, 716-729 [17] Lai, Z. P.; Bonilla, G.; Diaz, I.; Nery, J. G.; Sujaoti, K.; Amat, M. A.; Kokkoli, E.; Terasaki, O.; Thompson, R. W.; Tsapatsis, M.; Vlachos, D. G. Microstructural Optimization of a Zeolite Membrane for Organic Vapor Separation. Science. 2003, 300, 456-460. [18] Mintova, S.; Gilson, J. P.; Valtchev, V. Advances in nanosized zeolites. Nanoscale. 2013, 5, 6693-6703. [19] Meng, X. J.; Xiao, F. S. Green Routes for Synthesis of Zeolites. Chem. Rev. 2014, 114, 1521-1543.

25



[20] Choi, M.; Na, K.; Kim, J.; Sakamot, Y.; Terasaki, O.; Ryoo, R. Stable single-unit-cell nanosheets of zeolite MFI as active and long-lived catalysts. Nature. 2009, 461, 246-249. [21] Na, K.; Choi, M.; Park, W.; Sakamoto, Y., Terasaki, O.; Ryoo, R. Pillared MFI Zeolite Nanosheets of a Single-Unit-Cell Thickness. J. Am. Chem. Soc. 2010, 132, 4169-4177 [22] Bonilla, G.; Díaz, I.; Tsapatsis, M.; Jeong, H. K.; Lee, Y.; A., Vlachos. D. G. Zeolite (MFI) Crystal Morphology Control Using Organic Structure-Directing Agents. Chem. Mater. 2004, 16, 5697-5705. [23] Zeng, G.; Chen, C. B.; Li, D. B.; Hou, B.; Sun, Y. H. Exposure of (001) planes and (011) planes in MFI Zeolite. CrystEngComm. 2013, 15, 3521-3524. [24] Zhang, L.; Liu, S. L.; Xie, S. J.; Xu, L. Y. Organic template-free synthesis of ZSM-5/ZSM-11 co-crystalline zeolite. Micropor. Mesopor. Mater. 2012, 147, 117-126. [25] Kamimura, Y.; Chaikittisilp, W.; Itabashi, K.; Shimojima, A.; Okubo, T. Critical Factors in the Seed-Assisted Synthesis of Zeolite Beta and “Green Beta” from OSDA-Free Na+-Aluminosilicate Gels. Chem-Asian. J. 2010, 5, 2182-2191. [26] Georgieva, V.; Vicente, A.; Fernandez, C.; Retoux, R.; Palcic, A.; Valtchev, V.; Mintova, S. Control of Na-EMT Zeolite Synthesis by Organic Additives. Cryst. Growth Des. 2015, 15, 1898-1906. [27] Kang, N. Y.; Song, B. S.; Lee, C. W.; Choi, W. C.; Yoon, K. B.; Park, Y. K. The effect of Na2SO4 salt on the synthesis of ZSM-5 by template free crystallization method. Micropor. Mesopor. Mater. 2009, 118, 361-372. [28] Liu, C. Y.; Gu, W. Y.; Kong, D. J.; Guo, H. C. The significant effects of the alkali-metal cations on ZSM-5 zeolite synthesis: From mechanism to morphology. Micropor. Mesopor. Mater. 2014, 183, 30-36. [29] Lesthaeghe, D.; Vansteenkiste, P.; Verstraelen, T.; Ghysels, A.; Kirschhock, C. E. A.; Martens, J. A.; Speybroeck, V. V.; Waroquier, M. MFI Fingerprint: How Pentasil-Induced IR Bands Shift during Zeolite Nanogrowth. J. Phys. Chem. C. 2008, 112, 9186-9191. [30] Yu, Q. J.; Zhang, Q.; liu, J. W.; Li, C. Y.; Cui, Q. K. Inductive effect of various seeds on the organic template-free synthesis of zeolite ZSM-5. CrystEngComm. 2013, 15, 7680-7687.

26


Page 26 of 45

Page 27 of 45 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


[31] Sang, S. Y.; Chang, F. X.; Liu, Z. M.; He, C. Q.; He, Y. L.; Xu, L. Difference of ZSM-5 zeolites synthesized with various templates. Catal. Today. 2003, 93-95, 729-734. [32] Tian, D. Y.; Yan, W. F.; Cao, X. J.; Yu, J. H.; Xu, R. R. Morphology Changes of Transition-Metal-Substituted Aluminophosphate Molecular Sieve AlPO4-5 Crystals. Chem. Mater. 2008, 20, 2160-2164. [33] Cundy, C. S.; Cox, P. A. The hydrothermal synthesis of zeolites: Precursors, intermediates and reaction mechanism. Micropor. Mesopor. Mater. 2005, 82, 1-78. [34] Uguina, M. A.; Lucas, A. D.; Ruiz, F.; Serrano, D. P. Synthesis of ZSM-5 from ethanol-containing systems. Influence of the gel composition. Ind. Eng. Chem. Res. 1995, 34, 451-456. [35] Li, S. W.; Tuel, A.; Laprune, D.; Meunier, F.; Farrusseng, D. Transition-metal nanoparticles in hollow zeolite single crystals as bifunctional and size-selective hydrogenation catalysts. Chem. Mater. 2015, 27, 276-282. [36] Govender, K.; Boyle, D. S.; Kenway, P. B.; O'Brien, P. Understanding the factors that govern the deposition and morphology of thin films of ZnO from aqueous solution. J. Mater. Chem. 2004, 14, 2575-2591. [37] Jun, Y. W.; Choi, J. S.; Cheon, J. Symmetry-Controlled Colloidal Nanocrystals: Nonhydrolytic Chemical Synthesis and Shape Determining Parameters. J. Phys. Chem. B. 2005, 109, 14795-14806. [38] Pantaraks, P.; Flood, A. E. Effect of growth rate history on current crystal growth: A second look at surface effects on crystal growth rates. Cryst. Growth Des. 2005, 5, 365-371. [39] Olson, T. Y.; Orme, C. A.; Han, T. Y.; Worsley, M. A.; Rose, K. A.; Satcher, J. H.; Kuntz, J. D. Shape control synthesis of fluorapatite structures based on supersaturation: prismatic nanowires, ellipsoids, star, and aggregate formation. Crystengcomm. 2012, 14, 6384-6389. [40] Nguyen, T. T. H.; Hammond, R. B.; Roberts, K. J.; Marziano, I.; Nichols, G. Precision measurement of the growth rate and mechanism of ibuprofen {001} and {011} as a function of crystallization environment. CrystEngcomm. 2014, 16, 4568-4586. [41] Flood, A. E. Feedback between crystal growth rates and surface roughness. 27



Crystengcomm. 2010, 12, 313-323. [42] Bordawekar, S.; Kuvadia, Z.; Dandekar, P.; Mukherjee, S.; Doherty, M. Interesting morphological behavior of organic salt choline fenofibrate: Effect of supersaturation and polymeric impurity. Cryst. Growth Des. 2014, 14, 3800-3812. [43] Hammond, R. B.; Pencheva, K.; Roberts, K. J. A Structural−Kinetic Approach to Model Face-Specific Solution/Crystal Surface Energy Associated with the Crystallization of Acetyl Salicylic Acid from Supersaturated Aqueous/Ethanol Solution. Cryst. Growth Des. 2006, 6, 1324-1334. [44] Ren, N.; Yang, Z. J.; Lv, X. C.; Shi, J.; Zhang, Y. H.; Tang, Y. A seed surface crystallization approach for rapid synthesis of submicron ZSM-5 zeolite with controllable crystal size and morphology. Micropor. Mesopor. Mater. 2010, 131, 103-114. [45] Ren, N.; Bronić, J.; Jelić, T. A.; Palčić, A.; Subotić, B. Seed-Induced, Structure Directing Agent-Free Crystallization of Sub-Micrometer Zeolite ZSM-5: A Population Balance Analysis. Cryst. Growth Des. 2012, 12, 1736-1745.

28


Page 28 of 45

Page 29 of 45 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Captions Figure 1. Schematic representation of ZSM-5 zeolites with different morphologies: (a) Twinned boat, (b) Twinned coffin, (c) Pro-twinned coffin, and (d) Octagon. (La, Lb and Lc represented the crystal size of ZSM-5 zeolites in each axis, respectively) Figure 2. XRD patterns of ZSM-5 zeolites synthesized by adjusting n-butylamine amount: (a) Z-0.002-0.09-31; (b) Z-0.03-0.09-31; (c) Z-0.08-0.09-31; (d) Z-0.12-0.09-31; (e) Z-0.15-0.09-31; (f) Z-0.27-0.09-31. Figure 3. SEM images of ZSM-5 zeolites synthesized by adjusting n-butylamine amount: (a) Z-0.002-0.09-31; (b) Z-0.03-0.09-31; (c) Z-0.08-0.09-31; (d) Z-0.12-0.09-31; (e) Z-0.15-0.09-31; (f) Z-0.27-0.09-31. Figure 4. The variation of crystallinity and NBA amount in mother liquid along the crystallization time in system of (a) Z-0.03-0.09-31, (b) Z-0.08-0.09-31, (c) Z-0.27-0.09-31; (d) The influence of NBA amount on T0. (A denotes the lower limit of EA detector; T0 means the time point of “NBA-contained stage” transforming into “NBA-free stage”.) Figure 5. SEM images of Z-0.08-0.09-31sample with different crystallization time: (a) 10 h, (b) 14 h, (c) 16 h, (d) 18 h, (e) 19 h, (f) 20 h, (g) 21 h, (h) 22 h, (i) 38 h. Figure 6. XRD patterns of samples: (a) Z-0.03-0.09-Z, (b) Z-0.03-Y-31, (c) Z-0.08-0.09-Z and (d) Z-0.08-Y-31.(Y=[H2O]/[SiO2]; Z=[Na2O]/[SiO2]) Figure 7. SEM images of Z-0.03-0.09-Z samples: (a) Z-0.03-0.09-26, (b) Z-0.03-0.09-20, (c) Z-0.03-0.09-17.5, (d) Z-0.03-0.09-15. Figure 8. SEM images of Z-0.03-Y-31 samples: (a) Z-0.03-0.12-31, (b) Z-0.03-0.15-31, (c) Z-0.03-0.18-31. Figure 9. The variation of Si concentration along crystallization time in system of (a) Z-0.03-0.09-Z, (b) Z-0.03-Y-31, (c) Z-0.08-0.09-Z and (d) Z-0.08-Y-31. Figure 10. SEM images of Z-0.08-0.09-Z samples: (a) Z-0.08-0.09-36, (b) Z-0.08-0.09-31,

29



(c) Z-0.08-0.09-26, (b) Z-0.08-0.09-20. Figure 11. SEM images of Z-0.08-Y-31samples: (a) Z-0.08-0.10-36, (b) Z-0.08-0.12-36, (c) and (f) Z-0.08-0.125-36, (d) and (e) Z-0.08-0.13-36. Figure 12. Variation of (Lb-fact/Lb-theory) as a function of Y=[Na2O]/[Si] and Z=[H2O]/[Si] in systems of (a) Z-0.03-Y-Z and (b) Z-0.08-Y-Z.

Scheme 1. (a) The equilibrium shaped (blue, solid line) and kinetic shaped (red, dashed line) ZSM-5; (b) The formation of (011) planes in ZSM-5; The formation of (c) hexahedroned and (d) octahedroned ZSM-5.

30


Page 30 of 45

Page 31 of 45 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(a)

(b)

(c)

(011)

(d)

(001) (101)

Figure 1. Schematic representation of ZSM-5 zeolites with different morphologies: (a) Twinned boat, (b) Twinned coffin, (c) Pro-twinned coffin, which was the intermediate morphology between twinned coffin and twinned boat, and (d) Octagon. (La, Lb and Lc represented the crystal size of ZSM-5 zeolites in each axis, respectively)

31



28000

24000

Intensity/a.u.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 32 of 45

20000

a

16000

b 12000

c d

8000

e

4000

f 0 5

10

15

20

25

30

35

40

2-Theta (deg)

Figure 2. XRD patterns of ZSM-5 zeolites synthesized by adjusting n-butylamine amount: (a) Z-0.002-0.09-31; (b) Z-0.03-0.09-31; (c) Z-0.08-0.09-31; (d) Z-0.12-0.09-31; (e) Z-0.15-0.09-31; (f) Z-0.27-0.09-31.

32


Page 33 of 45 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(a)

(b)

(c)

1μm

1μm (e)

(d)

1μm (f)

1μm

1μm

1μm

Figure 3. SEM images of ZSM-5 zeolites synthesized by adjusting n-butylamine amount: (a) Z-0.002-0.09-31; (b) Z-0.03-0.09-31; (c) Z-0.08-0.09-31; (d) Z-0.12-0.09-31; (e) Z-0.15-0.09-31; (f) Z-0.27-0.09-31.

33



100

0.1

(a) Z-0.03-0.09-31

K=23.6

50

0 100

0.0

(b) Z-0.08-0.09-31

K=28.7

0.2 0.1

50

A 100 0

-1 NBA concentration (molL )

Crystallinity (%)

A

(c) Z-0.27-0.09-31

0.0

K=29.4

0.4 50 0.2 0 10

12

14

35

16

18

20

Crystallization time (h)

40

T0(h)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 34 of 45

22

24

0.0

Twinned Boat

(d)

0

30

Pro-twinned Coffin

25 20

Twinned Coffin

15 10 0.0

10

0.1

0.2

0.3

[NBA]/[Si]

0.4

0.5

Figure 4. The variation of crystallinity and NBA amount in mother liquid along the crystallization time in system of (a) Z-0.03-0.09-31, (b) Z-0.08-0.09-31, (c) Z-0.27-0.09-31; (d) The influence of NBA amount on T0. (A denotes the lower limit of EA detector; T0 means the time point of “NBA-contained stage” transforming into “NBA-free stage”.)

34


Page 35 of 45 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(a)

(b)

(c)

100nm (d)

1μm

1μm (e)

(f) (001) plane

1μm (g)

(001) plane

(101) plane

(001) plane

1μm

(h)

1μm (i)

(101) plane

1μm

1μm

1μm

Figure 5. SEM images of Z-0.08-0.09-31sample with different crystallization time: (a) 10 h, (b) 14 h, (c) 16 h, (d) 18 h, (e) 19 h, (f) 20 h, (g) 21 h, (h) 22 h, (i) 38 h.

35



40000

(a) Z-0.09-0.03-15

Intensity / a.u.

Intensity / a.u.

40000

30000 Z-0.09-0.03-17.5 20000

Z-0.09-0.03-20 Z-0.09-0.03-26

10000

(b)

30000

Z-0.03-0.18-31 20000

Z-0.03-0.15-31 Z-0.03-0.12-31

10000

Z-0.03-0.09-31

Z-0.09-0.03-31 0 5

10

15

20

25

2-Theta (deg)

30

35

0 5

40

(c)

40000

Intensity / a.u.

Z-0.09-0.08-20

20000

Z-0.09-0.08-26 10000

10

15

20

25

Z-0.09-0.08-31

10

15

20

25

35

40

(d) Z-0.08-0.13-36

30000

Z-0.08-0.125-36 20000

Z-0.08-0.12-36 Z-0.08-0.10-36

10000

Z-0.08-0.09-36

Z-0.09-0.08-36 0 5

30

2-Theta (deg)

30000

Intensity / a.u.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 36 of 45

30

35

40

2-Theta (deg)

0

5

10

15

20

25

30

35

40

2-Theta (deg)

Figure 6. XRD patterns of samples: (a) Z-0.03-0.09-Z, (b) Z-0.03-Y-31, (c) Z-0.08-0.09-Z and (d) Z-0.08-Y-31. (Y = [H2O]/[SiO2]; Z=[Na2O]/[SiO2])

36


Page 37 of 45 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(a)

(b)

1μm

1μm

(c)

(d)

(011) plane

1μm

1μm

Figure 7. SEM images of Z-0.03-0.09-Z samples: (a) Z-0.03-0.09-26, (b) Z-0.03-0.09-20, (c) Z-0.03-0.09-17.5, (d) Z-0.03-0.09-15.\

37



(b)

(a)

Page 38 of 45

(c)

1μm

1μm

1μm

Figure 8. SEM images of Z-0.03-Y-31 samples: (a) Z-0.03-0.12-31, (b) Z-0.03-0.15-31, (c) Z-0.03-0.18-31.

38


0.7

(a)

Si concentration (mol/L)

Z-0.03-0.09-31 Z-0.03-0.09-26 Z-0.03-0.09-20 Z-0.03-0.09-17.5 Z-0.03-0.09-15

(S2S1)

S2

0.6

S1 0.5

C0 = 0.47 mol/L

0.4

0.3

0.2

0.1

16

18

20

22

24

26

28

0.6

S2

0.5

S1

C0 = 0.38 mol/L 0.3

0.2

16

18

(c) S3

0.4

0.5

Z-0.08-0.09-36 Z-0.08-0.09-31 Z-0.08-0.09-26 Z-0.08-0.09-20

(S3S2)

S2 0.3

C0 = 0.29 mol/L 0.2

0.1

16

18

20

22

24

26

20

22

24

26

28

30



0.5

Z-0.03-0.09-31 Z-0.03-0.12-31 Z-0.03-0.15-31 Z-0.03-0.18-31

(S2S1)

0.4

0.1

30

(b)



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60



Page 39 of 45

28

30

(d)

Z-0.08-0.09-36 Z-0.08-0.10-36 Z-0.08-0.12-36 Z-0.08-0.125-36 Z-0.08-0.13-36

(S3S2S1)

S3

0.4

S2 S1

0.3

C0 = 0.26 mol/L 0.2

0.1

16

18


20

22

24

26

28

30


Figure 9. The variation of Si concentration along crystallization time in system of (a) Z-0.03-0.09-Z, (b) Z-0.03-Y-31, (c) Z-0.08-0.09-Z and (d) Z-0.08-Y-31.

39



(a)

Page 40 of 45

(b)

1μm (c)

1μm (d)

(011) plane

(001) plane

(011) plane

1μm

(101) plane

1μm

Figure 10. SEM images of Z-0.08-0.09-Z samples: (a) Z-0.08-0.09-36, (b) Z-0.08-0.09-31, (c) Z-0.08-0.09-26, (b) Z-0.08-0.09-20.

40


Page 41 of 45 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(a)

(b)

(c)

1μm

(d)

1μm

(e)

1μm

(001) plane (f) (101) plane

(011) plane

1μm

1μm

Figure 11. SEM images of Z-0.08-Y-31samples: (a) Z-0.08-0.10-36, (b) Z-0.08-0.12-36, (c) and (f) Z-0.08-0.125-36, (d) and (e) Z-0.08-0.13-36.

41



Y = [Na2O] / [SiO2]

0.05 1.5

0.10

0.15

0.20

(a) Z-0.03-Y-Z

Y = [Na2O] / [SiO2]

0.08 1.5

0.10

Lb-fact / Lb-theory (Y)

1.0

35

30

0.14

Lb-fact / Lb-theory (Y)

1.0

Lb-fact / Lb-theory (Z)

0.5

0.12

(b) Z-0.08-Y-Z

Lb-fact / Lb-theory

Lb-fact / Lb-theory

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 42 of 45

25

Lb-fact / Lb-theory (Z)

20

Z = [H2O] / [SiO2]

15

10

0.5

36

32

28

24

20

Z = [H2O] / [SiO2]

Figure 12. Variation of (Lb-fact/Lb-theory) as a function of Y = [Na2O]/[Si] and Z = [H2O]/[Si] in systems of (a) Z-0.03-Y-Z and (b) Z-0.08-Y-Z.

42


Page 43 of 45 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Scheme 1. (a) The equilibrium shaped (blue, solid line) and kinetic shaped (red, dashed line) ZSM-5; (b) The formation of (011) planes in ZSM-5; The formation of (c) hexahedroned and (d) octahedroned ZSM-5.

43



For Table of Contents Use Only

Area-controllable synthesis of (001), (101) and (011) planes in ZSM-5 zeolites

Kai Wang,a,b,c Mei Dong,*,b Xianjun Niu,b,c Junfen Li,b Zhangfeng Qin,b Weibin Fan,b Jianguo Wang*,b a

College of Chemical and Environmental Engineering, Anyang Institute of Technology, Anyang 455000,

PR China b State

Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, P.

O. Box 165, Taiyuan, Shanxi 030001, PR China. c University

of Chinese Academy of Sciences, Beijing 100049, PR China.

Area-controllable synthesis of (001), (101) and (011) planes in ZSM-5 zeolites was achieved though elaborately controlling the synthesis factors such as the alkalinity and the amounts of n-butylamine template and water.

44


Page 44 of 45

Page 45 of 45 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Though a comprehensive survey into the effect of synthesis factors, such as the amount of template nbutylamine, alkalinity and H2O amount, on the crystallization process and the morphology of products, the objective of area-controllable synthesis of (001), (101) and (011) planes in ZSM-5 zeolites was achieved. 35x56mm (150 x 150 DPI)


Area-controllable synthesis of (001), (101) and (011) planes in ZSM-5

Recommend Documents