Preparation of silica, alumina, titania and zirconia with different pore

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Kinetics, Catalysis, and Reaction Engineering

Preparation of silica, alumina, titania and zirconia with different pore sizes using sol-gel method and their properties as matrices in catalytic cracking Atsushi Ishihara, Kosuke Tatebe, Tadanori Hashimoto, and Hiroyuki Nasu Ind. Eng. Chem. Res., Just Accepted Manuscript • DOI: 10.1021/acs.iecr.8b03019 • Publication Date (Web): 15 Oct 2018 Downloaded from http://pubs.acs.org on October 16, 2018

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Industrial & Engineering Chemistry Research

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Preparation of silica, alumina, titania and zirconia with different pore sizes using sol-gel method and their properties as matrices in catalytic cracking

Atsushi Ishihara*, Kosuke Tatebe, Tadanori Hashimoto, Hiroyuki Nasu, Division of Chemistry for Materials, Graduate School of Engineering, Mie University, 1577 Kurima Machiya-Cho, Tsu-City, Mie Prefecture 514-8507, Japan, Corresponding author: Atsushi Ishihara E-mail: [email protected], TEL: 81-59-231-9434

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Abstract Different mesoporous sizes of oxides, silica, alumina, titania and zirconia were made by changing calcination temperature, and mixed catalysts, the mixtures of the oxides and microporous zeolite, were prepared. Conversions of n-dodecane using the β zeolite-mixed catalysts were much higher than those of the Y zeolite-mixed catalysts. Using the mixed catalysts, over-cracking was inhibited and the selectivity for gasoline increased, compared with those of zeolite singles and the catalysts mixed with kaolin. Curie point pyrolyzer (CPP) was also used as a facile estimation method of catalysts on catalytic cracking of VGO. In catalytic cracking of both n-dodecane and VGO, the product distribution hardly changed by patterns of matrices, but changed by types of zeolite. In contrast, the conversion changed, depending on matrix oxides, indicating that matrices could control the dispersion of zeolite and the diffusion of reactants by their pore structures to increase the catalytic activity. Keywords: Matrix oxide, Zeolite, Catalytic cracking, n-Dodecane, VGO, Curie point pyrolyzer


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1. Introduction In recent years, the demands for gasoline and diesel oil are increasing in the world year after year while that for fuel oil is decreasing, which leads to the increasing importance of catalytic cracking of vacuum gas oil (VGO) and atmospheric residue (AR). Although catalysts for catalytic cracking include zeolite, normally matrices such as alumina, silica and silica-alumina were used simultaneously. Zeolite has usually the higher activity and the higher selectivity for products than matrices. In order to generate these functions of zeolite effectively, zeolite particles are to be highly dispersed on the mesoporous matrices which diffuse the large molecules into the inside of a catalyst effectively. In the continued development of catalysts for catalytic cracking, the importance in the control of particle size and pore size of catalysts has been known for long years.1-4 Although the precise methods of controlling the pore structure of catalysts were not described in early literature, the control of particle size of zeolite and the introduction of mesopores in the inside of zeolite has come to be frequently reported in recent years.5-35 In order to control the particle size, the condition of hydrothermal synthesis was arranged or additives were added.25 On the other hand, organic compounds and carbonaceous materials were added as a template in order to introduce the mesopores into the structure of zeolite,9,13,26,32-35 and silicon sources other than raw material silicon of zeolite were used for making the combination between zeolite particles.12,29 Further, steam, alkali and acid treatments were adapted to introduce mesoporous structures into micropores of zeolites.7,8,10,11,27,30,31 In these studies, it has widely



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been recognized that when the catalyst system includes mesopores, the reactivity of the catalyst is improved in the activity. Further, it has been pointed out that the overall performance of a catalyst particle strongly depends on the ability of mass transport through its pore space.14 However, most of studies are treating with the preparation and the reactivity of zeolites themselves and researches for production and reactivity of matrices were very few. Further, if there would be researches using the matrix, many works are dealing with the mixture of zeolite and kaolin without pores, stable SiC or inactive SiO2.36,37 Most of them do not discuss the role of matrix in catalytic cracking, except only a few examples.38-46 In this situation, we are working on the production, characterization and effects of matrices on catalytic cracking and zeolite reactivity for many years.47-59 In the course of our study, we have found that matrices intrinsically have effects on the dispersion of zeolite particles, and that the existence of mesopores of matrices controls the activity of cracking while the existence of zeolite contributes to the selectivity of products as well as the activity. Further, not only small mesopores but also larger size of mesopores exceeding 10nm increased the activity largely. In the meantime, Curie point pyrolyzer (CPP) method was developed as a very useful facile method to estimate catalytic cracking of large molecules of vacuum gas oil (VGO),52,53,58 atmospheric residue (AR),58 fats like soybean oil (SB)49,51,57,59 etc. When the catalytic cracking of VGO, AR and SB catalyzed by catalysts mixed with different types of zeolites and silica-alumina matrix was compared at the same conversion, it was found that the product selectivity clearly changed depending on the types of zeolites. Further, it


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was also found that the activity largely changed depending on the presence of matrices. These results suggested that micropore sizes of zeolite would strongly control the product selectivity and that the dispersion of zeolite on the surface of matrix with large pores would be very important to obtain the higher activity. This also shows the precise design of pore structures of matrix materials is extremely important to obtain the higher activity. Silicas and silica-aluminas were mainly used in these studies where the acid property and the pore structure of matrices largely affected the reactivity of catalytic cracking. However, other oxides like alumina, titania, zirconia etc. were not investigated as matrices. Further, it has not been clarified which of acid properties and pore structures of matrices is more important for the reactivity of catalytic cracking. In this study, some oxide materials, differing in pore structure and acid property, were prepared to investigate the role of matrices for catalytic cracking and to know which of pore structures and acid properties is more important. Silicas, which have mesopores but do not have acid site, aluminas, which have both acid sites and mesopores, titanias and zirconias, which have small amounts of mesopores, and kaolin, which has neither mesopores nor acid sites, were used for the catalytic cracking of n-dodecane in a fixed-bed reactor and VGO using the CPP method.49,51,57-59 Oxides other than kaolin were prepared using the sol-gel method with and without an organic template and changing the calcination temperature to control the pore size of matrices oxides precisely.



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2. Experimental 2.1 Preparation of silica, alumina, titania and zirconia using the sol-gel method 1) Silica matrix Silicas were prepared according to the flowchart of Figure S1 (Figures S1 to S23 appear as the supporting information) using tetraethylorthosilicate (Si(OC2H5)4, TEOS, Wako), ion-exchanged water (H2O), ethanol (C2H5OH, Nakalai) and malic acid as an organic template60 (C4H6O5, Nakalai). A typical method47,48 was as follows: Ethanol and TEOS were mixed and stirred for 30 min in a 200mL beaker. After an aqueous solution of malic acid was added dropwise to the TEOS solution over 15 min at 25oC with stirring, the mixture was stirred for another 30 min at this temperature and was heated to 60oC to make a gelation, which means the state where a stirrer tip stops rotation. After the gelation, aging of the gel formed was continued for 24h at 60oC. The resulted matter was heated at a rate 2.4oC/min under 0.6 ml/min of dried air stream and was calcined at 600oC or 900oC for 3h. Sample names, amounts and molar ratios of reagents used were summarized in Table S1 (Tables S1 to S13 appear as the supporting information). For an example S-600, S means silica, a name of matter and 600 means temperature of calcination. 2) Alumina, titania and zirconia matrices Alumina, titania and zirconia matirices were prepared similarly and detail descriptions were given in Figures S2-S4 and their notes and Tables S2-S4.


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2.2 Preparation of mixed catalysts using zeolites and matrices A mixed catalyst was prepared using a zeolite, a matrix and a binder by the conventional kneading method.47,48,50,55,56 Zeolites used were β-zeolite (Tosoh HSZ-940HOA, SiO2/Al2O3: 37) and Y-zeolite (Catalysis Society of Japan, reference catalyst, JRC-Z-Y5.5, SiO2/Al2O3: 5.5). Kaolin (Wako) and silicas, aluminas, titanias and zirconias prepared in the present study were used as matrices. Alumina-sol, which includes 70% of Al2O3 and 30% of moisture with trace amount of acetic acid, (Cataloid AP-1, Nikki Shokubai Kasei) was used as a binder. As only zeolite and matrix cannot combine, this material was added in order to combine zeolite and matrix closely. A typical preparation method of a mixed catalyst was as follows: Zeolite, matrix and binder were mixed in a mortar and ion-exchanged water (7g) was added dropwise until the mixture became a clay-like matter which was molded into a cylinder-like pellet with 0.5 mm diameter by a sodium press machine (Miki Seiki). Titania-based mixed catalysts were heated at a rate 2.4oC/min and were calcined at 500 or 550oC for 3h depending on the calcination temperature of an original titania. Other catalysts were calcined at 600 ℃ for 3h. Tables S5 and S6 tabulates sample names, weight ratios of reagents and their weights of reagents. Basically the weight ratio of zeolite, matrix and binder is 27: 61: 12. For an example of a sample name, MAT(S-600)-β, MAT means an abbreviation of a term “matrix”, S-600 a sample name of matrix and β a type of zeolite. 2.3 Characterization of catalysts



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X-ray diffraction (XRD) patterns, N2 adsorption-desorption, NH3 adsorption-desorption were measured for zeolite singles and mixed catalysts.47-59 XRD patterns were measured in order to examine the crystal structures in the catalysts using X-ray diffraction measurement system (Ultima IV, Rigaku) (Details of measurement condition were given in the footnote of Figure S6a). Specific surface area, pore volume and pore size distribution were estimated by N2 adsorption and desorption technique.

Prior to the experiment, 0.040g of a sample was heated at 350oC in vacuum for

3 h in Belprep II (BEL Japan, Inc.).

Then, adsorption and desorption isotherms were obtained at 77K

using Belsorp Mini II (BEL Japan, Inc.). Ammonia

pulse

method

of

NH3

adsorption

and

desorption

was

applied

using

a

gas-chromatography with a thermal conductivity detector (GC-TCD) to know acidic properties of catalysts. 40mg of the samples was packed into a 6mm stainless tube reactor with silica wool, was heated to 600oC by 10oC/min under He 10cc/min flow and was kept for 3h.

After the reactor was

cooled to 100oC, 1.0 mL/pulse of NH3 was introduced into the catalyst several times until no more adsorption occurred. In order to obtain the amount of NH3 adsorbed, the reciprocal number of the peak area in GC-TCD per 1mL of NH3 (25oC, 1atm) was multiplied by the sum of peak areas corresponding to the amount of NH3 adsorbed. NH3 desorption was observed for the catalyst adsorbed by NH3 when temperature was raised to 650oC by 10oC/min after adsorption measurement.

Similarly the amount of

NH3 desorbed was calculated using the total peak area of NH3 desorbed. Ammonia gas was detected in


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the outlet of the reactor by GC-TCD (GC-8A, Shimadzu Co. Ltd.). GC measurement conditions are as follows: INJ/DET 170oC, COL 140oC, ATTN 16, Current 100 mA, column flow rate 50mL/min, carrier gas He. 2.4 Catalytic cracking reactions. Reaction apparatus of catalytic cracking of n-dodecane is shown in Figure 1.47,48,50,54-56 1.0 g of the catalyst bed supported by quartz sand at bottom and top was loaded in the center of a fixed bed down flow reactor (300 mm length and 8 mm internal diameter) and was heated to 500oC at heating rate 5oC/min under nitrogen stream 30mL/min. After stopping the nitrogen flow, the catalytic cracking of n-dodecane was performed at the following reaction conditions: Reaction temperature was 500oC, a flow rate of feed 1.33mL/min and reaction time 80sec. After this reaction, the liquid products formed were collected for 15 min in a cold ethanol trap at -50oC and for further 15min in water trap at 15oC under 30mL/min of N2 stream and the gas products formed were collected in a tedlar bag just after the liquid trap. The gas and liquid products were analyzed by GCs with a flame ionization detector (FID) and TCD. Measurement conditions were as follows:

Injection temp. 250oC, detector temp. 320oC,

ATTN 1, injection press 100.6kPa, column flow 0.86 mL/min, line speed 16.8cm/sec, total flow 170.8 mL/min, split ratio 200, column BP-1 (column length 60m, column diameter 0.25mm, film thickness 0.5micrometer), column initial temp 0oC 16min, heating rate 2oC/min, final temp 228oC, liquid sample 0.2 μL, gas sample 0.3 mL. Referring to JIS K 2536-2 and the analyses of the standard gasoline



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supplied from the Japan Petroleum Institute and the standard hydrocarbon gases supplied from GL science Co. Ltd. enabled the determination of all products. The most of products were smaller than n-dodecane. The amount of coke on a used catalyst was measured from its weight loss after calcination at 500oC for 12h. Total recovery of products including coke for most of catalysts was more than 95%.

n-C12H26 500oC 1.0 g 1.33 mL/min 80 sec N2 (30mL/min)

Figure1 Reaction apparatus for catalytic cracking of n-dodecane

Catalytic cracking of VGO:

The component of hydrotreated VGO was C 84.91%; H 12.13%,

sulfur content 100 ppm, Original VGO: V, Ni 0 ppm; S 2.85 %; C 85.48 %; H 11.6%; Asphaltene 0.18%; IBP 281 - FBP 570 oC; d. 0.96 g/ml at 15oC). The apparatus of CPP method (Japan Analytical Industry Co., Ltd.: JCI-22) is shown in Figure S5.49,51-53,57-59 At first, 0.20 mg of VGO and 1.50 mg of a catalyst were set in ferromagnetic foil (pyrofoil F500) and then the pyrolyzer was preheated at 150oC and an injection syringe of CPP was introduced into the injection port of GC. The experimental conditions are as follow: Reaction time was 5 sec, reaction temperature 500oC. He gas (0.45MPa) was


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used as an injection gas. All of the products in the gasoline fraction were analyzed by GC-FID (GC-2010, Shimadzu Co. Ltd.) by referring to JISK 2536-2.

The measurement conditions are same as

those for n-dodecane cracking. As the injection temperature was set at 250oC, products with higher boiling points than those of gasoline and light diesel fractions remained in the body of the CPP. The conversion of VGO was estimated by comparing total area of products with that of a standard gas including C1-C4 (GL Science Co. Ltd.) according to the following equation (1):

(1),

where PA means total peak area of products in VGO cracking measured by GC, CGAS the amount of carbon in the standard gas, CVGO the amount of carbon in VGO used (estimated by the elemental analysis), GA total peak area of the standard gas measured by GC. The cracking tests were repeated for one catalyst until the conversions came within a few %.52,53,58,59 This estimation is based on the fact that the area of FID is in proportion to the amount of carbon in a product.

3. Results and Discussion 3-1. Characterization of catalysts Figure 2 shows XRD patterns of matrices prepared. Silica matrices showed each broad peak in the



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range 15o-30o, indicating that silicas are in the amorphous phase. Alumina matrices showed small broad peaks of γ-alumina at 47o and 67o, indicating that very small crystals would be made by the sol-gel method. Both titania matrices of T-500 and T-550 showed a major peak at 25o, indicating that the anatase phase exists. Zirconia matrices of Z-600 and Z-900 showed a monoclinic phase with a major signal at 30o and a tetragonal phase with major signals at 28o and 31o respectively.

These XRD

patterns of silica, alumina, titania and zirconia prepared by corresponding alkoxides are approximately consistent with those of oxides in other catalysts by the sol-gel method.61-63 Figures 3 and 4 show XRD patterns of mixed catalysts with β-zeolite and Y-zeolite, respectively. It was confirmed that all the mixed catalysts left both zeolite peaks and their own peaks of matrices.47-50,55,56 XRD patterns of zeolite singles and mixed catalysts with kaolin and zeolite are also shown in Figures S6a and S6b and each mixed catalyst showed the existence of both crystals of kaolin and zeolite.52,53


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Figure 2 XRD patterns of silicas, aluminas, titanias and zirconias

β-zeolite Intensity (a.u.)

MAT(S-600)-β MAT(S-900)-β MAT(A-600)-β MAT(A-900)-β MAT(T-500)-β MAT(T-550)-β MAT(Z-600)-β MAT(Z-900)-β

10

20

30

40 2θ (°)

50

60

70

Figure 3 XRD patterns of mixed catalysts with β-zeolite

Y-zeolite

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


MAT(S-600)-Y MAT(A-900)-Y MAT(T-500)-Y MAT(Z-600)-Y

10

20

30

40

50

60

70

2θ (°)

Figure 4 XRD patterns of mixed catalysts with Y-zeolite

N2 adsorption and desorption measurements were performed to know the pore structures of catalysts. Adsorption and desorption isotherms and BJH pore size distributions are shown in Figures S7-S11 and Figures S12-S17, respectively. Isotherms of silicas showed hysteresis of type IV (Figure S7) and it was



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confirmed that smaller mesopores than 5nm existed as shown in Figure S12.50,54,55 Isotherms of alumina showed hysteresis of type III (Figure S7) and it was confirmed that very broad large mesopores distributed in the range 10-50 nm as shown in Figure S12.62,63 Isotherms of titanias and zirconias also showed each hysteresis of type IV (Figure S8).61 Figures S9, S10 and S11 show N2 adsorption and desorption isotherms for zeolite singles and their mixed catalysts. It was confirmed that the isotherms of mixed catalysts with silica, alumina, titania and zirconia were very similar to those of their original oxides. The mixed catalysts with kaolin showed type I isotherms because kaolin does not have significant pores and the existence of micropores of zeolites are reflected.52,53 Figures S12 and S13 show BJH pore size distributions of matrices themselves which estimate mesopores larger than 3.3nm in pore diameter. Two silicas formed mesopores with 4 to 5 nm of diameter while very broad mesopores of a few nm to 50 nm were observed for two aluminas (Figure S12). As crystals of aluminas are very fine, intercrystalline openings may form the wide range of mesopores. Further, T-500, T-550 and Z-600 showed peaks of BJH mesopore size distributions in the range 10-13nm while Z-900 showed a broad peak with a maximum pore distribution at 29nm (Figure S13). BJH pore size distributions of titanias and zirconias were much smaller than those of silicas and aluminas, indicating that pore volumes of titanias and zirconias were much smaller than those of silicas and aluminas.61 Figures S14-S17 show BJH pore size distributions of zeolite singles and their mixed catalysts.


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Except for zeolite singles and mixed catalysts with kaolin and Z-900, mixed catalysts with silicas, aluminas, titanias and zirconia Z-600 had significant amounts of mesopores.

Further, it was observed

that all BJH pore size distributions of mixed catalysts with aluminas tended to sharpen with the peaks in the range 10-14nm. This show that intercrystalline openings formed the wide range of mesopores in original aluminas and that the addition of alumina-sol binder would destroy the weak structure of original aluminas and promote the reconstruction of new mesopores in the mixed catalysts of aluminas. Tables S7-S9 tabulates pore properties from N2 adsorption and desorption measurements. Values for the BET method and the BJH method were almost same for alumina, titania or zirconia, indicating that most of pores of these oxides consisted of mesopores.61-63 Values of BET surface areas of silicas were larger than those of BJH surface areas, indicating that micropores still remained in silicas regardless of calcination temperature although significant amounts of mesopores existed.50,54,55 Alumina had the largest pore diameter and pore volume compared with silica, titania and zirconia although malic acid, an organic template, was not used at the preparation of alumina.

Surface areas and pore volumes

decreased with increasing calcination temperature for all the oxides and specifically the extents of decreases for silica and zirconia were significant. Similar tendency was observed for the mixed catalysts as shown in Tables S8 and S9 although the differences between oxides became small because of the use of same zeolite and binder. Further, the significant decreases in pore volumes and pore diameters were observed for alumina-based catalysts probably because inter-crystalline structure with



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fine crystals of alumina was reconstructed with fine particles of zeolites and alumina-sol binder. Although kaolin does not have significant amounts of pores, the mixed catalysts had micropores and mesopores because of the introduction of zeolite and binder.52,53 Tables S10 and S11 show amounts of NH3 desorbed and adsorbed per unit weight of a catalyst. Zeolite singles β and Y exhibited the highest amounts of NH3 adsorbed and desorbed among catalysts measured. When the amounts of NH3 adsorbed were compared with the amounts of Al atoms in zeolites estimated from the SiO2/Al2O3 (mol/mol) ratios, the ratios of NH3 adsorbed to Al included were 1:1 and 3:10 for β- and Y- zeolite singles, respectively, indicating that most of Al in β-zeolite is dispersed in zeolite crystals while Al in Y-zeolite may cohere as aluminum oxide.49,54 Although the mixed catalysts included one fourth amount of zeolite, the amounts of NH3 adsorbed and desorbed were higher than one fourth of their zeolite singles’ values probably because matrices also adsorbed significant amounts of NH3. Conversions of n-dodecane and VGO, which are described below in detail, are also tabulated in Tables S10 and S11. The values of both conversions were approximately related to the amounts of NH3 adsorbed and desorbed, indicating that the amount of acid sites controls the activity as believed generally.47-59 However, the results cannot be explained only by the amounts of acid sites and it seems that the pore structure would also affect the activity in catalytic cracking as described below in detail. 3.2 Catalytic cracking of n-dodecane using β- and Y-zeolite singles and their mixed catalysts


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Table S10 shows the product distribution and some catalytic properties of gasoline fraction for catalytic cracking of n-dodecane using β-zeolite single and β-zeolite-based mixed catalysts. Further, Figures 5 and S18 also show the detail distributions of paraffins, olefins, naphthenes and aromatics (PONA) and carbon numbers in products, respectively. When single β-zeolite was used, C1 to C4 gaseous fraction was higher and C5 to C11 gasoline fraction was lower than those of mixed catalysts, indicating that over-cracking would occur because of high abilities of acid sites for cracking and micropores for adsorption (Table S10 and Figure S18).

The mixed catalysts with silicas, aluminas

and titanias showed the same level of conversions as single zeolite and produced larger amounts of gasoline fraction although these mixed catalysts had only 25% of zeolite, indicating that the dispersion of zeolite in these catalysts inhibited over-cracking and successive coking, and increased the activity and the selectivity for gasoline fraction. The conversions for the mixed catalyst with kaolin and zirconias decreased probably because of the low values of surface areas and pore volumes, specifically mesoporous surface areas and pore volumes estimated by the BJH method. These observations were consistent with those in our previous reports.47-59 Although similar observation that the hierarchical structures of catalysts increase the activity in catalytic cracking has been reported by other researchers,5-46 they hardly discussed the effect of the structure of catalysts on the selectivity of products. As shown in Table S10 and Figure 5, the olefin to paraffin ratio (O/P) increased in the mixed catalysts, indicating that the ability of hydrogen transfer decreased because of the low amount of zeolite,



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that is, the low density of acid sites. The ratio of branched products to straight-chained products in the gasoline fraction (iso- /n-) was 2.17 for single β-zeolite, which was maintained for the mixed catalysts with alumina, titania and zirconia matrices, although those ratios of catalysts with kaolin and silicas decreased (Table S10). This means that, when silica and kaolin without acid sites were used, the ability of isomerization decreased. Further, when alumina, titania and zirconia were used, other types of acid sites different from those of zeolite may occur on the outer surface of zeolite where these matrices contact, which leads to maintaining the iso-/n- ratio. Similarly the ratio of multi-branched products to single-branched products (m/s) increased for the mixed catalysts compared with that of single zeolite probably because the diffusion of more bulky branched products in the inside of mixed catalysts was promoted in the presence of mesopores. Among the mixed catalysts the mixed catalyst with kaolin showed the lowest value of m/s, which may be related to that the values of mesoporous surface area, pore volume and pore diameter for the mixed catalyst with kaolin were almost the lowest and that the use of kaolin did not improve the diffusion of reactants or products. Although the amount of zeolite decreased in the mixed catalysts, values of RON were approximately maintained probably because the positive effects of the increase in the O/P and m/s ratios on RON value were balanced with the negative effects of the slight decreases in the iso-/n- ratio and the selectivity for aromatics in mixed catalysts. These observations for the product selectivity were approximately consistent with those in our previous reports47-59, indicating that the catalytic cracking reaction would have proceeded properly.


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Table S11 shows the product distribution and some catalytic properties of gasoline fraction for catalytic cracking of n-dodecane using Y-zeolite single and Y-zeolite-based mixed catalysts. Further, Figures 6 and S19 also show the detail distributions of PONA and carbon numbers in products,

Figure 5 Distribution of paraffins, olefins, naphthenes and aromatics for catalytic cracking of n-dodecane using β-zeolite single and β-zeolite-based mixed catalysts.

respectively. The tendencies of the reaction profiles of Y-zeolite-based catalysts were very similar to those of β-zeolite-based catalysts. However, conversions for Y-zeolite-based catalysts were much lower than those for β-zeolite-based catalysts while the selectivity for gasoline fraction of the former catalysts was clearly higher than the selectivity of the latter catalysts. We have already reported similar results where it was expected that the larger micropores of Y-zeolite would control the product selectivity and that the presence of matrix as well as the type of zeolite would control the activity.49,54,57



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In the present study, approximately similar tendency that the use of a matrix with the larger pore size and pore volume brings about the higher conversion was observed for both β-zeolite and Y-zeolite catalyst systems although the difference in the activity by the kind of matrix was much lower for Y-zeolite systems than for β-zeolite systems probably because of the low values of conversions for Y-zeolite systems.

Figure 6 Distribution of paraffins, olefins, naphthenes and

aromatics for catalytic cracking of

n-dodecane using Y-zeolite single and Y-zeolite-based mixed catalysts.

Some parameters in gasoline fraction with the use of Y-zeolite systems are also shown in Table S11 and were compared with those for β-zeolite systems. The O/P ratios for Y-zeolite systems were much lower than those of β-zeolite systems, indicating that the ability of hydrogen transfer for


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Y-zeolite itself was much higher than that for β-zeolite.54 The iso- /n- ratios for Y-zeolite systems were much higher than those for β-zeolite systems regardless of the kind of matrix, indicating that the larger microporous size of Y-zeolite than that of β-zeolite influenced the higher iso-/n- ratio.54 Similar to the cases of β-zeolite systems, the iso-/n- and m/s ratios of the catalyst with kaolin were lower than those of the catalysts with other matrices, indicating that the ability of isomerization for the catalyst with kaolin may be lower at the same conversion level. In this case of Y-zeolite systems, when silica, alumina, titania and zirconia were used, other types of acid sites different from those of zeolite might also occur on the outer surface of zeolite where these matrices contact, leading to the similar higher values of iso-/n- and m/s ratios for the catalysts using these matrices than those using kaolin. Similarly the m/s ratio increased for the mixed catalysts compared with that of single Y-zeolite probably because the diffusion of more bulky branched products in the inside of mixed catalysts was promoted in the presence of mesopores. This result is completely consistent with the case of β-zeolite systems. Although the amount of zeolite decreased in the mixed catalysts, values of RON increased for the mixed catalysts probably because the positive effects of the increase in the O/P and m/s ratios on RON value exceeded the negative effects of the slight decreases in the iso-/n- ratio and the selectivity for aromatics. 3.3 Catalytic cracking of VGO using β- and Y-zeolite singles and their mixed catalysts Results from catalytic cracking of VGO using β- and Y-zeolite single and their mixed catalysts are



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tabulated in Table S12 and S13, respectively. β- and Y-zeolite single showed 29% and 24% of VGO conversion while most of mixed catalysts showed higher conversions against the amount of zeolite as they had only one fourth zeolite, indicating that the decrease in the acid density of mixed catalysts inhibited both over-cracking and coke formation and kept the activity high. Further, among the mixed catalysts using β-zeolite MAT(A-600)-β showed the highest conversion of 46% while MAT(Kaolin)-β and MAT(Z-900)-β showed lower conversions than β-zeolite single. Among the mixed catalysts using Y-zeolite, MAT(S-600)-Y showed the highest conversion of 24% while other mixed catalysts showed lower conversions than Y-zeolite single. These results suggested that the activity would closely be related to the pore structure like surface area and pore volume of catalysts, of which the larger sizes promoted the diffusion to increase the activity. Figures 7 and S20 show PONA distribution and carbon number distribution in products for catalytic cracking of VGO using β-zeolite single and β-zeolite-based mixed catalysts. Figures 8 and S21 also show results from the catalytic cracking of VGO using Y-zeolite systems. Similar to the case in n-dodecane cracking, β- and Y-zeolite singles showed the higher selectivities for paraffins than the mixed catalysts because of its higher ability of hydrogen transfer. Further, zeolite singles accelerated over-cracking and produced the higher amounts of gaseous products while mixed catalysts inhibited the hydrogen transfer and increased the selectivity for gasoline fraction. On the other hand, PONA and carbon number distributions of mixed catalysts were almost same for the same type of zeolite, indicating that the selectivity of products would depend


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on the type of zeolite. Different from cracking of n-dodecane, VGO cracking produced the larger amounts of aromatics and the higher selectivity for gasoline fractions probably because of higher molecular weight distribution of VGO and the existence of aromatics in the raw material. Further, the values of iso-/n- and m/s ratios and RON in the gasoline fraction for VGO cracking were much higher than those of n-dodecane cracking. This also indicated that the larger amounts of branched-products and aromatics were produced because of the higher molecular weight distribution of VGO. That is, the larger molecules are easier to be adsorbed on catalyst surface, which would lead to the higher probability of isomerization and cyclization to aromatics. The differences in the values of O/P, iso-/nand m/s ratios and RON between matrices were very small compared with the differences between zeolite single and each mixed catalyst, indicating that the effects of matrices on the selectivity in products would be significantly small as matrices did not have the significant acid properties in themselves like silica, alumina, titania and zirconia used here.



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Figure 7 Distribution of paraffins, olefins, naphthenes and aromatics for catalytic cracking of VGO using β-zeolite single and β-zeolite-based mixed catalysts. n-Paraffin

i-Paraffin

n-Olefin i-Olefin Naphthene

Aromatic

Weight ratio (%)

Figure 8 Distribution of paraffins, olefins, naphthenes and aromatics for catalytic cracking of VGO using Y-zeolite single and Y-zeolite-based mixed catalysts.

Approximate tendency of above-mentioned results for VGO cracking were almost same between β- and Y-zeolite systems. Major differences were observed in values of the conversion, the selectivity of gasoline fraction, the ratios of O/P, iso-/n- and m/s, and RON. Values of the conversion, the O/P ratio and RON for β-zeolite systems were higher than those for Y-zeolite systems, values of the selectivity of gasoline and the ratio of iso-/n- for the former were lower, and values of m/s ratio were similar between β- and Y-zeolite systems. In this comparison, it is thought that the difference in the


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conversion would be derived from the strength of acid sites of zeolite. As the ability of hydrogen transfer of β-zeolite is lower than that of Y-zeolite, the O/P and aromatization becomes high leading to higher RON. The higher selectivity of gasoline fraction and the higher ratio of iso-/n- would be derived from the larger size of micropore in Y-zeolite. These results indicated that the selectivity for products would strongly depend on the type of zeolite and that the activity would also depend on the type of zeolite significantly. As the activity largely changed with changing the type of matrix oxide, however, only the type of zeolite has not controlled the activity.

Similar results have also been obtained from

cracking of VGO, AR and SB using other catalysts and CPP method,49,51,53,58,59 indicating that the reactions of these heavy molecules would properly have been performed and estimated using the CPP method. 3.4 Relationships between activity, and pore structure and acid property In order to elucidate the relationships between the activity in catalytic cracking and the pore structure and the acid property of catalysts, conversions of n-dodecane and VGO are plotted against parameters of pore structure from N2 adsorption and desorption and the amount of acid sites from NH3-TPD in Figures 9a-9e. Figures 9a-9e show changes in conversions of n-dodecane and VGO with pore volume by BET method (PV-BET), pore volumes by BJH method (PV-BJH), surface area by BET method (SA-BET), surface area by BJH method (SA-BJH) and the amount of NH3 desorbed (NH3-TPD), respectively, and also include corresponding regression lines with decision coefficients.



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Almost all lines showed positive slopes although there were both good and poor correlations. Further, the conversions of n-dodecane and VGO exhibited the significantly different decision coefficients for one same parameter.

The conversion of n-dodecane showed very good correlation with NH3-TPD and

good correlations with PV-BET and SA-BET, indicating that the conversion of n-dodecane would closely be related to the amount of acid sites in β-zeolite included in a catalyst and significantly be related to the amount of micropores of β-zeolite because the values of PV-BET and SA-BET include the contribution of micropores of β-zeolite.

However, the relationship between the conversion of

n-dodecane and the presence of mesopores seems to be more moderate. Similar results were observed for Y-zeolite and Y-zeolite containing mixed catalysts as in Figure S22. In the case of a small molecule like n-dodecane, only SA-BET and NH3-TPD of Y-zeolite systems had the strong contribution to the conversion of n-dodecane, indicating that the amount of acid sites in micropores of zeolite and the amount of micropores themselves would strongly affect the activity. On the other hand, the conversion of VGO showed very good correlations with PV-BET and PV-BJH and good correlation with NH3-TPD for β-zeolite systems (Figure 9), indicating that the conversion of VGO would closely be related to the amount of space derived from mesopores included in a matrix and significantly be related to the amount of acid sites in β-zeolite included in a catalyst. In order to know the relationships between activity, and pore structure and acid property, the conversions of n-dodecane and VGO are plotted against the product of NH3-TPD and PV-BET,


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PV-BJH, SA-BET or SA-BJH in Figures 10a-d. The high decision coefficients were maintained in plots of conversion of n-dodecane with the product PV-BETxNH3-TPD and with the product SA-BETxNH3-TPD. Further, the decision coefficients increased in plots of conversion of VGO with all the parameters. Specifically plots with the product PV-BETxNH3-TPD and with the product PV-BJHxNH3-TPD gave high values of the decision coefficient, suggesting that the coexistence of mesopores of matrices and acid sites of zeolite would collaboratively act and give the synergistic effects to increase the activity with promoting the diffusion of a large molecule of VGO to acid sites of zeolite.

b) 45

R² = 0.3226

40

70 60 50 40 30

R² = 0.6234

35 30

90

rsion of n-dodecane (%)

50

80

nversion of VGO (%)

90

80

50 R² = 0.1504

70 60

R² = 0.6007

15

35

25

40

20

30 20

40

30

50

ACS Paragon Plus Environment 25 20

45

15 C12Conv

onversion of VGO (%)

a) sion of n-dodecane (%)

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



28

d) R² = 0.3151

40

70

35

R² = 0.052

60

30

50

25

40

20

30

15

20

C12Conv

10

10

VGOConv

5

0

90

0 0

2

4

SA-BET/100

e) 90

6

8

40 35

60

R² = 0.2657

30

50

25

40

20

30

15

20

C12Conv

10

10

VGOConv

5

0

0 0

1

2

SA-BJH/100

3

4

(m2/g)

50 45 40

70

45

R² = 0.1451

70

(m2/g)

R² = 0.5872

80

50

80

Conversion of VGO (%)

45

Conversion of n-dodecane (%)

50

80


90

R² = 0.3532

35

60

30

50

25

40

20

30

15

20

C12Conv

10

VGOConv

10



c)


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

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0

0 2

3

4

5

6

7

NH3-TPD（10-4 mol/g）

Figure 9 Plots of conversions of n-dodecane and VGO against a) the pore volume in BET, b) the pore volume in BJH, c) the surface area in BET, d) the surface area in BJH, e) the amount of NH3-TPD. β-zeolite single and β-zeolite-based mixed catalysts.


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45 40

70

35

R² = 0.7165

60

30

50

25

40

20

30

15 C12Conv

20

10

VGOConv

10

5

0

0 0

1

2

3

4

60

R² = 0.4817

d)

40

70

35 R² = 0.1223

60

30

50

25

40

20

30

15 C12Conv

20

10

VGOConv

10

5

0


45

80

0 0

10

20

30

SA-BET/100 x NH3-TPD

(m2/g

40

x

10-4

35 30

50

25

40

20

30

15

20

C12Conv

10

VGOConv

10 5

0

0 1

2

3

4

PV-BJH x NH3-TPD (cm3/g x 10-4 mol/g)

50

90

40 R² = 0.6849

0


100

45

70

PV-BET x NH3-TPD (cm3/g x 10-4 mol/g)

c)

50

R² = 0.2296

80

90

50 45

80 R² = 0.2634

70

R² = 0.5019

30

50

25

40

20

30

15

20

C12Conv

10

VGOConv

10 5

0

0 0

50

40 35

60


80

90


R² = 0.4646

90


b)

50



a) 100


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

4

6

8

10

12

14

16

SA-BJH/100 x NH3-TPD (m2/g x 10-4 mol/g)

mol/g)

Figure 10 Plots of conversions of n-dodecane and VGO against a) the product of pore volume in BET and NH3-TPD, b) the product of pore volume in BJH and NH3-TPD, c) the product of surfce area in BET and NH3-TPD, d) the product of surface area in BJH and NH3-TPD. β-zeolite single and β-zeolite-based mixed catalysts.

In the case of Y-zeolite systems, plots of the conversion of n-dodecane with the product SA-BETxNH3-TPD gave much higher value of the decision coefficient than that of β-zeolite systems (Figure S23). This decision coefficient value for the product SA-BETxNH3-TPD was higher than those for single SA-BET (Figure S22c) and single NH3-TPD (Figure S22e). Similar result was obtained in



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the plots of the conversion of VGO and the relatively strong relationships were observed between the conversion of VGO, and SA-BET (Figure S22c) and NH3-TPD (Figure S22e). Further, the decision coefficient value for the product SA-BETxNH3-TPD (Figure S23c) was higher than those for single SA-BET and single NH3-TPD.

These results indicate that there would be the synergy between the

amount of micropores themselves of zeolite and the amount of acid sites in the micropores of zeolite. When the cracking of VGO was compared between β-zeolite-based catalysts and Y-zeolite-based catalysts (Figures 9, 10, S22 and S23), some differences were observed. The conversions of VGO using β-zeolite-based catalysts showed the relatively strong relationships with PV-BET and PV-BJH (Figures 9a and 9b) while those using Y-zeolite-based catalysts showed the strong relationship with SA-BET (Figure S22c). For both catalysts systems, the relationships with NH3-TPD were moderate (Figures 9e and S22e). When the VGO conversions vs the product of NH3-TPD and PV-BET, PV-BJH, SA-BET or SA-BJH were compared between β- and Y-zeolite-based catalysts (Figures 10 and S23), β-zeolite-based catalysts showed the stronger relationship between the conversion and the products of NH3-TPD and PV-BET, PV-BJH or SA-BJH (Figures 10a, b and d) than the relationship between the conversion and the single NH3-TPD, PV-BET, PV-BJH or SA-BJH (Figures 9a, b, d and e). The results indicated that the conversion of VGO would strongly be affected by not only the amounts of acid sites but also the presence of significant amounts of mesopores and that there may be the synergy between acid sites in micropores and spaces in mesopores. In contrast, Y-zeolite-based catalysts only showed


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the strong relationship between the conversion and the product of NH3-TPD and SA-BET (Figure S23c), however this relationship was weaker than the relationship between the conversion and the single SA-BET (Figure S22c). These results suggested that the significance of the pore structure of catalyst would change depending on the type of zeolite and the size of reactant molecules and that both sizes of micropores in zeolite and mesopores in matrices would largely affect the reactivity of cracking. When relatively smaller n-dodecane was used, NH3-TPD had the relationship with the conversion for both β- and Y-zeolite systems. On the other hand, when relatively larger VGO was used, β-zeolite systems, which had smaller micropores of zeolite, clearly showed the stronger relationship with mesopores. However, Y-zeolite systems, which had larger micropores of zeolite than β-zeolite, showed the stronger relationship with SA-BET, indicating that the larger micropores of Y-zeolite as well as its amount of acid sites strongly affected the whole reaction of cracking, which would weaken the effect of mesopores of matrices compared with the cases of β-zeolite systems. It was reported that when macro-ZSM-5 with 2μm crystal size and nano-ZSM-5 with 100nm crystal size were compared in the catalytic cracking of n-hexane, the effective factors (η) for macroand nano-ZSM-5 were 0.65 and 1.00, respectively.25 This meant that the catalytic cracking using nano-ZSM-5 was under the reaction-limiting condition while that using macro-ZSM-5 was under the transition condition between the reaction-limiting condition and diffusion-limiting condition. It was also reported that the better performance would be obtained by the shorter diffusion length of the



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micropore in the finer crystals of zeolite and the higher diffusion rate of a reactant in the intercrystal mesopore of a catalyst particle.64 There are some similar reports for the effects of crystal size of zeolite on the enhancement of activity in catalytic cracking.65,66 Crystal sizes of β and Y zeolites used here were 0.5-1μm and 0.2-0.4μm, respectively, in the commercial data. According to the data, cracking reactions using β zeolites may have more effect of diffusion, which is consistent with the fact that catalysts using β zeolite had the close relationship with values of pore volume especially for VGO cracking while catalysts using Y zeolite did not have so close relationship with values of pore volume even for VGO cracking. On the other hand, the diffusivities of n-octane in particles of industrial FCC catalysts and in zeolite USY were also reported by using pulsed field gradient NMR.22 It was shown that for guest molecules which are at least as large as n-octane, the rate of molecular exchange between catalyst particles and their surroundings was primarily determined by the coefficient of intraparticle diffusion rather than that of intracrystalline diffusion in the zeolite crystals. It was also pointed out that the intraparticle diffusivity may be increased by increasing the mean size of the macropores in the particles. In another related report,67 the mass transfer processes in REUSY zeolites and FCC catalyst particles were measured and distinguished by uptake method with an intelligent gravimetric analyzer (IGA) and by the frequency response (FR) technique. The results indicated that the diffusion time constants in the FCC catalyst particles are smaller than those in the REUSY zeolites, and the limiting steps for the


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overall mass transfer processes in the FCC catalyst particles are the diffusion process in the length scale of macropore of the matrix or/and the mass transfer at the zeolite–matrix interface rather than the intracrystalline diffusion one in the micropores of the zeolite crystals. Further an example of similar intraparticle diffusion has been reported for hierarchical nanocrystalline ZSM-5 zeolite prepared by seed silanization, where cracking of large molecule polyethylene was promoted.68 Hierarchical ZSM-5 zeolites prepared by hydrothermal synthesis with double templates to make both mesopores and micropores showed better performance in catalytic cracking probably because of the promotion due to the intraparticle diffusion.69,70 Mechanochemical milling and successive recrystallization of zeolite may also provide the example of improvement of catalytic performance by the intraparticle diffusion.71 It has also been reported that when the diffusion of heavy oil was calculated in the saturated adsorption experiment of FCC catalyst and silica model catalyst, the diffusion is restricted in the catalyst pores of less than 8 nm for heavy oil which has molecular diameter of more than 1.8nm, although the diffusion of heavy oil with molecular diameter less than 1.8nm was not restricted in the catalyst with pore diameter larger than 5.6nm.72 In our present study, it was shown that not only microporous structure of zeolite but also mesoporous structure of matrix would be related to the reactivity of catalytic cracking. Although the type of zeolite, the amounts of acid sites in zeolite, and the sizes of micropores and crystals largely affected the reactivity of catalytic cracking, it was found that the type of matrix and its pore structure also affected the reactivity to the same extent as the effects of zeolite.



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Figure 11 shows the adsorption and diffusion model of reactants and products in catalytic cracking using zeolite surrounded by matrix materials, which may explain partly that the catalytic cracking could be controlled by both effects of adsorption and diffusion.59 Generally the smaller pore has advantage for adsorption (e.g. TiO2, ZrO2 or kaolin series) and the larger pore does for diffusion (e.g. SiO2 and Al2O3 series). Further, when a catalyst has the higher activity, the concentration of products in a catalyst pore becomes higher. Large molecules are cracked to produce more reactive smaller molecules which may be converted to aromatics and cokes more rapidly. In the smaller pores, reactive molecules are thought to be difficult to eliminate from the catalyst system, which would lead to the rapid deactivation. The catalytic cracking by β series showed the increase in conversion with increasing the pore volume of β series, indicating that not only rapid diffusion of products but also moderate adsorption of reactants in the catalyst with large pore like MAT(SiO2 or Al2O3)-β would promote the reaction. On the contrary, the higher activity of β zeolite systems would increase the concentration of not only reactants but also products in the catalyst with small pore like MAT(TiO2, ZrO2 or kaolin)-β , which may lead to the confusion in the pore mouth of zeolite and promote the deactivation as shown in Figure 11. On the other hand, Y series showed much lower activity for catalytic cracking of both n-dodecane and VGO than β series, which means that the concentration of products in a pore of catalyst is very low. Such situation may promote the effective elimination of products with low concentration even for smaller pores of MAT(TiO2, ZrO2 or Kaolin)-Y in Figure 11. In fact Y series


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35

did not show the large difference in activity between catalysts with different matrices, indicating that the activity per an acid site of MAT(TiO2, ZrO2 or Kaolin)-Y is high although the activity per an acid site of MAT(SiO2 or Al2O3)-Y is low probably because of the weak adsorption ability of reactants and the low activity of Y zeolite. In the present study, the reaction profiles in catalytic cracking could be explained by the reactivity of zeolite for hydrocarbons, the pore size of matrices and the concentration of reactants and products. β zeolite systems has higher activity for cracking of hydrocarbons than Y zeolite systems, and thus produce the larger amounts of products which lead to the higher concentration of products around zeolite particles.

Therefore, on using β zeolite systems, the large space would be necessary to

promote the diffusion of products. In contrast, on using Y zeolite system, the relatively narrow pore would be preferred to promote the adsorption of reactants.

MAT(SiO2, Al2O3)-β

MAT(SiO2, Al2O3)-Y

Concentration of reactants and products is appropriate to maintain the high activity.

MAT(TiO2, ZrO2, Kaolin)-β

Concentration of reactants is too low to maintain the high activity.

MAT(TiO2, ZrO2, Kaolin)-Y Concentration of reactants is enough high and the concentration of products is enough low to maintain the high activity.

Concentration of reactants and products is very high. The blockage of pore mouth is easy to occur.

Reactant Large

Product Small

Zeolite pore mouth


Matrix pore mouth


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Figure 11 Adsorption and diffusion model of reactants and products in catalytic cracking using zeolite surrounded by matrix materials

4. Conclusions 1. In order to investigate the effect of pore size of metal oxide matrices on the catalytic cracking reactivity, mesoporous aluminas, silicas, titanias and zirconias with different pore size were prepared by the sol-gel method using corresponding alkoxides and changing the calcination temperature. Surface areas and pore volumes decreased for all kinds of oxides with increasing the calcination temperature whereas the pore size of alumina increased significantly. Mixed catalysts with different mesoporous sizes of oxides and microporous zeolite were made for catalytic cracking of n-dodecane and VGO. The XRD measurement of the mixed catalysts showed that crystal structures of zeolites were maintained and dispersed on oxides prepared. 2. The conversions of n-dodecane using catalysts with β-zeolite reached more than 80%. When the mixed catalysts were used, over-cracking of n-dodecane was inhibited and the selectivity for gasoline fraction increased in comparison with that of zeolite single. Further, although the mixed catalysts had only one fourth of zeolite, the similar conversions to that of zeolite single were maintained using the mixed catalysts. When matrices had larger pore volumes, the activity tended to increase, indicating that


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37

the matrices would contribute the diffusion of reactants and products to increase the activity. The distribution of products did not change largely between the mixed catalysts probably because matrices of oxides did not have significant acid sites, indicating that the selectivity for products would not change largely by changing only the pore structure of matrices. 3. The conversions of n-dodecane using catalysts with Y-zeolite were about 50% which was much lower than those of catalysts with β-zeolite. However, the selectivity of gasoline fraction was higher in Y-zeolite containing catalysts probably because this selectivity would strongly be related to the larger micropore size of Y-zeolite. In catalytic cracking of n-dodecane, the product distribution hardly changed by changing the kind of matrix oxide but did by changing the type of zeolite, while the conversion changed depending on the kinds of matrix oxide, indicating that matrix oxide could control the dispersion of zeolite to increase the catalytic activity. 4. The facile estimation of catalysts was achieved using the Curie point pyrolyzer in catalytic cracking of VGO and the use of mesoporous oxides as matrices inhibited the over-cracking and produced a large number of multi-branched hydrocarbons. The selectivity for products did not change by the kind of matrix while the conversions changed largely depending on the amount of pore volume of the matrix. These results were very similar to those from cracking of n-dodecane, indicating that CPP method would work as the estimation method of catalytic cracking of large molecules like VGO etc.



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Supporting information Table S1 Composition of solution for preparation of SiO2 Table S2 Composition of solution for preparation of Al2O3 Table S3 Composition of solution for preparation of TiO2 Table S4 Composition of solution for preparation of ZrO2 Table S5 Composition for preparation of mixed catalyst Table S6 Composition for preparation of mixed catalyst Table S7 Pore properties of catalysts obtained by N2　adsorption measurement Table S8 Pore properties of mixed catalysts and zeolites Table S9 Pore properties of mixed catalysts and zeolites Table S10 　 Product distribution and some catalytic properties of gasoline fraction for catalytic cracking of n-dodecane using β-zeolite single and β-zeolite-based mixed catalysts Table S11 　 Product distribution and some catalytic properties of gasoline fraction for catalytic cracking of n-dodecane using Y-zeolite single and Y-zeolite-based mixed catalysts Table S12 　 Product distribution and some catalytic properties of gasoline fraction for catalytic cracking of VGO using β-zeolite single and β-zeolite-based mixed catalysts Table S13 　 Product distribution and some catalytic properties of gasoline fraction for catalytic cracking of VGO using Y-zeolite single and Y-zeolite-based mixed catalysts


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Figure S1 Flowchart for preparation of SiO2 by sol-gel method. Figure S2 Flowchart for preparation of Al2O3 by sol-gel method. Fig. S3 Flowchart for preparation of TiO2 matrix. Fig. S4 Flowchart for preparation of ZrO2 matrix. Figure S5 Reaction apparatus for catalytic cracking of VGO Fig. S6a XRD patterns of β-zeolite single and a mixed catalyst with kaolin and β-zeolite. Fig. S6b XRD patterns of Y-zeolite single and a mixed catalyst with kaolin and Y-zeolite. Fig. S7 　Adsorption and desorption isotherms of kaolin, silicas and aluminas. Fig. S8 　Adsorption and desorption isotherms of titanias and zirconias. Fig. S9 　 Adsorption and desorption isotherms of β-zeolite single and mixed catalysts with kaolin, silicas and aluminas. Fig. S10 　 Adsorption and desorption isotherms of mixed catalysts with titanias and zirconias and β-zeilite. Fig. S11 　 Adsorption and desorption isotherm of Y-zeolite single and mixed catalysts with kaolin, silica, alumina, titania and zirconia and Y-zeolite. Fig. S12 BJH pore size distributions of kaolin, silicas and aluminas. Fig. S13 BJH pore size distribution of titanias and zirconias. Fig. S14 BJH pore size distributions of β-zeolite single and mixed catalysts with kaolin, silicas and



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aluminas. Fig. S15 BJH pore size distributions of mixed catalysts with titanias and zirconias and β-zeolite. Fig. S16 BJH pore size distributions of Y-zeolite single and mixed catalysts with kaolin, silica and alumina and Y-zeolite. Fig. S17 BJH pore size distributions of mixed catalysts with titania and zirconia and Y-zeolite. Fig. S18 Distribution of carbon numbers in products for catalytic cracking of n-dodecane using β-zeolite single and β-zeolite-based mixed catalysts. Fig. S19 Distribution of carbon numbers in products for catalytic cracking of n-dodecane using Y-zeolite single and Y-zeolite-based mixed catalysts. Fig. S20 Distribution of carbon numbers in products for catalytic cracking VGO using β-zeolite single and β-zeolite-based mixed catalysts. Fig. S21 Distribution of carbon numbers in products for catalytic cracking VGO using Y-zeolite single and Y-zeolite-based mixed catalysts. Fig. S22a Plots of conversions of n-dodecane and VGO against the pore volume in BET. Y-zeolite single and Y-zeolite-based mixed catalysts. Fig. S22b Plots of conversions of n-dodecane and VGO against the pore volume in BJH. Y-zeolite single and Y-zeolite-based mixed catalysts. Fig. S22c Plots of conversions of n-dodecane and VGO against the surface area in BET.


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Y-zeolite single and Y-zeolite-based mixed catalysts. Fig. S22d Plots of conversions of n-dodecane and VGO against the surface area in BJH. Y-zeolite single and Y-zeolite-based mixed catalysts. Fig. S22e Plots of conversions of n-dodecane and VGO against the amount of NH3-TPD. Y-zeolite single and Y-zeolite-based mixed catalysts. Fig. S23a Plots of conversions of n-dodecane and VGO against the product of pore volume in BET and NH3-TPD. Y-zeolite single and Y-zeolite-based mixed catalysts. Fig. S23b Plots of conversions of n-dodecane and VGO against the product of pore volume in BJH and NH3-TPD. Y-zeolite single and Y-zeolite-based mixed catalysts. Fig. S23c Plots of conversions of n-dodecane and VGO against the product of surface area in BET and NH3-TPD. Y-zeolite single and Y-zeolite-based mixed catalysts. Fig. S23d Plots of conversions of n-dodecane and VGO against the product of surface area in BJH and NH3-TPD. Y-zeolite single and Y-zeolite-based mixed catalysts.



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Figure captions


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Figure 1 Reaction apparatus for catalytic cracking of n-dodecane. Figure 2 XRD patterns of silicas, aluminas, titanias and zirconias. Figure 3 XRD patterns of mixed catalysts with β-zeolite. Figure 4 XRD patterns of mixed catalysts with Y-zeolite. Figure 5 Distribution of paraffins, olefins, naphthenes and aromatics for catalytic cracking of n-dodecane using β-zeolite single and β-zeolite-based mixed catalysts. Figure 6 Distribution of paraffins, olefins, naphthenes and aromatics for catalytic cracking of n-dodecane using Y-zeolite single and Y-zeolite-based mixed catalysts. Figure 7 Distribution of paraffins, olefins, naphthenes and aromatics for catalytic cracking of VGO using β-zeolite single and β-zeolite-based mixed catalysts. Figure 8 Distribution of paraffins, olefins, naphthenes and aromatics for catalytic cracking of VGO using Y-zeolite single and Y-zeolite-based mixed catalysts. Figure 9 Plots of conversions of n-dodecane and VGO using β -zeolite single and β-zeolite-based mixed catalysts against (a) the pore volume in BET, (b) the pore volume in BJH, (c) the surface area in BET, (d) the surface area in BJH, and (e) the amount of NH3-TPD. Figure 10 Plots of conversions of n-dodecane and VGO using β -zeolite single and β-zeolite-based mixed catalysts against (a) the product of pore volume in BET and NH3-TPD, (b) the product of pore volume in BJH and NH3-TPD, (c) the product of surfce area in BET and NH3-TPD, and (d) the product



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of surface area in BJH and NH3-TPD. Figure 11 Adsorption and diffusion model of reactants and products in catalytic cracking using zeolite surrounded by matrix materials.


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MAT(SiO2, Al2O3)-β

MAT(SiO2, Al2O3)-Y

Appropriate conc. Highly active


MAT(TiO2, ZrO2, Kaolin)-Y Appropriate conc. Highly active

High conc. Moderate Reactant Large

Product Small

Low conc. Moderate

Zeolite pore mouth

Matrix pore mouth

TOC graphic Adsorption and diffusion model of reactants and products in catalytic cracking using zeolite surrounded by matrix materials


Industrial & Engineering Chemistry Research 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

MAT(SiO2, Al2O3)-β

MAT(SiO2, Al2O3)-Y

Appropriate conc. Highly active


TOC Graphic

Product Small

Low conc. Moderate

MAT(TiO2, ZrO2, Kaolin)-Y Appropriate conc. Highly active

High conc. Moderate Reactant Large

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Zeolite pore mouth ACS Paragon Plus Environment

Matrix pore mouth

Preparation of silica, alumina, titania and zirconia with different pore

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