Adsorption of Ethane and Ethylene over 3D-Printed Ethane-Selective

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Adsorption of Ethane and Ethylene over 3D-Printed Ethane-Selective Monoliths Harshul Thakkar, Qasim Al-Naddaf, Natalia Legion, Morgan Hovis, Anirudh Krishnamurthy, Ali Asghar Rownaghi, and Fateme Rezaei ACS Sustainable Chem. Eng., Just Accepted Manuscript • DOI: 10.1021/ acssuschemeng.8b03685 • Publication Date (Web): 02 Oct 2018 Downloaded from http://pubs.acs.org on October 7, 2018

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ACS Sustainable Chemistry & Engineering

Adsorption of Ethane and Ethylene over 3D-Printed Ethane-Selective Monoliths Harshul Thakkar, Qasim Al-Naddaf, Natalia Legion, Morgan Hovis, Anirudh Krishnamurthy, Ali A. Rownaghi, Fateme Rezaei* Department of Chemical & Biochemical Engineering, Missouri University of Science and Technology, 1101 N State Street, Rolla, MO, 65409, United States Email: [email protected]

Abstract The use of paraffin-selective adsorbents in separation of paraffin/olefin pairs has been recently demonstrated as a sustainable platform for recovering a highly pure olefin product directly from adsorption step. These materials allow for development of a less-expensive and economically attractive technology for olefin/paraffin separation. Herein, we report formulation of paraffin-selective adsorbents into monolithic contactors and evaluation of their adsorptive performance in ethane/ethylene separation. More specifically, Ni(bdc)(ted)0.5 and ZIF-7 were used as ethane-selective adsorbents for development of monoliths via 3D printing. Their formulation was optimized according to the printability of the extruded paste and mechanical stability of the final monolith piece. Through equilibrium and dynamic adsorption experiments, it was demonstrated that formulation of the adsorbents into monoliths does not adversely affect their separation efficiency and the monoliths exhibit uptakes proportional to the adsorbent loading and comparable to their powder analogues. The application of IAST method predicted C2H6/C2H4 selectivities in the range of 1.9-11.8 and 1.2-2.0 for ZIF-7 and Ni-BT monoliths, respectively. The findings of this study highlight the feasibility of 3D printing as a facile and cost-effective approach in shaping paraffin-selective adsorbents into practical contactors. Keywords: MOF, ZIF, Adsorption, 3D-printed monolith, Ethane/ethylene separation

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Introduction Light olefins such as ethylene and propylene are very important building blocks for many essential chemicals and products, however, the production of polymers and other special chemicals from olefins requires the olefin to be of extremely high purity (>99.9%). Thus, the techniques for separating olefins and paraffins are of primary importance to the chemical industry.1 As a consequence of the similar sizes and volatilities, separation of ethylene and ethane from off-gases streams is typically carried out by a highly energy-intensive cryogenic distillation.2 Many alternative separations have been investigated, including absorption, adsorption and membrane-based separations.1,3 Recently, there has been a lot of interest in adsorptive separation of light olefins from the corresponding paraffins as a potentially sustainable route to the recovery of pure olefins.4–6 Todate, most of materials studied for paraffin/olefin separation preferentially adsorb olefins over paraffins as a result of strong chemical interaction with C-C double bond in the unsaturated alkene. Another critical drawback associated with these olefin-selective adsorbents is coke formation resulting from polymerization of the alkene which limits their commercial applications. Indeed, kinetic separation, based on molecular sieving properties appears to offer a more promising approach. However, most of kinetically selective adsorbents recover paraffin during adsorption step while olefin, the desired product, needs to be recovered in the subsequent desorption step (often with lower purity), thus adding complexity and additional cost for obtaining a sufficiently high purity olefin product. In addition, the energy requirements for this process are high owing to the significantly higher binding energy of the olefin with the adsorbent sites than that of the saturated paraffin.6–8


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Paraffin/olefin separation via paraffin-selective adsorbents by which the desired alkene product is obtained during adsorption appears to offer a more promising approach when a material with high paraffin/olefin selectivity is employed. From a practical point of view, it is much more advantageous to have the desired alkene product recovered in the adsorption step.9 The paraffin-selective adsorbents investigated so far include AlMePO-α, ZIF-7, ZIF-8, IRMOF8, IRMOF-4, Ni(bdc)(ted)0.5, MAF-49, PCN-250, In-OF-1, and carbon based materials.10–24 In particular, superior ethane adsorption capacity and C2H6/C2H4 selectivity were reported for Ni(bdc)(ted)0.5 with capacity and selectivity of 6.93 mmol/g and 7.8, respectively at 1 bar and 298 K.12 Previous works by Gascon and co-workers11,17,18 demonstrated that C2 and C3 alkanes are selectively adsorbed over the corresponding alkenes on the zeolite imidazolate framework ZIF-7 through a gate-opening mechanism.25–27 Most recently, in a similar study, Chen et al.19 showed that ZIF-7 is capable of selectively adsorbing the saturated alkane and rejecting the unsaturated alkene with the experimental selectivity in the range 1.5-1.9 at 50 °C. The current body of research on paraffin-selected adsorbents focuses primarily on powdered adsorbents considers their large-scale deployment requirements. One way to facilitate their industrial-scale implementation is to shape them into structured adsorbents such as monoliths that can easily be adopted to various processes. Monolithic structures offer a suitable gas-solid contacting platform for scaling up various gas separation processes.28 These contactors allow for enhanced mass and heat transfer characteristics while resulting in low pressure drop across the bed in comparison to traditional beads and pellets configurations. Most recently, we applied 3D printing technique to formulate various porous materials into monolithic contactors for applications in gas separation and catalysis.29–35 In particular, MOF-74 and UTSA-16 were extruded into 3D-printed monoliths via different approaches such as premade MOF printing or


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in-situ crystal growth in a 3D-printed monolith.31,33 Evaluation of their adsorptive performance in CO2 capture revealed high separation efficiency which was comparable to that of parent MOF with good mechanical integrity. 3D printing offers a facile and low-cost manufacturing approach for developing structured adsorbents with tailored geometry and structural configuration.36,37 In this investigation, we aimed at applying 3D printing technique to fabricate two paraffinselective adsorbents into structured configurations for use in ethane/ethylene separation. The following sections discuss the monoliths development and characterization followed by equilibrium and dynamic adsorption experiments that evaluate their separation performance compared to their powders counterparts.

Experimental Section Materials Development All chemicals used in this study were purchased from Sigma Aldrich and used without any further purification or post-treatment. Both Ni(bdc)(ted)0.5 and ZIF-7 powders were prepared using conventional hydrothermal synthesis procedures reported elsewhere.24,38 The formulation of Ni(bdc)(ted)

0.5

into 3D-printed monoliths was carried out using a two-solution based

procedure, as depicted in Figure 1. In the first step, an appropriate amount of as-made Ni(bdc)(ted)0.5 MOF was dissolved in ethanol (as a solvent) at 60 ºC for 2-3 h while a second solution was prepared by mixing poly(vinyl) alcohol (PVA, as a binder) and dimethyl sulfoxide (DMSO) (as a solvent). In the next step, while ethanol was evaporating from the first solution, the second solution was added dropwise until a homogeneous paste was obtained. The 3Dprinted ZIF-7 monoliths were prepared using the conventional powder-mixture procedure developed by our group, as reported in our earlier work.29 For this material, silica was used as a


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binder mainly because the use of PVA did not give rise to an extrudable paste. Briefly, ZIF-7 and silica powders were mixed for 30 min at room temperature. Upon achieving a homogenous powder mixture, a mixture of methanol and water (as a solvent) in 90:10 volume ratio was introduced to it followed by mixing the solution for 2-3 hours at 60 º C to achieve a smooth and extrudable paste with proper viscosity. While preparing pastes, the propeller speed was varied from 500 to 1000 rpm. After achieving an extrudable viscous paste, it was then loaded into a tube (3 cc, Norson EFD, USA) and piston (Norson EFD, USA) was placed at the end of the tube to ensure even air flow inside the tube. At extrusion end, a nozzle (Tecchon) of 0.85 mm diameter was attached and the paste was extruded by pressurizing air (< 1 bar) into the tube. The deposition of paste in a layer-by-layer pattern resulted in printing of a monolithic configuration with parallel channels. After printing, the monoliths were heated at 100 ºC for 2-3 h to prevent the development of cracks. For convenience, in the rest of the discussion, Ni(bdc)(ted)0.5 and ZIF-7 powders are denoted as “Ni-BT-P” and “ZIF-7-P”, respectively, whereas 3D-printed Ni(bdc)(ted)0.5 and ZIF7 monoliths are designated as “Ni-BT-M” and “ZIF-7-M”, respectively.


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Figure 1. Schematic of 3D-printed Ni-BT monolith preparation. The compositional ratios of the Ni-BT and ZIF-7 pastes are tabulated in Table 1. The primary goal here was to demonstrate successful formulation of MOF powders into monolithic structures with high mechanical strength. To achieve this goal, the paste and solvent compositions were optimized and MOF loadings of 80 and 85 wt% were found to yield an extrudable paste with relatively good mechanical integrity for Ni-BT and ZIF-7, respectively. Table 1. Compositional ratio of 3D-printed monoliths. Monolith

MOF (wt%)

Silica (wt%)

PVA (wt%)

Solvent (vol.%)

Ni(bdc)(ted)0.5

80

-

20

Ethanol:DMSO (92-95:5-8)

ZIF-7

85

15

-

Water:Methanol (10:90)

Characterization of 3D-Printed Monoliths The degree of crystallinity of ZIF and MOF materials in the form of 3D-printed monoliths was assessed by X-ray diffraction (XRD) analysis. The XRD patterns were recorded using a PANalytical X’Pert Multipurpose X-ray diffractometer with a scan step size of 0.02°/step at the rate of 147.4 s/step. Textural properties were determined by N2 physisorption experiments at 77 K on a Micromeritics 3Flex instrument. For these measurements, approximately 100 mg of both ZIF-7 and Ni-BT samples were degassed at 250 and 150 ºC, respectively, for 8 h to remove all guest molecules prior to the test. The methods used to evaluate specific surface area and pore volume were Brunauer−Emmet-Teller (BET) at 0.05-0.3 relative pressure (P/P0) and Horvath– Kawazoe method at P/P0 = 0.99, respectively. Fourier transform infrared (FTIR) spectra of the adsorbents were obtained using a Nicolet-FTIR Model 750 spectrometers. Field-emission


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scanning electron microscopy (SEM) (Hitachi, Model S4700) was employed to assess the surface morphology of the obtained monoliths. Prior to taking SEM images, the monoliths mounted on SEM stubs were dried and sputter-coated with an Au-Pd thin film to obtain high resolution images. The thermal stability of the adsorbent monoliths was also evaluated using TGA (Q500, TA Instruments). The temperature was varied from 25 to 800 °C at the rate of 20 °C/min. Fractional uptake curves were obtained using TGA (Q500, TA Instruments) at 25 °C and 1 bar. All samples were degassed at 150 °C under nitrogen at 60 mL/min to drive off preadsorbed gas molecules. Upon cooling down to 25 °C, the samples were exposed to pure ethane and ethylene gases with the flow rate of 40 mL/min. The uptakes were normalized and presented with respect to time.

Mechanical Strength of 3D-printed Monolith The compressive strength of 3D-printed monoliths was investigated using an Instron 3369 mechanical testing instrument (Instron, Norwood, MA). Prior to compression tests, 3D-printed Ni-BT and ZIF-7 monoliths were polished by 3M sand paper to obtain smooth surface. Upon achieving smooth surface, each monolith was centered on the bottom plate of the instrument, followed by the application of 500 N load through the top plate which was moving axially with a rate of 2.5 mm/min. While top plate was crushing the monolith, the stress-strain data was recorded until the monolith broke. Ethane/Ethylene Adsorption Measurements The potential separation performance of the printed monoliths was determined through equilibrium adsorption measurements by collecting ethane and ethylene adsorption isotherms over both monolith and powders at three different temperatures (25, 40, and 50 ºC) using pure


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gases. Prior to adsorption isotherm analysis, the samples of ZIF-7 and Ni-BT were outgassed under vacuum at 250 ºC and 150 ºC, respectively, for 8 h to remove all pre-adsorbed gases, moisture and impurities on PreVac (Micromeritics). The ethane/ethylene separation efficiency of 3D-printed Ni-BT and ZIF-7 monoliths was also evaluated by estimating equilibrium selectivities using the ideal adsorption solution theory (IAST) for various ethane/ethylene gas mixtures. The best models to fit the adsorption isotherms of the materials were found to be Toth model (equation 1) for Ni-BT monolith and two-step Langmuir-Freundlich model (equation 2) for ZIF-7. q=

 −∆H  b = b0 exp    RT 

q sat bp

(1 + (bp) )

n 1/ n

q1sat ( b1 p )

1/ n1

q=

1 + ( b1 p )

1/ n1

q2sat ( b2 p )

1/ n2

+

1 + ( b2 p )

1/ n2

+

q3sat b3 p 1 + b3 p

(1)

(2)

In the above equations, q is the amount of pure adsorbate adsorbed on the surface, qsat is maximum adsorbate loading, b represents the affinity or coefficient of sites 1, 2, and 3, ∆H is the enthalpy of adsorption, R is gas constant, T is the temperature, p is the partial pressure at equilibrium, and n1 and n2 are surface heterogeneity of sites 1 and 2, respectively. Each model was combined with the IAST to calculate the selectivity values using equation 3.

α ij =

qi / q j

(3)

pi / p j

where ‫ݍ‬௜ and ‫ݍ‬௝ are the working capacities in the bulk gas and adsorbed phases, respectively while pi and pj represent the partial pressures of ethane and ethylene gases.

Results and Discussion Characterization Results of 3D-Printed Monoliths


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The XRD patterns of 3D-printed Ni-BT and ZIF-7 monoliths and their corresponding powders are presented in Figure 2. For Ni-BT, the appearance of diffraction peaks at 8.2°, 9.4°, 12.5°, and 16.5° in the spectrum of the monolith identical to the peaks of its powder analogue confirmed its uniform crystalline structure in monolithic form (Figure 2a). Furthermore, the diffraction peaks of the powder were found to be in agreement with previously reported results in the literature.24,39 Similarly, Figure 2b reveals that 3D-printed ZIF-7 monolith retained its crystalline structure after printing into monolith form as its diffraction peaks were found to be equivalent to those of ZIF-7 powder. The characteristic diffraction peaks at 8.4°, 9.3°, 15.9°, 16.4°, 18.6°, and 19.3° match well with the literature data.40 The less intense reflections for the monoliths relative to the powders could be attributed to the lower concentration of the active component presented in the monolithic structure (see Table 1) than in the pure powder form. These results reveal that neither the printing conditions nor the presence of additives severely affected the crystallinity of the MOF and ZIF adsorbents in the 3D-printed monoliths. (a)

(b)

Intensity (a.u.)

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


Ni-BT-P

ZIF-7-P

Ni-BT-M

5

10

15

20

2θ θ (degree)

25

ZIF-7-M

30

5

10

15

20

2θ θ (degree)

25

30

Figure 2. XRD patterns of 3D-printed (a) Ni-BT and (b) ZIF-7 monoliths and their corresponding powders. The N2 physisorption isotherms and pore size distribution (PSD) curves of the adsorbents are presented in Figure 3 and Figure S1 (Supporting Information). The textural properties of Ni-


9


BT powder were found to be consistent with previously reported results.24 As shown in Figure 3a, both powder and monolith forms of Ni-BT exhibited type I isotherms with a steep N2 uptake at low partial pressures (< 0.1 P/P0) which is associated with micropore filling, followed by a plateau at high partial pressures (> 0.1 P/P0), confirming the microporous nature of Ni-BT in both forms. In Figure 3b, the PSD curves of Ni-BT displayed a micropore peak at ~1.2 nm for monolith and powder samples which further endorsing the microporous nature of the material. It should also be noted here that 3D-printed Ni-BT monolith showed relatively lower N2 uptake to its powder counterpart (22% lower) which could be associated with its lower MOF content (80 wt%). Notably, no mesopores were formed in the structure of this MOF monolith as opposed to 3D-printed MOF-74 and UTSA-16 monoliths developed previously with bentonite clay (15 wt%) and PVA (5 wt%).41 The presence of bentonite clay may have caused the formation of larger mesopores within the monolith structure in our earlier work, whereas in the structure of the current monoliths, the silica and PVA did not play such a role. Ni-BT-P Ni-BT-M

600

(a)

550 500

400

350

dV/dlog(D) Pore Volume (cm3/g)

650

Quantity Adsorbed (cm3/g STP)

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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1.2

(b)

1.2 nm Ni-BT-P Ni-BT-M

1.0 0.8 0.6 0.4 0.2 0.0

0.0

0.2

0.4

0.6

Relative Pressure (P/P0)

0.8

1.0

0

5

10

15

20

25

30

35

40

45

50

Pore Diameter (nm)

Figure 3. (a) N2 physisorption isotherms and (b) PSD curves of 3D-printed Ni-BT monolith and its corresponding powder.


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Unlike Ni-BT sorbent, ZIF-7 interestingly showed totally different textural properties. As shown in Figure S1 (Supporting Information), ZIF-7 powder exhibited a complex N2 adsorptiondesorption isotherm which could be associated with the absence of gate-opening mechanism at such low temperature and pressure and also the inaccessibility of its pores to the N2 molecules, as suggested by Houndonougbo et al.42 and He et al. 40 Such unusual N2 physisorption isotherm trend and PSD curve of ZIF-7 powder were found to be in agreement with previously reported results by Collados et al.43 Moreover, as evident from this figure, the 3D-printed ZIF-7 monolith displayed relatively higher nitrogen uptake than its corresponding powder, which could be correlated to the mesoporous silica that was employed as a binder during paste preparation (see Table 1). For this monolith, typical type IV N2 physisorption isotherms with H1-type hysteresis loop was obtained owing to the mesoporous nature of incorporated silica. The 3D-printed silica monoliths prepared in our earlier work exhibited a similar mesoporous trend.30 According to the Horvath–Kawazoe method, this monolith possesses ~10 nm sized mesopores, as evident from Figure S1 (Supporting Information). As shown in Table 2, the BET surface area and pore volume of the Ni-BT experienced approximately 73% drop upon formulation into monolith, from 1802 m2/g and 0.88 cm3/g for the powder to 1325 m2/g and 0.66 cm3/g for the 3D-printed monolith, respectively. Considering the MOF content of 80 wt%, the slightly lower surface area and pore volume of the monolith than its proportional values could be associated with the presence of the additives (DMSO, and PVA) that remained within the monolith structure after drying and activation steps, thereby partially blocking the pores. The estimated BET surface area and pore volume of ZIF-7 monoliths were found to be 40 m2/g and 0.13 cm3/g, respectively. Although, ZIF-7 powder exhibited extremely low surface area and pore volume (16 m2/g and 0.05 cm3/g, respectively), the obtained values


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were consistent with the results reported in the literature. It is well established in the literature that ZIF-7 is inaccessible to nitrogen at 77 K, as stated earlier.38,42–44 The theoretical calculations predict a surface area of 405 m2/g and a pore volume of 0.207 cm3/g for this material; however, the experimental data are much lower than these theoretical values. For instance, CuadradoCollados et al.43 reported a BET surface area of < 20 m2/g and total pore volume of ~ 0.01 cm3/g for their DMF-based ZIF-7 samples. The higher surface area and porosity of ZIF-7-M than those of ZIF-7-P is the result of larger pores of the monolith, stemming from the presence of 15 wt% silica, that enabled the accessibility of the N2 molecules.

Table 2. Textural properties of 3D-printed monoliths and their powder counterparts. SBET[a]

Vmicro[b]

Vmeso[c]

dmicroo[d]

dmeso[d]

(m2/g)

(cm3/g)

(cm3/g)

(nm)

(nm)

Ni-BT-P

1802

0.88

-

1.20

-

Ni-BT-M

1325

0.66

-

1.20

-

ZIF-7-P

16

0.05

-

1.60

-

ZIF-7-M

40

-

0.13

-

10.0

Sample

[a] Obtained at P/P0 in the range of 0.05-0.3. [b] Estimated by t-plot. [c] Estimated by subtracting Vmicro from the total volume at P/P0 = 0.99. [d] Estimated using Horvath– Kawazoe method.

The presence of DMF in the pores of ZIF-7 powder and monolith was evaluated by FTIR analysis and the results are presented in Figure S2 (Supporting Information). The ZIF-7 powder displayed a transmittance characteristic peak at 1667 cm-1 associated with C=O and methyl stretching vibrations, coupled with a peak related to C-N vibration at 1090 cm-1 which indicated the presence of DMF. A same peak at 1667 cm-1 was observed for ZIF-7 monolith, albeit with reduced intensity as a result of the methanol used as a solvent during monolith preparation.


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Moreover, the presence of a peak at 1100 cm-1 which corresponds to Si-O-Si asymmetric stretching vibrations confirmed the successful incorporation of silica into the monolith structure. Surface morphology of 3D-printed Ni-BT and ZIF-7 monoliths are illustrated in Figure 4. The overview of low magnification SEM images in Figure 4a and 4d demonstrates the wall thickness and channel size of 0.8 and 1.2 mm, respectively, for Ni-BT and 0.85 and 1.25 mm, respectively, for ZIF-7 monoliths. The SEM images of Ni-BT monolith at high magnification (5 and 10 µm) in Figure 4b and 4c depict the uniform distribution of cuboid shape Ni-BT crystals (yellow arrows) with sizes ranging from nano- to micrometer, that were well attached to the PVA binder molecules. Similarly, cube-shape crystals of ZIF-7 (yellow arrows) were found to be well distributed within the printed monolith, as illustrated in Figure 4e and 4f. Notably, the cuboid and cube shape of Ni-BT and ZIF-7 crystals, respectively, were found to be identical to the previously reported results.24,45 Additional SEM images of large Ni-BT and ZIF-7 crystals are presented in Figure S3 (Supporting Information).

Figure 4. SEM images of 3D-printed (a-c) Ni-BT MOF and (d-f) ZIF-7 monoliths.


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To quantify the amount of incorporated additives such as DMSO and PVA, the thermogravimetric tests were conducted on the printed monoliths and the corresponding TG/DTA curves are presented in Figure 5. Several peaks in the temperature range of 200-800 ºC were observed for adsorbents in powder and monolith forms. The appearance of two weight losses at 220 and 310 ºC for 3D-printed Ni-BT monolith (Figure 5a) can be attributed to the evaporation of DMSO and PVA, respectively, used during monolith preparation. In addition, the weight loss between 210 and 350 ºC was found to be 21% which was close to the PVA composition (20 wt%). Both Ni-BT powder and 3D-printed monolith showed an intense derivative weight peak at ~440 ºC (Figure 5a) as a result of the MOF’s structural deformation. ZIF-7 samples on the other hand showed a major weight loss at 650 ºC (Figure 5b) which could be ascribed partly to the removal of DMF from the structure as discussed previously and further supported by FTIR spectra (see Figure S2), and partly to the structure collapse. The peaks observed above 700 ºC are correlated with structural collapse of ZIF-7 in both monolith and powder forms. After structural collapse, the retained residuals at 900 ºC were found to be ~50 and 33.5 wt% for 3D-printed ZIF-7 monolith and its powder analogue, respectively. The 16.5 wt% residual difference between ZIF-7 monolith and powder forms corresponds to the incorporated silica in the monolith structure. It should also be noted here that a small weight loss observed below 175 ºC was due to the removal of moisture from the ZIF-7-M


14

1.5

480 oC

100

650 oC

(a)

(b)

100

1.2 60

0.9

80 ZIF-7-P

0.6

60

730 oC 800 oC

0.3

20 0 100

0.0 0.9

o

440 C

DW (g. oC)

40

Weight (%)

Ni-BT-P

0.8 0.6

80

Weight (%)

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


0.4 0.2

40 0.0 o

650 C

0.6

100

80 0.6

310 oC

60 40

Ni-BT-M 0.3

220 oC

DW (g. oC)

Page 15 of 28

0.4

80 ZIF-7-M

730 oC 800 oC 0.2

60

20

0.0 0.0

0 100

200

300

400

500

600

700

800

100

200

900

Temperature (°C)

300

400

500

600

700

800

900

Temperature (°C)

Figure 5. Thermogravimetric analysis of 3D-printed (a) Ni-BT and (b) ZIF-7 monoliths and their corresponding powders.

Mechanical Strength of 3D-Printed Monoliths The mechanical integrity of the structured adsorbents is one of the key requirements for their industrial use, thus, it is necessary to assess the mechanical properties of the 3D-printed monoliths. The recorded stress-strain curves of the monolithic samples determined from compression tests are illustrated in Figure 6. In addition, the corresponding Young’s modulus data calculated from these curves is tabulated in Table S1. Remarkably, the 3D-printed Ni-BT and ZIF-7 monoliths exhibited high stability under compression with compressive strengths of 1.7 and 0.8 MPa, respectively, which were found to be higher than those of 3D-printed zeolites and MOFs monoliths developed in our previous works, owing to the higher content of PVA polymer that was used as a binder .29,31 As shown in Figure 6a, the Ni-BT monolith underwent elastic deformation showing 0.07 mm/mm deformation before fracture at 1.7 MPa, whereas its ZIF-7 monolith analogue displayed a completely rigid behavior with almost no deformation prior to fracture at 0.8 MPa (Figure 6b). The better mechanical stability of the Ni-BT stems from the presence of PVA with the 20 wt% loading that strongly bounded to the MOF crystals (see


15


Figure 4b) whereas, the early catastrophic failure of ZIF-7 monolith could be associated with the silica as its mesoporous texture could be easily deformed at lower compressive loads. Moreover, the lower Young’s modulus (23 MPa) clearly indicates the outstanding ability of 3D-printed NiBT monolith to withstand high applied forces, implying a better mechanical strength to preclude

(a)

Ni-BT-M

2.0

1.5

1.0

0.5

Compressive Strength (MPa)

the attrition and loss of the adsorbent during operation.

Compressive Strength (MPa)

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 16 of 28

0.8

(b)

Zr-7-M

0.6

0.4

0.2

0.0 0.000

0.025

0.050

0.075

0.100

Strain (mm/mm)

0.0 0.000

0.005

0.010

0.015

0.020

Strain (mm/mm)

Figure 6. Stress-strain curves for 3D-printed (a) Ni-BT and (b) ZIF-7 monoliths.

Ethane/Ethylene Adsorption Measurements To evaluate separation performance of the 3D-printed monoliths, the ethane and ethylene adsorption isotherms were measured at 25 ºC and the results are presented in Figure 7. For comparison purposes, the adsorption isotherms over powder adsorbents were also collected and included in this figure. Overall, the results indicated that both monoliths exhibit a comparative ethane-ethylene uptake to their powder counterparts confirming that the materials retained their adsorptive characteristics after formulation into monolith. As illustrated in Figure 7a, the maximum attainable ethane and ethylene adsorption capacities of 3D-printed Ni-BT monolith were found to be 4.1 and 2. 9 mmol/g, respectively. These capacities, when compared to powder


16

Page 17 of 28

form, were found to be proportional to the MOF loading (80 wt%). Notably, both forms of NiBT showed higher affinity towards ethane over ethylene mainly due to the larger molecular size of ethane, as the surface attraction force acts better with large molecules, and its higher polarizability which consequently improves the Van der Waals attractive interactions with the adsorbent surface.46–48 In addition, density functional theory (DFT) calculations have confirmed strong interaction of ethane over ethylene in the Ni-BT framework.9,18,49 For ZIF-7 samples, a typical type IV or S-shape isotherm was observed as illustrated in Figure 7b, which found to be consistent with previously reported results from other research groups.17,50 The S-shape trend of ethane-ethylene isotherms is associated with the gate opening effect of ZIF-7 topology.50 A steep rise in ethane uptake from 0.15 to 0.25 bar over ZIF-7 monolith can be clearly seen which originates from opening of six membered ring of benzimidazolate linker and rapidly filling the cavities. The total ethane and ethylene uptakes achieved over this monolith were 85% (2.8 mmol/g) and 87% (2.5 mmol/g) of those of ZIF-7 powder.

6

(a)

Ni-BT-M-C2 H6 Ni-BT-P-C2H4

5

Ni-BT-M-C2 H4

4

3

2

25 °C

1

0

(b)

ZIF-7-P-C2 H6 ZIF-7-M-C 2H6 ZIF-7-P-C 2H4 ZIF-7-M-C2H4

4.0

Amount Adsorbed (mmol/g)

Ni-BT-P-C2H6

Amount Adsorbed (mmol/g)

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


3.5 3.0 2.5 2.0 1.5 1.0

25 °C 0.5 0.0

0.0

0.2

0.4

0.6

0.8

1.0

0.0

0.2

Pressure (bar)

0.4

0.6

0.8

1.0

Pressure (bar)

Figure 7. Ethane/ethylene adsorption isotherms for 3D-printed (a) Ni-BT and (b) ZIF-7 samples at 25 ºC.


17


To have a better understanding of kinetics of ethane and ethylene adsorption over the printed monoliths, we also assessed the adsorption response times using TGA and compared them with those for the adsorbent powders. The representative fractional uptake curves for NiBT samples shown in Figure 8a revealed that ethane/ethylene adsorption rates in 3D-printed monoliths were only slightly improved. Both forms of Ni-BT adsorbent achieved 90% of their saturation capacity within the first 4 min. On the other hand, ZIF-7 monolith displayed much better performance than ZIF-7 powder in terms of adsorption rates, as clearly evident from Figure 8b. While 90% of ethane capacity was achieved in the first 5 min for ZIF-7-M, it took about 15 min for ZIF-7-P to reach 90% of its ethane capacity. The same behavior was observed for ethylene adsorption. The difference in adsorption rates could be explained by heat effects. As a result of larger capacity, the heat effects were more for the powder than for the monolith. However, at low fractional uptakes up to 0.2-0.4 (up to 2.5 min), the difference between the two samples is marginal indicating that the uptake rates were less affected by the heat effects. Notably, the adsorption rates were faster over Ni-BT samples than over ZIF-7 materials, implying that the diffusional resistances are more significant in the ZIF-7 than in the Ni-BT monoliths. 1.0

1.0

(a) Ni-BT

0.6

0.4

C2H6 - P C2H6 - M C2H4 - P C2H4 - M

0.2

(b)

0.8

Fractional Uptake

0.8

Fractional Uptake

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 18 of 28

ZIF-7 0.6

0.4

C2 H6 - P C2 H6 - M C2 H4 - P C2 H4 - M

0.2

0.0

0.0 0

2

4

6

8

10

12

14

0

5

Time (min)

10

15

20

25

30

Time (min)


18

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Figure 8. Fractional uptake curves for ethane and ethylene over (a) Ni-BT and (b) ZIF-7 samples at 25 °C and 1.0 bar.

Furthermore, ethane and ethylene adsorption isotherms over printed monoliths were measured at two additional temperatures (40 and 55 ºC) to enable determination of the adsorption parameters needed for selectivity calculations. As expected, the monoliths showed the decreasing trend in ethane and ethylene uptake with temperature, as a result of exothermic nature of gas-solid interaction (Figure 9). In addition, good fits with low average relative errors (AREs) were obtained in all cases. The corresponding fitting parameters are tabulated in Table S2 and S3 (Supporting Information). The worth mentioning observation in Figure 9c and 9d is that ethane-ethylene isotherms were shifted to higher pressures with increasing temperature which could be attributed to the temperature and pressure induced gate opening phenomenon commonly reported for ZIF-7, as discussed previously. This shifting effect in adsorbate uptake was found to be identical with ZIF-7 powder form, as illustrated in Figure S4 (Supporting Information). At 55 °C, the ethylene uptake over ZIF-7 started at much higher pressures than at 25 and 40 ºC, with much smaller uptake at 1.1 bar, implying a better separation performance at pressures below 0.8 bar at this temperature, as depicted in Figure 9b and Figure S4 (Supporting Information). The isosteric heats of adsorption of ethane and ethylene over 3D-printed monoliths were also estimated using Clausius-Clapeyron equation and as the results show (Figure S5, Supporting Information), both hydrocarbons adsorbed strongly on ZIF-7-M with heats of adsorption of 40.8 and 37.9 kJ/mol, respectively, whereas, weaker interactions with Ni-BT-M were inferred from the estimated heats of adsorption of 23.6 and 21.8 kJ/mol for ethane and ethylene, respectively at zero coverage.


19


5

Ethylene Adsorbed (mmol/g)

Ethane Adsorbed (mmol/g)

ARE = 3.3%

3

ARE = 1.8%

2

(b)

Ni-BT-M

ARE = 2.5%

25 oC 40 oC 55 oC

4

3.5

(a)

Ni-BT-M

1

3.0

ARE= 2.3%

25 oC 40 oC 55 oC

2.5

ARE= 2.4%

2.0 1.5

ARE= 2.4%

1.0 0.5 0.0

0 0.0

0.2

0.4

0.6

0.8

0.0

1.0

0.2

ZIF-7-M

(c) ARE = 2.5%

25 oC 40 oC

2.5

55 oC

3.0

Ethylene Adsorbed (mmol/g)

3.0

0.4

0.6

0.8

1.0

Pressure (bar)

Pressure (bar)

Ethane Adsorbed (mmol/g)

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 20 of 28

ARE = 1.9%

2.0 ARE = 1.3%

1.5 1.0 0.5

ZIF-7-M

(d) ARE = 1.7%

25 oC

2.5

40 oC 55 oC ARE = 8.6%

2.0 1.5

ARE = 5.8%

1.0 0.5

0.0

0.0

0.0

0.2

0.4

0.6

0.8

1.0

0.0

0.2

0.4

0.6

0.8

1.0

Pressure (bar)

Pressure (bar)

Figure 9. Ethane and ethylene adsorption isotherms for 3D-printed (a-b) Ni-BT and (c-d) ZIF-7 monoliths at 25, 40 and 55 ºC.

Ethane/Ethylene Selectivity Estimation The plots of calculated IAST selectivities for binary C2H6/C2H4 gas mixture with three different mole ratios (C2H6:C2H4 = 10:90, C2H6:C2H4 = 50:50, C2H6:C2H4 = 90:10) as a function of total pressure are presented in Figure 10. Both 3D-printed Ni-BT and ZIF-7 monoliths showed decrease in selectivity with increasing ethane partial pressure, consistent with previously published results in the literature.18,21 In the case of Ni-BT monolith, a typical decreasing trend with pressure was obtained for C2H6/C2H4 selectivity in all three cases, albeit with a relatively small drop with pressure, as shown in Figure 10a. C2H6:C2H4 = 10:90 exhibited the highest


20

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selectivity values in the range of 1.2-2.0. In the case of 3D-printed ZIF-7 monolith, a completely different trend was obtained as can be seen in Figure 10b. While at lower pressures (0.01 to 0.16 bar) uniform selectivity values were obtained irrespective of gas concentration, different behaviors were observed at higher pressures. Remarkably, due to gate-opening effect, high separation selectivities around 11.8 (P/P0 = 0.3) for 10:90 and 11.0 (at P/P0 = 0.55) for equimolar ethane-ethylene mixture were attained. These high ethane/ethylene selectivity values over ZIF-7M are among the highest selectivities reported for ethane-selective adsorbents in the literature. Wu et al.18 suggested that the applicability of IAST to gate-opening adsorbents is highly dependent on the appropriate model used to fit the adsorption isotherms. As we obtained similar selectivity trends to the literature data, we can conclude that the IAST model is suitable in predicting the selectivity values for out 3D-printed monoliths.

16

(a)

C 2H6 :C 2H 4 = 0.1:0.9 C 2H6 :C 2H 4 = 0.5:0.5 C 2H6 :C 2H 4 = 0.9:0.1

2.2

Ni-BT-M

C2H6:C2H 4 = 0.1:0.9 C2H6:C2H 4 = 0.5:0.5

14

C2H6/C2H4 Selectivity

2.4

C2H6/C2H4 Selectivity

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


(b) ZIF-7-M

C2H6:C2H 4 = 0.9:0.1

12

2.0 1.8

10

1.6 1.4 1.2

8 6 4

1.0

2

0.8 0.6

0 0.0

0.2

0.4

0.6

0.8

1.0

0.0

0.2

Total Pressure (bar)

0.4

0.6

0.8

1.0

Total Pressure (bar)

Figure 10. IAST selectivity for ethane and ethylene mixtures over 3D-printed (a) Ni-BT and (b) ZIF-7 monoliths at 25 ºC.

Conclusion


21


Page 22 of 28

In this study, we reported the development of 3D-printed Ni(bdc)(ted)0.5 and ZIF-7 monoliths and evaluated their adsorption efficiency in separating ethane and ethylene. The optimum composition of the final monoliths contained 80 and 85 wt% Ni-BT and ZIF-7 adsorbents. The mechanical test results revealed the structural stability of the 3D-printed monoliths with compressive strengths of 1.7 and 0.8 MPa for Ni-BT and ZIF-7 monoliths, respectively which were higher than the previously reported results for other 3D-printed monoliths. In both cases, the monoliths exhibited a comparative adsorption performance to their powder analogues with ethane-ethane capacities proportional to the adsorbent loadings. The maximum C2H6 and C2H4 capacities at 25 °C and 1 bar were found to be 2.8 mmol/g and 2.75 mmol/g, respectively for ZIF-7 monolith and 4.2 and 2.9 mmol/g, respectively for Ni-BT monolith. Moreover, the application of IAST method predicted C2H6/C2H4 selectivities in the range of 1.9-11.8 and 1.2-2.0 for ZIF-7 and Ni-BT monoliths, respectively. Supporting Information The supporting Information covers additional FTIR spectra for ZIF-7 samples, SEM images of 3D-printed monoliths, ethane-ethylene adsorption isotherms for monoliths and powders at 40 and 55 °C, the fitting parameters of the ethane/ethylene adsorption isotherms, mechanical testing data and heats of adsorption plots. Author Information Corresponding Author *

Email: [email protected]

ORCID: 0000-0002-4214-4235


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Acknowledgement The funding from Innovation at Missouri S&T (Miner Tank) is acknowledged. The authors thank Materials Research Center (MRC) of Missouri S&T for SEM and XRD.

References: (1) Eldridge, R. B. Olefin/Paraffin Separation Technology: A Review. Ind. Eng. Chem. Res. 1993, 32, 2208–2212, DOI: 10.1021/ie00022a002. (2)

Place, Sterrett. Jubin R, C. B. Materials for Separation Technologies: Energy and Emission Reduction Opportunities; U.S. Depratment of Energy, 2005.

(3)

Lamia, N.; Jorge, M.; Granato, M. A.; Almeida Paz, F. A.; Chevreau, H.; Rodrigues, A. E. Adsorption of Propane, Propylene and Isobutane on a Metal–organic Framework: Molecular Simulation and Experiment. Chem. Eng. Sci. 2009, 64 (14), 3246–3259, DOI:10.1016/j.ces.2009.04.010.

(4)

Bao, Z.; Alnemrat, S.; Yu, L.; Vasiliev, I.; Ren, Q.; Lu, X.; Deng, S. Adsorption of Ethane, Ethylene, Propane, and Propylene on a Magnesium-Based Metal-Organic Framework. Langmuir 2011, 27 (22), 13554–13562, DOI:10.1021/la2030473.

(5)

Grande, C. A.; Lind, A.; Vistad, Ø.; Akporiaye, D. Olefin−Paraffi n Separation Using Calcium-ETS-4. Ind. Eng. Chem. Res. 2014, 53, 15522–15530, DOI: 10.1021/ie5004703.

(6)

Martins, V. F. D.; Ribeiro, A. M.; Chang, J. S.; Loureiro, J. M.; Ferreira, A.; Rodrigues, A. E. Towards Polymer Grade Ethylene Production with Cu-BTC: Gas-Phase SMB versus PSA. Adsorption 2018, 24 (2), 203–219, DOI:10.1007/s10450-017-9930-1.

(7)

Martins, V. F. D.; Ribeiro, A. M.; Plaza, M. G.; Santos, J. C.; Loureiro, J. M.; Ferreira, A. F. P.; Rodrigues, A. E. Gas-Phase Simulated Moving Bed: Propane/Propylene Separation on 13X Zeolite. J. Chromatogr. A 2015, 1423, 136–148, DOI:10.1016/j.chroma.2015.10.038.

(8)

Vanessa F. D. Martins, Ana M. Ribeiro, Joao C. Santos, Jose M. Loureiro, Kristin Gleichmann, Alexandre Ferreira, and A. E. R. Development of Gas-Phase SMB Technology for Light Olefin/Paraffin Separations Vanessa. AIChE J 2016, 62, 2490–2500, DOI:10.1002/aic.

(9)

Liao, P. Q.; Zhang, W. X.; Zhang, J. P.; Chen, X. M. Efficient Purification of Ethene by an Ethane-Trapping Metal-Organic Framework. Nat. Commun. 2015, 6, 1–9, DOI:10.1038/ncomms9697.

(10)

Kroon, M. C.; Vega, L. F.; M.C. Kroon, L. F. V. Selective Paraffin Removal from Ethane/Ethylene Mixtures by Adsorption into Aluminum Methylphosphonate-α: A Molecular Simulation Study. Langmuir 2009, 25 (4), 2148–2152, DOI:10.1021/la803042z.

(11)

van den Bergh, J.; Gücüyener, C.; Pidko, E. A.; Hensen, E. J. M. M.; Gascon, J.; Kapteijn,


23


Page 24 of 28

F. Understanding the Anomalous Alkane Selectivity of ZIF-7 in the Separation of Light Alkane/Alkene Mixtures. Chemistry 2011, 17 (32), 8832–8840, DOI:10.1002/chem.201100958. (12)

Wang, X.; Wu, Y.; Zhou, X.; Xiao, J.; Xia, Q.; Wang, H.; Li, Z. Novel C-PDA Adsorbents with High Uptake and Preferential Adsorption of Ethane over Ethylene. Chem. Eng. Sci. 2016, 155, 338–347, DOI:10.1016/j.ces.2016.08.026.

(13)

Liang, W.; Zhang, Y.; Wang, X.; Wu, Y.; Zhou, X.; Xiao, J.; Li, Y.; Wang, H.; Li, Z. Asphalt-Derived High Surface Area Activated Porous Carbons for the Effective Adsorption Separation of Ethane and Ethylene. Chem. Eng. Sci. 2017, 162, 192–202, DOI:10.1016/j.ces.2017.01.003.

(14)

Ma, C.; Wang, X.; Wang, X.; Yuan, B.; Wu, Y.; Li, Z. Novel Glucose-Based Adsorbents (Glc-As) with Preferential Adsorption of Ethane over Ethylene and High Capacity. Chem. Eng. Sci. 2017, 172, 612–621, DOI:10.1016/j.ces.2017.07.020

(15)

Lahoz-Martín, F. D.; Calero, S.; Gutiérrez-Sevillano, J. J.; Martin-Calvo, A. Adsorptive Separation of Ethane and Ethylene Using IsoReticular Metal-Organic Frameworks. Microporous Mesoporous Mater. 2017, 248, 40–45, DOI:10.1016/j.micromeso.2017.04.009.

(16)

Pires, J., Pinto, L.; Saini, V. K. Ethane Selective IRMOF-8 and Its Signi Fi Cance in Ethane − Ethylene Separation by Adsorption. ACS Appl. Mater. Interfaces 2014, 6, 12093–12099, DOI: 10.1021/am502686g.

(17)

Gücüyener, C.; Van Den Bergh, J.; Gascon, J.; Kapteijn, F. Ethane/Ethene Separation Turned on Its Head: Selective Ethane Adsorption on the Metal-Organic Framework ZIF-7 through a Gate-Opening Mechanism. J. Am. Chem. Soc. 2010, 132 (50), 17704–17706, DOI:10.1021/ja1089765.

(18)

Wu, Y.; Chen, H.; Liu, D.; Qian, Y.; Xi, H. Adsorption and Separation of Ethane/Ethylene on ZIFs with Various Topologies: Combining GCMC Simulation with the Ideal Adsorbed Solution Theory (IAST). Chem. Eng. Sci. 2015, 124, 144–153, DOI:10.1016/j.ces.2014.07.019.

(19)

Chen, D.-L.; Wang, N.; Xu, C.; Tu, G.; Zhu, W.; Krishna, R. A Combined Theoretical and Experimental Analysis on Transient Breakthroughs of C2H6/C2H4 in Fixed Beds Packed with ZIF-7. Microporous Mesoporous Mater. 2015, 208, 55–65, DOI:10.1016/j.micromeso.2015.01.019.

(20)

Bo, U.; Barth, B.; Paula, C.; Kuhnt, A.; Schwieger, W.; Mundstock, A.; Caro, J.; Hartmann, M. Ethene/Ethane and Propene/Propane Separation via the Olefin and Paraffin Selective Metal − Organic Framework Adsorbents CPO-27 and ZIF ‑ 8. Langmuir 2013, 29, 8592–8600, DOI: 10.1021/la401471g.

(21)

Pires, J.; Pinto, M. L.; Granadeiro, C. M.; Barbosa, A. D. S.; Cunha-Silva, L.; Balula, S. S.; Saini, V. K. Effect on Selective Adsorption of Ethane and Ethylene of the Polyoxometalates Impregnation in the Metal-Organic Framework MIL-101. Adsorption 2013, 20 (4), 533–543, DOI:10.1007/s10450-013-9592-6.


24

Page 25 of 28 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


(22)

Chen, Y.; Qiao, Z.; Lv, D.; Wu, H.; Shi, R.; Xia, Q.; Wang, H.; Zhou, J.; Li, Z. Selective Adsorption of Light Alkanes on a Highly Robust Indium Based Metal-Organic Framework. Ind. Eng. Chem. Res. 2017, 56 (15), 4488–4495.

(23)

Chen, Y.; Qiao, Z.; Wu, H.; Lv, D.; Shi, R.; Xia, Q.; Zhou, J.; Li, Z. An Ethane-Trapping MOF PCN-250 for Highly Selective Adsorption of Ethane over Ethylene. Chem. Eng. Sci. 2018, 175, 110–117, DOI:10.1016/j.ces.2017.09.032.

(24)

Liang, W.; Xu, F.; Zhou, X.; Xiao, J.; Xia, Q.; Li, Y.; Li, Z. Ethane Selective Adsorbent Ni(Bdc)(Ted)0.5 with High Uptake and Its Significance in Adsorption Separation of Ethane and Ethylene. Chem. Eng. Sci. 2016, 148, 275–281, DOI:10.1016/j.ces.2016.04.016..

(25)

Reyes, Sebastian C., Jose G. Santiesteban, Zheng Ni Charanjit S. Paur, Pavel Kortunov, John Zengel, H.; Deckman, W. Separation of Methane from Higher Carbon Number Hydrocarbons Utilizing Zeolitic Imidazolate Framework Materials. US 8192709 2012.

(26)

Reyes, Sebastian C., Jose G. Santiesteban, Zheng Ni Charanjit S. Paur, Pavel Kortunov, John Zengel, H.; Deckman, W. Separation of Carbon Dioxide from Methane Utilizing Zeolitic Imidazolate Framework Materials. US 8142745 2012.

(27)

Reyes, Sebastian C., Jose G. Santiesteban, Zheng Ni Charanjit S. Paur, Pavel Kortunov, John Zengel, H.; Deckman, W. Separation of Carbon Dioxide from Nitrogen Utilizing Zeolitic Imidazolate Framework Materials. US 8142745 2012.

(28)

Rezaei, F.; Webley, P. Structured Adsorbents in Gas Separation Processes. Sep. Purif. Technol. 2010, 70 (3), 243–256, DOI:10.1016/j.seppur.2009.10.004.

(29)

Thakkar, H. V.; Eastman, S.; Hajari, A.; Rownaghi, A. A.; Knox, J. C.; Rezaei, F. 3DPrinted Zeolite Monoliths for CO2 Removal from Enclosed Environments. ACS Appl. Mater. Interfaces 2016, 8, 27753−27761, DOI:10.1021/acsami.6b09647.

(30)

Thakkar, H.; Eastman, S.; Al-Mamoori, A.; Hajari, A.; Rownaghi, A. A.; Rezaei, F. Formulation of Aminosilica Adsorbents into 3D-Printed Monoliths and Evaluation of Their CO2 Capture Performance. ACS Appl. Mater. Interfaces 2017, 9 (8), 7489–7498, DOI:10.1021/acsami.6b16732.

(31)

Thakkar, H.; Eastman, S.; Al-Naddaf, Q.; Rownaghi, A. A.; Rezaei, F. 3D-Printed MetalOrganic Framework Monoliths for Gas Adsorption Processes. ACS Appl. Mater. Interfaces 2017, 9 (41), 35908–35916, DOI:10.1021/acsami.7b11626.

(32)

Thakkar, H.; Lawson, S.; Rownaghi, A. A.; Rezaei, F. Development of 3D-Printed Polymer-Zeolite Composite Monoliths for Gas Separation. Chem. Eng. J. 2018, 348, 109– 116, DOI:10.1016/j.cej.2018.04.178.

(33)

Lawson, S.; Al-naddaf, Q.; Krishnamurthy, A.; Amour, M. S.; Griffin, C.; Rownaghi, A. A.; Knox, J. C.; Rezaei, F. UTSA-16 Growth within 3D-Printed Co-Kaolin Monoliths With. ACS Appl. Mater. Interfaces 2018, 10, 19076−19086, DOI:10.1021/acsami.8b05192.

(34)

Li, X.; Li, W.; Rezaei, F.; Rownaghi, A. Catalytic Cracking of N-Hexane for Producing Light Olefins on 3D-Printed Monoliths of MFI and FAU Zeolites. Chem. Eng. J. 2018,


25


Page 26 of 28

333, 545–553, DOI.org/10.1016/j.cej.2017.10.001. (35)

Xin Li, Abdo-Alslam Alwakwak, Fateme Rezaei, A. A. R. Synthesis of Cr, Cu, Ni, and YDoped 3D-Printed ZSM-5 Monoliths and Their Catalytic Performance for n-Hexane Cracking. ACS Appl. Energy Mater. 2018, 1 (6), 2740–2748, DOI:10.1021/acsaem.8b00412.

(36)

Couck, S.; Lefevere, J.; Mullens, S.; Protasova, L.; Meynen, V.; Desmet, G.; Baron, G. V.; Denayer, J. F. M. M. CO2, CH4 and N2 Separation with a 3DFD-Printed ZSM-5 Monolith. Chem. Eng. J. 2017, 308, 719–726, DOI:10.1016/j.cej.2016.09.046.

(37)

Couck, S.; Cousin, J.; Remi, S.; Perre, S. Van Der; Baron, G. V; Ruch, P.; Denayer, J. F. M. 3D-Printed SAPO-34 Monoliths for Gas Separation. Microporous Mesoporous Mater. 2018, 255, 185–191, DOI:10.1016/j.micromeso.2017.07.014.

(38)

Chen, D. L.; Wang, N.; Wang, F. F.; Xie, J.; Zhong, Y.; Zhu, W.; Johnson, J. K.; Krishna, R. Utilizing the Gate-Opening Mechanism in ZIF-7 for Adsorption Discrimination between N2O and CO2. J. Phys. Chem. C 2014, 118 (31), 17831–17837.

(39)

Guerrero-Medina, J.; Mass-Gonzlez, G.; Pacheco-Londoo, L.; Hernndez-Rivera, S. P.; Fu, R.; Hernndez-Maldonado, A. J. Long and Local Range Structural Changes in M[(Bdc)(Ted)0.5] (M = Zn, Ni or Cu) Metal Organic Frameworks upon Spontaneous Thermal Dispersion of LiCl and Adsorption of Carbon Dioxide. Microporous Mesoporous Mater. 2015, 212, 8–17.

(40)

He, M.; Yao, J.; Li, L.; Wang, K.; Chen, F.; Wang, H. Synthesis of Zeolitic Imidazolate Framework-7 in a Water/Ethanol Mixture and Its Ethanol-Induced Reversible Phase Transition. Chempluschem 2013, 78 (10), 1222–1225, DOI:10.1002/cplu.201300193.

(41)

Li, X.; Rezaei, F.; Rownaghi, A. Methanol-to-olefin conversion on 3D-printed ZSM-5 monolith catalysts: Effects of metal doping, mesoporosity and acid strength, Microporous Mesoporous Mater. 276 (2019) 1–12. doi.org/10.1016/j.micromeso.2018.09.016..

(42)

Houndonougbo, Y.; Signer, C.; He, N.; Morris, W.; Furukawa, H.; Ray, K. G.; Olmsted, D. L.; Asta, M.; Laird, B. B.; Yaghi, O. M. A Combined Experimental-Computational Investigation of Methane Adsorption and Selectivity in a Series of Isoreticular Zeolitic Imidazolate Frameworks. J. Phys. Chem. C 2013, 117 (20), 10326–10335, DOI:10.1021/jp3096192.

(43)

Cuadrado Collados, C.; Fernandez-Catalá, J.; Fauth, F.; Cheng, Y.; Daemen, L. L.; Ramirez-Cuesta, A. J.; Silvestre-Albero, J. Understanding the Breathing Phenomena in Nano-ZIF-7 upon Gas Adsorption. J. Mater. Chem. A 2017, 20938–20946, DOI:10.1039/C7TA05922A.

(44)

Park, K. S.; Ni, Z.; Côté, A. P.; Choi, J. Y.; Huang, R.; Uribe-Romo, F. J.; Chae, H. K.; O’Keeffe, M.; Yaghi, O. M. Exceptional Chemical and Thermal Stability of Zeolitic Imidazolate Frameworks. Proc. Natl. Acad. Sci. U. S. A. 2006, 103, 10186–10191, DOI:10.1073/pnas.0602439103.

(45)

Arami-Niya, A.; Birkett, G.; Zhu, Z.; Rufford, T. E. Gate Opening Effect of Zeolitic Imidazolate Framework ZIF-7 for Adsorption of CH4 and CO2 from N2. J. Mater. Chem.


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A 2017, 21389–21399, DOI:10.1039/C7TA03755D. (46)

Sun, X.; Li, Y.; Xi, H.; Xia, Q. Adsorption Performance of a MIL-101(Cr)/Graphite Oxide Composite for a Series of n-Alkanes. RSC Adv. 2014, 4 (99), 56216–56223, DOI:10.1039/C4RA08598A.

(47)

Pillai, R. S.; Pinto, M. L.; Pires, J.; Jorge, M.; Gomes, J. R. B. Understanding Gas Adsorption Selectivity in IRMOF-8 Using Molecular Simulation. ACS Appl. Mater. Interfaces 2015, 7 (1), 624–637, DOI:10.1021/am506793b.

(48)

Li, J.-R.; Kuppler, R. J.; Zhou, H.-C. Selective Gas Adsorption and Separation in MetalOrganic Frameworks. Chem. Soc. Rev. 2009, 38 (5), 1477–1504, DOI:10.1039/b802426j.

(49)

Pires, J.; Pinto, M. L.; Saini, V. K. Ethane Selective IRMOF-8 and Its Significance in Ethane-Ethylene Separation by Adsorption. ACS Appl. Mater. Interfaces 2014, 6 (15), 12093–12099, DOI:10.1021/am502686g.

(50)

Cai, W.; Lee, T.; Lee, M.; Cho, W.; Han, D. Y.; Choi, N.; Yip, A. C. K.; Choi, J. Thermal Structural Transitions and Carbon Dioxide Adsorption Properties of Zeolitic Imidazolate Framework-7 (ZIF-7). J. Am. Chem. Soc. 2014, 136 (22), 7961–7971, DOI:10.1021/ja5016298.


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Graphical Abstract

3D printing MOF Monolith MOF Powder

Formulation of paraffin-selective MOF monoliths by 3D printing technique for sustainable and energy-efficient separation of ethane/ethylene pair


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Adsorption of Ethane and Ethylene over 3D-Printed Ethane-Selective

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