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Dianhua Liu - One of the best experts on this subject based on the ideXlab platform.
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a one step synthesis method of Durene directly from syngas using integrated catalyst of cu zno al2o3 and co nb hzsm 5
Chemical Engineering Science, 2019Co-Authors: Lengkang Jiao, Muhammad Asif Nawaz, Like Cheng, Chen Meng, Tianhui Yang, Muhammad Tariq, Dianhua LiuAbstract:Abstract In recent years, the demand for Durene has been increased as the raw material of polyimide. However, traditional synthesis methods of Durene require a large number of steps with lower efficiency. In this study, a novel synthesis method of a bifunctional integrated catalyst had been utilized, in which the methanol synthesis catalyst Cu/ZnO/Al2O3 (CZA) and the aromatization catalyst Co-Nb/HZSM-5 were combined, to synthesize Durene from syngas in one step. Syngas was converted to methanol and dimethyl ether (DME) followed by the production of different aromatics with a high concentration of Durene through the shape selectivity of zeolite. The optimal reaction conditions of 330 °C, 4 MPa, 200 h−1, 3% Co loading, CZA/HZSM-5 = 3:2 and a unique pseudo-physical coating (PC) integrated method were applied to increase Durene selectivity up to 39.71% in aromatics. Different techniques such as XRD, BET, XPS and NH3-TPD were employed to characterize different catalysts, and a variety of experiments were proceeded to compare different routes of methanol and FT synthesis. These results explain that the high selectivity of tetra-methylbenzene (tetra-MB) was due to the alkylation of trimethylbenzene (tri-MB) induced by methanol on HZSM-5 surface. This work demonstrated that the integrated catalyst could be advantageous for direct conversion of syngas to tri-MB and finally to the desired Durene and it would open up the new avenues in future perspectives.
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A one-step synthesis method of Durene directly from syngas using integrated catalyst of Cu/ZnO/Al2O3 and Co-Nb/HZSM-5
Chemical Engineering Science, 2019Co-Authors: Jiao Lengkang, Muhammad Asif Nawaz, Like Cheng, Chen Meng, Tianhui Yang, Muhammad Tariq, Dianhua LiuAbstract:Abstract In recent years, the demand for Durene has been increased as the raw material of polyimide. However, traditional synthesis methods of Durene require a large number of steps with lower efficiency. In this study, a novel synthesis method of a bifunctional integrated catalyst had been utilized, in which the methanol synthesis catalyst Cu/ZnO/Al2O3 (CZA) and the aromatization catalyst Co-Nb/HZSM-5 were combined, to synthesize Durene from syngas in one step. Syngas was converted to methanol and dimethyl ether (DME) followed by the production of different aromatics with a high concentration of Durene through the shape selectivity of zeolite. The optimal reaction conditions of 330 °C, 4 MPa, 200 h−1, 3% Co loading, CZA/HZSM-5 = 3:2 and a unique pseudo-physical coating (PC) integrated method were applied to increase Durene selectivity up to 39.71% in aromatics. Different techniques such as XRD, BET, XPS and NH3-TPD were employed to characterize different catalysts, and a variety of experiments were proceeded to compare different routes of methanol and FT synthesis. These results explain that the high selectivity of tetra-methylbenzene (tetra-MB) was due to the alkylation of trimethylbenzene (tri-MB) induced by methanol on HZSM-5 surface. This work demonstrated that the integrated catalyst could be advantageous for direct conversion of syngas to tri-MB and finally to the desired Durene and it would open up the new avenues in future perspectives.
Taishung Chung - One of the best experts on this subject based on the ideXlab platform.
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natural gas purification and olefin paraffin separation using thermal cross linkable co polyimide zif 8 mixed matrix membranes
Journal of Membrane Science, 2013Co-Authors: Mohammad Sadegh Askari, Taishung ChungAbstract:Abstract Using three 6FDA-based polyimides (6FDA-Durene, 6FDA-Durene/DABA (9/1), 6FDA-Durene/DABA (7/3)) and nano-size zeolitic imidazolate framework-8 (ZIF-8), we have fabricated mixed matrix membranes (MMMs) with uniform morphology comprising ZIF-8 as high as 40 wt% loading by directly mixing as-synthesized ZIF-8 suspension into the polymer solution. Permeability of all gases (CO 2 , CH 4 , C 3 H 6 , and C 3 H 8 ) increases rapidly with an increase in ZIF-8 loading. However, the addition of ZIF-8 nano-particles into the polymer matrix increases the ideal CO 2 /CH 4 selectivity of only 6.87%, while the ideal C 3 H 6 /C 3 H 8 selectivity improves 134% from 11.68 to 27.38 for the MMM made of 6FDA-Durene/DABA (9/1) and 40 wt% ZIF-8. Experimental data show that the plasticization resistance and gas pair selectivity of MMMs are strongly dependent on the amount of cross-linkable moiety and annealing temperature. MMMs made of 6FDA-Durene do not show considerable improvements on resistance against CO 2 -induced plasticization after annealing at 200–400 °C, while MMMs synthesized from cross-linkable co-polyimides (6FDA-Durene/DABA (9/1) and 6FDA-Durene/DABA (7/3)) show significant enhancements in CO 2 /CH 4 and C 3 H 6 /C 3 H 8 selectivity as well as plasticization suppression characteristics up to a CO 2 pressure of 30 atm after annealing at 400 °C due to the cross-linking reaction of the carboxyl acid (COOH) in the DABA moiety. The MMM made of 6FDA-Durene/DABA (9/1) and 40 wt% ZIF-8 possess a notable ideal C 3 H 6 /C 3 H 8 selectivity of 27.38 and a remarkable C 3 H 6 permeability of 47.3 Barrer. After thermally annealed at 400 °C, the MMM made of 6FDA-Durene/DABA (9/1) and 20 wt% ZIF-8 shows a CO 2 /CH 4 selectivity of 19.61 and an impressive CO 2 permeability 728 Barrer in mixed gas tests. The newly developed MMMs may have great potential for industrial nature gas purification and C 3 H 6 /C 3 H 8 separation.
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synthesis cross linking and carbonization of co polyimides containing internal acetylene units for gas separation
Journal of Membrane Science, 2007Co-Authors: Youchang Xiao, Huai Ming Guan, Taishung Chung, Michael D. GuiverAbstract:Abstract Cross-linkable polyimides containing internal acetylene units have been synthesized by random copolymerization of 6FDA dianhydride, 2,3,5,6-tetramethyl-1,4-phenylenediamine (Durene) and 4,4′-diaminodiphenylacetylene (p-intA) diamine as materials for gas separation. Compared with 6FDA-Durene polyimide, 6FDA-Durene/p-intA co-polyimide shows denser polymer chain packing, which is confirmed by wide-angle X-ray diffraction (WAXD). The thermally treated co-polyimides are insoluble in various solvents and show an increase in T g , indicating the formation of network structures among the polymer chains. Differential scanning calorimetry (DSC) and FT-Raman suggest that cross-linking arises from Diels-Alder cycloaddition between the internally arranged acetylene units along the polymer main chain, resulting in extended conjugated aromatic structures. The thermally cross-linked membranes show enhanced resistance to CO 2 plasticization up to around 5 × 10 6 Pa (700 psi). The rigidified membrane structure provides increased gas selectivity without severely compromising gas permeability. The gas separation performance of carbonized membranes is remarkably superior to those of neat and cross-linked copolyimides because of a large increase in rigidification in the polymer matrix. A Diels-Alder cycloaddition reaction produces a much more rigid and planar conjugated aromatic structure in the polymer chains and results in a higher degree of graphitization during carbonization, which is confirmed by XPS and WAXD. Carbon membranes derived from co-polyimides with more internal acetylene units show much better gas separation performance than those derived from polyimides without internal acetylene units.
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Gas‐sorption properties of 6FDA–Durene/1,4‐phenylenediamine (pPDA) and 6FDA–Durene/1,3‐phenylenediamine (mPDA) copolyimides
Journal of Applied Polymer Science, 2003Co-Authors: Si-xue Cheng, Taishung Chung, Rong Wang, Rohit H. VoraAbstract:We investigated the sorption isotherms of O2, N2, CH4, and CO2 gases in 6FDA–Durene, 6FDA–1,4-phenylenediamine (6FDA–pPDA), and 6FDA–1,3-phenylenediamine (6FDA–mPDA) homopolymers and 6FDA–Durene/pPDA and 6FDA–Durene/mPDA copolyimides. The solubilities decrease in the order of the inherent condensabilities of the penetrant gases, namely, CO2, CH4, O2, and N2. The chemical structures of the polymer, as well as the chain packing, determine the sorption properties of these homopolymers and copolymers. The FDA–Durene homopolymer has the highest solubility for all gases because of its high specific free volume and fractional free volume. The solubilities of the copolymers increase with an increasing 6FDA–Durene content, while the solubility selectivities of the copolymers only vary slightly. The values of KD (Henry's law constant) and CH′ (Langmuir site capacity) of these copolyimides decrease with a decreasing 6FDA–Durene content. To our surprise, contradictory to the previous known fact that the meta-connected materials tend to have denser molecular packing than that of the para-linked materials for homopolymers, the 6FDA–Durene/mPDA 80/20 copolymer has higher gas solubilities than those of the 6FDA–Durene/pPDA 80/20 copolymer. The random moiety sequence within the copolymer may be the main cause for the abnormal phenomenon. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2187–2193, 2003
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gas sorption properties of 6fda Durene 1 4 phenylenediamine ppda and 6fda Durene 1 3 phenylenediamine mpda copolyimides
Journal of Applied Polymer Science, 2003Co-Authors: Taishung Chung, Si-xue Cheng, Rong Wang, Rohit H. VoraAbstract:We investigated the sorption isotherms of O2, N2, CH4, and CO2 gases in 6FDA–Durene, 6FDA–1,4-phenylenediamine (6FDA–pPDA), and 6FDA–1,3-phenylenediamine (6FDA–mPDA) homopolymers and 6FDA–Durene/pPDA and 6FDA–Durene/mPDA copolyimides. The solubilities decrease in the order of the inherent condensabilities of the penetrant gases, namely, CO2, CH4, O2, and N2. The chemical structures of the polymer, as well as the chain packing, determine the sorption properties of these homopolymers and copolymers. The FDA–Durene homopolymer has the highest solubility for all gases because of its high specific free volume and fractional free volume. The solubilities of the copolymers increase with an increasing 6FDA–Durene content, while the solubility selectivities of the copolymers only vary slightly. The values of KD (Henry's law constant) and CH′ (Langmuir site capacity) of these copolyimides decrease with a decreasing 6FDA–Durene content. To our surprise, contradictory to the previous known fact that the meta-connected materials tend to have denser molecular packing than that of the para-linked materials for homopolymers, the 6FDA–Durene/mPDA 80/20 copolymer has higher gas solubilities than those of the 6FDA–Durene/pPDA 80/20 copolymer. The random moiety sequence within the copolymer may be the main cause for the abnormal phenomenon. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2187–2193, 2003
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the physical and gas permeation properties of 6fda Durene 2 6 diaminotoluene copolyimides
Polymer, 2001Co-Authors: Songlin Liu, Rong Wang, Ye Liu, Mei Lin Chng, Taishung ChungAbstract:Abstract The physical and gas transport properties of homo-polyimides, 6FDA-Durene and 6FDA-2, 6-diaminotoluene (2,6-DAT), and their copolyimides, 6FDA-Durene/2,6-DAT with different diamine ratios, were characterized. The glass transition temperatures of the copolyimides obtained from DSC experiments were about 6–10°C lower than that calculated from the Fox equation. The experimental results for the gas permeability, diffusivity and solubility of this series of polyimides fitted well with that predicted from the logarithm of property versus volume fraction. The gas permeability of 6FDA-Durene/2,6-DAT decreased with increasing 6FDA-2,6-DAT content. However, the selectivity of gases pairs, such as CO2/N2, O2/N2 and H2/N2, increased with the addition of 6FDA-2,6-DAT. The permeability coefficients of H2, He, O2, N2 and CO2 decreased with the kinetic molecular diameters of the gas molecules, with an exception of helium. The diffusion coefficients for the gases of O2, N2 and CO2 were found to decrease with the effective diameters of the penetrant molecules. The solubility coefficients of the gases increased with the condensability of the gas molecules. By decoupling the permselectivity of gas pairs of CO2/N2, O2/N2, it was found that the permselectivity of CO2/N2 was mainly controlled by the solubility selectivity, while in the gas pair of O2/N2, the permselectivity was dominated by the diffusivity selectivity.
Yusaku Ikegami - One of the best experts on this subject based on the ideXlab platform.
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Proton tunneling of tropolone in Durene single crystal as studied by time-resolved EPR detected excitation spectroscopy
The Journal of Chemical Physics, 1999Co-Authors: Tadaaki Ikoma, Kimio Akiyama, Shozo Tero-kubota, Yusaku IkegamiAbstract:We have measured the excitation spectra for tropolone–OH in Durene single crystal and tropolone–OD in deuterated Durene using a time-resolved electron paramagnetic resonance (TREPR) detection method that makes possible to separate the signals due to magnetically different sites. The tunneling doublet with 3 cm−1 was observed in the sharp zero-phonon line. The small splitting indicates that the crystal field increases the barrier of double-minimum potential for the proton tunneling in the S1 state. Moderately asymmetric potentials of the S0 and S1 states, where the energetic imbalance between two wells in the S1 state potential is opposite the S0 state potential, reasonably explained the observed unusual intensity ratio of the tunneling doublet (01+
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proton tunneling of tropolone in Durene single crystal as studied by time resolved epr detected excitation spectroscopy
Journal of Chemical Physics, 1999Co-Authors: Tadaaki Ikoma, Kimio Akiyama, Shozo Terokubota, Yusaku IkegamiAbstract:We have measured the excitation spectra for tropolone–OH in Durene single crystal and tropolone–OD in deuterated Durene using a time-resolved electron paramagnetic resonance (TREPR) detection method that makes possible to separate the signals due to magnetically different sites. The tunneling doublet with 3 cm−1 was observed in the sharp zero-phonon line. The small splitting indicates that the crystal field increases the barrier of double-minimum potential for the proton tunneling in the S1 state. Moderately asymmetric potentials of the S0 and S1 states, where the energetic imbalance between two wells in the S1 state potential is opposite the S0 state potential, reasonably explained the observed unusual intensity ratio of the tunneling doublet (01+<01−). A well-resolved progression of a phonon band with a 15 cm−1 separation was also obtained in Durene crystal at very low temperature. From a Franck–Condon analysis of the relative intensity of the phonon band, it was clarified that the stable configuration ...
Chen Meng - One of the best experts on this subject based on the ideXlab platform.
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a one step synthesis method of Durene directly from syngas using integrated catalyst of cu zno al2o3 and co nb hzsm 5
Chemical Engineering Science, 2019Co-Authors: Lengkang Jiao, Muhammad Asif Nawaz, Like Cheng, Chen Meng, Tianhui Yang, Muhammad Tariq, Dianhua LiuAbstract:Abstract In recent years, the demand for Durene has been increased as the raw material of polyimide. However, traditional synthesis methods of Durene require a large number of steps with lower efficiency. In this study, a novel synthesis method of a bifunctional integrated catalyst had been utilized, in which the methanol synthesis catalyst Cu/ZnO/Al2O3 (CZA) and the aromatization catalyst Co-Nb/HZSM-5 were combined, to synthesize Durene from syngas in one step. Syngas was converted to methanol and dimethyl ether (DME) followed by the production of different aromatics with a high concentration of Durene through the shape selectivity of zeolite. The optimal reaction conditions of 330 °C, 4 MPa, 200 h−1, 3% Co loading, CZA/HZSM-5 = 3:2 and a unique pseudo-physical coating (PC) integrated method were applied to increase Durene selectivity up to 39.71% in aromatics. Different techniques such as XRD, BET, XPS and NH3-TPD were employed to characterize different catalysts, and a variety of experiments were proceeded to compare different routes of methanol and FT synthesis. These results explain that the high selectivity of tetra-methylbenzene (tetra-MB) was due to the alkylation of trimethylbenzene (tri-MB) induced by methanol on HZSM-5 surface. This work demonstrated that the integrated catalyst could be advantageous for direct conversion of syngas to tri-MB and finally to the desired Durene and it would open up the new avenues in future perspectives.
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A one-step synthesis method of Durene directly from syngas using integrated catalyst of Cu/ZnO/Al2O3 and Co-Nb/HZSM-5
Chemical Engineering Science, 2019Co-Authors: Jiao Lengkang, Muhammad Asif Nawaz, Like Cheng, Chen Meng, Tianhui Yang, Muhammad Tariq, Dianhua LiuAbstract:Abstract In recent years, the demand for Durene has been increased as the raw material of polyimide. However, traditional synthesis methods of Durene require a large number of steps with lower efficiency. In this study, a novel synthesis method of a bifunctional integrated catalyst had been utilized, in which the methanol synthesis catalyst Cu/ZnO/Al2O3 (CZA) and the aromatization catalyst Co-Nb/HZSM-5 were combined, to synthesize Durene from syngas in one step. Syngas was converted to methanol and dimethyl ether (DME) followed by the production of different aromatics with a high concentration of Durene through the shape selectivity of zeolite. The optimal reaction conditions of 330 °C, 4 MPa, 200 h−1, 3% Co loading, CZA/HZSM-5 = 3:2 and a unique pseudo-physical coating (PC) integrated method were applied to increase Durene selectivity up to 39.71% in aromatics. Different techniques such as XRD, BET, XPS and NH3-TPD were employed to characterize different catalysts, and a variety of experiments were proceeded to compare different routes of methanol and FT synthesis. These results explain that the high selectivity of tetra-methylbenzene (tetra-MB) was due to the alkylation of trimethylbenzene (tri-MB) induced by methanol on HZSM-5 surface. This work demonstrated that the integrated catalyst could be advantageous for direct conversion of syngas to tri-MB and finally to the desired Durene and it would open up the new avenues in future perspectives.
Muhammad Asif Nawaz - One of the best experts on this subject based on the ideXlab platform.
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a one step synthesis method of Durene directly from syngas using integrated catalyst of cu zno al2o3 and co nb hzsm 5
Chemical Engineering Science, 2019Co-Authors: Lengkang Jiao, Muhammad Asif Nawaz, Like Cheng, Chen Meng, Tianhui Yang, Muhammad Tariq, Dianhua LiuAbstract:Abstract In recent years, the demand for Durene has been increased as the raw material of polyimide. However, traditional synthesis methods of Durene require a large number of steps with lower efficiency. In this study, a novel synthesis method of a bifunctional integrated catalyst had been utilized, in which the methanol synthesis catalyst Cu/ZnO/Al2O3 (CZA) and the aromatization catalyst Co-Nb/HZSM-5 were combined, to synthesize Durene from syngas in one step. Syngas was converted to methanol and dimethyl ether (DME) followed by the production of different aromatics with a high concentration of Durene through the shape selectivity of zeolite. The optimal reaction conditions of 330 °C, 4 MPa, 200 h−1, 3% Co loading, CZA/HZSM-5 = 3:2 and a unique pseudo-physical coating (PC) integrated method were applied to increase Durene selectivity up to 39.71% in aromatics. Different techniques such as XRD, BET, XPS and NH3-TPD were employed to characterize different catalysts, and a variety of experiments were proceeded to compare different routes of methanol and FT synthesis. These results explain that the high selectivity of tetra-methylbenzene (tetra-MB) was due to the alkylation of trimethylbenzene (tri-MB) induced by methanol on HZSM-5 surface. This work demonstrated that the integrated catalyst could be advantageous for direct conversion of syngas to tri-MB and finally to the desired Durene and it would open up the new avenues in future perspectives.
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A one-step synthesis method of Durene directly from syngas using integrated catalyst of Cu/ZnO/Al2O3 and Co-Nb/HZSM-5
Chemical Engineering Science, 2019Co-Authors: Jiao Lengkang, Muhammad Asif Nawaz, Like Cheng, Chen Meng, Tianhui Yang, Muhammad Tariq, Dianhua LiuAbstract:Abstract In recent years, the demand for Durene has been increased as the raw material of polyimide. However, traditional synthesis methods of Durene require a large number of steps with lower efficiency. In this study, a novel synthesis method of a bifunctional integrated catalyst had been utilized, in which the methanol synthesis catalyst Cu/ZnO/Al2O3 (CZA) and the aromatization catalyst Co-Nb/HZSM-5 were combined, to synthesize Durene from syngas in one step. Syngas was converted to methanol and dimethyl ether (DME) followed by the production of different aromatics with a high concentration of Durene through the shape selectivity of zeolite. The optimal reaction conditions of 330 °C, 4 MPa, 200 h−1, 3% Co loading, CZA/HZSM-5 = 3:2 and a unique pseudo-physical coating (PC) integrated method were applied to increase Durene selectivity up to 39.71% in aromatics. Different techniques such as XRD, BET, XPS and NH3-TPD were employed to characterize different catalysts, and a variety of experiments were proceeded to compare different routes of methanol and FT synthesis. These results explain that the high selectivity of tetra-methylbenzene (tetra-MB) was due to the alkylation of trimethylbenzene (tri-MB) induced by methanol on HZSM-5 surface. This work demonstrated that the integrated catalyst could be advantageous for direct conversion of syngas to tri-MB and finally to the desired Durene and it would open up the new avenues in future perspectives.
