Micro-mesoporous ZK-1 molecular sieves with different Si/Al ratios were used as supports for binary Co-Mo hydrodesulfurization（HDS） catalysts.The CoMo/ZK-1 catalysts were prepared using an over-loading impregnation ...Micro-mesoporous ZK-1 molecular sieves with different Si/Al ratios were used as supports for binary Co-Mo hydrodesulfurization（HDS） catalysts.The CoMo/ZK-1 catalysts were prepared using an over-loading impregnation method,and characterized using N2 physisorption,X-ray diffraction,temperature-programmed NH3 desorption,temperature-programmed reduction（TPR）,ultraviolet-visible diffuse reflectance spectroscopy,and high-resolution transmission electron microscopy（HRTEM）.The results show that the CoMo/ZK-1 catalysts have high surface areas（～700 m^2/g）,large pore volumes,and hierarchical porous structures,which promote the dispersion of Co and Mo oxide phases on the ZK-1 supports.The TPR results show that the interactions between the Co and Mo oxide phases and the ZK-1 support are weaker than those in the CoMo/γ-Al2O3 catalyst.The HRTEM results show that the CoMo/ZK-1 catalysts have better MoS2 dispersion and more active edge sites.The catalysts were tested in HDS of dibenzothiophene.Under mild reaction conditions,the activity of Co and Mo sulfides supported on ZK-1 was higher than those of Co and Mo sulfides supported on ZSM-5,A1KIT-1,and γ-Al2O3.展开更多
Micro-mesoporous ZSM-5 zeolites were obtained by the post-treatment of tetrahydroxy ammonium hydroxide(TPAOH) solution with different concentration.The hierarchical pore structure formed during the desilication proces...Micro-mesoporous ZSM-5 zeolites were obtained by the post-treatment of tetrahydroxy ammonium hydroxide(TPAOH) solution with different concentration.The hierarchical pore structure formed during the desilication process facilitates the dispersion of Pt nanoparticles and Pt/ZSM-5 catalysts exhibit rather high catalytic activity for the deep oxidation of various VOCs at low temperature.The catalyst treated with TPAOH of 0.1 mol/L(Pt/ZSM-5(0.1)) shows the lowest degradation temperature(T90%) of 128 and 142℃, respectively for benzene and n-hexane.Compared with the untreated Pt/ZSM-5 catalyst, the abundant mesopores, small Pt particle size and finely dispersed Pt contribute to the superior catalytic activity and stability of the Pt/ZSM-5 catalysts for VOCs removal.More importantly, the existence of H_(2)O in the feed gases hardly affected the activity of Pt/ZSM-5(0.1) catalyst at the low reaction temperature of 128℃, which is very important for VOCs low-temperature removal in the future practical applications.展开更多
The conversion of biomass waste into eco-nomical and high-performance energy storage devices receives significant attention.Herein,a facile and green method to prepare porous active carbon from walnut sep-tum is appli...The conversion of biomass waste into eco-nomical and high-performance energy storage devices receives significant attention.Herein,a facile and green method to prepare porous active carbon from walnut sep-tum is applied to the electrode materials of supercapacitors.The effect of chemical etching reagent(KOH)on the microstructure and specific capacitance of the porous car-bon are explored.The modified BC-2.0,with a KOH/walnut septum mass ratio of 2∶1,exhibits large specific surface area of 1003.9 m^(2)·g^(-1)with hierarchical micro-mesoporous structures.BC-2.0 reveals a superior specific capacitance of 457 F·g^(-1)at 1 A·g^(-1).The flexible sym-metric supercapacitor in gel electrolyte(KOH/PVA)exhi-bits considerable synergetic energy-power output performance.The results indicate that walnut septum is a better precursor to obtain activated carbons relative to other biomass carbon sources.The large mesoporosity after activation effectively boosts the electrochemical properties of supercapacitor.Consequently,the walnut septum has potential to be a superior electrode material for supercapacitors.展开更多
A Y-zeolite-containing composite material with micro/mesoporous structure had been synthesized from kaolin by means of the in-situ crystallization method. The obtained samples were investigated by XRD and BET methods....A Y-zeolite-containing composite material with micro/mesoporous structure had been synthesized from kaolin by means of the in-situ crystallization method. The obtained samples were investigated by XRD and BET methods. Evaluation of catalytic activity of both the commercial Y-zeolite and the novel Y-zeolite-containing composite material was carried out in the pulse micro-chromatography platform with two probe molecules of different molecular sizes： VGO feedstock and 1,3,5 tri-isopropyl benzene. It was found that the Y-zeolite-containing composite material was richer in external surface and meso-/macro-pores; the Y-zeolite-containing composite material demonstrated a smaller rate of deactivation compared to the commercial Y-zeolite.展开更多
A novel micro-mesoporous silicoaluminophosphate(MUS-5) with controlled morphology has been first synthesized in a two-step route.The physical properties of the silicoaluminophosphate were characterized using XRD,SEM,T...A novel micro-mesoporous silicoaluminophosphate(MUS-5) with controlled morphology has been first synthesized in a two-step route.The physical properties of the silicoaluminophosphate were characterized using XRD,SEM,TEM,nitrogen adsorption-desorption and NH3-TPD techniques.When the pH value of the solution system was varied in the range from 2.0 to 5.0,three different morphologies of silicoaluminophosphate including chain-like,flower-like and barrel-like morphology were obtained.Catalytic tests showed that the silicoaluminophosphate exhibited higher catalytic activity compared with the conventional microporous SAPO-5 under the same conditions for catalytic cracking of 1,3,5-triisopropylbenzene heavy aromatics.The remarkable catalytic reactivity was mainly attributed to the presence of the hierarchical porosity in the silicoaluminophosphate catalyst.展开更多
Nitrogenization is an effective method for improving the capacitive deionization(CDI)performance of porous carbon materials.In particular,polymer organic frameworks with heteroatom doping,containing an ordered pore st...Nitrogenization is an effective method for improving the capacitive deionization(CDI)performance of porous carbon materials.In particular,polymer organic frameworks with heteroatom doping,containing an ordered pore structure and excellent electrochemical stability,are ideal precursors for carbon materials for high-performance CDI.In this study,a nitrogen-enriched micro-mesoporous carbon(NMC)electrode was fabricated by carbonizing a Schiff base network-1 at 500,600,and 700℃.Scanning electron microscopy,Fourier transform infrared spectroscopy,X-ray diffraction,N_(2) adsorption-desorption,the contact angle of water,cyclic voltammetry,and electrochemical impedance spectroscopy were used to characterize the morphological structure,wettability,Brunauer–Emmett–Teller surface areas,and electrochemical performance of the NMCs.The results showed that the NMC carbonized at 600℃ achieved the best specific capacitance(152.33 F/g),as well as a high electrosorption capacity(25.53 mg/g)because of its chemical composition(15.57%N)and surface area(312 m^(2)/g).These findings prove that NMC is viable as an electrode material for desalination by high-performance CDI applications.展开更多
This work presents a synthesis of bimetallic NiMo and NiW modified ZSM-5/MCM-41 composites and their heterogeneous catalytic conversion of crude palm oil( CPO) to biofuels. The ZSM-5/MCM-41 composites were synthesized...This work presents a synthesis of bimetallic NiMo and NiW modified ZSM-5/MCM-41 composites and their heterogeneous catalytic conversion of crude palm oil( CPO) to biofuels. The ZSM-5/MCM-41 composites were synthesized through a self-assembly of cetyltrimethylammonium bromide( CTAB) surfactant with silica-alumina from ZSM-5 zeolite,prepared from natural kaolin by the hydrothermal technique. Subsequently,the synthesized composites were deposited with bimetallic NiMo and NiW by impregnation method. The obtained catalysts presented a micro-mesoporous structure,confirmed by XRD,SEM,TEM,EDX,NH_3-TPD,XRF and N_2 adsorption-desorption measurements. The results of CPO conversion demonstrate that the catalytic activity of the synthesized catalysts decreases in the series of NiMo-ZSM-5/MCM-41 > NiW-ZSM-5/MCM-41 > Ni-ZSM-5/MCM-41 > Mo-ZSM-5/MCM-41 > W-ZSM-5/MCM-41 > NiMo-ZSM-5 > NiW-ZSM-5 > ZSM-5/MCM-41 > ZSM-5 > MCM-41. It was found that the bimetallic NiMo-and NiW-ZSM-5/MCM-41 catalysts give higher yields of liquid hydrocarbons than other catalysts at a given conversion. Types of hydrocarbon in liquid products,identified by simulated distillation gas chromatography-flame ionization detector( SimDis GC-FID),are gasoline( 150-200 ℃; C5-12),kerosene( 250-300 ℃; C5-20) and diesel( 350 ℃; C7-20).Moreover,the conversion of CPO to biofuel products using the NiMo-and NiW-ZSM-5/MCM-41 catalysts offers no statistically significant difference( P> 0.05) at 95% confidence level,evaluated by SPSS analysis.展开更多
In the process of toluene adsorption, the choice of adsorbent is the key. In this work, micro-mesoporous carbon materials were prepared and characterized. The synthesis process was performed by using MCM-41 as the tem...In the process of toluene adsorption, the choice of adsorbent is the key. In this work, micro-mesoporous carbon materials were prepared and characterized. The synthesis process was performed by using MCM-41 as the template, and sucrose and furfuryl alcohol as the carbon source, respectively. The toluene adsorption capacity of studied adsorbents was evaluated under different toluene initial concentration, temperature and bed height. In order to further improve the adsorption capacity, nitric acid was used for modification of the selected adsorbent. The adsorption performance after modification was also investigated. The prepared carbon materials were characteristic of typical type IV isotherms and pore size distribution was focused on micropores and mesopores. Compared with MCM-41, the prepared carbon materials showed high toluene adsorption capacity. After modification the specific surface area and oxygen groups of adsorbent were increased, making the adsorption capacity increase from 185.3 mg/g to a maximum value of 514.7 mg/g. The adsorption capacity of adsorbent mainly depended on its surface area and surface chemical property.展开更多
The hierarchically structured micro-mesoporous spheres(MMS) composed of mesoporous silica and Ti-containing mordenite (Ti-MOR) zeolite were self-assembled in an oil-in-water microemulsion system containing tetrabutyl ...The hierarchically structured micro-mesoporous spheres(MMS) composed of mesoporous silica and Ti-containing mordenite (Ti-MOR) zeolite were self-assembled in an oil-in-water microemulsion system containing tetrabutyl orthosilicate as silica source, cetyltrimethylammonium bromide as template and aluminum sulfate as additive. The composite materials possessed the connatural microporosity of zeolite together with the disordered mesopores(5.41 nm) in silica part. With a special focus on the importance of aluminum sulfate additive, a possible formation mechanism has been proposed, in which double electrostatic interactions played the crucial role of mediating the mesosilica species and zeolite crystals. The obtained MMS materials, with a tunable particle dimension(250-720 μm) and a changeable content of active component Ti-MOR(44%-70%), showed enhanced catalytic activity and lifetime in the liquid-phase ammoximation of cyclohexanone in comparison to the parent Ti-MOR powder.展开更多
Adsorption of pure CO_(2) and N2 and separation of CO_(2)/N2 mixture in MFI zeolite and MFI/MCM-41 micro/mesoporous composite have been studied by using atomistic simulations.Fully atomistic models of MFI and MFI/MCM-...Adsorption of pure CO_(2) and N2 and separation of CO_(2)/N2 mixture in MFI zeolite and MFI/MCM-41 micro/mesoporous composite have been studied by using atomistic simulations.Fully atomistic models of MFI and MFI/MCM-41 are constructed and characterized.A bimodal pore size distribution is observed in MFI/MCM-41 from simulated small-and broad-angle X-ray diffrac-tion patterns.The density of MFI/MCM-41 is lower than MFI,while its free volume and specific surface area are greater than MFI due to the presence of mesopores.CO_(2) is preferentially adsorbed than N2,and thus,the loading and isosteric heat of CO_(2) are greater than N2 in both MFI and MFI/MCM-41.CO_(2) isotherm in MFI/MCM-41 is similar to that in MFI at low pressures,but resembles that in MCM-41 at high pressures.N2 shows similar amount of loading in MFI,MCM-41 and MFI/MCM-41.The selectivity of CO_(2) over N2 in the three adsorbents decreases in the order of MFI>MFI/MCM-41>MCM-41.With increasing pressure,the selectivity increases in MFI and MFI/MCM-41,but decreases in MCM-41.The self-diffusivity of CO_(2) and N2 in MFI decreases as loading increases,while in MFI/MCM-41,itfirst increases and then drops.展开更多
采用水热合成法辅加磁场成功制备了b、c复合轴向型ZSM-5分子筛,考察了磁感线分布、磁场强度和作用时间对ZSM-5分子筛结构和甲醇芳构化反应催化性能的影响。结果表明,磁场强度和作用时间可以精密调控材料的孔径分布;磁场强度47.1 m T,平...采用水热合成法辅加磁场成功制备了b、c复合轴向型ZSM-5分子筛,考察了磁感线分布、磁场强度和作用时间对ZSM-5分子筛结构和甲醇芳构化反应催化性能的影响。结果表明,磁场强度和作用时间可以精密调控材料的孔径分布;磁场强度47.1 m T,平行磁感线位置下作用5 h,合成材料具有b、c-复合轴取向结构,介孔的比表面积和孔容比分别达到67%和78%。相比常规ZSM-5,新材料具有更高的催化稳定性,反应20 h后的甲醇转化率和芳烃收率保持在98%和36%以上。展开更多
基金financially supported by the National Natural Science Foundation of China (NNSFC,21206017)~~
文摘Micro-mesoporous ZK-1 molecular sieves with different Si/Al ratios were used as supports for binary Co-Mo hydrodesulfurization（HDS） catalysts.The CoMo/ZK-1 catalysts were prepared using an over-loading impregnation method,and characterized using N2 physisorption,X-ray diffraction,temperature-programmed NH3 desorption,temperature-programmed reduction（TPR）,ultraviolet-visible diffuse reflectance spectroscopy,and high-resolution transmission electron microscopy（HRTEM）.The results show that the CoMo/ZK-1 catalysts have high surface areas（～700 m^2/g）,large pore volumes,and hierarchical porous structures,which promote the dispersion of Co and Mo oxide phases on the ZK-1 supports.The TPR results show that the interactions between the Co and Mo oxide phases and the ZK-1 support are weaker than those in the CoMo/γ-Al2O3 catalyst.The HRTEM results show that the CoMo/ZK-1 catalysts have better MoS2 dispersion and more active edge sites.The catalysts were tested in HDS of dibenzothiophene.Under mild reaction conditions,the activity of Co and Mo sulfides supported on ZK-1 was higher than those of Co and Mo sulfides supported on ZSM-5,A1KIT-1,and γ-Al2O3.
基金supported by a grant from the National Key Research and Development Program of China (No.2016YFC0204300)the Nature Science Foundation of China (No.21477109)。
文摘Micro-mesoporous ZSM-5 zeolites were obtained by the post-treatment of tetrahydroxy ammonium hydroxide(TPAOH) solution with different concentration.The hierarchical pore structure formed during the desilication process facilitates the dispersion of Pt nanoparticles and Pt/ZSM-5 catalysts exhibit rather high catalytic activity for the deep oxidation of various VOCs at low temperature.The catalyst treated with TPAOH of 0.1 mol/L(Pt/ZSM-5(0.1)) shows the lowest degradation temperature(T90%) of 128 and 142℃, respectively for benzene and n-hexane.Compared with the untreated Pt/ZSM-5 catalyst, the abundant mesopores, small Pt particle size and finely dispersed Pt contribute to the superior catalytic activity and stability of the Pt/ZSM-5 catalysts for VOCs removal.More importantly, the existence of H_(2)O in the feed gases hardly affected the activity of Pt/ZSM-5(0.1) catalyst at the low reaction temperature of 128℃, which is very important for VOCs low-temperature removal in the future practical applications.
基金financially supported by the National Natural Science Foundation of China (Nos. 51874079 and 11775226)the Natural Science Foundation of Hebei Province (Nos. E2018501091, E2020501001 and E2021501029)+2 种基金Hebei Province Key Research and Development Plan Project (No.19211302D)the Natural Science Foundation of Liaoning Province (No. 2019-MS-110)the Fundamental Research Funds for the Central Universities (No. N2023040 and N2123035)
文摘The conversion of biomass waste into eco-nomical and high-performance energy storage devices receives significant attention.Herein,a facile and green method to prepare porous active carbon from walnut sep-tum is applied to the electrode materials of supercapacitors.The effect of chemical etching reagent(KOH)on the microstructure and specific capacitance of the porous car-bon are explored.The modified BC-2.0,with a KOH/walnut septum mass ratio of 2∶1,exhibits large specific surface area of 1003.9 m^(2)·g^(-1)with hierarchical micro-mesoporous structures.BC-2.0 reveals a superior specific capacitance of 457 F·g^(-1)at 1 A·g^(-1).The flexible sym-metric supercapacitor in gel electrolyte(KOH/PVA)exhi-bits considerable synergetic energy-power output performance.The results indicate that walnut septum is a better precursor to obtain activated carbons relative to other biomass carbon sources.The large mesoporosity after activation effectively boosts the electrochemical properties of supercapacitor.Consequently,the walnut septum has potential to be a superior electrode material for supercapacitors.
文摘A Y-zeolite-containing composite material with micro/mesoporous structure had been synthesized from kaolin by means of the in-situ crystallization method. The obtained samples were investigated by XRD and BET methods. Evaluation of catalytic activity of both the commercial Y-zeolite and the novel Y-zeolite-containing composite material was carried out in the pulse micro-chromatography platform with two probe molecules of different molecular sizes： VGO feedstock and 1,3,5 tri-isopropyl benzene. It was found that the Y-zeolite-containing composite material was richer in external surface and meso-/macro-pores; the Y-zeolite-containing composite material demonstrated a smaller rate of deactivation compared to the commercial Y-zeolite.
基金supported by the National Basic Research Program of China (2003CB615802)
文摘A novel micro-mesoporous silicoaluminophosphate(MUS-5) with controlled morphology has been first synthesized in a two-step route.The physical properties of the silicoaluminophosphate were characterized using XRD,SEM,TEM,nitrogen adsorption-desorption and NH3-TPD techniques.When the pH value of the solution system was varied in the range from 2.0 to 5.0,three different morphologies of silicoaluminophosphate including chain-like,flower-like and barrel-like morphology were obtained.Catalytic tests showed that the silicoaluminophosphate exhibited higher catalytic activity compared with the conventional microporous SAPO-5 under the same conditions for catalytic cracking of 1,3,5-triisopropylbenzene heavy aromatics.The remarkable catalytic reactivity was mainly attributed to the presence of the hierarchical porosity in the silicoaluminophosphate catalyst.
基金supported by the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program(No.2017BT01Z032)the National Natural Science Foundation of China(No.21577027)the 2017 Central Special Fund for Soil,Preliminary Study on Harmless Treatment and Comprehensive Utilization of Tailings in Dabao Mountain(No.18HK0108)。
文摘Nitrogenization is an effective method for improving the capacitive deionization(CDI)performance of porous carbon materials.In particular,polymer organic frameworks with heteroatom doping,containing an ordered pore structure and excellent electrochemical stability,are ideal precursors for carbon materials for high-performance CDI.In this study,a nitrogen-enriched micro-mesoporous carbon(NMC)electrode was fabricated by carbonizing a Schiff base network-1 at 500,600,and 700℃.Scanning electron microscopy,Fourier transform infrared spectroscopy,X-ray diffraction,N_(2) adsorption-desorption,the contact angle of water,cyclic voltammetry,and electrochemical impedance spectroscopy were used to characterize the morphological structure,wettability,Brunauer–Emmett–Teller surface areas,and electrochemical performance of the NMCs.The results showed that the NMC carbonized at 600℃ achieved the best specific capacitance(152.33 F/g),as well as a high electrosorption capacity(25.53 mg/g)because of its chemical composition(15.57%N)and surface area(312 m^(2)/g).These findings prove that NMC is viable as an electrode material for desalination by high-performance CDI applications.
基金The financial supported by Nakhon Ratchasima Rajabhat University,Nakhon Ratchasimathe National Research Council of Thailand+3 种基金Center of Excellence for Innovation in Chemistry (PERCH-CIC)Office of the Higher Education CommissionMinistry of Education and Materials Chemistry Research CenterDepartment of Chemistry Faculty of Science,Khon Kaen University,Thailand
文摘This work presents a synthesis of bimetallic NiMo and NiW modified ZSM-5/MCM-41 composites and their heterogeneous catalytic conversion of crude palm oil( CPO) to biofuels. The ZSM-5/MCM-41 composites were synthesized through a self-assembly of cetyltrimethylammonium bromide( CTAB) surfactant with silica-alumina from ZSM-5 zeolite,prepared from natural kaolin by the hydrothermal technique. Subsequently,the synthesized composites were deposited with bimetallic NiMo and NiW by impregnation method. The obtained catalysts presented a micro-mesoporous structure,confirmed by XRD,SEM,TEM,EDX,NH_3-TPD,XRF and N_2 adsorption-desorption measurements. The results of CPO conversion demonstrate that the catalytic activity of the synthesized catalysts decreases in the series of NiMo-ZSM-5/MCM-41 > NiW-ZSM-5/MCM-41 > Ni-ZSM-5/MCM-41 > Mo-ZSM-5/MCM-41 > W-ZSM-5/MCM-41 > NiMo-ZSM-5 > NiW-ZSM-5 > ZSM-5/MCM-41 > ZSM-5 > MCM-41. It was found that the bimetallic NiMo-and NiW-ZSM-5/MCM-41 catalysts give higher yields of liquid hydrocarbons than other catalysts at a given conversion. Types of hydrocarbon in liquid products,identified by simulated distillation gas chromatography-flame ionization detector( SimDis GC-FID),are gasoline( 150-200 ℃; C5-12),kerosene( 250-300 ℃; C5-20) and diesel( 350 ℃; C7-20).Moreover,the conversion of CPO to biofuel products using the NiMo-and NiW-ZSM-5/MCM-41 catalysts offers no statistically significant difference( P> 0.05) at 95% confidence level,evaluated by SPSS analysis.
基金financially supported by the Independent Project Program of State Key Laboratory of Petroleum Pollution Control (No. PPCIP2017005)the CNPC Research Institute of Safety and Environmental Technologythe Top Talents Project of China University of Petroleum (grant No. 2015011)
文摘In the process of toluene adsorption, the choice of adsorbent is the key. In this work, micro-mesoporous carbon materials were prepared and characterized. The synthesis process was performed by using MCM-41 as the template, and sucrose and furfuryl alcohol as the carbon source, respectively. The toluene adsorption capacity of studied adsorbents was evaluated under different toluene initial concentration, temperature and bed height. In order to further improve the adsorption capacity, nitric acid was used for modification of the selected adsorbent. The adsorption performance after modification was also investigated. The prepared carbon materials were characteristic of typical type IV isotherms and pore size distribution was focused on micropores and mesopores. Compared with MCM-41, the prepared carbon materials showed high toluene adsorption capacity. After modification the specific surface area and oxygen groups of adsorbent were increased, making the adsorption capacity increase from 185.3 mg/g to a maximum value of 514.7 mg/g. The adsorption capacity of adsorbent mainly depended on its surface area and surface chemical property.
基金This work was supported by the Project of China Ministry of Science and Technology(No.2021YFA1501401)the National Natural Science Foundation of China(Nos.21972044,21872052)the Fundamental Research Funds for the Central Universities,China.
文摘The hierarchically structured micro-mesoporous spheres(MMS) composed of mesoporous silica and Ti-containing mordenite (Ti-MOR) zeolite were self-assembled in an oil-in-water microemulsion system containing tetrabutyl orthosilicate as silica source, cetyltrimethylammonium bromide as template and aluminum sulfate as additive. The composite materials possessed the connatural microporosity of zeolite together with the disordered mesopores(5.41 nm) in silica part. With a special focus on the importance of aluminum sulfate additive, a possible formation mechanism has been proposed, in which double electrostatic interactions played the crucial role of mediating the mesosilica species and zeolite crystals. The obtained MMS materials, with a tunable particle dimension(250-720 μm) and a changeable content of active component Ti-MOR(44%-70%), showed enhanced catalytic activity and lifetime in the liquid-phase ammoximation of cyclohexanone in comparison to the parent Ti-MOR powder.
基金supported by the National Natural Science Foundation of China(Grant Nos.20736002,20776045)the National High Technology Research and Development Program of China(No.2008AA062302)+1 种基金Program for Changjiang Scholars and Innovative Research Team in University of China(No.IRT0721)the 111 Project of China(No.B08021).
文摘Adsorption of pure CO_(2) and N2 and separation of CO_(2)/N2 mixture in MFI zeolite and MFI/MCM-41 micro/mesoporous composite have been studied by using atomistic simulations.Fully atomistic models of MFI and MFI/MCM-41 are constructed and characterized.A bimodal pore size distribution is observed in MFI/MCM-41 from simulated small-and broad-angle X-ray diffrac-tion patterns.The density of MFI/MCM-41 is lower than MFI,while its free volume and specific surface area are greater than MFI due to the presence of mesopores.CO_(2) is preferentially adsorbed than N2,and thus,the loading and isosteric heat of CO_(2) are greater than N2 in both MFI and MFI/MCM-41.CO_(2) isotherm in MFI/MCM-41 is similar to that in MFI at low pressures,but resembles that in MCM-41 at high pressures.N2 shows similar amount of loading in MFI,MCM-41 and MFI/MCM-41.The selectivity of CO_(2) over N2 in the three adsorbents decreases in the order of MFI>MFI/MCM-41>MCM-41.With increasing pressure,the selectivity increases in MFI and MFI/MCM-41,but decreases in MCM-41.The self-diffusivity of CO_(2) and N2 in MFI decreases as loading increases,while in MFI/MCM-41,itfirst increases and then drops.
文摘采用水热合成法辅加磁场成功制备了b、c复合轴向型ZSM-5分子筛,考察了磁感线分布、磁场强度和作用时间对ZSM-5分子筛结构和甲醇芳构化反应催化性能的影响。结果表明,磁场强度和作用时间可以精密调控材料的孔径分布;磁场强度47.1 m T,平行磁感线位置下作用5 h,合成材料具有b、c-复合轴取向结构,介孔的比表面积和孔容比分别达到67%和78%。相比常规ZSM-5,新材料具有更高的催化稳定性,反应20 h后的甲醇转化率和芳烃收率保持在98%和36%以上。
