Composite thermochemical energy storage(TCES)represents an exciting field of thermal energy storage which could address the issue of seasonal variance in renewable energy supply.However,there are open questions about ...Composite thermochemical energy storage(TCES)represents an exciting field of thermal energy storage which could address the issue of seasonal variance in renewable energy supply.However,there are open questions about their performance and the root cause of some observed phenomena.Some researchers have observed the breakdown of particles in their production phase,and in their use.This study seeks to investigate the underlying cause of this breakdown.SEM and EDX analysis have been conducted on MgCl2 impregnated 13X zeolite composites of differing diameters,as well as LiX zeolite.This was done in order to study the level of impregnation of salt into the zeolite matrix,as well as the effect this impregnation process has on the morphology of the zeolite.Analysis was conducted using ImageJ software to study the effect of the impregnation process on the diameter of the particles.It has been found that a by weight impregnation concentration of magnesium chloride of 11.90%for the LiX zeolite,and 7.59%and 5.26%for the large diameter 13X zeolite and the small diameter 13X zeolite respectively has been achieved.It has been found that the impregnation process significantly affects themorphology of 13X zeolite particles,causing large fissures to form,and eventually resulting in the previously found breakdown of these particles.It has been verified that a primary factor influencing the breakdown of the 13X zeolite particles is the efflorescence and sub-fluorescence phenomena,which leads to a build-up of crystals in the zeolite pores.It has also been found that prolonged impregnation times and the use of high concentration salt solutions in the soaking process can induce significant crystal growth which also leads to the breakdown of these particles.Results demonstrate that LiX zeolite is the optimum host matrix choice in these conditions.These results will allow for the design of more resilient composite TCES particles.展开更多
In this review, we summaries the past few year work on the chemistry of CWA’s and their simulants on various heterogeneous surfaces of zeolites, composites of zeolites and doped zeolite with transition metal oxides. ...In this review, we summaries the past few year work on the chemistry of CWA’s and their simulants on various heterogeneous surfaces of zeolites, composites of zeolites and doped zeolite with transition metal oxides. This review elaborates an updated literature overview on the degradation of CWA’s and its simulants. The data written in this review were collected from the peer-reviewed national and international literature.展开更多
For investigating the effect of dealumination on the pore structure and catalytic performance, ZSM-5/Y composite zeolites synthesized in situ from NaY gel were dealuminated by steaming at different temperatures. XRD ...For investigating the effect of dealumination on the pore structure and catalytic performance, ZSM-5/Y composite zeolites synthesized in situ from NaY gel were dealuminated by steaming at different temperatures. XRD (X-ray diffraction) characterization indicates that the relative crystallinity of the composite zeolites decreases with the increase in Si/Al ratio after steaming. N2 adsorption-desorption suggests that more mesopores are formed while the BET (Brunauer, Emmett and Teller) specific surface area and the micropore specific surface area decrease as the temperature of steaming rises. Daqing heavy oil was used as feedstock to test the catalytic cracking activity of ZSM-5/Y composite zeolites. The experimental results of the catalytic cracking performance reveal that the distribution of products differs due to the different conditions of hydrothermal treatment. Further hydrothermal treatment leads to an increase in the yield of light oil, and a decrease in the yield of gas products and coke.展开更多
Y-β zeolite composites were hydrotherrnally synthesized by using high silica Y zeolite as the precursor and characterized by XRD, N2 adsorption, SEM and IR spectra of pyridine. The result showed that the N2 adsorptio...Y-β zeolite composites were hydrotherrnally synthesized by using high silica Y zeolite as the precursor and characterized by XRD, N2 adsorption, SEM and IR spectra of pyridine. The result showed that the N2 adsorption-desorption isotherm of the zeolite composites had a distinct hysteresis loop, and the SEM result showed that the zeolite composites had a different morphology from Y, β and the corresponding physical zeolite mixture. The acid catalytic performance of the zeolite composite catalysts was investigated in the hydrocracking and hydroisomerization of n-octane, and the results showed that the composite materials exhibited an excellent hydrocracking activity and good hydroisomerization performance. The yield of i-C4 over the zeolite composite catalyst was 4.45% higher than that on the corresponding zeolite mixture in the n-octane hydrocracking process at 553 K. The isomerization ability of n-octane over the composite catalyst was 3.6 fold that of the corresponding mixture at 503 K.展开更多
This study investigated the adsorption ability of ZCHC （zeolite/chitosan hybrid composite） as adsorbent for chromium （Cr（Ⅵ））, ZCHC was prepared with sol-gel method by mixing zeolite and chitosan. Adsorption exp...This study investigated the adsorption ability of ZCHC （zeolite/chitosan hybrid composite） as adsorbent for chromium （Cr（Ⅵ））, ZCHC was prepared with sol-gel method by mixing zeolite and chitosan. Adsorption experiment from aqueous solutions containing known amount of Cr（Ⅵ） using zeolite, chitosan and ZCHC was explored to evaluate the efficiency of ZCHC as adsorbent for Cr in a batch system. The amount of Cr（Ⅵ） adsorbed at different pH values, initial concentrations, adsorbent dosages, and contact times were determined by ICP-AES （inductively coupled plasma-atomic emission spectrometry） in order to determine the optimum conditions for Cr（Ⅵ） adsorption. Furthermore, the adsorption mechanism of Cr（Ⅵ） by zeolite, chitosan and ZCHC was investigated by applying Langmuir and Freundlich isotherm equations to the data obtained. In addition, the rates of adsorption were found to conform to pseudo-second order kinetics.展开更多
Zeolite/TiO-2 composite photocatalysts were prepared by adding a certain amount of mordenite in TiO-2, and degradation experiments on toluene through photocatalytic reactions were implemented. In this paper, these pho...Zeolite/TiO-2 composite photocatalysts were prepared by adding a certain amount of mordenite in TiO-2, and degradation experiments on toluene through photocatalytic reactions were implemented. In this paper, these photocatalysts were characterized by using SEM, IR, RAMAN, XRD and UV-Vis to shed light on the microstructure and photocatalytic performance of the composite photocatalysts. The results indicated that the structural hydroxy of zeolite can participate in bonding reaction with TiO-2, the addition of zeolite can greatly reduce the diameter of nanometer TiO-2 particles in the composite photocatalysts, and enhance the ultraviolet light absorptance of the composite photocatalysts. When the percentage content of zeolite reached 20%, the photocatalytic performance of this catalyst would be highest, with the toluene conversion rate up to {94.58%}.展开更多
The composite ZSM—5 zeolite/vermiculite catalyst,in which tiny ZSM—5 zeolite parti- cles embedded in the vermiculite substrate,has been synthesized by hydrothermal method with vermiculite as silicon source.The catal...The composite ZSM—5 zeolite/vermiculite catalyst,in which tiny ZSM—5 zeolite parti- cles embedded in the vermiculite substrate,has been synthesized by hydrothermal method with vermiculite as silicon source.The catalytic behavior of resulting catalyst for xylene isomerization,propylene aromatization and toluene disproportionation is better than that of HZSM—5 zeolite.展开更多
Red soil,the most critical soil resource in tropical/subtropical regions worldwide,faces tremendous threats,including nutrient deficiency,acidification,and heavy metal contamination.There is a great demand for multifu...Red soil,the most critical soil resource in tropical/subtropical regions worldwide,faces tremendous threats,including nutrient deficiency,acidification,and heavy metal contamination.There is a great demand for multifunctional eco-materials capable of modifying this situation.Herein,we used widely distributed soil and biomass to develop a zeolite/biochar composite for synergistic red soil remediation and amendment.With the composite material,the Pb^(2+) and Cd^(2+) remediation efficiencies reached 92.8%and 92.9%,respectively,in stems under optimal conditions.Moreover,the acidity and nutrient deficiency conditions of red soil significantly improved.The atomic-scale interaction mechanism during the remediation and amendment process was elucidated with complementary characterization methods,which revealed that in the zeolite/biochar composite material,zeolite contributes to longterm heavy metal remediation effects.Simultaneously,biochar is responsible for soil quality amendment and short-term heavy metal remediation.Furthermore,for the first time,single-atom heavy metal ions were observed on biochar during the remediation process,indicating the broad distribution of single atoms in the natural environment.展开更多
n-Alkane isomerization is a critical reaction that can affect parameters in oil refining, such as the gasoline octane number and diesel oil solidifying point. In this study, a catalyst support, mordenite (MOR)/silicoa...n-Alkane isomerization is a critical reaction that can affect parameters in oil refining, such as the gasoline octane number and diesel oil solidifying point. In this study, a catalyst support, mordenite (MOR)/silicoaluminophosphate (SAPO)-11 composite zeolite with core/shell structure, was synthesized by hydrothermal method with MOR acting as the seed for crystallization. The crystal structure, elemental composition, surface area, pore volume, and acidity of the catalyst was thoroughly characterized. In addition, the catalytic performance of the as-obtained Pt/MOR/SAPO-11 in the hydroisomerization of n-dodecane was tested. The results indicated that the properties and catalytic performance of the composite molecular sieve were quite different from those of the pure zeolites and physical mixture of MOR and SAPO-11 (MOR+SAPO-11). Compared with the physical mixture, MOR and SAPO-11 were more tightly bound in MOR/SAPO-11 because of chemical bonding. Moreover, the acidity and pore structure were favorable to the catalytic hydroisomerization of n-dodecane. Pt/MOR/SAPO-11 exhibited higher isomerization activity than the Pt-loaded pristine MOR and MOR+SAPO-11. Thus, the core-shell composite molecular sieve has promising industrial applications as the catalyst support.展开更多
Traditional solvent recovery in the extraction step of edible oil processing is distillation,which consumes large amounts of energy.If the distillation is replaced by membrane process,the energy consumption can be red...Traditional solvent recovery in the extraction step of edible oil processing is distillation,which consumes large amounts of energy.If the distillation is replaced by membrane process,the energy consumption can be reduced greatly.In this work,two kinds of membrane,PDMS(polydimethylsiloxane) composite membrane and Zeolite filled PDMS membrane were prepared,in which asymmetric microporous PVDF(polyvinylidenefluoride) membrane prepared with phase inversion method was functioned as the microporous supporting layer in the flat-plate composite membrane.The different function compositions of the PDMS/PVDF composite membranes were characterized by reflection Fourier transform infrared(FTIR) spectroscopy.The surface and section of PDMS/PVDF composite membranes were investigated by scanning electron microscope(SEM).The PDMS NF(nanofiltration) membranes were then applied in the recovery of hexane from soybean oil/hexane miscellas(1:3,mass ratio).The effects of pressure(0.5-1.5 MPa),cross-linking temperature and PDMS layer thickness on membrane performances were investigated.The results indicated that both two kinds of NF membranes were promising for solvent recovery,and zeolite filled in PDMS NF membrane could enhance the separation performance.展开更多
A ZSM-5/MAPO composite catalyst was prepared by adding ZSM-5 zeolite powder to a conventional molecular sieve synthesis system, followed by modification with NH_4H_2PO_4. The samples were characterized by XRD, SEM, IR...A ZSM-5/MAPO composite catalyst was prepared by adding ZSM-5 zeolite powder to a conventional molecular sieve synthesis system, followed by modification with NH_4H_2PO_4. The samples were characterized by XRD, SEM, IR, NH_3-TPD, and BET analyses. The catalytic property of the samples toward the methanol-to-olefin(MTO) reaction was evaluated in a connected in series two-stage unit equipped with a continuous flow(once-through) fixed-bed tubular reactor similar to an industrial reactor. The first reactor mainly converted methanol into dimethyl ether and water, followed by being subject to continuous reaction in the second reactor, in which DME was converted to hydrocarbons. The composites exhibited the typical framework topology of MFI, AEI and AFI, which represented the ZSM-5 zeolite, the molecular sieves AlPO-18 or SAPO-18, AlPO-5 or SAPO-5, respectively. The composites showed several advantages for optimizing the zeolite acidity, enhancing the mass transfer, and restraining the side reactions. Catalytic reaction results showed that the composites exhibited higher selectivity to light olefins(84.0%) and lower selectivity to C_2―C_4 alkanes and C_5^+ hydrocarbons than pure ZSM-5. Moreover, the composite zeolite loaded with 3% of P demonstrated improved catalytic activity and stability for the conversion of methanol to propylene, because the coking rate was obviously suppressed.展开更多
In this paper,the kaolin/urea intercalation composites prepared by direct intercalation method and the catalysis composites containing ZSM-5 molecular sieve synthesized based on the kaolin/urea intercalation composite...In this paper,the kaolin/urea intercalation composites prepared by direct intercalation method and the catalysis composites containing ZSM-5 molecular sieve synthesized based on the kaolin/urea intercalation composites by an in-situ crystallization technique were investigated.The effects of the intercalation ratios and de-intercalation rate and the amounts of added kaolin/urea intercalation composite on the synthesis of the catalysis composites containing the ZSM-5 molecular sieve were studied.The samples were characterized by X-ray diffraction,FT-IR,TG-DTA,N2 adsorption-desorption,and SEM,respectively.The results showed that the structure of the samples prepared by kaolin/urea intercalation composite was pure ZSM-5 molecular sieve.The crystallinity of ZSM-5 molecular sieve increased at first and then decreased with the increase of intercalation ratio of kaolin/urea intercalation composite.When the intercalation ratio was 62%,the crystallinity of ZSM-5 molecular sieve was lower.When the amount of added kaolin/urea intercalation composite with an intercalation ratio of 22%was 3%,the crystallinity of ZSM-5 zeolite was improved to reach 65%.Compared to the crystallization product formed without adding kaolin/urea intercalation composite,the crystallinity of ZSM-5 molecular sieve has increased by 54.8%.The catalytic composites containing ZSM-5 molecular sieve had better thermal stability with a wide pore structure,featuring a particle diameter of about 2.5μm,a BET specific surface area of 236 m^2/g,and a pore size of 10.6 nm.展开更多
Systematic analysis and comparative study of the chemical compositions of rocks and ores from the main types of zeolite deposits in the surroundings of the Songliao Basin have shown that the process of formation of ze...Systematic analysis and comparative study of the chemical compositions of rocks and ores from the main types of zeolite deposits in the surroundings of the Songliao Basin have shown that the process of formation of zeolite from volcanic and pyroclastic rocks is generally characterized by the relative purification of SiO\-2, i.e., SiO\-2/Al\-2O\-3 ratios tend to increase, alkali earth elements (CaO+MgO) and H\-2O are relatively enriched, and the alkali metals (K\-2O+Na\-2O) are depleted in their total amount. The alkali metals K and Na follow different rules of migration and enrichment during the formation of mordenite and clinoptilolite. In the process of formation of mordenite more Na\++ will be imported and K\++ will be lost remarkably. On the contrary, in the process of formation clinoptilolite more K\++ will be incorporated and Na\++ will become obviously depleted.展开更多
采用阳离子型季铵盐二甲基二烯丙基氯化铵(DMDAAC)对球磨后的天然沸石进行改性处理,将其等量替代部分炭黑后填充至天然橡胶(NR)中,制备天然沸石或改性沸石/NR复合材料,并对其进行结构表征和性能测试。通过离子交换反应,DMDAAC可以吸附...采用阳离子型季铵盐二甲基二烯丙基氯化铵(DMDAAC)对球磨后的天然沸石进行改性处理,将其等量替代部分炭黑后填充至天然橡胶(NR)中,制备天然沸石或改性沸石/NR复合材料,并对其进行结构表征和性能测试。通过离子交换反应,DMDAAC可以吸附在沸石表面,改变了沸石表面的化学性质,降低了沸石的极性,从而改善了沸石在NR中的分散效果,提升胶料的力学性能。结果表明,当替代量为5份时,硫化胶的抗拉强度可达28.6 MPa、撕裂强度为119.3 kN/m;阿克隆磨耗体积最小,为0.28 cm 3;抗屈挠疲劳效果最好,为31.5万次。当替代量为10份时,硫化胶的断裂伸长率可达491%,同时硫化胶还具有较高的抗湿滑性能和较小的滚动阻力。展开更多
The objective of this study is to explore the optimum composition of Y and ZSM-5 zeolites to develop novel catalysts for obtaining lower gasoline olefins content and higher propylene yield. Five composite zeolite cata...The objective of this study is to explore the optimum composition of Y and ZSM-5 zeolites to develop novel catalysts for obtaining lower gasoline olefins content and higher propylene yield. Five composite zeolite catalysts with varying Y zeolite/ZSM-5 zeolite ratios have been prepared in this work to investigate the synergy between the Y zeolite and ZSM-5 zeolite on the selectivity to protolytic cracking, β-scission, oligomerization, and hydrogen transfer reactions using a FCC naphtha feedstock at 480 ℃ in a confined fluidized bed reactor. Experimental results showed that the composite catalyst with a Y zeolite/ZSM-5 zeolite ratio of 1:4 had the highest protolytic cracking and β-scission ability, which was even higher than that of pure ZSM-5 catalyst. On the other hand, the catalyst with a Y zeolite/ZSM-5 zeolite ratio of 3:2 exhibited the strongest hydrogen transfer functionality while the pure Y zeolite based catalyst had the highest oligomerization ability. For all the catalysts tested, increasing conversion enhanced the selectivity to protolytic cracking and hydrogen transfer reactions but reduced the selectivity to β-scission reaction. However, no clear trend was identified for the selectivity to oligomerization when an increased conversion was experienced.展开更多
基金funded by the UKRI DTP Scholarship:EP/R513040/1.
文摘Composite thermochemical energy storage(TCES)represents an exciting field of thermal energy storage which could address the issue of seasonal variance in renewable energy supply.However,there are open questions about their performance and the root cause of some observed phenomena.Some researchers have observed the breakdown of particles in their production phase,and in their use.This study seeks to investigate the underlying cause of this breakdown.SEM and EDX analysis have been conducted on MgCl2 impregnated 13X zeolite composites of differing diameters,as well as LiX zeolite.This was done in order to study the level of impregnation of salt into the zeolite matrix,as well as the effect this impregnation process has on the morphology of the zeolite.Analysis was conducted using ImageJ software to study the effect of the impregnation process on the diameter of the particles.It has been found that a by weight impregnation concentration of magnesium chloride of 11.90%for the LiX zeolite,and 7.59%and 5.26%for the large diameter 13X zeolite and the small diameter 13X zeolite respectively has been achieved.It has been found that the impregnation process significantly affects themorphology of 13X zeolite particles,causing large fissures to form,and eventually resulting in the previously found breakdown of these particles.It has been verified that a primary factor influencing the breakdown of the 13X zeolite particles is the efflorescence and sub-fluorescence phenomena,which leads to a build-up of crystals in the zeolite pores.It has also been found that prolonged impregnation times and the use of high concentration salt solutions in the soaking process can induce significant crystal growth which also leads to the breakdown of these particles.Results demonstrate that LiX zeolite is the optimum host matrix choice in these conditions.These results will allow for the design of more resilient composite TCES particles.
文摘In this review, we summaries the past few year work on the chemistry of CWA’s and their simulants on various heterogeneous surfaces of zeolites, composites of zeolites and doped zeolite with transition metal oxides. This review elaborates an updated literature overview on the degradation of CWA’s and its simulants. The data written in this review were collected from the peer-reviewed national and international literature.
文摘For investigating the effect of dealumination on the pore structure and catalytic performance, ZSM-5/Y composite zeolites synthesized in situ from NaY gel were dealuminated by steaming at different temperatures. XRD (X-ray diffraction) characterization indicates that the relative crystallinity of the composite zeolites decreases with the increase in Si/Al ratio after steaming. N2 adsorption-desorption suggests that more mesopores are formed while the BET (Brunauer, Emmett and Teller) specific surface area and the micropore specific surface area decrease as the temperature of steaming rises. Daqing heavy oil was used as feedstock to test the catalytic cracking activity of ZSM-5/Y composite zeolites. The experimental results of the catalytic cracking performance reveal that the distribution of products differs due to the different conditions of hydrothermal treatment. Further hydrothermal treatment leads to an increase in the yield of light oil, and a decrease in the yield of gas products and coke.
文摘Y-β zeolite composites were hydrotherrnally synthesized by using high silica Y zeolite as the precursor and characterized by XRD, N2 adsorption, SEM and IR spectra of pyridine. The result showed that the N2 adsorption-desorption isotherm of the zeolite composites had a distinct hysteresis loop, and the SEM result showed that the zeolite composites had a different morphology from Y, β and the corresponding physical zeolite mixture. The acid catalytic performance of the zeolite composite catalysts was investigated in the hydrocracking and hydroisomerization of n-octane, and the results showed that the composite materials exhibited an excellent hydrocracking activity and good hydroisomerization performance. The yield of i-C4 over the zeolite composite catalyst was 4.45% higher than that on the corresponding zeolite mixture in the n-octane hydrocracking process at 553 K. The isomerization ability of n-octane over the composite catalyst was 3.6 fold that of the corresponding mixture at 503 K.
文摘This study investigated the adsorption ability of ZCHC （zeolite/chitosan hybrid composite） as adsorbent for chromium （Cr（Ⅵ））, ZCHC was prepared with sol-gel method by mixing zeolite and chitosan. Adsorption experiment from aqueous solutions containing known amount of Cr（Ⅵ） using zeolite, chitosan and ZCHC was explored to evaluate the efficiency of ZCHC as adsorbent for Cr in a batch system. The amount of Cr（Ⅵ） adsorbed at different pH values, initial concentrations, adsorbent dosages, and contact times were determined by ICP-AES （inductively coupled plasma-atomic emission spectrometry） in order to determine the optimum conditions for Cr（Ⅵ） adsorption. Furthermore, the adsorption mechanism of Cr（Ⅵ） by zeolite, chitosan and ZCHC was investigated by applying Langmuir and Freundlich isotherm equations to the data obtained. In addition, the rates of adsorption were found to conform to pseudo-second order kinetics.
文摘Zeolite/TiO-2 composite photocatalysts were prepared by adding a certain amount of mordenite in TiO-2, and degradation experiments on toluene through photocatalytic reactions were implemented. In this paper, these photocatalysts were characterized by using SEM, IR, RAMAN, XRD and UV-Vis to shed light on the microstructure and photocatalytic performance of the composite photocatalysts. The results indicated that the structural hydroxy of zeolite can participate in bonding reaction with TiO-2, the addition of zeolite can greatly reduce the diameter of nanometer TiO-2 particles in the composite photocatalysts, and enhance the ultraviolet light absorptance of the composite photocatalysts. When the percentage content of zeolite reached 20%, the photocatalytic performance of this catalyst would be highest, with the toluene conversion rate up to {94.58%}.
文摘The composite ZSM—5 zeolite/vermiculite catalyst,in which tiny ZSM—5 zeolite parti- cles embedded in the vermiculite substrate,has been synthesized by hydrothermal method with vermiculite as silicon source.The catalytic behavior of resulting catalyst for xylene isomerization,propylene aromatization and toluene disproportionation is better than that of HZSM—5 zeolite.
基金supported by the National Key Research and Development Program of China(No.2021YFA1202500)the Guangdong Provincial Key Laboratory of Soil and Groundwater Pollution Control(No.2023B1212060002)+1 种基金the Stable Support Plan Program of Shenzhen Natural Science Foundation(No.20231122110855002)the High level of special funds(No.G03050K001)from SUSTech and a Special Fund for the Science and Technology Innovation Strategy of Guangdong Province(No.PDJH2021C0033).
文摘Red soil,the most critical soil resource in tropical/subtropical regions worldwide,faces tremendous threats,including nutrient deficiency,acidification,and heavy metal contamination.There is a great demand for multifunctional eco-materials capable of modifying this situation.Herein,we used widely distributed soil and biomass to develop a zeolite/biochar composite for synergistic red soil remediation and amendment.With the composite material,the Pb^(2+) and Cd^(2+) remediation efficiencies reached 92.8%and 92.9%,respectively,in stems under optimal conditions.Moreover,the acidity and nutrient deficiency conditions of red soil significantly improved.The atomic-scale interaction mechanism during the remediation and amendment process was elucidated with complementary characterization methods,which revealed that in the zeolite/biochar composite material,zeolite contributes to longterm heavy metal remediation effects.Simultaneously,biochar is responsible for soil quality amendment and short-term heavy metal remediation.Furthermore,for the first time,single-atom heavy metal ions were observed on biochar during the remediation process,indicating the broad distribution of single atoms in the natural environment.
基金the National Natural Science Fund of China (2016-Z0030)the Natural Science Foundation of Liaoning Province (L2017LQN008, L2016020)the Fushun Science & Technology Program (2011ZX05039-003)
文摘n-Alkane isomerization is a critical reaction that can affect parameters in oil refining, such as the gasoline octane number and diesel oil solidifying point. In this study, a catalyst support, mordenite (MOR)/silicoaluminophosphate (SAPO)-11 composite zeolite with core/shell structure, was synthesized by hydrothermal method with MOR acting as the seed for crystallization. The crystal structure, elemental composition, surface area, pore volume, and acidity of the catalyst was thoroughly characterized. In addition, the catalytic performance of the as-obtained Pt/MOR/SAPO-11 in the hydroisomerization of n-dodecane was tested. The results indicated that the properties and catalytic performance of the composite molecular sieve were quite different from those of the pure zeolites and physical mixture of MOR and SAPO-11 (MOR+SAPO-11). Compared with the physical mixture, MOR and SAPO-11 were more tightly bound in MOR/SAPO-11 because of chemical bonding. Moreover, the acidity and pore structure were favorable to the catalytic hydroisomerization of n-dodecane. Pt/MOR/SAPO-11 exhibited higher isomerization activity than the Pt-loaded pristine MOR and MOR+SAPO-11. Thus, the core-shell composite molecular sieve has promising industrial applications as the catalyst support.
基金Supported by the State Key Development Program for Basic Research of China （2009CB623404） the National Natural Science Foundation of China （20736003 20906056） the National High Technology Research and Development Program of China （2007AA06Z317 2008EG111021）
文摘Traditional solvent recovery in the extraction step of edible oil processing is distillation,which consumes large amounts of energy.If the distillation is replaced by membrane process,the energy consumption can be reduced greatly.In this work,two kinds of membrane,PDMS(polydimethylsiloxane) composite membrane and Zeolite filled PDMS membrane were prepared,in which asymmetric microporous PVDF(polyvinylidenefluoride) membrane prepared with phase inversion method was functioned as the microporous supporting layer in the flat-plate composite membrane.The different function compositions of the PDMS/PVDF composite membranes were characterized by reflection Fourier transform infrared(FTIR) spectroscopy.The surface and section of PDMS/PVDF composite membranes were investigated by scanning electron microscope(SEM).The PDMS NF(nanofiltration) membranes were then applied in the recovery of hexane from soybean oil/hexane miscellas(1:3,mass ratio).The effects of pressure(0.5-1.5 MPa),cross-linking temperature and PDMS layer thickness on membrane performances were investigated.The results indicated that both two kinds of NF membranes were promising for solvent recovery,and zeolite filled in PDMS NF membrane could enhance the separation performance.
基金financially supported by the National International Cooperation S & T Project of China (No.2015DFA40660)
文摘A ZSM-5/MAPO composite catalyst was prepared by adding ZSM-5 zeolite powder to a conventional molecular sieve synthesis system, followed by modification with NH_4H_2PO_4. The samples were characterized by XRD, SEM, IR, NH_3-TPD, and BET analyses. The catalytic property of the samples toward the methanol-to-olefin(MTO) reaction was evaluated in a connected in series two-stage unit equipped with a continuous flow(once-through) fixed-bed tubular reactor similar to an industrial reactor. The first reactor mainly converted methanol into dimethyl ether and water, followed by being subject to continuous reaction in the second reactor, in which DME was converted to hydrocarbons. The composites exhibited the typical framework topology of MFI, AEI and AFI, which represented the ZSM-5 zeolite, the molecular sieves AlPO-18 or SAPO-18, AlPO-5 or SAPO-5, respectively. The composites showed several advantages for optimizing the zeolite acidity, enhancing the mass transfer, and restraining the side reactions. Catalytic reaction results showed that the composites exhibited higher selectivity to light olefins(84.0%) and lower selectivity to C_2―C_4 alkanes and C_5^+ hydrocarbons than pure ZSM-5. Moreover, the composite zeolite loaded with 3% of P demonstrated improved catalytic activity and stability for the conversion of methanol to propylene, because the coking rate was obviously suppressed.
基金This work was financially supported by the National Natural Science Foundation of China(No.21371055)the Key Project of Scientific Research Project of Hunan Education Department(No.18A313).
文摘In this paper,the kaolin/urea intercalation composites prepared by direct intercalation method and the catalysis composites containing ZSM-5 molecular sieve synthesized based on the kaolin/urea intercalation composites by an in-situ crystallization technique were investigated.The effects of the intercalation ratios and de-intercalation rate and the amounts of added kaolin/urea intercalation composite on the synthesis of the catalysis composites containing the ZSM-5 molecular sieve were studied.The samples were characterized by X-ray diffraction,FT-IR,TG-DTA,N2 adsorption-desorption,and SEM,respectively.The results showed that the structure of the samples prepared by kaolin/urea intercalation composite was pure ZSM-5 molecular sieve.The crystallinity of ZSM-5 molecular sieve increased at first and then decreased with the increase of intercalation ratio of kaolin/urea intercalation composite.When the intercalation ratio was 62%,the crystallinity of ZSM-5 molecular sieve was lower.When the amount of added kaolin/urea intercalation composite with an intercalation ratio of 22%was 3%,the crystallinity of ZSM-5 zeolite was improved to reach 65%.Compared to the crystallization product formed without adding kaolin/urea intercalation composite,the crystallinity of ZSM-5 molecular sieve has increased by 54.8%.The catalytic composites containing ZSM-5 molecular sieve had better thermal stability with a wide pore structure,featuring a particle diameter of about 2.5μm,a BET specific surface area of 236 m^2/g,and a pore size of 10.6 nm.
基金ThisstudywassupportedjointlybytheNationalNaturalScienceFoundationofChina (No .40 0 72 0 30 )andtheProgramspon soredbytheMinistry
文摘Systematic analysis and comparative study of the chemical compositions of rocks and ores from the main types of zeolite deposits in the surroundings of the Songliao Basin have shown that the process of formation of zeolite from volcanic and pyroclastic rocks is generally characterized by the relative purification of SiO\-2, i.e., SiO\-2/Al\-2O\-3 ratios tend to increase, alkali earth elements (CaO+MgO) and H\-2O are relatively enriched, and the alkali metals (K\-2O+Na\-2O) are depleted in their total amount. The alkali metals K and Na follow different rules of migration and enrichment during the formation of mordenite and clinoptilolite. In the process of formation of mordenite more Na\++ will be imported and K\++ will be lost remarkably. On the contrary, in the process of formation clinoptilolite more K\++ will be incorporated and Na\++ will become obviously depleted.
文摘采用阳离子型季铵盐二甲基二烯丙基氯化铵(DMDAAC)对球磨后的天然沸石进行改性处理,将其等量替代部分炭黑后填充至天然橡胶(NR)中,制备天然沸石或改性沸石/NR复合材料,并对其进行结构表征和性能测试。通过离子交换反应,DMDAAC可以吸附在沸石表面,改变了沸石表面的化学性质,降低了沸石的极性,从而改善了沸石在NR中的分散效果,提升胶料的力学性能。结果表明,当替代量为5份时,硫化胶的抗拉强度可达28.6 MPa、撕裂强度为119.3 kN/m;阿克隆磨耗体积最小,为0.28 cm 3;抗屈挠疲劳效果最好,为31.5万次。当替代量为10份时,硫化胶的断裂伸长率可达491%,同时硫化胶还具有较高的抗湿滑性能和较小的滚动阻力。
基金financial support from the National Key Technology R&D Program (2012BAE05B01) of China
文摘The objective of this study is to explore the optimum composition of Y and ZSM-5 zeolites to develop novel catalysts for obtaining lower gasoline olefins content and higher propylene yield. Five composite zeolite catalysts with varying Y zeolite/ZSM-5 zeolite ratios have been prepared in this work to investigate the synergy between the Y zeolite and ZSM-5 zeolite on the selectivity to protolytic cracking, β-scission, oligomerization, and hydrogen transfer reactions using a FCC naphtha feedstock at 480 ℃ in a confined fluidized bed reactor. Experimental results showed that the composite catalyst with a Y zeolite/ZSM-5 zeolite ratio of 1:4 had the highest protolytic cracking and β-scission ability, which was even higher than that of pure ZSM-5 catalyst. On the other hand, the catalyst with a Y zeolite/ZSM-5 zeolite ratio of 3:2 exhibited the strongest hydrogen transfer functionality while the pure Y zeolite based catalyst had the highest oligomerization ability. For all the catalysts tested, increasing conversion enhanced the selectivity to protolytic cracking and hydrogen transfer reactions but reduced the selectivity to β-scission reaction. However, no clear trend was identified for the selectivity to oligomerization when an increased conversion was experienced.
