In this paper we used MOF-5 and Cu3(BTC)2to separate CO2/CH4 and CH4/N2 mixtures under dynamic conditions. Both materials were synthesized and pelletized, thus allowing for a meaningful characterization in view of pro...In this paper we used MOF-5 and Cu3(BTC)2to separate CO2/CH4 and CH4/N2 mixtures under dynamic conditions. Both materials were synthesized and pelletized, thus allowing for a meaningful characterization in view of process scale-up. The materials were characterized by X-ray diffraction(XRD) and scanning electron microscopy(SEM). By performing breakthrough experiments, we found that Cu3(BTC)2separated CO2/CH4 slightly better than MOF-5. Because the crystal structure of Cu3(BTC)2includes unsaturated accessible metal sites formed via dehydration, it predominantly interacted with CO2 molecules and more easily captured them. Conversely, MOF-5 with a suitable pore size separated CH4/N2 more efficiently in our breakthrough test.展开更多
The separation of gas molecules with similar physicochemical properties is of high importance but practically entails a substantial energy penalty in chemical industry. Meanwhile, clean energy gases such as H_2 and CH...The separation of gas molecules with similar physicochemical properties is of high importance but practically entails a substantial energy penalty in chemical industry. Meanwhile, clean energy gases such as H_2 and CH_4 are considered as promising candidates for the replacement of traditional fossil fuels. However, the technologies for the storage of these gases are still immature. In addition, the release of anthropogenic toxic gases into the atmosphere is a worldwide threat of growing concern. Both in academia and industry, considerable research efforts have been devoted to developing advanced porous materials for the effective and energy-efficient separation, storage, or capture of the related gases. In contrast to conventional inorganic porous materials such as zeolites and activated carbons, metal–organic frameworks(MOFs) are considered as a type of promising materials for gas separation and storage. In this contribution, we review the recent research advance of MOFs in some relevant applications, including CO_2 capture, O_2 purification, separation of light hydrocarbons, separation of noble gases, storage of gases(CH_4,H_2, and C_2 H_2) for energy, and removal of some gaseous air pollutants(NH_3, NO_2, and SO_2). Finally, an outlook regarding the challenges of the future research of MOFs in these directions is given.展开更多
Magnesium ion-exchanged a-zirconium phosphates(Mg-α-ZrP) with particle sizes of 600 and 80 nm were prepared through the sealed ion-exchange and one-step hydrothermal synthesis methods, respectively. It was found that...Magnesium ion-exchanged a-zirconium phosphates(Mg-α-ZrP) with particle sizes of 600 and 80 nm were prepared through the sealed ion-exchange and one-step hydrothermal synthesis methods, respectively. It was found that larger particles of Mg-α-ZrP had a higher load-carrying capacity than that of smaller particles, whereas smaller Mg-α-ZrP particles had better anti-wear properties than that of larger Mg-α-ZrP particles under mild loads. The correlation between the particle size of the sample and the surface roughness of the friction pair thus seems to be a key factor influencing the performance.展开更多
Introduced a method of synthesizing hierarchical EU-1 zeolite with organosilanes as additive, and studied the influences of following different kinds of organosilanes on the synthesis of hierarchical EU-1 zeolite: γ-...Introduced a method of synthesizing hierarchical EU-1 zeolite with organosilanes as additive, and studied the influences of following different kinds of organosilanes on the synthesis of hierarchical EU-1 zeolite: γ-glycidoxy propyl trimethoxy silane(GPTMS), N-β-(aminoethyl)-γ-aminopropyl methyl dimethoxyl silane(APAEDMS),and N-(β-aminoethyl)-γ-aminopropyl dimethoxyl(ethyoxyl) silane(TMPED). The hierarchical EU-1 samples were characterized by XRD, SEM, N_2 adsorption, FT-IR and NH_3-TPD to analyze the crystallinity, morphology, surface area, pore size distribution and acidity. The results showed that hierarchical EU-1 zeolites were successfully synthesized; organosilanes have great influence on crystal morphology of EU-1 zeolites; the exterior surface area of hierarchical EU-1 zeolite, which synthesized with organosilanes(APAEDMS) adding into synthesis system, increased by 62.1% and mesopore volume increased by 129.1% compared with conventional EU-1 zeolites, thus can reduce the diffusional restriction markedly in catalytic reaction. The catalytic performance of hierarchical EU-1zeolites were evaluated in m-xylene isomerization on fixed bed reactor. The catalytic data showed that the isomerization activity PX/X of the hierarchical EU-1 zeolites reached around 24.09% in theoretical thermodynamic equilibrium from 23.83%, and the selectivity of C_8 aromatic hydrocarbon increased from 75.16% to 84.87%. The conversion of p-xylene increased from 16.30% to 18.41%.展开更多
The formation mechanism of methane(CH4) during coal evolution has been investigated by density functional theory(DFT) of quantum chemistry. Thermogenic gas, which is generated during the thermal evolution of medium ra...The formation mechanism of methane(CH4) during coal evolution has been investigated by density functional theory(DFT) of quantum chemistry. Thermogenic gas, which is generated during the thermal evolution of medium rank coal, is the main source of coalbed methane(CBM). Ethylbenzene(A) and 6,7-dimethyl-5,6,7,8-tetrahydro-1-hydroxynaphthalene(B) have been used as model compounds to study the pyrolysis mechanism of highly volatile bituminous coal(R), according to the similarity of bond orders and bond lengths. All possible paths are designed for each model. It can be concluded that the activation energies for H-assisted paths are lower than others in the process of methane formation; an H radical attacking on β-C to yield CH4 is the dominant path for the formation of CH4 from highly volatile bituminous coal. In addition, the calculated results also reveal that the positions on which H radical attacks and to which intramolecular H migrates have effects on methyl cleavage.展开更多
The main disadvantage of microporous SSZ-13 catalyst used in the methanol to olefins(MTO) process is its rapid deactivation due to its relatively low coke resistance. Meanwhile, the hierarchical zeolites usually exhib...The main disadvantage of microporous SSZ-13 catalyst used in the methanol to olefins(MTO) process is its rapid deactivation due to its relatively low coke resistance. Meanwhile, the hierarchical zeolites usually exhibit improved catalytic stability thanks to their better mass transfer ability. Herein, the hierarchically nanoporous SSZ-13 zeolites were one-pot synthesized by using N,N,N-trimethyl-1-adamantanammonium hydroxide as a microporous structure directing agent and C_(18)H_(37) N^+(CH_3)_2 C_6H_(12) N^+(CH_3)_2 C_6 H_(13)(Br^-)_2(hereinafter abbreviated as C_(18-6-6) Br_2) as a mesoporogen. The hierarchically nanoporous SSZ-13 catalyst was characterized by XRD, N_2 physisorption, SEM, TEM, TG-DTG, ^(27) Al and ^(29) SiNMR spectroscopy and NH_3-TPD techniques. The results showed that the hierarchical SSZ-13 zeolite synthesized in the presence of the C_(18-6-6) Br_2 surfactant exhibits aggregates of primary nanocrystals and contains the well-developed mesopores and excellent acidity. Compared to its conventional counterpart, the hierarchical SSZ-13 zeolite has longer catalytic lifetime and higher selectivity for ethylene and propylene in the MTO reaction, which can be attributed to the synergistic effect of their good acidity and improved diffusion properties resulted from the hierarchical pore structure.展开更多
Nanostructured mesoporous Ni Co2O4,Co3O4 and Ni O spinel oxides were prepared through the hydroxide coprecipitation method using EG(ethylene glycol) as solvent without any template.The Ni Co2O4 powders were analyzed b...Nanostructured mesoporous Ni Co2O4,Co3O4 and Ni O spinel oxides were prepared through the hydroxide coprecipitation method using EG(ethylene glycol) as solvent without any template.The Ni Co2O4 powders were analyzed by TGA,XRD,N2adsorption-desorption,SEM and EDS.And the electrocatalytic properties of Ni Co2O4/Ti,Co3O4/Ti and Ni O/Ti electrodes for oxygen evolution in 0.1 mol/L KOH(p H = 13)were tested by cyclic voltammetry,Tafel curves and electrolysis.The result shows that Ni Co2O4/Ti electrode has higher electrocatalytic activity in oxygen evolution reaction than Co3O4/Ti and NiO/Ti electrodes.Ni Co2O4/Ti electrode prepared at 350°C has the highest apparent current density and the highest true current density.The Tafel slope of Ni Co2O4/Ti electrode prepared at 350°C is 68.49 m V/dec.展开更多
The solid solution(Ce Zr)O_2 catalyst was synthesized, and it was modified with metal oxides by incipient impregnation. Morphology and structure were characterized by X-ray diffraction, transmission electron microscop...The solid solution(Ce Zr)O_2 catalyst was synthesized, and it was modified with metal oxides by incipient impregnation. Morphology and structure were characterized by X-ray diffraction, transmission electron microscope, nitrogen ad/desorption and H_2-temperature program reduction techniques. The catalytic properties of methane oxidation were also investigated. The results showed that solid solution possessed a mesoporous structure and exhibited excellent catalytic performance. The activity of solid solution was improved effectively by nickel doping, and the optimal loading is 15 wt%. The stability of(Ce Zr)O_2 and modified(Ce Zr)O_2 indicated that the structure of pristine solid solution played a key role in promoting molecules diffusion and spatial confining oxide particle sintering.展开更多
EU-1 zeolites were sequentially treated with low-concentration sodium carbonate(Na_2CO_3) and hydrochloric acid(HCl) solutions.The obtained samples were characterized by X-ray diffraction(XRD),scanning electron micros...EU-1 zeolites were sequentially treated with low-concentration sodium carbonate(Na_2CO_3) and hydrochloric acid(HCl) solutions.The obtained samples were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),N_2 adsorption/desorption,temperature programmed desorption of NH_3(NH_3-TPD),solid state^(27)A1 nuclear magnetic resonance(^(27)A1 NMR),and the catalytic performances of the treated samples were tested in the xylene isomerization reaction.The results showed that the external surface area and mesoporous volume of the sample sequentially treated with 0.05 mol·L^(-1) Na_2CO_3 and 0.1 mol·L^(-1) HCl solutions reached73.9 m^2·g^(-1) and 0.162 cm^3·g^(-1),respectively.The catalytic performances of EU-1 zeolites were significantly improved,that the activity of the probe reaction increased from 23.03%to 23.61%and the selectivity increased from85.09%to 87.14%compared with those of parent sample.Furthermore,it was found that only amorphous silica and alumina species was dissolved during the post-treatment process,but the framework structure and the acidic properties of EU-1 zeolite remained intact.展开更多
A zeolite Mazzite (MAZ) analogue with high silica content has been synthesized from a Na2O-Al2O3-SiO2-morpholine-H2O system. The crystal morphology of this MAZ analogue was found to consist of spherical agglomerates o...A zeolite Mazzite (MAZ) analogue with high silica content has been synthesized from a Na2O-Al2O3-SiO2-morpholine-H2O system. The crystal morphology of this MAZ analogue was found to consist of spherical agglomerates of diameter up to 17 μm. It has been unequivocally demonstrated that zeolite Mordenite (MOR) or amorphous material was produced instead in the absence of either morpholine or Na+. Associated phases indicate that the MAZ may be a “intermediate phase” between the crystallization fields of zeolites Analcime (ANA) and MOR. Thus, the zeolite MAZ analogue is seemingly derived from the cooperative structure-directing effect of the organic molecule morpholine and the inorganic cation Na+. The results of CHN elemental analyses as well as of thermogravimetric (TG) analyses confirmed that morpholine had been incorporated into the zeolitic structure.展开更多
Samples of methane molecules grade diameter channel CHA-type molecular sieves(Chabazite-K, SAPO-34 and SSZ-13) were investigated using the adsorption separation of CH4/N2 mixtures. The isotherms recorded for CH4 and N...Samples of methane molecules grade diameter channel CHA-type molecular sieves(Chabazite-K, SAPO-34 and SSZ-13) were investigated using the adsorption separation of CH4/N2 mixtures. The isotherms recorded for CH4 and N2 follow a typical type-Ι behavior, which were fitted well with the Sips model(R2>0.999) and the selectivity was calculated using IAST theory. The results reveal that Chabazite-K has the highest selectivity(SCH4/N= 5.5).2 SSZ-13 has the largest capacity, which can adsorb up to a maximum of 30.957 cm3·g-1(STP) of CH4, due to it having the largest pore volume and surface area, but the lowest selectivity(SCH4/N2= 2.5). From the breakthrough test, we can conclude that SSZ-13 may be a suitable candidate for the recovery of CH4 from low concentration methane(CH4<20%) based on its larger pore volume and higher CH4 capacity. Chabazite-K is more suited to the separation of high concentration methane(CH4>50%) due to its higher selectivity.展开更多
Two isomeric metal-organic frameworks(MOFs) with 2-dimensional(2D) and 3-dimensional(3D) topologies both comprised of Cu(Ⅱ) and OTf(OTf = trifluoromethanesulfonate) ions were synthesized and characterized.The CO_2,CH...Two isomeric metal-organic frameworks(MOFs) with 2-dimensional(2D) and 3-dimensional(3D) topologies both comprised of Cu(Ⅱ) and OTf(OTf = trifluoromethanesulfonate) ions were synthesized and characterized.The CO_2,CH_4 and N_2 adsorption properties of the two isomeric MOFs were investigated from 263 K to 298 K at0.1 MPa.The results showed that the 2D MOF exhibited a higher selectivity for CO_2 from CO_2/CH_4 and CH_4from CH_4/N_2 compared to the 3D MOF,even though it possessed a lower surface area and pore volume.The higher adsorption heats of gases on the 2D MOF inferred the strong adsorption potential energy in the layered MOFs.Dynamic separation experiments using CO_2/CH_4 and CH_4/N_2 mixtures on the two MOFs proved that the2 D MOF had a longer elution time than the 3D MOF as well as better separation abilities.展开更多
In order to remove N_(2) from low quality natural gas,a mathematical model has been established by Aspen adsorption,using the CH_(4)-selective sorbent silicalite-1 pellets.The dynamic adsorption isotherm was first sim...In order to remove N_(2) from low quality natural gas,a mathematical model has been established by Aspen adsorption,using the CH_(4)-selective sorbent silicalite-1 pellets.The dynamic adsorption isotherm was first simulated by breakthrough simulation of a CH_(4)/N_(2) mixture at different adsorption pressures and feed flow rates based on breakthrough experiments.The resulting simulated CH_(4) dynamic adsorption amounts were very close to the experimental data at three different adsorption pressures(100,200,and 300 kPa).Moreover,a single-bed,three-step pressure swing adsorption(PSA)experiment was performed,and the results were in good agreement with the simulated data,further corroborating the accuracy of the gas dynamic adsorption isotherm obtained by the simulation method.Finally,based on the simulated dynamic adsorption isotherm of CH_(4) and N_(2),a four-bed,eight-step PSA process has been designed,which enriched 75%(vol)CH_(4) and 80%(vol)CH_(4) to 95%(vol)and 99%(vol),and provided 99%(vol)recovery.展开更多
Ferrierite(FER) zeolites were synthesized by solid transformation at different alkalinities(OH-/Al2O3 molar ratios). The in situ delamination of FER zeolites were achieved and their catalytic performances in the catal...Ferrierite(FER) zeolites were synthesized by solid transformation at different alkalinities(OH-/Al2O3 molar ratios). The in situ delamination of FER zeolites were achieved and their catalytic performances in the catalytic cracking of C4 hydrocarbons were examined. The relationships among the OH-/Al2O3 molar ratio, FER structure,composition, surface acidity and catalytic performance in C4 hydrocarbon cracking were investigated. The results of X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, inductively coupled plasma atomic emission spectroscopy, N2 adsorption, NH3temperature-programmed desorption and catalytic cracking showed that with increasing OH-/Al2O3 molar ratio in the synthesis gel, the Si O2/Al2O3 molar ratio of the as-synthesized FER zeolite decreased, the amount of acid sites in the corresponding H-FER increased, and the acid strength weakened. Additionally, the FER zeolite was delaminated at the mesoscale. H-FER5 synthesized at the highest alkalinity had the largest number of acid sites and exhibited the highest catalytic activity in C4 hydrocarbon catalytic cracking among three of the prepared catalysts. H-FER3 synthesized at the secondhighest alkalinity showed that the highest yield of benzene and toluene because of the secondary pores resulted from the gaps between the layers, which were beneficial to the diffusion and formation of large molecules.展开更多
基金supported by the National Natural Science Foundation of China(No.21136007 and 51302184)
文摘In this paper we used MOF-5 and Cu3(BTC)2to separate CO2/CH4 and CH4/N2 mixtures under dynamic conditions. Both materials were synthesized and pelletized, thus allowing for a meaningful characterization in view of process scale-up. The materials were characterized by X-ray diffraction(XRD) and scanning electron microscopy(SEM). By performing breakthrough experiments, we found that Cu3(BTC)2separated CO2/CH4 slightly better than MOF-5. Because the crystal structure of Cu3(BTC)2includes unsaturated accessible metal sites formed via dehydration, it predominantly interacted with CO2 molecules and more easily captured them. Conversely, MOF-5 with a suitable pore size separated CH4/N2 more efficiently in our breakthrough test.
基金supported from the Natural Science Foundation of China (Grant Nos. 21771012, 21601008 and 21576006)the National Natural Science Fund for Innovative Research Groups (Grant No. 51621003)the China Postdoctoral Science Foundation (Grant No. 2016M600879)
文摘The separation of gas molecules with similar physicochemical properties is of high importance but practically entails a substantial energy penalty in chemical industry. Meanwhile, clean energy gases such as H_2 and CH_4 are considered as promising candidates for the replacement of traditional fossil fuels. However, the technologies for the storage of these gases are still immature. In addition, the release of anthropogenic toxic gases into the atmosphere is a worldwide threat of growing concern. Both in academia and industry, considerable research efforts have been devoted to developing advanced porous materials for the effective and energy-efficient separation, storage, or capture of the related gases. In contrast to conventional inorganic porous materials such as zeolites and activated carbons, metal–organic frameworks(MOFs) are considered as a type of promising materials for gas separation and storage. In this contribution, we review the recent research advance of MOFs in some relevant applications, including CO_2 capture, O_2 purification, separation of light hydrocarbons, separation of noble gases, storage of gases(CH_4,H_2, and C_2 H_2) for energy, and removal of some gaseous air pollutants(NH_3, NO_2, and SO_2). Finally, an outlook regarding the challenges of the future research of MOFs in these directions is given.
基金Funded by the Key Program of National Natural Science Foundation of China(No.21436008)the General Program of National Natural Science Foundation of China(No.51372162)+1 种基金Young Scientists Fund of the National Natural Science Foundation of China(No.21506145)the Natural Science Foundation for Young Scientists of Shanxi Province,China(No.2015021032)
文摘Magnesium ion-exchanged a-zirconium phosphates(Mg-α-ZrP) with particle sizes of 600 and 80 nm were prepared through the sealed ion-exchange and one-step hydrothermal synthesis methods, respectively. It was found that larger particles of Mg-α-ZrP had a higher load-carrying capacity than that of smaller particles, whereas smaller Mg-α-ZrP particles had better anti-wear properties than that of larger Mg-α-ZrP particles under mild loads. The correlation between the particle size of the sample and the surface roughness of the friction pair thus seems to be a key factor influencing the performance.
基金Supported by the National Innovation Fund for Small and Medium-sized Technology-based Firms(14C26211400552)
文摘Introduced a method of synthesizing hierarchical EU-1 zeolite with organosilanes as additive, and studied the influences of following different kinds of organosilanes on the synthesis of hierarchical EU-1 zeolite: γ-glycidoxy propyl trimethoxy silane(GPTMS), N-β-(aminoethyl)-γ-aminopropyl methyl dimethoxyl silane(APAEDMS),and N-(β-aminoethyl)-γ-aminopropyl dimethoxyl(ethyoxyl) silane(TMPED). The hierarchical EU-1 samples were characterized by XRD, SEM, N_2 adsorption, FT-IR and NH_3-TPD to analyze the crystallinity, morphology, surface area, pore size distribution and acidity. The results showed that hierarchical EU-1 zeolites were successfully synthesized; organosilanes have great influence on crystal morphology of EU-1 zeolites; the exterior surface area of hierarchical EU-1 zeolite, which synthesized with organosilanes(APAEDMS) adding into synthesis system, increased by 62.1% and mesopore volume increased by 129.1% compared with conventional EU-1 zeolites, thus can reduce the diffusional restriction markedly in catalytic reaction. The catalytic performance of hierarchical EU-1zeolites were evaluated in m-xylene isomerization on fixed bed reactor. The catalytic data showed that the isomerization activity PX/X of the hierarchical EU-1 zeolites reached around 24.09% in theoretical thermodynamic equilibrium from 23.83%, and the selectivity of C_8 aromatic hydrocarbon increased from 75.16% to 84.87%. The conversion of p-xylene increased from 16.30% to 18.41%.
基金supported by the Major Projects of National Science and Technology(Grant No.2011ZX05040-005-002-001)the National Natural Science Foundation of China(Grant No.21276171 and 21276003)+1 种基金the National Younger Natural Science Foundation of China(Grant No.21103120)China Postdoctoral Science Foundation(Grant No.2012M520608)
文摘The formation mechanism of methane(CH4) during coal evolution has been investigated by density functional theory(DFT) of quantum chemistry. Thermogenic gas, which is generated during the thermal evolution of medium rank coal, is the main source of coalbed methane(CBM). Ethylbenzene(A) and 6,7-dimethyl-5,6,7,8-tetrahydro-1-hydroxynaphthalene(B) have been used as model compounds to study the pyrolysis mechanism of highly volatile bituminous coal(R), according to the similarity of bond orders and bond lengths. All possible paths are designed for each model. It can be concluded that the activation energies for H-assisted paths are lower than others in the process of methane formation; an H radical attacking on β-C to yield CH4 is the dominant path for the formation of CH4 from highly volatile bituminous coal. In addition, the calculated results also reveal that the positions on which H radical attacks and to which intramolecular H migrates have effects on methyl cleavage.
基金the National Natural Science Foundation of China(No.51371123)the Natural Science Foundation of Shanxi Province(No.201701D121024)the Research Project Supported by Shanxi Scholarship Council of China(No.2017-042)for providing financial support for this study
文摘The main disadvantage of microporous SSZ-13 catalyst used in the methanol to olefins(MTO) process is its rapid deactivation due to its relatively low coke resistance. Meanwhile, the hierarchical zeolites usually exhibit improved catalytic stability thanks to their better mass transfer ability. Herein, the hierarchically nanoporous SSZ-13 zeolites were one-pot synthesized by using N,N,N-trimethyl-1-adamantanammonium hydroxide as a microporous structure directing agent and C_(18)H_(37) N^+(CH_3)_2 C_6H_(12) N^+(CH_3)_2 C_6 H_(13)(Br^-)_2(hereinafter abbreviated as C_(18-6-6) Br_2) as a mesoporogen. The hierarchically nanoporous SSZ-13 catalyst was characterized by XRD, N_2 physisorption, SEM, TEM, TG-DTG, ^(27) Al and ^(29) SiNMR spectroscopy and NH_3-TPD techniques. The results showed that the hierarchical SSZ-13 zeolite synthesized in the presence of the C_(18-6-6) Br_2 surfactant exhibits aggregates of primary nanocrystals and contains the well-developed mesopores and excellent acidity. Compared to its conventional counterpart, the hierarchical SSZ-13 zeolite has longer catalytic lifetime and higher selectivity for ethylene and propylene in the MTO reaction, which can be attributed to the synergistic effect of their good acidity and improved diffusion properties resulted from the hierarchical pore structure.
基金supported by the National Natural Science Foundation of China(No.21476153,21136007)the Natural Science Foundation of Shanxi Province(2014011017-1)the Program for the Outstanding Innovative Teams of Higher Learning Institutions of Shanxi
文摘Nanostructured mesoporous Ni Co2O4,Co3O4 and Ni O spinel oxides were prepared through the hydroxide coprecipitation method using EG(ethylene glycol) as solvent without any template.The Ni Co2O4 powders were analyzed by TGA,XRD,N2adsorption-desorption,SEM and EDS.And the electrocatalytic properties of Ni Co2O4/Ti,Co3O4/Ti and Ni O/Ti electrodes for oxygen evolution in 0.1 mol/L KOH(p H = 13)were tested by cyclic voltammetry,Tafel curves and electrolysis.The result shows that Ni Co2O4/Ti electrode has higher electrocatalytic activity in oxygen evolution reaction than Co3O4/Ti and NiO/Ti electrodes.Ni Co2O4/Ti electrode prepared at 350°C has the highest apparent current density and the highest true current density.The Tafel slope of Ni Co2O4/Ti electrode prepared at 350°C is 68.49 m V/dec.
基金Supported by the National Natural Science Foundation of China(21136007 and51572185)the Natural Science Foundation of Shanxi Province(2014011016-4)the Coal-Based Key Scientific and Technological Project of Shanxi Province(MQ2014-10)
文摘The solid solution(Ce Zr)O_2 catalyst was synthesized, and it was modified with metal oxides by incipient impregnation. Morphology and structure were characterized by X-ray diffraction, transmission electron microscope, nitrogen ad/desorption and H_2-temperature program reduction techniques. The catalytic properties of methane oxidation were also investigated. The results showed that solid solution possessed a mesoporous structure and exhibited excellent catalytic performance. The activity of solid solution was improved effectively by nickel doping, and the optimal loading is 15 wt%. The stability of(Ce Zr)O_2 and modified(Ce Zr)O_2 indicated that the structure of pristine solid solution played a key role in promoting molecules diffusion and spatial confining oxide particle sintering.
文摘EU-1 zeolites were sequentially treated with low-concentration sodium carbonate(Na_2CO_3) and hydrochloric acid(HCl) solutions.The obtained samples were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),N_2 adsorption/desorption,temperature programmed desorption of NH_3(NH_3-TPD),solid state^(27)A1 nuclear magnetic resonance(^(27)A1 NMR),and the catalytic performances of the treated samples were tested in the xylene isomerization reaction.The results showed that the external surface area and mesoporous volume of the sample sequentially treated with 0.05 mol·L^(-1) Na_2CO_3 and 0.1 mol·L^(-1) HCl solutions reached73.9 m^2·g^(-1) and 0.162 cm^3·g^(-1),respectively.The catalytic performances of EU-1 zeolites were significantly improved,that the activity of the probe reaction increased from 23.03%to 23.61%and the selectivity increased from85.09%to 87.14%compared with those of parent sample.Furthermore,it was found that only amorphous silica and alumina species was dissolved during the post-treatment process,but the framework structure and the acidic properties of EU-1 zeolite remained intact.
文摘A zeolite Mazzite (MAZ) analogue with high silica content has been synthesized from a Na2O-Al2O3-SiO2-morpholine-H2O system. The crystal morphology of this MAZ analogue was found to consist of spherical agglomerates of diameter up to 17 μm. It has been unequivocally demonstrated that zeolite Mordenite (MOR) or amorphous material was produced instead in the absence of either morpholine or Na+. Associated phases indicate that the MAZ may be a “intermediate phase” between the crystallization fields of zeolites Analcime (ANA) and MOR. Thus, the zeolite MAZ analogue is seemingly derived from the cooperative structure-directing effect of the organic molecule morpholine and the inorganic cation Na+. The results of CHN elemental analyses as well as of thermogravimetric (TG) analyses confirmed that morpholine had been incorporated into the zeolitic structure.
基金financial support from the National Natural Science Foundation of China (Nos. 51672186, 21676175)
文摘Samples of methane molecules grade diameter channel CHA-type molecular sieves(Chabazite-K, SAPO-34 and SSZ-13) were investigated using the adsorption separation of CH4/N2 mixtures. The isotherms recorded for CH4 and N2 follow a typical type-Ι behavior, which were fitted well with the Sips model(R2>0.999) and the selectivity was calculated using IAST theory. The results reveal that Chabazite-K has the highest selectivity(SCH4/N= 5.5).2 SSZ-13 has the largest capacity, which can adsorb up to a maximum of 30.957 cm3·g-1(STP) of CH4, due to it having the largest pore volume and surface area, but the lowest selectivity(SCH4/N2= 2.5). From the breakthrough test, we can conclude that SSZ-13 may be a suitable candidate for the recovery of CH4 from low concentration methane(CH4<20%) based on its larger pore volume and higher CH4 capacity. Chabazite-K is more suited to the separation of high concentration methane(CH4>50%) due to its higher selectivity.
基金Supported by National Natural Science Foundation of China(No.21136007,No.51302184)the National Research Fund for Fundamental Key Projects(No.2014CB260402)
文摘Two isomeric metal-organic frameworks(MOFs) with 2-dimensional(2D) and 3-dimensional(3D) topologies both comprised of Cu(Ⅱ) and OTf(OTf = trifluoromethanesulfonate) ions were synthesized and characterized.The CO_2,CH_4 and N_2 adsorption properties of the two isomeric MOFs were investigated from 263 K to 298 K at0.1 MPa.The results showed that the 2D MOF exhibited a higher selectivity for CO_2 from CO_2/CH_4 and CH_4from CH_4/N_2 compared to the 3D MOF,even though it possessed a lower surface area and pore volume.The higher adsorption heats of gases on the 2D MOF inferred the strong adsorption potential energy in the layered MOFs.Dynamic separation experiments using CO_2/CH_4 and CH_4/N_2 mixtures on the two MOFs proved that the2 D MOF had a longer elution time than the 3D MOF as well as better separation abilities.
文摘In order to remove N_(2) from low quality natural gas,a mathematical model has been established by Aspen adsorption,using the CH_(4)-selective sorbent silicalite-1 pellets.The dynamic adsorption isotherm was first simulated by breakthrough simulation of a CH_(4)/N_(2) mixture at different adsorption pressures and feed flow rates based on breakthrough experiments.The resulting simulated CH_(4) dynamic adsorption amounts were very close to the experimental data at three different adsorption pressures(100,200,and 300 kPa).Moreover,a single-bed,three-step pressure swing adsorption(PSA)experiment was performed,and the results were in good agreement with the simulated data,further corroborating the accuracy of the gas dynamic adsorption isotherm obtained by the simulation method.Finally,based on the simulated dynamic adsorption isotherm of CH_(4) and N_(2),a four-bed,eight-step PSA process has been designed,which enriched 75%(vol)CH_(4) and 80%(vol)CH_(4) to 95%(vol)and 99%(vol),and provided 99%(vol)recovery.
基金Supported by the NSFC of China(20973123)the National Basic Research Program of China(2012CB215002)+1 种基金the International Science and Technology Cooperative Program of China(2010DFB40440)Shanxi Basic Research Projects(2012011005-7,2012011008-3)
文摘Ferrierite(FER) zeolites were synthesized by solid transformation at different alkalinities(OH-/Al2O3 molar ratios). The in situ delamination of FER zeolites were achieved and their catalytic performances in the catalytic cracking of C4 hydrocarbons were examined. The relationships among the OH-/Al2O3 molar ratio, FER structure,composition, surface acidity and catalytic performance in C4 hydrocarbon cracking were investigated. The results of X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, inductively coupled plasma atomic emission spectroscopy, N2 adsorption, NH3temperature-programmed desorption and catalytic cracking showed that with increasing OH-/Al2O3 molar ratio in the synthesis gel, the Si O2/Al2O3 molar ratio of the as-synthesized FER zeolite decreased, the amount of acid sites in the corresponding H-FER increased, and the acid strength weakened. Additionally, the FER zeolite was delaminated at the mesoscale. H-FER5 synthesized at the highest alkalinity had the largest number of acid sites and exhibited the highest catalytic activity in C4 hydrocarbon catalytic cracking among three of the prepared catalysts. H-FER3 synthesized at the secondhighest alkalinity showed that the highest yield of benzene and toluene because of the secondary pores resulted from the gaps between the layers, which were beneficial to the diffusion and formation of large molecules.
基金Supported by the National Natural Science Foundation of China（Nos.21671147, 51203109） and the Funding of the State Key Laboratory of Coal and Coalbed Methane Co-mining, China.
基金Supported by the National Natural Science Foundation of China（Nos.21136007, 51572185）, the Natural Science Foundation of Shanxi Province, China（No.2014011016-4） and the Coal-Based Key Scientific and Technological Project of Shanxi Province, China（No.MQ2014-10）.
基金We appreciate the financial funding supported by the National Natural Science Foundation of China （No. 51402205）, Natural Science Foundation of Shanxi （No. 2015021058） and Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi （No. STIP-2016131）.
文摘为发展反应(OER ) 的氧的高度有效、便宜的催化剂的发展为支持切开的水的全面效率是极其迫切的。此处，我们与改变 Fe 的原子比率到报导一系列非结晶的 NiFeB nanoparticles 的制造(Ni + Fe )(<sub > 由一个灵巧的化学减小的方法的 Fe </sub>) 。非结晶的 NiFeB ( <sub > Fe </sub>= 0.20 ) nanoparticles ，联合优点在充实硼酸盐的 NiFeOOH 催化表面层，内在的非结晶的 nanostructures ，和 Fe 的优化的度的 situ 形成做，向在大量 pH 的 OER 的显示的高度活跃的 electrocatalytic 性能珍视(从对中立条件碱)。催化剂在 10 妈 / 厘米 <sup>2</sup> 在玻璃质的碳上与 43 mV/dec 的一个 Tafel 斜坡在 Ni 泡沫和 251 mV 上与 40 mV/dec 的一个 Tafel 斜坡展出了 216 mV 的相对低的过电位在 1 M KOH 溶液，比商业 RuO <sub>2</sub> 的表明大得多的 OER 效率。NiFeB 的 OER 表演测试的长期的稳定性(<sub > Fe </sub>= 0.20 ) 由 chronoamperometry (过电位()= 320 mV ) 超过 200 h 没揭示降级的证据。灵巧的、可伸缩的合成和高度活跃的水氧化为 OER electrocatalysis 使 NiFeB nanoparticles 很吸引人。
