A carbon-based sulfonated catalyst was prepared by direct sulfonation and carbonization （in moderate conditions：200 ＆#176;C, 12 h） of red liquor solids, a by-product of paper-making process. The prepared sulfonate...A carbon-based sulfonated catalyst was prepared by direct sulfonation and carbonization （in moderate conditions：200 ＆#176;C, 12 h） of red liquor solids, a by-product of paper-making process. The prepared sulfonated cata-lyst （SC） had aromatic structure, composed of carbon enriched inner core, and oxygen-containing （SO3H, COOH, OH） groups enriched surface. The SO3H, COOH, OH groups amounted to 0.74 mmol·g^-1, 0.78 mmol·g^-1, 2.18 mmol·g^-1, respectively. The fresh SC showed much higher catalytic activity than that of the traditional solid acid catalysts （strong-acid 732 cation exchange resin, hydrogen type zeolite socony mobile-five （HZSM-5）, sulfated zir-conia） in esterification of oleic acid. SC was deactivated during the reactions, through the mechanisms of leaching of sulfonated species and formation of sulfonate esters. Two regeneration methods were developed, and the catalytic activity can be mostly regenerated by regeneration Method 1 and be fully regenerated by regeneration Method 2, respectively.展开更多
TiO_2 modified Al_2O_3 binary oxide was prepared by a wet-impregnation method and used as the support for ruthenium catalyst. The catalytic performance of Ru/TiO_2–Al_2O_3catalyst in CO_2 methanation reaction was inv...TiO_2 modified Al_2O_3 binary oxide was prepared by a wet-impregnation method and used as the support for ruthenium catalyst. The catalytic performance of Ru/TiO_2–Al_2O_3catalyst in CO_2 methanation reaction was investigated. Compared with Ru/Al_2O_3 catalyst, the Ru/TiO_2–Al_2O_3catalytic system exhibited a much higher activity in CO_2 methanation reaction. The reaction rate over Ru/TiO_2–Al_2O_3 was 0.59 mol CO_2·(g Ru)1·h-1, 3.1 times higher than that on Ru/Al_2O_3[0.19 mol CO_2·(gRu)-1·h-1]. The effect of TiO_2 content and TiO_2–Al_2O_3calcination temperature on catalytic performance was addressed. The corresponding structures of each catalyst were characterized by means of H_2-TPR, XRD, and TEM. Results indicated that the averaged particle size of the Ru on TiO_2–Al_2O_3support is 2.8 nm, smaller than that on Al_2O_3 support of 4.3 nm. Therefore, we conclude that the improved activity over Ru/TiO_2–Al_2O_3catalyst is originated from the smaller particle size of ruthenium resulting from a strong interaction between Ru and the rutile-TiO_2 support, which hindered the aggregation of Ru nanoparticles.展开更多
A solid superacid catalyst Pt-SO42-/ZrO2-A12O3 for n-pentane isomerization, was prepared by incipient-wetness impregnation. Preparetion conditions, namely, calcination temperature, concentration of sulfuric acid solut...A solid superacid catalyst Pt-SO42-/ZrO2-A12O3 for n-pentane isomerization, was prepared by incipient-wetness impregnation. Preparetion conditions, namely, calcination temperature, concentration of sulfuric acid solution used in impregnation and Al2O3 concentration, were varied to investigate the effects on catalytic performance of Pt-SO42-/ZrO2-A12O3. The results showed that the PtSZA catalyst exhibited excellent catalytic performance for n-pentane isomerization. Under optimized preparation conditions of calcination temperature of 650°C, reaction time for 3 h, concentration of sulfuric acid solution for 0.5 mol/L, 30% of Al2O3 concentration and 0.3% of Pt concentration, the n-pentane conversion and isopentane selectivity of Pt-SO42-/ZrO2-A12O3 could reach up to 62.17% and 91.60%, respectively.展开更多
The reduction process of Eu2O3 on TiO2 and other supports is investigated in detail by Mossbauer spectroscopy. The reducibility of Eu2O3 is greatly enhanced when it is supported on a surface of support. This is due to...The reduction process of Eu2O3 on TiO2 and other supports is investigated in detail by Mossbauer spectroscopy. The reducibility of Eu2O3 is greatly enhanced when it is supported on a surface of support. This is due to the solid-solid interaction between the oxide and the support.展开更多
γ-Al2O3 membranes were successfidly deposited on the top of porous α-Al2O3 support by sol-gel process and characterized by means of XRD , SEM, N2 adsorption and gas permeation. The γ-Al2O3 membranes, free of pin-h...γ-Al2O3 membranes were successfidly deposited on the top of porous α-Al2O3 support by sol-gel process and characterized by means of XRD , SEM, N2 adsorption and gas permeation. The γ-Al2O3 membranes, free of pin-holes and cracks, adhere tightly to the supports and have a thlekness of about 7μm. When sintered at 400 ℃ , γ-Al2O3 membranes have a rutrrow pore size distribution, with a pore diameter of 3.6nm, and the transport of both H2 and CO2 in supported γ-Al2O3 membrane is governed by Knudsen mechanism, with H2 permeance of 3.3× 10^-6 molm^-2Pa^-1s^-1 and H2/ CO2 permselectivity close to the ideal Knudsen value at 50 ℃ . The γ-Al2O3 membranes are suitable for being used as the substrates of microparoas membranes .展开更多
An aqueous sol-gel method for the synthesis of γ-Al2O3 supports has been developed for the use in tar reforming applications. It was determined the influences of two different aluminum precursors (aluminum sec-butoxi...An aqueous sol-gel method for the synthesis of γ-Al2O3 supports has been developed for the use in tar reforming applications. It was determined the influences of two different aluminum precursors (aluminum sec-butoxide (Al[OCH(CH3)CH2CH3]3) and aluminum nitrate (Al(NO3)3)) on the textural and crystallographic properties of Al2O3 supports. Only the formation of γ-Al2O3 is aimed in order to use these alumina materials as catalytic supports, because it presents high specific surface area and pore volume values. Additionally, the synthesis of γ-Al2O3 was realized with the use of a functionalized silicon precursor, [3-(2-aminoethylamino)propyl]trimethoxysilane, called EDAS. By the presence of an ethylenediamine group in this molecule, it is possible to chelate metallic ions and to highly increase their dispersion at a molecular level during the synthesis of metallic catalysts supported on alumina, which is an asset for catalytic applications. So it was developed a synthesis sol-gel procedure for the cogelation between the functionalized silicon alkoxide EDAS and alumina precursor. The alumina supports synthesized with Al(NO3)3 as precursor presented higher porous values than the ones obtained with aluminium sec-butoxide precursor. Since nitrate salts are much easier to handle than alkoxides, these observations allowed validating Al(NO3)3 as aluminum source for the future synthesis procedures for metallic catalysts supported on alumina.展开更多
The reduction process of Eu2O3 on TiO2 and other supports is investigated in detail by Mossbauer spectroscopy. The reducibility of Eu2O3 is greatly enhanced when it is supported on a surface of support. This is due to...The reduction process of Eu2O3 on TiO2 and other supports is investigated in detail by Mossbauer spectroscopy. The reducibility of Eu2O3 is greatly enhanced when it is supported on a surface of support. This is due to the solid-solid interaction between the oxide and the support.展开更多
Ni-based catalysts doped with copper additives were studied on their role in ethanol steam reforming reaction. The effects of Cu content, support species involving Al2O3-SIO2, Al2O3-MgO, Al2O3-ZnO, and Al2O3-La2O3, on...Ni-based catalysts doped with copper additives were studied on their role in ethanol steam reforming reaction. The effects of Cu content, support species involving Al2O3-SIO2, Al2O3-MgO, Al2O3-ZnO, and Al2O3-La2O3, on the catalytic performance were studied. Characterizations by TPR, XRD, NH3-TPD, XPS, and TGA indicated that catalysts 30Ni5Cu/Al2O3-MgO and 30Ni5Cu/Al2O3-ZnO have much higher H2 selectivity than 30Ni5Cu/Al2O3-SiO2, as well as good coke resistance. H2 selectivity for 30Ni5Cu/Al2O3-MgO catalyst was 73.3% at 450 ℃ and increased to 94.0% at 600℃, whereas for 30Ni5Cu/Al2O3-ZnO catalyst, the H2 selectivity was 63.6% at 450 ℃ and 95.2% at 600℃. TheseAl2O3-MgO and Al2O3-ZnO supported Ni-Cu bimetallic catalysts may have important applications in the production of hydrogen by ethanol steam reforming reactions.展开更多
Nickel-alumina catalysts supported on cordierite monoliths of honeycomb structure surpass essentially the conventional granulated ones with respect to the output in carbon dioxide reforming of methane. Adjusting the s...Nickel-alumina catalysts supported on cordierite monoliths of honeycomb structure surpass essentially the conventional granulated ones with respect to the output in carbon dioxide reforming of methane. Adjusting the surface acid-base properties of catalysts by introduction of alkali metal （Na, K） oxides inhibits the carbonization and as a result, improves the operational stability of these catalysts. An effect of promotion of nickel-alumina based composite doped by lanthanum oxide is found. This effect, caused by an additional route for the CO2 activation on Ni-La2O3/Al2O3/cordierite catalyst, is displayed in increase of methane conversion under conditions of an oxidant excess.展开更多
The adsorption properties of atomic and molecular species on Ir4/MgO and Ir4/γ-Al2O3 have been systematically studied by means of planewave density functional theory（DFT）calculations using the periodic boundary con...The adsorption properties of atomic and molecular species on Ir4/MgO and Ir4/γ-Al2O3 have been systematically studied by means of planewave density functional theory（DFT）calculations using the periodic boundary conditions.The binding energies of these species were ordered as follows：H2O〈C2H4〈H〈OH〈S〈N〈O〈C.The adsorption energies of adatoms on Ir4/MgO were larger than those on Ir4/γ-Al2O3 except hydrogen atom,but were in reverse for the molecules calculated.In addition,the difference of adsorption energies on MgO and γ-Al2O3 supports has been elucidated by analyzing the electronic properties.A detailed investigation on state density clarifies the nature of the magnitude of adsorption energy.These calculated results are consistent well with the available experimental and theoretical results.展开更多
Au/Al2O3 catalyst was prepared by a modified anion impregnation method and investigated with respect to its initial activity and stability for low-temperature CO oxidation.The activity changes of the catalyst were exa...Au/Al2O3 catalyst was prepared by a modified anion impregnation method and investigated with respect to its initial activity and stability for low-temperature CO oxidation.The activity changes of the catalyst were examined after separate treatment in CO＋O2 or CO2 ＋O2 .Furthermore,in situ FT-IR studies were performed to investigate the species on the surface when CO or CO＋O2 or CO2 ＋O2 was selected separately as adsorption gas.The results showed that Au/Al2O3 catalyst exhibited very high initial activity,but the catalytic activity was found to decrease gradually during CO oxidation with time on stream.And also,the activity of the catalyst declined after treatment in CO＋O2 or CO2 ＋O2 .The formation and accumulation of carbonate-like species during CO oxidation or treatment in CO＋O2 or CO2 ＋O2 might be mainly responsible for the activity decrease,which was reversible.展开更多
Alumina membranes without pinholes and cracks were prepared by the sol-gel process using anunordum aluminium sulphate as the starting material. The effects of different preparing conditions on morphology characteristi...Alumina membranes without pinholes and cracks were prepared by the sol-gel process using anunordum aluminium sulphate as the starting material. The effects of different preparing conditions on morphology characteristics of the membrane were investigated by scanning electron microscopy and 3D rotational microscopy. The preparing conditions include the amounts of drying control chemical additives （DCCA）, sintering procedure and sol-gel concentration. The results showed that PVA is a good crack-preventing reagent and the morphology of supported membranes was affected by ninny factors, including Al2O3 concentration, PVA/Al2O3 ratio, heating rate, membrane thickness and intrinsic defects of the substrate surface.展开更多
A Pd-Fe-B/γ-Al2O3 amorphous alloy catalyst was prepared by impregnation and chemical reduction with borohydrine aqueous solution. The catalyst was characterized by X-ray diffraction（XRD）, scanning electron microsc...A Pd-Fe-B/γ-Al2O3 amorphous alloy catalyst was prepared by impregnation and chemical reduction with borohydrine aqueous solution. The catalyst was characterized by X-ray diffraction（XRD）, scanning electron microscope（SEM）, differential scanning calorimetry（DSC） and elecdes design suite（EDS） and was used for catalytic hydrogenation of 5-nitro-2-chloro-2＇, 4＇-dimethylbenzenesulfonanilide （NCD）. The amorphous alloy catalyst shows significantly high activity and selectively for hydrogenation of NCD to 5-Amino-2-chloro- 2＇, 4＇-dimethyibenzenesuifonanilide （ACD）.展开更多
TWC-equipped exhausts are widely used in gasoline-fueled vehicles to meet stringent emission regulations. The main components in TWCs are precious metals such as palladium (Pd), platinum (Pt), and rhodium (Rh) as the ...TWC-equipped exhausts are widely used in gasoline-fueled vehicles to meet stringent emission regulations. The main components in TWCs are precious metals such as palladium (Pd), platinum (Pt), and rhodium (Rh) as the active component, and inorganic oxides such as γ-alumina (Al 2 O 3 ), ceria (CeO 2 ), zirconia (ZrO 2 ) and ceria-zirconia (CeO 2-ZrO 2 ) are used as the support. Interaction of precious metals and support plays an important role in the thermal stability and catalytic performance of TWCs. The support can improve the dispersion of precious metals and suppress the sintering of precious metals at high temperature. In the same, precious metals can also enhance the redox performance and oxygen storage capacity of support. This paper reviews the reaction phenomenon and mechanism of precious metals (Pt, Pd, Rh) and supports such as Al 2 O 3 , CeO 2-based composite oxides.展开更多
Ce-Zr-Al-Nd2O3 （CZAN） support materials were prepared by co-precipitation and impregnation methods, respectively. They were characterized by X-ray diffTaction （XRD）, low temperature nitrogen adsorption-desorption,...Ce-Zr-Al-Nd2O3 （CZAN） support materials were prepared by co-precipitation and impregnation methods, respectively. They were characterized by X-ray diffTaction （XRD）, low temperature nitrogen adsorption-desorption, oxygen pulsing technique, H2-temperamre programmed reduction （H2-TPR） and X-ray photoelectron spectroscopy （XPS）. The Pd-only three-way catalysts （Pd-TWC） supported on these materials were prepared by incipient wetness method and studied by activity tests. The results demonstrated that the CZAN supports obtained by the two methods showed better structural, textural and redox properties than the CZA without Nd2O3, and the addition of Nd203 improved the catalytic activity of TWC. Especially, the CZAN-i support prepared by impregnation method had better thermal stability and redox property. Meanwhile, the Pd/CZAN-i catalyst exhibited the best catalytic performance. XPS measurements indicated that the Nd-modified samples possessed more Ce3＋ and oxygen vacancies on the surface of samples, which led to a better redox property. The excellent redox property of support materials helped to improve the catalytic activity of TWC.展开更多
La2O3 doped Fe2O3 support was prepared by co-precipitation method,and gold was loaded by deposition-precipitation.Thermal stability of gold catalyst was enhanced considerably by La2O3 doping.Even when calcined at 500 ...La2O3 doped Fe2O3 support was prepared by co-precipitation method,and gold was loaded by deposition-precipitation.Thermal stability of gold catalyst was enhanced considerably by La2O3 doping.Even when calcined at 500 oC for 12 h,the catalyst doped with La2O3 could convert 90% of CO at 28.9 oC,while the catalyst without La2O3 doping achieved 90% CO conversion at 43.5 oC.Characterization techniques,such as N2 adsorption-desorption,X-ray diffraction(XRD),transmission electron microscopic(TEM) and thermogravime...展开更多
16.6%Co/γ-Al2O3 catalysts prepared by incipient wetness impregnation method were used for Fischer-Tropsch synthesis. The support was pre-treated with different concentration of NH4NO3 aqueous solution. The effect of ...16.6%Co/γ-Al2O3 catalysts prepared by incipient wetness impregnation method were used for Fischer-Tropsch synthesis. The support was pre-treated with different concentration of NH4NO3 aqueous solution. The effect of support pre-treatment on the properties of support and performance of supportedcobalt-based catalysts was investigated. To treat the support with NH4NO3 aqueous solution enlarged the pore of γ-Al2O3, decreased the impurity Na2O content, and weakened the surface acidity of γ-Al2O3. The change in the properties of the support decreased the interaction between cobalt species and support, enhanced the CO hydrogenation rate and the C5＋ selectivity. For all catalysts, increasing the reaction temperature increased the CO hydrogenation rate or the CO conversion, slightly decreased the total hydrocarbon selectivity, and favored the formation of methane and light hydrocarbons, while the chain growth probability decreased. For 16.6%Co/γ-Al2O3 catalysts, prepared with the support treated with 100 g/L NH4NO3 aqueous solution, the CO conversion, the CH4 selectivity, and the C5＋ selectivity were 83.13%, 6.86% and 82.75% respectively, and the chain growth probability was 0.83 under the condition of 493 K, 1.5 MPa, 500 h-1 and the molar ratio of H2 to CO being 2.0 in feed.展开更多
基金Supported by the National Natural Science Foundation of China(21276076)the Fundamental Research Funds for the Central Universities of China(WA1014003)State Key Laboratory of Chemical Engineering(SKL-ChE-10C06)
文摘A carbon-based sulfonated catalyst was prepared by direct sulfonation and carbonization （in moderate conditions：200 ＆#176;C, 12 h） of red liquor solids, a by-product of paper-making process. The prepared sulfonated cata-lyst （SC） had aromatic structure, composed of carbon enriched inner core, and oxygen-containing （SO3H, COOH, OH） groups enriched surface. The SO3H, COOH, OH groups amounted to 0.74 mmol·g^-1, 0.78 mmol·g^-1, 2.18 mmol·g^-1, respectively. The fresh SC showed much higher catalytic activity than that of the traditional solid acid catalysts （strong-acid 732 cation exchange resin, hydrogen type zeolite socony mobile-five （HZSM-5）, sulfated zir-conia） in esterification of oleic acid. SC was deactivated during the reactions, through the mechanisms of leaching of sulfonated species and formation of sulfonate esters. Two regeneration methods were developed, and the catalytic activity can be mostly regenerated by regeneration Method 1 and be fully regenerated by regeneration Method 2, respectively.
基金Supported by the National Natural Science Foundation of China(211031735127108721476226 and 51471076)DICP Fundamental Research Program for Clean Energy(DICPM201307)
文摘TiO_2 modified Al_2O_3 binary oxide was prepared by a wet-impregnation method and used as the support for ruthenium catalyst. The catalytic performance of Ru/TiO_2–Al_2O_3catalyst in CO_2 methanation reaction was investigated. Compared with Ru/Al_2O_3 catalyst, the Ru/TiO_2–Al_2O_3catalytic system exhibited a much higher activity in CO_2 methanation reaction. The reaction rate over Ru/TiO_2–Al_2O_3 was 0.59 mol CO_2·(g Ru)1·h-1, 3.1 times higher than that on Ru/Al_2O_3[0.19 mol CO_2·(gRu)-1·h-1]. The effect of TiO_2 content and TiO_2–Al_2O_3calcination temperature on catalytic performance was addressed. The corresponding structures of each catalyst were characterized by means of H_2-TPR, XRD, and TEM. Results indicated that the averaged particle size of the Ru on TiO_2–Al_2O_3support is 2.8 nm, smaller than that on Al_2O_3 support of 4.3 nm. Therefore, we conclude that the improved activity over Ru/TiO_2–Al_2O_3catalyst is originated from the smaller particle size of ruthenium resulting from a strong interaction between Ru and the rutile-TiO_2 support, which hindered the aggregation of Ru nanoparticles.
文摘A solid superacid catalyst Pt-SO42-/ZrO2-A12O3 for n-pentane isomerization, was prepared by incipient-wetness impregnation. Preparetion conditions, namely, calcination temperature, concentration of sulfuric acid solution used in impregnation and Al2O3 concentration, were varied to investigate the effects on catalytic performance of Pt-SO42-/ZrO2-A12O3. The results showed that the PtSZA catalyst exhibited excellent catalytic performance for n-pentane isomerization. Under optimized preparation conditions of calcination temperature of 650°C, reaction time for 3 h, concentration of sulfuric acid solution for 0.5 mol/L, 30% of Al2O3 concentration and 0.3% of Pt concentration, the n-pentane conversion and isopentane selectivity of Pt-SO42-/ZrO2-A12O3 could reach up to 62.17% and 91.60%, respectively.
文摘The reduction process of Eu2O3 on TiO2 and other supports is investigated in detail by Mossbauer spectroscopy. The reducibility of Eu2O3 is greatly enhanced when it is supported on a surface of support. This is due to the solid-solid interaction between the oxide and the support.
文摘γ-Al2O3 membranes were successfidly deposited on the top of porous α-Al2O3 support by sol-gel process and characterized by means of XRD , SEM, N2 adsorption and gas permeation. The γ-Al2O3 membranes, free of pin-holes and cracks, adhere tightly to the supports and have a thlekness of about 7μm. When sintered at 400 ℃ , γ-Al2O3 membranes have a rutrrow pore size distribution, with a pore diameter of 3.6nm, and the transport of both H2 and CO2 in supported γ-Al2O3 membrane is governed by Knudsen mechanism, with H2 permeance of 3.3× 10^-6 molm^-2Pa^-1s^-1 and H2/ CO2 permselectivity close to the ideal Knudsen value at 50 ℃ . The γ-Al2O3 membranes are suitable for being used as the substrates of microparoas membranes .
文摘An aqueous sol-gel method for the synthesis of γ-Al2O3 supports has been developed for the use in tar reforming applications. It was determined the influences of two different aluminum precursors (aluminum sec-butoxide (Al[OCH(CH3)CH2CH3]3) and aluminum nitrate (Al(NO3)3)) on the textural and crystallographic properties of Al2O3 supports. Only the formation of γ-Al2O3 is aimed in order to use these alumina materials as catalytic supports, because it presents high specific surface area and pore volume values. Additionally, the synthesis of γ-Al2O3 was realized with the use of a functionalized silicon precursor, [3-(2-aminoethylamino)propyl]trimethoxysilane, called EDAS. By the presence of an ethylenediamine group in this molecule, it is possible to chelate metallic ions and to highly increase their dispersion at a molecular level during the synthesis of metallic catalysts supported on alumina, which is an asset for catalytic applications. So it was developed a synthesis sol-gel procedure for the cogelation between the functionalized silicon alkoxide EDAS and alumina precursor. The alumina supports synthesized with Al(NO3)3 as precursor presented higher porous values than the ones obtained with aluminium sec-butoxide precursor. Since nitrate salts are much easier to handle than alkoxides, these observations allowed validating Al(NO3)3 as aluminum source for the future synthesis procedures for metallic catalysts supported on alumina.
文摘The reduction process of Eu2O3 on TiO2 and other supports is investigated in detail by Mossbauer spectroscopy. The reducibility of Eu2O3 is greatly enhanced when it is supported on a surface of support. This is due to the solid-solid interaction between the oxide and the support.
基金973 Program (2006CB202500)the National Natural Science Foundation of China (20676096)New Century Excellent Talents in University.9gram (2006CB202500)
文摘Ni-based catalysts doped with copper additives were studied on their role in ethanol steam reforming reaction. The effects of Cu content, support species involving Al2O3-SIO2, Al2O3-MgO, Al2O3-ZnO, and Al2O3-La2O3, on the catalytic performance were studied. Characterizations by TPR, XRD, NH3-TPD, XPS, and TGA indicated that catalysts 30Ni5Cu/Al2O3-MgO and 30Ni5Cu/Al2O3-ZnO have much higher H2 selectivity than 30Ni5Cu/Al2O3-SiO2, as well as good coke resistance. H2 selectivity for 30Ni5Cu/Al2O3-MgO catalyst was 73.3% at 450 ℃ and increased to 94.0% at 600℃, whereas for 30Ni5Cu/Al2O3-ZnO catalyst, the H2 selectivity was 63.6% at 450 ℃ and 95.2% at 600℃. TheseAl2O3-MgO and Al2O3-ZnO supported Ni-Cu bimetallic catalysts may have important applications in the production of hydrogen by ethanol steam reforming reactions.
文摘Nickel-alumina catalysts supported on cordierite monoliths of honeycomb structure surpass essentially the conventional granulated ones with respect to the output in carbon dioxide reforming of methane. Adjusting the surface acid-base properties of catalysts by introduction of alkali metal （Na, K） oxides inhibits the carbonization and as a result, improves the operational stability of these catalysts. An effect of promotion of nickel-alumina based composite doped by lanthanum oxide is found. This effect, caused by an additional route for the CO2 activation on Ni-La2O3/Al2O3/cordierite catalyst, is displayed in increase of methane conversion under conditions of an oxidant excess.
文摘The adsorption properties of atomic and molecular species on Ir4/MgO and Ir4/γ-Al2O3 have been systematically studied by means of planewave density functional theory（DFT）calculations using the periodic boundary conditions.The binding energies of these species were ordered as follows：H2O〈C2H4〈H〈OH〈S〈N〈O〈C.The adsorption energies of adatoms on Ir4/MgO were larger than those on Ir4/γ-Al2O3 except hydrogen atom,but were in reverse for the molecules calculated.In addition,the difference of adsorption energies on MgO and γ-Al2O3 supports has been elucidated by analyzing the electronic properties.A detailed investigation on state density clarifies the nature of the magnitude of adsorption energy.These calculated results are consistent well with the available experimental and theoretical results.
基金supported by the Science and Research Reward Fund Program of Shandong Excellent Young Scientist of China (2007BS04033)
文摘Au/Al2O3 catalyst was prepared by a modified anion impregnation method and investigated with respect to its initial activity and stability for low-temperature CO oxidation.The activity changes of the catalyst were examined after separate treatment in CO＋O2 or CO2 ＋O2 .Furthermore,in situ FT-IR studies were performed to investigate the species on the surface when CO or CO＋O2 or CO2 ＋O2 was selected separately as adsorption gas.The results showed that Au/Al2O3 catalyst exhibited very high initial activity,but the catalytic activity was found to decrease gradually during CO oxidation with time on stream.And also,the activity of the catalyst declined after treatment in CO＋O2 or CO2 ＋O2 .The formation and accumulation of carbonate-like species during CO oxidation or treatment in CO＋O2 or CO2 ＋O2 might be mainly responsible for the activity decrease,which was reversible.
基金Project supported by National Natural Science Foundation ofChina (Grant No .20373040) Science Foundation of Science andTechnology Commission of Zhejiang Province ( Grant No .0252nm101) Science Foundation of Shanghai MunicipalCommission of Science and Technology (Grant No .0452nm019)
文摘Alumina membranes without pinholes and cracks were prepared by the sol-gel process using anunordum aluminium sulphate as the starting material. The effects of different preparing conditions on morphology characteristics of the membrane were investigated by scanning electron microscopy and 3D rotational microscopy. The preparing conditions include the amounts of drying control chemical additives （DCCA）, sintering procedure and sol-gel concentration. The results showed that PVA is a good crack-preventing reagent and the morphology of supported membranes was affected by ninny factors, including Al2O3 concentration, PVA/Al2O3 ratio, heating rate, membrane thickness and intrinsic defects of the substrate surface.
文摘A Pd-Fe-B/γ-Al2O3 amorphous alloy catalyst was prepared by impregnation and chemical reduction with borohydrine aqueous solution. The catalyst was characterized by X-ray diffraction（XRD）, scanning electron microscope（SEM）, differential scanning calorimetry（DSC） and elecdes design suite（EDS） and was used for catalytic hydrogenation of 5-nitro-2-chloro-2＇, 4＇-dimethylbenzenesulfonanilide （NCD）. The amorphous alloy catalyst shows significantly high activity and selectively for hydrogenation of NCD to 5-Amino-2-chloro- 2＇, 4＇-dimethyibenzenesuifonanilide （ACD）.
基金National Science technology Support Plan Projects"(2012BAE06B00)
文摘TWC-equipped exhausts are widely used in gasoline-fueled vehicles to meet stringent emission regulations. The main components in TWCs are precious metals such as palladium (Pd), platinum (Pt), and rhodium (Rh) as the active component, and inorganic oxides such as γ-alumina (Al 2 O 3 ), ceria (CeO 2 ), zirconia (ZrO 2 ) and ceria-zirconia (CeO 2-ZrO 2 ) are used as the support. Interaction of precious metals and support plays an important role in the thermal stability and catalytic performance of TWCs. The support can improve the dispersion of precious metals and suppress the sintering of precious metals at high temperature. In the same, precious metals can also enhance the redox performance and oxygen storage capacity of support. This paper reviews the reaction phenomenon and mechanism of precious metals (Pt, Pd, Rh) and supports such as Al 2 O 3 , CeO 2-based composite oxides.
基金Project supported by National Natural Science Foundation of China (20773090, 20803049)the Specialized Research Fund for the Doctoral Program of Higher Education (20070610026, 200806100009)
文摘Ce-Zr-Al-Nd2O3 （CZAN） support materials were prepared by co-precipitation and impregnation methods, respectively. They were characterized by X-ray diffTaction （XRD）, low temperature nitrogen adsorption-desorption, oxygen pulsing technique, H2-temperamre programmed reduction （H2-TPR） and X-ray photoelectron spectroscopy （XPS）. The Pd-only three-way catalysts （Pd-TWC） supported on these materials were prepared by incipient wetness method and studied by activity tests. The results demonstrated that the CZAN supports obtained by the two methods showed better structural, textural and redox properties than the CZA without Nd2O3, and the addition of Nd203 improved the catalytic activity of TWC. Especially, the CZAN-i support prepared by impregnation method had better thermal stability and redox property. Meanwhile, the Pd/CZAN-i catalyst exhibited the best catalytic performance. XPS measurements indicated that the Nd-modified samples possessed more Ce3＋ and oxygen vacancies on the surface of samples, which led to a better redox property. The excellent redox property of support materials helped to improve the catalytic activity of TWC.
基金supported by the Henkel Professorship of Tongji University
文摘La2O3 doped Fe2O3 support was prepared by co-precipitation method,and gold was loaded by deposition-precipitation.Thermal stability of gold catalyst was enhanced considerably by La2O3 doping.Even when calcined at 500 oC for 12 h,the catalyst doped with La2O3 could convert 90% of CO at 28.9 oC,while the catalyst without La2O3 doping achieved 90% CO conversion at 43.5 oC.Characterization techniques,such as N2 adsorption-desorption,X-ray diffraction(XRD),transmission electron microscopic(TEM) and thermogravime...
基金This work was supported by the Doctoral Foundation of China(No.20050251006).
文摘16.6%Co/γ-Al2O3 catalysts prepared by incipient wetness impregnation method were used for Fischer-Tropsch synthesis. The support was pre-treated with different concentration of NH4NO3 aqueous solution. The effect of support pre-treatment on the properties of support and performance of supportedcobalt-based catalysts was investigated. To treat the support with NH4NO3 aqueous solution enlarged the pore of γ-Al2O3, decreased the impurity Na2O content, and weakened the surface acidity of γ-Al2O3. The change in the properties of the support decreased the interaction between cobalt species and support, enhanced the CO hydrogenation rate and the C5＋ selectivity. For all catalysts, increasing the reaction temperature increased the CO hydrogenation rate or the CO conversion, slightly decreased the total hydrocarbon selectivity, and favored the formation of methane and light hydrocarbons, while the chain growth probability decreased. For 16.6%Co/γ-Al2O3 catalysts, prepared with the support treated with 100 g/L NH4NO3 aqueous solution, the CO conversion, the CH4 selectivity, and the C5＋ selectivity were 83.13%, 6.86% and 82.75% respectively, and the chain growth probability was 0.83 under the condition of 493 K, 1.5 MPa, 500 h-1 and the molar ratio of H2 to CO being 2.0 in feed.
