Coal gangue was calcinated under air, nitrogen, carbon dioxide, air-hydrogen, and hydrogen atmospheres. The effects of different calcination temperatures and atmospheres on the mineral composition of activated coal ga...Coal gangue was calcinated under air, nitrogen, carbon dioxide, air-hydrogen, and hydrogen atmospheres. The effects of different calcination temperatures and atmospheres on the mineral composition of activated coal gangue were investigated by X-ray diffraction. Moreover, the acid leaching kinetics of aluminum oxide from coal gangue was investigated with sulfuric acid. It showed that the air atmosphere promoted kaolinite decomposition during coal gangue calcination. The hydrogen atmosphere promoted the activation and decomposition of kaolinite at reaction temperatures exceeding 650℃. The carbon dioxide atmosphere eliminated the influence of residual carbon on coal gangue. When the ratio of acid/coal gangue was 1.5 and reaction temperature was 650℃, the sulfuric acid leaching rate under air, air-hydrogen, carbon dioxide, hydrogen and nitrogen atmospheres were 93.66%, 90.90%, 84.06%, 81.91% and 77.54% respectively. The acid leaching reaction process conformed to unreacted shrinking core model of particle unchanged, and was controlled by the interracial chemical reaction. The reaction kinetic equation for the leaching process was 1-（1-x）1/3=kt with an apparent activation energy of 48.97 kJ/mol.展开更多
The preparation of highly active supported noble metal catalysts with a low noble metal loading has always been the ultimate goal of researchers working on catalysis.Hydrothermally treated Pt/Al_(2)O_(3)(Pt/Al_(2)O_(3...The preparation of highly active supported noble metal catalysts with a low noble metal loading has always been the ultimate goal of researchers working on catalysis.Hydrothermally treated Pt/Al_(2)O_(3)(Pt/Al_(2)O_(3)-H)exhibits better catalytic activity than that(Pt/Al_(2)O_(3)-C)treated via the conventional calcination approach.At the high space velocity of100,000 m L/(g·hr),the temperature that correspond to 50%toluene conversion(T50)of Pt/Al_(2)O_(3)-H is 115℃ lower than that of Pt/Al_(2)O_(3)-C,and the turnover frequency(TOF)value can reach 0.0756 sec-1.The mechanism by which the hydrothermal approach enhances Pt/Al_(2)O_(3) activity has been investigated.The structure associated with the high catalytic activity of Pt nanoparticles(NPs)can be retained via hydrothermal treatment.Furthermore,the support is transformed to AlO(OH)with numerous surface hydroxyl groups,which in turn can facilitate the adsorption of toluene.And the synergistic effects of Pt NPs and AlO(OH)increases the contents of Pt in oxidation state and active oxygen,which are beneficial for toluene oxidation.展开更多
基金supported by National Natural Science Foundation of China(51074170)Shaanxi Key Technology R&D Program(2016GY-147)+1 种基金Key Laboratory of Coal Resources Exploration and Comprehensive UtilizationMinistry of Land and Resources Open Research Topic(KF2016-3)
文摘Coal gangue was calcinated under air, nitrogen, carbon dioxide, air-hydrogen, and hydrogen atmospheres. The effects of different calcination temperatures and atmospheres on the mineral composition of activated coal gangue were investigated by X-ray diffraction. Moreover, the acid leaching kinetics of aluminum oxide from coal gangue was investigated with sulfuric acid. It showed that the air atmosphere promoted kaolinite decomposition during coal gangue calcination. The hydrogen atmosphere promoted the activation and decomposition of kaolinite at reaction temperatures exceeding 650℃. The carbon dioxide atmosphere eliminated the influence of residual carbon on coal gangue. When the ratio of acid/coal gangue was 1.5 and reaction temperature was 650℃, the sulfuric acid leaching rate under air, air-hydrogen, carbon dioxide, hydrogen and nitrogen atmospheres were 93.66%, 90.90%, 84.06%, 81.91% and 77.54% respectively. The acid leaching reaction process conformed to unreacted shrinking core model of particle unchanged, and was controlled by the interracial chemical reaction. The reaction kinetic equation for the leaching process was 1-（1-x）1/3=kt with an apparent activation energy of 48.97 kJ/mol.
基金supported by the National Natural Science Foundation of China(Nos.21506194,21676255)the Zhejiang Provincial Natural Science Foundation of China(Nos.LZ21E080001,2017C03007,2017C33106)。
文摘The preparation of highly active supported noble metal catalysts with a low noble metal loading has always been the ultimate goal of researchers working on catalysis.Hydrothermally treated Pt/Al_(2)O_(3)(Pt/Al_(2)O_(3)-H)exhibits better catalytic activity than that(Pt/Al_(2)O_(3)-C)treated via the conventional calcination approach.At the high space velocity of100,000 m L/(g·hr),the temperature that correspond to 50%toluene conversion(T50)of Pt/Al_(2)O_(3)-H is 115℃ lower than that of Pt/Al_(2)O_(3)-C,and the turnover frequency(TOF)value can reach 0.0756 sec-1.The mechanism by which the hydrothermal approach enhances Pt/Al_(2)O_(3) activity has been investigated.The structure associated with the high catalytic activity of Pt nanoparticles(NPs)can be retained via hydrothermal treatment.Furthermore,the support is transformed to AlO(OH)with numerous surface hydroxyl groups,which in turn can facilitate the adsorption of toluene.And the synergistic effects of Pt NPs and AlO(OH)increases the contents of Pt in oxidation state and active oxygen,which are beneficial for toluene oxidation.
