By using high-alumina fly ash as raw material,a process was proposed for activating the fly ash with Na_(2)CO_(3)calcination and extracting aluminum from activated clinker with sulfuric acid leaching.The feasibility o...By using high-alumina fly ash as raw material,a process was proposed for activating the fly ash with Na_(2)CO_(3)calcination and extracting aluminum from activated clinker with sulfuric acid leaching.The feasibility of roasting process of activated fly ash by Na_(2)CO_(3)was discussed based on thermodynamic analysis.The experimental results showed that Na_(2)CO_(3)gradually reactes with mullite over 700 K to produce NaAlSiO_(4).The optimal process conditions for the activation stage are:a material ratio of 1:1 between sodium carbonate and fly ash,a calcination temperature of 900℃,and a calcination time of 2.5 hours.Under these conditions,the leaching rate of aluminum is 90.3%.By comparing the SEM and XRD analysis of raw and clinker materials,it could be concluded that the mullite phase of fly ash is almost completely destroyed and transformed into sodium aluminosilicate with good acid solubility.展开更多
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Funded by the National Natural Science Foundation of China(No.U1710257)the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi(No.2019L0656)+2 种基金the Doctoral Research Foundation of Taiyuan University of Science and Technology,China(No.20142001)the Open Foundation Program of Key Laboratory for Ecological Metallurgy of Multimetallic Mineral,Ministry of Education,China(No.2020003)the Supported by Fundamental Research Program of Shanxi Province,China(No.202103021224281)。
文摘By using high-alumina fly ash as raw material,a process was proposed for activating the fly ash with Na_(2)CO_(3)calcination and extracting aluminum from activated clinker with sulfuric acid leaching.The feasibility of roasting process of activated fly ash by Na_(2)CO_(3)was discussed based on thermodynamic analysis.The experimental results showed that Na_(2)CO_(3)gradually reactes with mullite over 700 K to produce NaAlSiO_(4).The optimal process conditions for the activation stage are:a material ratio of 1:1 between sodium carbonate and fly ash,a calcination temperature of 900℃,and a calcination time of 2.5 hours.Under these conditions,the leaching rate of aluminum is 90.3%.By comparing the SEM and XRD analysis of raw and clinker materials,it could be concluded that the mullite phase of fly ash is almost completely destroyed and transformed into sodium aluminosilicate with good acid solubility.
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.
