NH_(3) selective catalytic reduction(SCR) has been widely recognized as a promising technique for reducing nitrogen oxides from diesel vehicle exhausts. High-efficiency SCR catalysts that could perform at low temperat...NH_(3) selective catalytic reduction(SCR) has been widely recognized as a promising technique for reducing nitrogen oxides from diesel vehicle exhausts. High-efficiency SCR catalysts that could perform at low temperatures are essential to denitration. In this work, a series of bimetallic CeCu-SAPO-34 molecular sieves were synthesized by one-step hydrothermal method. The Ce Cu-SAPO-34 maintained good crystallinity and a regular hexahedron appearance of Cu-SAPO-34 after introducing Ce species, while exhibiting a higher specific surface area and pore volume. The as-prepared CeCu-SAPO-34 with 0.02%(mass) Ce constituent exhibited the best catalytic activity below 300℃ and a maximum NO_(x) conversion of 99% was attained;the NO_(x) removal rates of more than 68% and 94% were achieved at 150℃ and 200℃, respectively. And the introduction of cerium species in Cu-SAPO-34 improves the low-temperature hydrothermal stability of the catalyst towards NH_(3)-SCR reaction. Additionally, the introduced Ce species could enhance the formation of abundant weak Br?nsted acid centers and promote the synergistic effect between CuO grains and isolated Cu^(2+) to enhance the redox cycle, which benefit the NH_(3)-SCR reaction.This work provides a facile synthesis method of high-efficiency SCR denitration catalysts towards diesel vehicles exhaust treatment under low temperature.展开更多
Accurately predicting distributions of concentration and temperature field in fixed-bed column is essential for designing adsorption processes.In this study,a two-dimensional(2D),axisymmetric,nonisothermal,dynamic ads...Accurately predicting distributions of concentration and temperature field in fixed-bed column is essential for designing adsorption processes.In this study,a two-dimensional(2D),axisymmetric,nonisothermal,dynamic adsorption model was established by coupling equations of mass,momentum and energy balance,and solved by finite element analysis.The simulation breakthrough curves fit well with the low-concentration CO_(2) adsorption experimental data,indicating the reliability of the established model.The distributions of concentration and temperature field in the column for CO_(2) adsorption and separation from CO_(2)/N_(2) were obtained.The sensitivity analysis of the adsorption conditions shows that the operation parameters such as feed flow rate,feed concentration,pellet size,and column height-to-diameter ratio produce a significant effect on the dynamic adsorption performance.The multi-physics coupled 2D axisymmetric model could provide a theoretical foundation and guidance for designing CO_(2) fixed-bed adsorption and separation processes,which could be extended to other mixed gases as well.展开更多
基金supported by Project of Central Government for Local Science and Technology Development of China (2022JH6/100100050)the National Natural Science Foundation of China (21776028)Liaoning Key Laboratory of Chemical Additive Synthesis and Separation (ZJKF2001)。
文摘NH_(3) selective catalytic reduction(SCR) has been widely recognized as a promising technique for reducing nitrogen oxides from diesel vehicle exhausts. High-efficiency SCR catalysts that could perform at low temperatures are essential to denitration. In this work, a series of bimetallic CeCu-SAPO-34 molecular sieves were synthesized by one-step hydrothermal method. The Ce Cu-SAPO-34 maintained good crystallinity and a regular hexahedron appearance of Cu-SAPO-34 after introducing Ce species, while exhibiting a higher specific surface area and pore volume. The as-prepared CeCu-SAPO-34 with 0.02%(mass) Ce constituent exhibited the best catalytic activity below 300℃ and a maximum NO_(x) conversion of 99% was attained;the NO_(x) removal rates of more than 68% and 94% were achieved at 150℃ and 200℃, respectively. And the introduction of cerium species in Cu-SAPO-34 improves the low-temperature hydrothermal stability of the catalyst towards NH_(3)-SCR reaction. Additionally, the introduced Ce species could enhance the formation of abundant weak Br?nsted acid centers and promote the synergistic effect between CuO grains and isolated Cu^(2+) to enhance the redox cycle, which benefit the NH_(3)-SCR reaction.This work provides a facile synthesis method of high-efficiency SCR denitration catalysts towards diesel vehicles exhaust treatment under low temperature.
基金supported by the National Natural Science Foundation of China(21776028)Key Research and Development Projects of Liaoning Province(2017308004)。
文摘Accurately predicting distributions of concentration and temperature field in fixed-bed column is essential for designing adsorption processes.In this study,a two-dimensional(2D),axisymmetric,nonisothermal,dynamic adsorption model was established by coupling equations of mass,momentum and energy balance,and solved by finite element analysis.The simulation breakthrough curves fit well with the low-concentration CO_(2) adsorption experimental data,indicating the reliability of the established model.The distributions of concentration and temperature field in the column for CO_(2) adsorption and separation from CO_(2)/N_(2) were obtained.The sensitivity analysis of the adsorption conditions shows that the operation parameters such as feed flow rate,feed concentration,pellet size,and column height-to-diameter ratio produce a significant effect on the dynamic adsorption performance.The multi-physics coupled 2D axisymmetric model could provide a theoretical foundation and guidance for designing CO_(2) fixed-bed adsorption and separation processes,which could be extended to other mixed gases as well.
