Ammonia Selective Catalytic Reduction(NHs-SCR)technology has been employed to eliminate NO_(x) from diesel engine exhaust,with Cu-SSZ-13 serving as the commercial catalyst.The greenhouse gas N_(2)O is produced as a by...Ammonia Selective Catalytic Reduction(NHs-SCR)technology has been employed to eliminate NO_(x) from diesel engine exhaust,with Cu-SSZ-13 serving as the commercial catalyst.The greenhouse gas N_(2)O is produced as a byproduct when using Cu-SSZ-13 as the NH_(3)-SCR catalyst.To achieve synergistic control of pollutants and greenhouse gases in diesel engine exhaust,rational design of Cu-SSZ-13 catalysts is required.In this study,the effect of Brønsted acid sites in Cu-SSZ-13 catalysts on the formation of N_(2)O was investigated.Mild thermal treatmentwas innovatively employed to prepare Cu-SSZ-13 catalysts with different amounts of Brønsted acid sites.EPR,H_(2)-TPR,NH_(3)-TPD,NMR were utilized to determine that the Brønsted acid sites were modified while the Cu species remained unchanged.Thereby an accurate assessment of the influence of Brønsted acid sites on N_(2)O formation could be achieved.Our results showed that Cu-SSZ-13 with more Brønsted acid sites produced less N_(2)O during the NH_(3)-SCR reaction.In the low-temperature region,the presence of framework acid sites facilitates the decomposition of the NH_(4)NO_(3)assisted by NO to form N_(2)and H_(2)O,reducing the formation of N_(2)O.In the high-temperature region,the Brønsted acid sites promote the decomposition of NH_(2)NO into N_(2)and H_(2)O.Meanwhile,the N_(2)O-SCR reaction can also be promoted by Brønsted acid sites,thereby decreasing N_(2)O emissions.This study suggests that in the future design and synthesis of Cu-SSZ-13 zeolites,attention should be paid to creating more Brønsted acid sites in Cu-SSZ-13 to reduce N_(2)O emissions.展开更多
Direct converting carbon dioxide into hydrocarbon fuels and value-added chemicals would offer a very attractive approach for efficient utilization of CO_(2) as a carbon resource.Although,olefins,aromatics and gasoline...Direct converting carbon dioxide into hydrocarbon fuels and value-added chemicals would offer a very attractive approach for efficient utilization of CO_(2) as a carbon resource.Although,olefins,aromatics and gasoline have been successfully synthesized by CO_(2) hydrogenation,highly selective conversion of CO_(2) and H_(2) into C_(2+)hydrocarbon is still challenging due to a high C-C coupling barrier and inhibiting the production of other long-chain hydrocarbons.Here,we report a composite catalyst made of InZrO_(x) and SSZ-13 molecular sieve(InZrO_(x)+SSZ-13),which exhibits 74.5% propane selectivity at 623 K.The 8-MR micropores and the higher strength of the acid for SSZ-13 benefit the formation of propane.Compared with pure InO_(x) and m-ZrO_(2) the composite oxide InZrO_(x) containing more oxygen vacancies,exhibits to be more readily reduced by H_(2) and easier to adsorb and desorb CO_(2) within the reaction temperature.All those could be beneficial to the activation and conversion of H_(2) and CO_(2).The catalytic performance of InZrO_(x)+SSZ-13 in CO_(2) hydrogenation provides a potential for production of propane.展开更多
基金supported by the National Key R&D Program of China(Nos.2023YFC3707200 and 2022YFC3704400)the National Natural Science Foundation of China(Nos.52200136,22402220,and 52225004)Hangzhou Qianjiang Distinguished Experts Project.
文摘Ammonia Selective Catalytic Reduction(NHs-SCR)technology has been employed to eliminate NO_(x) from diesel engine exhaust,with Cu-SSZ-13 serving as the commercial catalyst.The greenhouse gas N_(2)O is produced as a byproduct when using Cu-SSZ-13 as the NH_(3)-SCR catalyst.To achieve synergistic control of pollutants and greenhouse gases in diesel engine exhaust,rational design of Cu-SSZ-13 catalysts is required.In this study,the effect of Brønsted acid sites in Cu-SSZ-13 catalysts on the formation of N_(2)O was investigated.Mild thermal treatmentwas innovatively employed to prepare Cu-SSZ-13 catalysts with different amounts of Brønsted acid sites.EPR,H_(2)-TPR,NH_(3)-TPD,NMR were utilized to determine that the Brønsted acid sites were modified while the Cu species remained unchanged.Thereby an accurate assessment of the influence of Brønsted acid sites on N_(2)O formation could be achieved.Our results showed that Cu-SSZ-13 with more Brønsted acid sites produced less N_(2)O during the NH_(3)-SCR reaction.In the low-temperature region,the presence of framework acid sites facilitates the decomposition of the NH_(4)NO_(3)assisted by NO to form N_(2)and H_(2)O,reducing the formation of N_(2)O.In the high-temperature region,the Brønsted acid sites promote the decomposition of NH_(2)NO into N_(2)and H_(2)O.Meanwhile,the N_(2)O-SCR reaction can also be promoted by Brønsted acid sites,thereby decreasing N_(2)O emissions.This study suggests that in the future design and synthesis of Cu-SSZ-13 zeolites,attention should be paid to creating more Brønsted acid sites in Cu-SSZ-13 to reduce N_(2)O emissions.
基金the financial support from the National Natural Science Foundation of China(Grant Nos.21978285,21991093,21991090)the“Transformational Technologies for Clean Energy and Demonstration”,Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA21030100)。
文摘Direct converting carbon dioxide into hydrocarbon fuels and value-added chemicals would offer a very attractive approach for efficient utilization of CO_(2) as a carbon resource.Although,olefins,aromatics and gasoline have been successfully synthesized by CO_(2) hydrogenation,highly selective conversion of CO_(2) and H_(2) into C_(2+)hydrocarbon is still challenging due to a high C-C coupling barrier and inhibiting the production of other long-chain hydrocarbons.Here,we report a composite catalyst made of InZrO_(x) and SSZ-13 molecular sieve(InZrO_(x)+SSZ-13),which exhibits 74.5% propane selectivity at 623 K.The 8-MR micropores and the higher strength of the acid for SSZ-13 benefit the formation of propane.Compared with pure InO_(x) and m-ZrO_(2) the composite oxide InZrO_(x) containing more oxygen vacancies,exhibits to be more readily reduced by H_(2) and easier to adsorb and desorb CO_(2) within the reaction temperature.All those could be beneficial to the activation and conversion of H_(2) and CO_(2).The catalytic performance of InZrO_(x)+SSZ-13 in CO_(2) hydrogenation provides a potential for production of propane.
