The size of the nanoparticles and the number of oxygen vacancies have a significant effect on the catalytic activity of copper-based catalysts used for the synthesis of methanol from syngas.In this study,the authors p...The size of the nanoparticles and the number of oxygen vacancies have a significant effect on the catalytic activity of copper-based catalysts used for the synthesis of methanol from syngas.In this study,the authors prepared a series of catalysts CuO/ZnO/Al_(2)O_(3)/CeO_(2)(CZAC)with CuO particles of different sizes and varying number of oxygen vacancies on the surface by changing the added volume of CeO2 by using the co-precipitation method.The properties of the catalysts were characterized and their activity was evaluated by using high-pressure fixed-bed reaction equipment.The results showed that the addition of CeO_(2)to CuO/ZnO/Al_(2)O_(3)not only influenced the size of the CuO particles and metal-metal interactions,but also had an effect on the concentrations of oxygen vacancies and strongly basic sites.The presence of CuO particles of small sizes and a large numbers of oxygen vacancies on the surface of the catalyst were beneficial to its activity for the synthesis of methanol.The catalyst CZAC,when modified by 5%of CeO_(2),recorded CuO particles of the smallest size(8.9 nm),strong intermetallic interactions,and the highest concentrations of oxygen vacancies and strongly basic sites.It also exhibited the highest catalytic activity,with a space-time yield of methanol of 0.315 g/(h·g)that was higher than that of the enterprise RK-5 catalyst[0.215 g/(h·g)].展开更多
This paper is devoted to introduce a novel complex fifth-order memristive circuit system and its applications in synchronous stability and weak signal detection.Firstly,the typical dynamical behaviors of the memristiv...This paper is devoted to introduce a novel complex fifth-order memristive circuit system and its applications in synchronous stability and weak signal detection.Firstly,the typical dynamical behaviors of the memristive system are discussed by chaotic phase portrait,complexity analysis,one-parameter bifurcation and Lyapunov exponent spectrum.Secondly,the adaptive control method is applied to realize the synchronization between the drive memristive system(DMS) and the response memristive system(RMS).The results indicate that the synchronization method has strong robustness and anti-interference ability.Thirdly,the weak signal detection of the novel five-dimensional memristive system is realized by using the extreme sensitivity of chaotic system to initial values.Finally,the fifth-order memristive circuit is designed by using basic electronic elements and simulated by Multisim software.And the anti-interference ability and sensitivity of the fifth-order memristive circuit are further verified by adding different weak disturbance signals at different positions of the circuit.展开更多
基金supported by the Nature Science Foundation of China(Grant 22262006,22068009)the Supported by Guizhou Provincial Science and Technology Projects(ZK[2023]ordinary 050,[2023]General 403)+4 种基金the Science and Technology Support Plan Projects of Guizhou Province(Grant(2018)2192)the Scientific and Technological Innovation Talents Team of Guizhou(2018-5607)the Science and Technology Foundation of Guizhou Province(20177254)the One hundred Person Project of Guizhou Province(No.20165655)the Innovation Group Project of Education Department in Guizhou Province(No.2021010)。
文摘The size of the nanoparticles and the number of oxygen vacancies have a significant effect on the catalytic activity of copper-based catalysts used for the synthesis of methanol from syngas.In this study,the authors prepared a series of catalysts CuO/ZnO/Al_(2)O_(3)/CeO_(2)(CZAC)with CuO particles of different sizes and varying number of oxygen vacancies on the surface by changing the added volume of CeO2 by using the co-precipitation method.The properties of the catalysts were characterized and their activity was evaluated by using high-pressure fixed-bed reaction equipment.The results showed that the addition of CeO_(2)to CuO/ZnO/Al_(2)O_(3)not only influenced the size of the CuO particles and metal-metal interactions,but also had an effect on the concentrations of oxygen vacancies and strongly basic sites.The presence of CuO particles of small sizes and a large numbers of oxygen vacancies on the surface of the catalyst were beneficial to its activity for the synthesis of methanol.The catalyst CZAC,when modified by 5%of CeO_(2),recorded CuO particles of the smallest size(8.9 nm),strong intermetallic interactions,and the highest concentrations of oxygen vacancies and strongly basic sites.It also exhibited the highest catalytic activity,with a space-time yield of methanol of 0.315 g/(h·g)that was higher than that of the enterprise RK-5 catalyst[0.215 g/(h·g)].
基金supported by the National Natural Science Foundation of China (No.62061014)the President Fund Innovation Team Project of Hexi University (No.CXTD2022003)。
文摘This paper is devoted to introduce a novel complex fifth-order memristive circuit system and its applications in synchronous stability and weak signal detection.Firstly,the typical dynamical behaviors of the memristive system are discussed by chaotic phase portrait,complexity analysis,one-parameter bifurcation and Lyapunov exponent spectrum.Secondly,the adaptive control method is applied to realize the synchronization between the drive memristive system(DMS) and the response memristive system(RMS).The results indicate that the synchronization method has strong robustness and anti-interference ability.Thirdly,the weak signal detection of the novel five-dimensional memristive system is realized by using the extreme sensitivity of chaotic system to initial values.Finally,the fifth-order memristive circuit is designed by using basic electronic elements and simulated by Multisim software.And the anti-interference ability and sensitivity of the fifth-order memristive circuit are further verified by adding different weak disturbance signals at different positions of the circuit.
