采用水热法和聚合物保护的硼氢化钠还原法制备了α-MnO_2及其负载Au-Pd的催化剂,考察了催化消除乙酸乙酯、间二甲苯及二者混合物的性能.XRD、SEM和TEM以及H2-TPR表征催化剂的物化性质.在反应物浓度为1000 mg/L,与O_2摩尔比为1:400,空速...采用水热法和聚合物保护的硼氢化钠还原法制备了α-MnO_2及其负载Au-Pd的催化剂,考察了催化消除乙酸乙酯、间二甲苯及二者混合物的性能.XRD、SEM和TEM以及H2-TPR表征催化剂的物化性质.在反应物浓度为1000 mg/L,与O_2摩尔比为1:400,空速为40000 m L/(g·h)的条件下,0.91Au0.48Pd/α-MnO_2比α-MnO_2的催化性能优越与其具有更好的低温还原性能有关.展开更多
Heterogeneous Pd nanocatalysts are efficient catalysts for the Heck reaction but require multi-step,sophisticated procedures and harsh reaction conditions.In this work,a green and facile strategy has been developed to...Heterogeneous Pd nanocatalysts are efficient catalysts for the Heck reaction but require multi-step,sophisticated procedures and harsh reaction conditions.In this work,a green and facile strategy has been developed to decorate Pd nanoparticles on polydopamine(PDA)-coated multi-walled carbon nanotubes(Pd/CNTs-PDA)via a one-pot method.The obtained nanoparticles were characterized by various techniques including transmission electron microscopy,X-ray diffraction,and X-ray photoelectron spectroscopy,which proved that Pd NPs are well-dispersed on the PDA and between the surfaces of the PDA and CNTs.The resultant Pd/CNTs-PDA catalysts exhibit excellent catalytic reactivity toward the Heck reaction at low temperatures.Moreover,by DFT simulation,we found that during the PDA polymerization process,a large number of unsaturated—N=and C=O species are more active than the groups on the PDA end product to anchor Pd NPs.The results provide evidence that the catalyst synthesized by the onepot method exhibited good activity because sufficient active sites could be created to effectively promote Pd NPs dispersion during the dopamine polymerization process.Additionally,the Pd/CNTs-PDA catalyst was successfully employed in Heck cross-coupling reactions with various functionalized substrates.This method opens a window for the fabrication of high-performance nanocomposite catalysts under mild conditions using simple methods and has several potential applications.展开更多
从Pd纳米粒子溶胶出发,采用一步沉淀法和浸渍法分别制备了0.5%(质量分数)Pd/Ce0.6Zr0.4-x Y x O2(x=0,0.03,0.05,0.1)负载型三效催化剂,考察了贵金属纳米粒子的负载方法以及Y的掺杂量对三效催化活性和水热稳定性的影响。结果表明,和浸...从Pd纳米粒子溶胶出发,采用一步沉淀法和浸渍法分别制备了0.5%(质量分数)Pd/Ce0.6Zr0.4-x Y x O2(x=0,0.03,0.05,0.1)负载型三效催化剂,考察了贵金属纳米粒子的负载方法以及Y的掺杂量对三效催化活性和水热稳定性的影响。结果表明,和浸渍法制备的催化剂相比,采用一步沉淀法制备的催化剂具有更高的三效催化活性。对于一步沉淀法制备的催化剂,Y的掺杂量对新鲜样品的三效催化活性影响不大,然而,900℃水热老化后,Y的掺杂量为0.05的Pd/Ce0.6Zr0.35Y0.05O2催化剂表现出最佳的催化活性,且其三效窗口也最为稳定。以上研究结果表明,一步沉淀法是一种从贵金属纳米溶胶出发制备纳米三效催化剂的有效方法,且在铈锆储氧材料中掺杂适量的Y元素可以进一步提高催化剂的三效催化活性和水热稳定性。展开更多
文摘采用水热法和聚合物保护的硼氢化钠还原法制备了α-MnO_2及其负载Au-Pd的催化剂,考察了催化消除乙酸乙酯、间二甲苯及二者混合物的性能.XRD、SEM和TEM以及H2-TPR表征催化剂的物化性质.在反应物浓度为1000 mg/L,与O_2摩尔比为1:400,空速为40000 m L/(g·h)的条件下,0.91Au0.48Pd/α-MnO_2比α-MnO_2的催化性能优越与其具有更好的低温还原性能有关.
基金supported by the National Natural Science Foundation of China(Nos.21506174,21406039)the Fundamental Research Funds for the Central Universities,Southwest Minzu University(2020NYBPY04)+1 种基金the China Scholarship Council Program(201908510082)Guangdong Natural Science Foundation(2017A030307038)。
文摘Heterogeneous Pd nanocatalysts are efficient catalysts for the Heck reaction but require multi-step,sophisticated procedures and harsh reaction conditions.In this work,a green and facile strategy has been developed to decorate Pd nanoparticles on polydopamine(PDA)-coated multi-walled carbon nanotubes(Pd/CNTs-PDA)via a one-pot method.The obtained nanoparticles were characterized by various techniques including transmission electron microscopy,X-ray diffraction,and X-ray photoelectron spectroscopy,which proved that Pd NPs are well-dispersed on the PDA and between the surfaces of the PDA and CNTs.The resultant Pd/CNTs-PDA catalysts exhibit excellent catalytic reactivity toward the Heck reaction at low temperatures.Moreover,by DFT simulation,we found that during the PDA polymerization process,a large number of unsaturated—N=and C=O species are more active than the groups on the PDA end product to anchor Pd NPs.The results provide evidence that the catalyst synthesized by the onepot method exhibited good activity because sufficient active sites could be created to effectively promote Pd NPs dispersion during the dopamine polymerization process.Additionally,the Pd/CNTs-PDA catalyst was successfully employed in Heck cross-coupling reactions with various functionalized substrates.This method opens a window for the fabrication of high-performance nanocomposite catalysts under mild conditions using simple methods and has several potential applications.
基金Project supported by the Ministry of Science and Technology of China(No.2011CB932403)the National Natural Science Foundation of China(Nos.21131005,21021061,20925103,20923004)the Fok Ying Tung Education Foundation(No.121011)~~
文摘从Pd纳米粒子溶胶出发,采用一步沉淀法和浸渍法分别制备了0.5%(质量分数)Pd/Ce0.6Zr0.4-x Y x O2(x=0,0.03,0.05,0.1)负载型三效催化剂,考察了贵金属纳米粒子的负载方法以及Y的掺杂量对三效催化活性和水热稳定性的影响。结果表明,和浸渍法制备的催化剂相比,采用一步沉淀法制备的催化剂具有更高的三效催化活性。对于一步沉淀法制备的催化剂,Y的掺杂量对新鲜样品的三效催化活性影响不大,然而,900℃水热老化后,Y的掺杂量为0.05的Pd/Ce0.6Zr0.35Y0.05O2催化剂表现出最佳的催化活性,且其三效窗口也最为稳定。以上研究结果表明,一步沉淀法是一种从贵金属纳米溶胶出发制备纳米三效催化剂的有效方法,且在铈锆储氧材料中掺杂适量的Y元素可以进一步提高催化剂的三效催化活性和水热稳定性。
