Pd-supported ZSM-5 zeolites prepared through ion exchange technique were used as a dehydrogenation catalyst for synthesis of o-phenylphenol from cyclohexanone. When Si/Al ratio in the catalyst was 85∶1 or more, an ob...Pd-supported ZSM-5 zeolites prepared through ion exchange technique were used as a dehydrogenation catalyst for synthesis of o-phenylphenol from cyclohexanone. When Si/Al ratio in the catalyst was 85∶1 or more, an obvious reduction in attenuation rate of catalyst activity was observed. When the Si/Al ratio was of 17∶1 or less, polymer compounds could be formed on the surface of zeolite, that would decrease the dehydrogenation activity due to the reduction of the specific surface area of the catalyst.展开更多
采用共沉淀法和机械混合法制备了铜锌催化剂,并利用TPR、XRD和N2O吸附分解催化剂表征手段分析了铜锌催化剂中ZnO和Cu在仲丁醇(sec-butanol,SBA)脱氢反应中的作用。研究表明,Cu0是SBA脱氢的活性中心,ZnO具有分散铜物种和抗烧结能力。ZnO...采用共沉淀法和机械混合法制备了铜锌催化剂,并利用TPR、XRD和N2O吸附分解催化剂表征手段分析了铜锌催化剂中ZnO和Cu在仲丁醇(sec-butanol,SBA)脱氢反应中的作用。研究表明,Cu0是SBA脱氢的活性中心,ZnO具有分散铜物种和抗烧结能力。ZnO能够有效分散铜物种和阻止Cu0烧结的原因是在催化剂制备过程中形成了(CuZn)x(OH)y(CO3)z(x=1,5;y=2,6,z=1,2)前体,经焙烧形成了高分散的CuO-ZnO固溶体。同时,通过SBA催化脱氢反应测试筛选了适宜的Cu/Zn摩尔比,当Cu/Zn为1∶1时,表现出良好的反应活性,常压、240℃下质量空速为17.5 h 1时,该催化剂对SBA转化率达到80.54%,甲乙酮(methyl ethyl ketone,MEK)收率达到76.04%。铜锌催化剂的脱氢活性与Cu0比表面积不呈线性关系,SBA脱氢反应是一结构敏感型反应。展开更多
Pd-Ag/ceramic composite membrane, which was prepared by improved electroless plating with osmosis , exhibited higher hydrogen flux,reaching 0.619 mol·s -1 ·m -2 (673 K,Δ p =0.196 MPa). The catalytic dehydro...Pd-Ag/ceramic composite membrane, which was prepared by improved electroless plating with osmosis , exhibited higher hydrogen flux,reaching 0.619 mol·s -1 ·m -2 (673 K,Δ p =0.196 MPa). The catalytic dehydrogenation of isobutane in the Pd-Ag/ceramic composite membrane reactor was studied. The effects of various operating parameters,such as reaction temperature, linear velocity of feed gas, linear velocity of purge gas, molar ratio of nitrogen to isobutane in feed gas, and pressure of feed gas on conversion of isobutane were investigated. It was observed that the conversion of isobutane (50.5% at 723 K) in the membrane reactor exceeded the equilibrium conversion (18.8% at 723 K) and that in the fixed-bed reactor (15.5% at 723 K). From experimental results for dehydrogenation of isobutane in the membrane reactor, it was found that when a certain partial pressure of hydrogen was maintained in the reaction-side of the reactor, the formation of accumulative carbon overlayers on the surface of dehydrogenation catalyst and membrane was inhibited to some extent, which reduced the deactivation rate of catalyst and membrane.展开更多
文摘Pd-supported ZSM-5 zeolites prepared through ion exchange technique were used as a dehydrogenation catalyst for synthesis of o-phenylphenol from cyclohexanone. When Si/Al ratio in the catalyst was 85∶1 or more, an obvious reduction in attenuation rate of catalyst activity was observed. When the Si/Al ratio was of 17∶1 or less, polymer compounds could be formed on the surface of zeolite, that would decrease the dehydrogenation activity due to the reduction of the specific surface area of the catalyst.
文摘采用共沉淀法和机械混合法制备了铜锌催化剂,并利用TPR、XRD和N2O吸附分解催化剂表征手段分析了铜锌催化剂中ZnO和Cu在仲丁醇(sec-butanol,SBA)脱氢反应中的作用。研究表明,Cu0是SBA脱氢的活性中心,ZnO具有分散铜物种和抗烧结能力。ZnO能够有效分散铜物种和阻止Cu0烧结的原因是在催化剂制备过程中形成了(CuZn)x(OH)y(CO3)z(x=1,5;y=2,6,z=1,2)前体,经焙烧形成了高分散的CuO-ZnO固溶体。同时,通过SBA催化脱氢反应测试筛选了适宜的Cu/Zn摩尔比,当Cu/Zn为1∶1时,表现出良好的反应活性,常压、240℃下质量空速为17.5 h 1时,该催化剂对SBA转化率达到80.54%,甲乙酮(methyl ethyl ketone,MEK)收率达到76.04%。铜锌催化剂的脱氢活性与Cu0比表面积不呈线性关系,SBA脱氢反应是一结构敏感型反应。
文摘Pd-Ag/ceramic composite membrane, which was prepared by improved electroless plating with osmosis , exhibited higher hydrogen flux,reaching 0.619 mol·s -1 ·m -2 (673 K,Δ p =0.196 MPa). The catalytic dehydrogenation of isobutane in the Pd-Ag/ceramic composite membrane reactor was studied. The effects of various operating parameters,such as reaction temperature, linear velocity of feed gas, linear velocity of purge gas, molar ratio of nitrogen to isobutane in feed gas, and pressure of feed gas on conversion of isobutane were investigated. It was observed that the conversion of isobutane (50.5% at 723 K) in the membrane reactor exceeded the equilibrium conversion (18.8% at 723 K) and that in the fixed-bed reactor (15.5% at 723 K). From experimental results for dehydrogenation of isobutane in the membrane reactor, it was found that when a certain partial pressure of hydrogen was maintained in the reaction-side of the reactor, the formation of accumulative carbon overlayers on the surface of dehydrogenation catalyst and membrane was inhibited to some extent, which reduced the deactivation rate of catalyst and membrane.
