Trace amounts of noble metal-doped Ni/Mg（AI）O catalysts were pre- pared starting from Mg-Al hydrotalcites （HTs） and tested in daily start-up and shut-down （DSS） operation of steam reforming （SR） of methane or ...Trace amounts of noble metal-doped Ni/Mg（AI）O catalysts were pre- pared starting from Mg-Al hydrotalcites （HTs） and tested in daily start-up and shut-down （DSS） operation of steam reforming （SR） of methane or partial oxidation （PO） of propane. Although Ni/Mg（Al）O catalysts prepared from Mg（Ni）-Al HT exhibited high and stable activity in stationary SR, PO and dry reforming of methane and propane, the Ni/Mg（Al）O catalysts were drastically deactivated due to Ni oxidation by steam as purge gas when they were applied in DSS SR of methane. Such deactivation was effectively suppressed by doping trace amounts of noble metal on the catalysts by using a ＂memory effect＂ of HTs. Moreover, the noble metal-doped Ni/Mg（Al）O catalysts exhibited ＂intelligent＂ catalytic behaviors, i.e., self-activation and self-regenerative activity, leading to high and sustainable activity during DSS operation. Pt was the most effective among noble metals tested. The self-activation occurred by the reduction of Ni2＋ in Mg（Ni,Al）O periclase to Ni^0 assisted by hydrogen spillover from Pt （or Pt-Ni alloy）. The self-regenerative activity was accomplished by self-redispersion of active Ni^0 particles due to a reversible reductionoxidation movement of Ni between the outside and the inside of the Mg（Al）O periclase crystal; surface Ni^0 was oxidized to Ni2＋ by steam and incorporated into Mg（Ni2＋,Al）O periclase, whereas the Ni2＋ in the periclase was reduced to Ni^0 by the hydrogen spillover and appeared as the fine Ni^0 particles on the catalyst surface. Further a ＂green＂ preparation of the Pt/Ni/[Mg3.sAl]O catalysts was accomplished starting from commercial Mg3.5-AI HT by calcination, followed by sequential impregnation of Ni and Pt.展开更多
介绍了以环氧乙烷、乙酸乙酯为原料,Mg Al O体系(镁铝复合氧化物,LDO)作为催化剂,一步合成乙二醇单乙醚醋酸酯(EGEEA)的方法。系统考察了催化剂前体-水滑石(LDH)的制备条件和后期煅烧条件,如滴加方式、滴加过程的pH值、镁铝比、煅烧时...介绍了以环氧乙烷、乙酸乙酯为原料,Mg Al O体系(镁铝复合氧化物,LDO)作为催化剂,一步合成乙二醇单乙醚醋酸酯(EGEEA)的方法。系统考察了催化剂前体-水滑石(LDH)的制备条件和后期煅烧条件,如滴加方式、滴加过程的pH值、镁铝比、煅烧时间、晶化时间和煅烧温度等对LDO性能的影响。实验结果表明,未经晶化的水滑石制得的催化剂活性偏低。部分制备条件影响LDO的选择性。对LDO的煅烧条件研究结果表明,煅烧温度、煅烧时间均影响LDO的活性和选择性。乙二醇单乙醚醋酸酯收率为39 83%。展开更多
采用等体积浸渍法制备了不同钒负载量的VOX/Mg-Al-O催化剂,采用XRD、氮气吸附-脱附、FT-IR、H2-TPR等催化剂表征方法对所制备的催化剂进行分析表征,并将催化剂用于环己烷脱氢的催化反应,以研究催化剂表面物种性质与其氧化脱氢反应性能...采用等体积浸渍法制备了不同钒负载量的VOX/Mg-Al-O催化剂,采用XRD、氮气吸附-脱附、FT-IR、H2-TPR等催化剂表征方法对所制备的催化剂进行分析表征,并将催化剂用于环己烷脱氢的催化反应,以研究催化剂表面物种性质与其氧化脱氢反应性能之间的关系。结果表明:当钒负载量为4%左右时,催化剂表面以还原性能好、单层分散的孤立态和聚合态钒氧物种为主;当钒负载量高于4%时,催化剂表面开始形成还原性能较差的镁钒酸盐物种。当采用4 VOX/Mg-Al-O催化剂、反应温度475℃、烃氧比为2、空气流量100 m L/min的操作条件下,在催化剂表面所形成的低价钒氧物种为环己烷脱氢反应的活性物种,可获得较好的环己烷氧化脱氢制取环己烯的催化性能。展开更多
基金supported by the New Energy and Industrial Technology Development Organization (NEDO),Japan
文摘Trace amounts of noble metal-doped Ni/Mg（AI）O catalysts were pre- pared starting from Mg-Al hydrotalcites （HTs） and tested in daily start-up and shut-down （DSS） operation of steam reforming （SR） of methane or partial oxidation （PO） of propane. Although Ni/Mg（Al）O catalysts prepared from Mg（Ni）-Al HT exhibited high and stable activity in stationary SR, PO and dry reforming of methane and propane, the Ni/Mg（Al）O catalysts were drastically deactivated due to Ni oxidation by steam as purge gas when they were applied in DSS SR of methane. Such deactivation was effectively suppressed by doping trace amounts of noble metal on the catalysts by using a ＂memory effect＂ of HTs. Moreover, the noble metal-doped Ni/Mg（Al）O catalysts exhibited ＂intelligent＂ catalytic behaviors, i.e., self-activation and self-regenerative activity, leading to high and sustainable activity during DSS operation. Pt was the most effective among noble metals tested. The self-activation occurred by the reduction of Ni2＋ in Mg（Ni,Al）O periclase to Ni^0 assisted by hydrogen spillover from Pt （or Pt-Ni alloy）. The self-regenerative activity was accomplished by self-redispersion of active Ni^0 particles due to a reversible reductionoxidation movement of Ni between the outside and the inside of the Mg（Al）O periclase crystal; surface Ni^0 was oxidized to Ni2＋ by steam and incorporated into Mg（Ni2＋,Al）O periclase, whereas the Ni2＋ in the periclase was reduced to Ni^0 by the hydrogen spillover and appeared as the fine Ni^0 particles on the catalyst surface. Further a ＂green＂ preparation of the Pt/Ni/[Mg3.sAl]O catalysts was accomplished starting from commercial Mg3.5-AI HT by calcination, followed by sequential impregnation of Ni and Pt.
文摘介绍了以环氧乙烷、乙酸乙酯为原料,Mg Al O体系(镁铝复合氧化物,LDO)作为催化剂,一步合成乙二醇单乙醚醋酸酯(EGEEA)的方法。系统考察了催化剂前体-水滑石(LDH)的制备条件和后期煅烧条件,如滴加方式、滴加过程的pH值、镁铝比、煅烧时间、晶化时间和煅烧温度等对LDO性能的影响。实验结果表明,未经晶化的水滑石制得的催化剂活性偏低。部分制备条件影响LDO的选择性。对LDO的煅烧条件研究结果表明,煅烧温度、煅烧时间均影响LDO的活性和选择性。乙二醇单乙醚醋酸酯收率为39 83%。
文摘采用等体积浸渍法制备了不同钒负载量的VOX/Mg-Al-O催化剂,采用XRD、氮气吸附-脱附、FT-IR、H2-TPR等催化剂表征方法对所制备的催化剂进行分析表征,并将催化剂用于环己烷脱氢的催化反应,以研究催化剂表面物种性质与其氧化脱氢反应性能之间的关系。结果表明:当钒负载量为4%左右时,催化剂表面以还原性能好、单层分散的孤立态和聚合态钒氧物种为主;当钒负载量高于4%时,催化剂表面开始形成还原性能较差的镁钒酸盐物种。当采用4 VOX/Mg-Al-O催化剂、反应温度475℃、烃氧比为2、空气流量100 m L/min的操作条件下,在催化剂表面所形成的低价钒氧物种为环己烷脱氢反应的活性物种,可获得较好的环己烷氧化脱氢制取环己烯的催化性能。
