Promoting effect of Rh, Pd and Pt noble metals to the Ni/Mg(Al)O catalysts for the DSS-like operation in CH4 steam reforming
Promoting effect of Rh, Pd and Pt noble metals to the Ni/Mg(Al)O catalysts for the DSS-like operation in CH4 steam reforming
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DOI：
10.1016/j.apcata.2006.05.022
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发表时间：
2006-08
影响因子：
5.5
通讯作者：
Takéshi Miyata;Dalin Li;Masato Shiraga;T. Shishido;Y. Oumi;T. Sano;K. Takehira
中科院分区：
文献类型：
--
作者：
Takéshi Miyata;Dalin Li;Masato Shiraga;T. Shishido;Y. Oumi;T. Sano;K. Takehira
考察了添加Rh、Pd和Pt等贵金属对Ni/Mg（Al）O催化剂在甲烷水蒸气重整反应中的日常开停车性能的影响。采用共沉淀法制备了Mg 2. 5（Ni 0. 5）-Al水滑石，经煅烧得到Mg 2. 5（Al，Ni 0. 5）O方镁石。当方镁石粉末浸入Rh（III）、Pd（II）或Pt（II）的硝酸盐水溶液中时，由于“记忆效应”，水滑石在Mg2.5（Al，Ni0.5）O颗粒表面重新形成，导致在焙烧后形成高度分散的贵金属-Ni负载催化剂然后还原。在Ni/Mg 2. 5（Al）O催化剂上，贵金属的加入降低了Mg 2. 5（Al，Ni 0. 5）O方镁石中Ni 2+的还原温度，增加了Ni 0的吸氢量。当Rh-、Pd-和Pt-Ni 0.5/Mg 2. 5（Al）O催化剂在蒸汽吹扫下用于DSS类操作时，由于Ni金属被蒸汽氧化而导致的失活被从贵金属到Ni的氢溢出有效地抑制。特别地，在使用Rh和Pt两者的情况下，仅0.05wt%的贵金属负载量就足以有效地抑制类DSS操作期间的失活。
Effects of the additions of noble metal, i.e. Rh, Pd and Pt, on Ni/Mg(Al)O catalyst have been investigated for the daily start-up and shut-down (DSS) operation under steam purging in the steam reforming of CH4. Mg2.5(Ni0.5)-Al hydrotalcite was prepared by coprecipitation and calcined to form Mg2.5(Al,Ni0.5)O periclase. When the powders of the periclase were dipped in an aqueous solution of the nitrate of Rh(III), Pd(II) or Pt(II), the hydrotaclite was reconstituted on the surface of Mg2.5(Al,Ni0.5)O particles due to a “memory effect,” resulting in the formation of highly dispersed noble metal-Ni supported catalysts after the calcination followed by the reduction. The addition of noble metal on Ni resulted in a decrease in the reduction temperature of Ni2+in Mg2.5(Al,Ni0.5)O periclase and an increase in the amount of H2uptake on the Ni0over the Ni/Mg2.5(Al)O catalyst. When Rh-, Pd- and Pt-Ni0.5/Mg2.5(Al)O catalysts were tested for the DSS-like operation under steam purging, the deactivation due to the Ni metal oxidation by steam was effectively suppressed by hydrogen spillover from noble metal to Ni. Especially, only 0.05wt% of noble metal loading was enough to suppress effectively the deactivation during the DSS-like operation in the case of using both Rh and Pt.