用SC2O3作为促进剂,研发出一种SC2O3掺杂的高效新型nI-zrO2基催化剂,该催化剂对CO和CO2共甲烷化制合成天然气(Sng)显示出高的活性和优异的热稳定性.在组成经优化的nI6zr3SC1催化剂上,0.1 MPA,573k,V(H2)∶V(CO)∶V(CO2)∶V(n2)=75∶15∶5∶5,出口空速gHSV=40 000Ml/(H·g)的反应条件下,在反应开始之后的20~332H的反应过程中,CO和CO2的转化率一直分别保持在100%和85%的高水平,产物甲烷的选择性一直保持在100%.耐热试验结果显示,在973k下经历24H甲烷化反应、而后降至573k的nI6zr3SC1催化剂试样上,(CO+CO2)的总转化率仍能稳定地保持在80.2%的水平;而不含SC2O3的原基质催化剂(nI6zr4)在经历相同耐热试验过程之后的(CO+CO2)总转化率骤降至2.7%,暗示其因烧结而失活.催化剂的表征结果证实,可观量的SC3+溶解入zrO2晶格导致具有C-zrO2结构的单一C-(zr-SC)Oy相的生成并使其稳定化,这类C-(zr-SC)Oy相与nI6zr3SC1催化剂的高活性,尤其与优良的热稳定性,密切相关.A type of highly efficient Ni-ZrO2catalysts doped with Sc2O3for co-methanation of CO and CO2 was developed,and displayed high activity and excellent thermal stability.Over a Ni6Zr3Sc1catalyst under the reaction conditions of 0.1 MPa,573 K,V(H2)∶V(CO)∶V(CO2)∶V(N2)=75∶15∶5∶5,GHSV=40 000mL/(h·g)(outlet),the observed conversion of CO and CO2maintained continuously at high levels of 100%and 85%,respectively,during 20-332hafter the reaction started,with the corresponding selectivity of CH4product being 100%.The results of heat-resisting test showed that,over the Ni6Zr3Sc1catalyst after undergoing 24h of the methanation operation at 973Kfollowed by going down to 573K,the total conversion of(CO+CO2)still maintained stable at the level of 80.2%,whereas that of the Sc2O3-free Ni6Zr4catalyst after undergoing the same heat-resisting test fell to 2.7%,implying that it was deactivated due to sintering.The results of the catalyst characterization demonstrated that solution of a considerable amount of Sc3+in the ZrO2lattice resulted in the formation of(Zr-Sc)Oy composite oxide with simple c-ZrO2phase-structure,which was closely associated with the high activity,especially the extremely high thermal stability,of the Ni6Zr3Sc1catalyst.国家重点基础研究发展计划(973)项目(2011CBA00508); 优秀国家重点实验室基金项目(20923004); 教育部创新团队项目(IRT1036
