摘要
CH4与CO_2干重整反应对于环境保护和天然气资源的合理利用具有重要意义。SiO_2和Al_2O_3是适用于甲烷干重整反应的两种典型的催化剂载体。为了阐明这两种载体对催化剂性能的影响,本研究采用等体积浸渍法制备了Ni/Al_2O_3和Ni/SiO_2催化剂,并利用BET、TEM、H2-TPR、XRD、TG和Raman等技术对还原和反应后的催化剂进行了表征。结果表明,由于载体的性质不同,Ni基催化剂在甲烷干重整中的催化性能也不同。Ni/SiO_2催化剂的初始活性较高,但由于其金属-载体相互作用较弱,催化稳定性较差,在800℃下反应15 h其催化活性急剧下降;较弱的金属-载体相互作用使得Ni/SiO_2催化剂上的Ni颗粒较大,有利于积炭前驱物种的生成,导致催化剂快速失活。而对于Ni/Al_2O_3催化剂,金属-载体相互作用较强,Ni颗粒较小,但由于Ni与Al_2O_3生成了NiAlxOy物种,有效活性位减少,其催化活性相对较低,但催化稳定性较好,干重整反应进行50 h其活性保持稳定; Ni与Al_2O_3之间较强的相互作用有利于形成小且稳定的Ni粒子,能减少积炭,因而具有优异的催化稳定性。
Dry reforming of methane(DRM)with CO2 is of great significance in the environmental protection and the utilization of natural gas.SiO2 and Al2O3 are two typical catalyst supports used in DRM.To elucidate the effect of these two supports on the catalytic performance,in this work,Ni/SiO2 and Ni/Al2O3 catalysts are prepared by the incipient wetness method and characterized by BET,TEM,H2-TPR,XRD,TG and Raman technologies.The results indicate that the performance of Ni-based catalyst is closely related to the properties of support and the Ni/SiO2 and Ni/Al2O3 catalysts are rather different in their DRM performance.Ni/SiO2 catalyst exhibits higher initial activity but poor stability;its catalytic activity decreases rapidly in 15 h for DRM at 800℃.Because of the weak metal-support interaction,Ni species on the Ni/SiO2 catalyst is present as large Ni particles,which may promote the formation of coke precursors,viz.,the multi-carbon Cn species,leading to the fast carbonaceous deposition and catalyst deactivation.In contrast,the Ni/Al2O3 catalyst displays a lower activity but a much higher stability;its activity in DRM keeps stable in 50 h.Although Ni particles in the Ni/Al2O3 catalyst is much smaller,the strong metal-support interaction promotes the formation of NiAlxOy species during the catalyst preparation process,which may lead to a decrease in the content of active Ni species and give the Ni/Al2O3 catalyst a relatively low catalytic activity in DRM;however,the strong metal-support interaction between Ni and Al2O3 is also of benefit to the formation and stabilization of small Ni particles,which can alleviate the carbanceous deposition and afford the Ni/Al2O3 catalyst a better stability.
作者
徐艳
堵锡华
李靖
王鹏
朱捷
葛奉娟
周俊
宋明
朱文友
XU Yan;DU Xi-hua;LI Jing;WANG Peng;ZHU Jie;GE Feng-juan;ZHOU Jun;SONG Ming;ZHU Wen-you(School of Chemistry and Chemical Engineering,Xuzhou University of Technology,Xuzhou 221018,China)
出处
《燃料化学学报》
EI
CAS
CSCD
北大核心
2019年第2期199-208,共10页
Journal of Fuel Chemistry and Technology
基金
supported by the National Natural Science Foundation of China(21703194)
the Natural Science Foundation of Jiangsu Province(BK20171168,BK20171169)
Natural Science Foundation of Jiangsu Higher Education Institutions of China(17KJB530010,17KJB150038 and18KJA430015)
Key Research Project of Social Development of Xuzhou(KC17154)
Research Project of Xuzhou University of Technology(XKY2017217)
