IM-5分子筛在Ni-Cu催化剂甲烷热裂解制氢反应中的作用研究

Effect of IM-5 on the Methane Decomposition to Produce Hydrogen over Ni-Cu Bimetallic Catalyst

甲烷热裂解制氢并生成高附加值的纳米碳材料,被认为是极具发展前景的氢气生产途径,但高性能催化剂的研发仍存在诸多挑战.我们选择多种载体(TS-1、IM-5、Y、介孔SiO_(2)、γ-Al_(2)O_(3)、CNTs),采用浸渍法制备Ni-Cu负载催化剂,通过低温N2吸附-脱附、XRD、SEM和H2-TPR等系列表征方法对样品进行分析,考察不同载体对催化剂甲烷裂解制氢和纳米碳材料的影响.实验结果发现,分子筛载体独特的孔道结构有利于金属颗粒的分散,能有效避免反应中界面效应导致的催化剂失活,可提高催化剂反应活性并延长反应寿命,也显著提高了其碳产率.其中以IM-5分子筛为载体的催化剂表现最佳,在反应温度为700℃时,NiCu/IM-5催化剂甲烷转化率高达80%,氢气选择性达100%,反应400 min后活性未见明显降低.NiCu/IM-5催化剂碳产率高达1446 gC/gcat,是NiCu/SiO_(2)催化剂的5.7倍,NiCu/γ-Al_(2)O_(3)催化剂的7.1倍.

Decomposition of methane produces hydrogen and high value-added nanocarbon materials is considered to be the most promising hydrogen production route.But there are still many challenges in the development of high-performance catalysts.A series of Ni-Cu supported catalysts were prepared by impregnation with different supports(TS-1,IM-5,Y,SiO_(2),γ-Al_(2)O_(3)and CNTs).The samples were analyzed by low-temperature N2 adsorption-desorption,XRD,SEM and H2-TPR characterization methods.The effects of different supports on the active and carbon nanomaterials in methane decomposition were investigated.The results show that the unique pore structure of zeolite promote the dispersion of metal particles.Effectively avoiding the catalyst deactivation which caused by boundary effect,improving the reaction activity and prolonging the reaction life of catalyst.At the same time,the carbon yield was significantly increased.The catalyst supported by IM-5 has the best performance.The methane conversion of NiCu/IM-5 is up to 80%and the hydrogen selectivity is 100%at 700℃.The activity of NiCu/IM-5 without obvious deactivation within 400 min.The carbon yield of NiCu/IM-5 catalyst as high as to 1446 gC/gcat,about 5.7 times higher than NiCu/SiO_(2) and 7.1 times higher than NiCu/γ-Al_(2)O_(3)catalyst.