High Catalytic Activity And Stability Of Ni/Ce_xZr_1-xO₂/MSU-H For CH₄/CO₂ Dry Reforming Reaction

As common greenhouse gases,the emission of CO₂ is increasing,and how to reduce its emission is of very important significance for people all around the world.2-D hexagonally ordered mesoporous MSU-H support with large S_BET,high thermal and hydrothermal stabilities was prepared by a simple one-step synthesis method using P123 as surfactant,then a series of mesoporous 10 wt%Ni/7.5 wt%Ce_xZr_1-xO₂/MSU-H catalysts was prepared by sol-gel method.Nitrogen isothermal adsorption?BET?,XRD,FT-IR,H₂-TPR,O₂-TPD,UV-Vis,HRTEM and TG/DSC characterization methods were used to characterized related catalysts and CH₄/CO₂reforming reaction was conducted to examine the catalytic performance about different components and Ce/Zr ratio of catalysts,different temperature and long-time?60 h?stability test.The research results show that the Ni/Ce_0.75Zr_0.25O₂/MSU-H catalyst presents high catalytic activity,stability and the ability of coke-resistance for CH₄/CO₂reforming reaction due to high S_BET?428 m²/g?and smaller Ni°nanoparticle size?3.14 nm?under the condition that T=700??CH₄:CO₂=1:1?GHSV=24 L·g^-1·h^-1.The Ni/Ce_0.75Zr_0.25O₂/MSU-H catalyst shows best catalytic performance in 700?and has little caobon-deposition.The Ni/Ce_0.75Zr_0.25O₂/MSU-H catalyst with high specific surface area?428 m²/g?and smaller Ni°nanoparticles in 60 h long time stability test process at 700?and other same conditions presents higher conversion rate:CH₄?79%?and CO₂?ca.87%?,and almost no deactivation.The high dispersed Ni^o nanoparticles over MSU-H promoted the decomposition of CH₄ and the carbon species accumulated on active Ni°sites reacting with crystal lattice oxygen in Ce_0.75Zr_0.25O₂ to form CO molecules.In the meantime,the remained oxygen vacancies on the interface between Ni°and Ce_0.75Zr_0.25O₂ could be supplemented via CO₂.HRTEM images and XRD results of Ni/Ce_0.75Zr_0.25O₂/MSU-H verified that high dispersion of Ni nanoparticles over Ni/Ce_0.75Zr_0.25O₂/MSU-H catalytst correlated closely with the synergistic action between Ce_0.75Zr_0.25O₂ and MSU-H as well as hexagonally ordered structure of MSU-H,which can provide effectively the oxygen storage capacity and inhibit the formation of coke.