Preparation Of Ni-Cu-CeO₂/MgSiO Catalyst And It's Catalytic Reaction Behaviors For CH₄ Oxidating Direct To H₂ And CO₂

Hydrogen is an important material in petroleum refining and chemical industry,and it is also a kind of clean fuel. Hydrogen and carbon dioxide produced directlyfrom methane reacting with oxygen and water is a new technology way forsimplifying the process of hydrogen production and making the utilization of carbondioxide. In the present work, the catalytic performance and reaction kinetics ofMgSiO supported Ni,Cu,Ni-Cu catalysts were studied and discussed.The supported Ni-Cu,Ni,Cu catalysts were prepared by the method ofisovolumic impregnating of the surface complex oxide MgO-SiO₂ (MgSiO) support.The BET, XRD, TEM, and TPR results show that metal disperses uniformly on thesurface of MgSiO, that these catalysts maintain the skeleton structure of SiO₂support,and that there are three active sites:metallic sites M(Ni,Cu), Lewis acid sitesMg²⁺ and Lewis base sites Mg-O-on the surface of catalysts. The IR and TPD resultsof CH₄ and H₂O chemisorption indicate that the Ni-Cu alloy is more active for thechemisorption and activation of CH₄ and H₂O than that of single metal. The additionof CeO₂ increses the chemisorption intensity and amount of CH₄ and H₂O on thesurface of the Ni-Cu/MgSiO catalyst.Temperature-programmed surface reaction (TPSR) and micro-reactor resultsreveal that the intermediate product [CH₃OH] becomes CO and H₂ firstly onsupported Ni catalyst, then CO turn to CO₂ and H₂ by the water gas-shift reaction(WGS).While on supported Ni-Cu catalyst, CO₂ and H₂ can be produced directly fromthe intermediate product [CH₃OH] reacting with dissociated H₂O. Under the optimalreaction conditions of 460 ℃;mole ratio CH₄/O2/H₂O =1/0.5/3;space velocity of methane1 400 h-1,the conversion of CH₄ over 39%, and the selectivity of H₂ and CO₂ 99% and98% respectively is obtained on the Ni-Cu-CeO₂/MgSiO catalyst. The promoter CeO₂can resist carbon deposition ,and increase the stability and longevity of catalysts.