Ni/Mg-Al Oxide Catalysts for Low-Temperature CO_2 Reforming with CH_4: Effect of Preparation Method on Catalytic Performances

摘要

To develop an environmental friendly reaction and fully utilize the greenhouse gas, CO_2 reforming with CH4 (CRM) is an attractive process but challenging subject for industrial application. In CRM reaction, catalysts were deactivated due to carbon deposition, which is thermodynamically favored at reaction conditions. The high reaction temperature (>700°C) was widely used because it was beneficial to CH_4 and CO_2 conversion and retarded coke formation. However, a lower temperature operation could give rise to decreasing energy costs. And an economical moderate degree of CH4/CO_2 conversion could be provided by a facile on-site recycling of educts. Nevertheless, carbon formation also is a critical issue for low-temperature CRM reaction. In this contribution, we compared the Ni/Mg-Al oxide catalysts prepared by co-precipitation and impregnation method to elucidate the effects of the preparation method on activity and stability of catalysts in low-temperature CRM reaction. Compared with impregnation method, the approach of co-precipitation enables Ni species evenly dispersed on the support. And the catalyst obtained from co-precipitation method has a stronger CO_2 adsorption capacity. The activity measurements of these catalysts were conducted at the reaction condition of 500°C, latm, GHSV of 24000 mL/g_(cat)?h, the molar ratio of CH_4 to CO_2 is 1:1, and no inert components. The Ni/Mg-Al oxide catalysts prepared by co-precipitation had the high CH4 conversion of 11.0% (almost reach to equilibrium conversion) for 25 h without deactivation.