Investigation Of Support And Catalyst By Co-precipitation Method For Sulfur-resistant Methanation

CO methanation process is the core technology of transforming coal into naturalgas. The shortened process of transforming coal into natural gas can be achieved bythe sulfur-resistant methanation process, and the development of highly active sulfur-resistant methanation catalyst is the key technology.In this article, a series of composite oxide supports was prepared byco-precipitation method and Mo-based catalysts were prepared by impregnationmethod. It was found that ZrO2-Al2O3is the optimum support for the methanationreaction. Afterwards, we studied the influence of ZrO2-Al2O3preparation method (byimpregnation method, deposition precipitation method and coprecipitation method) onthe performance of MoO3/ZrO2-Al2O3catalyst. The results showed that the Mo-basedcatalyst with support prepared by coprecipitation method has the highest methanationactivity, and the optimum content of ZrO2is15wt.%due to the well dispersion andthe amorphous degree of the active Mo species on the surface of15wt.%ZrO2-Al2O3.The optimum MoO3loading on the25%ZrO2-75%Al2O3is identified as20wt.%,which is close to the monlayer threshold value of the25%ZrO2-75%Al2O3support.Furthermore, the addition of NiO or CoO additives can modify the stability of catalysteffectively.Compared with the conventional impregnation method, the coprecipitationmethod can keep a higher Mo dispersion with a high MoO3loading. Therefore, weprepared MoO3/ZrO2catalysts with coprecipitation method in this article and theresults showed the optimum MoO3loading is25wt.%. In addtion, the influence ofbath temperature on the performance of catalysts was investigated. It was found thatwhen the bath temperature is65C or85C, the activities of catalysts areconsiderable and higher than that prepared at the temperature of45C. Comparedwith MoO3/Al2O3catalyst prepared by coprecipitation method, the sulfur-resistantmethanation performance of MoO3/ZrO2catalyst was much higher. The resultsindicated that a greater number of active Mo species were highly dispersed onMoO3/ZrO2surface. The influence of reaction temperatures on MoO3/ZrO2was alsoinvestigated and the results showed that the catalytic activity as well as CH4selectivity increases with the increase of the reaction temperature.