Study On Scale-up Preparation Of Methanation Catalyst For Synthetic Natural Gas From Coal

The energy structure of lean oil,less gas and rich coal in china,increasingly stringent environmental requirements and increased demond of natural gas promote the development of the industry of synthetic natural gas from coal.This is the project to develop a new catalyst of AM-830 based on the successful experience of AM-820 preparation in our laboratory,then to inverstigate its scale-up preparation towards industrialization as well as to,comply with the CNOOC's industry needs of Synthetic natural gas from coal.The main contents of this work include optimizinge the preparation process for the AM-830 catalyst in lab scale,preparation scale-up and physicochemical characterization of the AM-830 catalyst from different scales.The main results are as follows.1)It was found in lab scale preparation that the optimal molar ratio of the AM-830 catalyst is 6:3:1,the best coprecipitation method for AM-830 catalyst is co-flow,the optimal concentration of the feed liquid is 0.65mol/L,the best co-precipitation temperature is 80?,the best aging time is 2 hours,the optimum washing temperature of AM830 catalyst is 20?.2)We prepared and scale-up the catalysts of AM830-0.2kg,AM830-lkg,AM830-5kg,AM830-10kg,and found that they have the samilar catalytic activity for the CO methanation,indicating that the scale-up preparation of the AM-830 catalyst is basically successful.The CO conversion and CH4 selectivity in the AM830-10kg were 100%and 99%,respectively,after the 400 hour stability test,meaning that the AM830-10kg catalyst has good operation stability.The CO conversion and CH4 selectivity in the AM830-10kg were 100%and 99%,respectively,after the 800 ? thermal treatment,demonstrating that the AM830-10kg catalyst has good thermal stability.The results of XRF,BET,XRD,H2-TPR,SEM and TEM showed that the AM830-0.2kg,AM830-1kg,AM830-5kg,AM830-10kg catalysts have similar texture,phase structure,element composition and reducibility.Therefore,the scale-up preparation of AM-830 catalyst is successful.3)We found that the Na⁺ in the AM-830 catalyst will enter the crystal lattice of ZrO₂,which promote the formation of the ZrO₂ crystals.With the increase content of Na⁺,the Na⁺ in the ZrO₂ crystals will reach saturation.The excess Na⁺ will accumulate on the catalyst pore and surface,which wil reduce the activity of the catalyst.Besides we found that the Na⁺ will weaken the interaction between the active component NiO and the carrier ZrO₂,which made the catalyst surface formate a lot of free NiO and increase the basicity of the catalyst.Moreover,this will cause disproportionation and carbon deposition on catalysts during the methanation.