Study On Al₂O₃ Supported Mo Based Sulfur-resistant Methanation Catalysts

SNG production from coal could utilize the coal resources to produce clean fuel,which could relieve the pressure of natural gas and reduce environmental pollution.Methanation is the key step in the process of SNG,and the technology of sulfur-resistant methanation will make the process simplified and economical.The Mo based catalyst has good performance for sulfur resistant methanation.Therefore,we studied the active sites for mathanation and the structure-activity of MoP and MoS₂ catalysts in this paper.The MoP/Al₂O₃ catalyst was evaluated for sulfur-resistant methanation.The effect of reduction temperature,H₂S concentration and H₂/CO on sulfur-resistant methanation were respectively investigated.The catalyst prepared at 550°C showed the best activity?CO conversion=26%?.The results showed that reduction temperature can influence the degree of dispersion of catalyst by changing the crystallite dimension of AlPO₄.Meanwhile,the textural properties of catalyst could be destroyed when catalyst was used in high concentration of H₂S and low molar ratio of H₂/CO.The effect of citric acid on sulfur-resistant methanation over MoO₃/Al₂O₃ catalyst was investigated.The catalyst prepared by simultaneously impregnation method exhibits the best methanation activity among all preparation methods.The citric acid can improve the dispersion of Mo species on the catalyst surface to transform the crystalline MoO₃ and Al₂?MoO₄?₃ into the amorphous Mo species.Also the interaction between Al₂O₃ support and Mo species was abated by adding citric acid.The effect of citric acid on sulfur-resistant methanation over CoO-MoO₃/Al₂O₃catalyst was investigated.The catalyst exhibits the best activity?CO conversion=49%?as the content of citric acid is under the condition of n?CA?/n?MoO₃?=2.The results showed that by adding citric acid,the BET surface area was increased,which avoid the generation of crystalline CoMoO₄ and Co₃O₄.Also,the interaction between Al₂O₃support and active component was weaken,which increased the degree of sulfidation.