Preparation And Properties Of Efficient Catalysts For SNG Production From Syngas

Natural gas is safe, superior and scarce resources. SNG production from coal is imminent as China is rich in coal and short of natural gas, and its critical process is syngas to SNG. However, methanation catalysts are the core technology of syngas to SNG. Studying efficient catalysts is not only good for solving natural gas shortage issue, but for filling the national blank of related technologies on SNG production from coal.Glucose complexation method was used to prepare catalysts with different MgO content, NiO loading and additives. Urea combustion method was used to prepare catalysts with different NiO loading, conditions and additives. These catalysts were characterized by XRD, BET and XPS, and they were evaluated in fixed bed reactor. The effect of various factors on structure and properties of catalysts were discussed.Catalysts11.2%NiO/MgAl2O4@Al2O3(BL) with MgO content from8.1%to16.1wt%were prepared with glucose combustion method and the optimum MgO content was16.1%. Catalysts with nickle loading from7.5%to44.8%had high performance. As NiO loading was26.1%, the catalyst almost showed the best structure and properties. The best reaction temperature was 230℃, and the CO conversion and CH4selectivity was99.3%and97.1%respectively. La2O3, CoO, MnO all promoted the properties of catalysts and La2O3was the best one.As NiO loading was26.1%, catalysts prepared with urea combustion method showed the best structure and properties. When n(Urea):n(Ni) was3:1, combustion temperature was450℃and combustion time was40min, catalysts prepared had good physical texture and properties. La2O3, MgO, CoO, MnO, Fe2O3improved catalysts’ structure and properties and La2O3was the optimal one. CO conversion was100%and CH4selectivity reached98.4%as temperature was230℃. The catalyst26.1%NiO-2.6%La2O3/γ-Al2O3was still excellent after1464hours’ evaluation.The catalyst26.1%NiO/MgAl2O4@A-1(6.1%MgO) experienced1076hours’ stability test and exhibited good CO2methanation properties as there’s5vol%CO2in CO. The catalyst26.1%NiO/MgAl2O4@A-2(6.1%MgO) experienced600hours’ stability test and was deactivated after520hours’ evaluation as there’s5ppm H2S in CO. XRD characterization found the carbon deposition on the surface of the catalyst, which was further proved by XPS. Besides, sulfur was also detected. Both of them might have caused catalysts’ deactivation.