Co-Generation Of Methane With Liquid Product And Low Temperature Methanol Synthesis From Syngas

The fossil energy in China is characterized with abundant coal, a little natural gas and poor oil, which leads to the serious contradiction between energy supply and demand and increasing dependence of imported oil with the sustained economic development. Therefore, for ensuring the energy security and economy development, it’s of high-significance to explore energy substitute for oil through the utilization of rich coal resource.First of all, co-generation of methane with liquid fuels/higher alcohols from syngas was studied through investigating the catalytic performance of mixture and compound of Fischer-Tropsch synthesis(FTS) catalyst and methanation catalyst, mixture and compound of higher alcohol synthesis(HAS) catalyst and methanation catalyst, aimed at solving the synthetic natural gas (SNG) peaking problem and co-producing some high value-added chemical products and then guaranteeing a stable market profit for coal to natural gas industry. Furthermore, as an extension of co-production system stated above, low temperature methanol synthesis(LTMS) from syngas was studied through investigating the effect of ZnO preparation method on the LTMS performance of Cu/ZnO catalyst, which was attempted to optimize the LTMS process and realize the highly efficient and comprehensive utilization of coal.FTS catalyst 10wt.%Co/SiO2 and methanation catalyst 10wt.%Ni/SiO2 were prepared with impregnation method where SiO2 was applied as the support. Then, the catalytic performance of mixture catalyst was investigated at different mixing ratios (weight ratio 10wt.%Co/SiO2: 10wt.%Ni/SiO2 weight ratio=1:2,1:1,2:1),240-350℃, 1-3MPa and H2/CO=1-3.It was found that CO conversion varied between 5% and 99% and CH4 selectivity changed from 20% to 90% while C5+ selectivity varied between 0 and 62% at the reaction conditions described above. What’s more, reaction temperature affected the activity and selectivity in co-producing methane with liquid fuels most, followed by the effect of H2/CO. Increasing reaction pressure had little effect on the selectivity of CH4 and C5t when the pressure is higher than 2MPa.The FTS-methanation bi-functional catalyst 6.7wt.%Ni 3.3wt.%Co/SiO2 was then prepared through co-impregnating the metal nitrates on SiO2. Compared with single cobalt based or nickel based catalyst, there existed a stronger interaction between Ni and Co in the bi-functional catalyst, which resulted in a better reducibility, metal dispersion and reaction stability. Consequently,6.7wt.%Ni 3.3wt.%Co/SiO2 had good performance with a double CO conversion and matched C5+ selectivity compared with the mixed catalyst at the same condition.HAS catalyst 10wt.%Cu10wt.%Co/SiO2 were prepared with co-impregnation method where SiO2 was applied as the support. Then, the catalytic performance of mixture catalyst was investigated at different mixing ratios (weight ratio 10wt.%Cu10wt.%Co/SiO2:10wt.%Ni/SiO2 weight ratio=1:2,1:1,2:1),240-350℃, 1-3MPa and H2/CO=1-3.It was found that CO conversion varied between 9% and 98% and CH4 selectivity changed from 35% to 80% while C5+ and alcohol selectivity varied among 0-16% and 0-12% respectively at the reaction conditions described above. What’s more, reaction temperature affected the activity and selectivity in co-producing methane with liquid fuels most, followed by the effect of H2/CO. The HAS-methanation bi-functional catalyst 5wt.%Cu 5wt.%Co5wt.%Ni/SiO2 was then prepared through co-impregnating the metal nitrates on SiO2. Compared with the mixed catalyst at the same condition,5wt.%Cu5wt.%Co5wt.%Ni/SiO2 was in possession of a lower activity while a higher methane and alcohol selectivity.Homogenous precipitation method(HP), sol-gel method(SG), micro-emulsion method(ME) were applied to prepare ZnO. Based on the home-made ZnO and commercial ZnO,16.7wt.%Cu/ZnO and 44.4wt.%Cu/ZnO were synthesized with impregnation method and deposition-precipitation method respectively. The LTMS performance over Cu/ZnO was studied and it’s indicated that ZnO prepared through traditional method had a too small surface area to disperse copper and the highest CO conversion changed between 8% and 22% and the activity loss arose easily at the later period in LTMS reaction over obtained Cu/ZnO. Cu-ZnO catalyst prepared with co-precipitation method had stronger Cu-Zn interaction and better LTMS activity and stability than the supported Cu/ZnO catalyst. The co-precipitated Cu-ZnO catalyst was more competitive in LTMS industry while proper match of copper loading and support capacity or seeking for method to obtain ZnO of high specific surface area to ensure well-dispersed copper is a promising research.