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题名	钴基催化剂制备及其催化合成汽油类烃的性能; Fischer-Tropsch synthesis of gasoline-range hydrocarbons from syngas over cobalt-based catalysts
作者	李宇萍
学位类别	博士
答辩日期	2008-12-30
授予单位	中国科学院广州能源研究所
授予地点	广州能源研究所
导师	吴创之
关键词	Co基催化剂 钌 费托合成 汽油类烃（C5~C12) 生物质合成气
其他题名	Fischer-Tropsch synthesis of gasoline-range hydrocarbons from syngas over cobalt-based catalysts
中文摘要	There is an urgent demand for clean, liquid fuels for transportation. In China, the total consumption amount of gasoline/diesel was more than 80 million ton during 2000. The overall import amount of crude oil will be 0.2 billion ton in 2020. At the same time, the liquid fuel production was less than the actual requirement. It has been expected that at least 0.03~0.05 billion oil fuels is needed from non-oil technology to keep sustainable development of economy in 2010. The only solving method is to find new ways to get liquid fuels, such as catalytic Fischer-Tropsch(F-T) synthesis of synthesis gas from coal/natural gas/biomass. F-T synthesis to get gasoline/diesel has been carried out in South Africa and Middle East from coal or natural gas in large scale. However, this process was still depending on traditional fossil fuels. Second-generation biofuels are usually bio-chemical or thermo- produced from non-edible part of biomass residues as corn stalk or rice husk. That enhances the economic competition, fatally associated with most first-generation biofuels like food-ethanol. Thermo-chemical production of petroleum-gasoline(diesel) substitutes from biomass is more attractive because the catalytic F-T synthesis processes are almost identical to those industrialized ones from coal/natural gas-derived syngas in case biomass syngas is obtained, which is an effect supplement for transportation fuels. While hydrocarbon distribution of traditional F-T synthesis from coal/natural gas over Co- or Fe-based catalyst is determined by the limit of Andson-Schultz-Flory (ASF) law and the selectivity to heavy products is high with low selectivity to gasoline. Usually the following hydrocraking and hydroisomerization are needed to obtain gasoline/diesel fuels. At the same time biomass syngas is generally CO2-rich with low H2/C ratio, which is unfavorable for F-T synthesis directly over Co- or Fe-based catalyst. In the present work, the hybrid support of mesoporous SiO2 and microporous zeolite were used to prepare multifunctional catalysts. The support features of the impregnated Co-based catalysts, such as the texture properties of SiO¬2, the types of zeolite with different SiO2/Al2O3 ratio were evaluated to synthesize gasoline-range hydrocarbons（C5~C12）. Noble metal (Ru) was loaded to modify the catalytic activity of Co/SiO2/HZSM-5 catalysts. The F-T synthesis performance of biomass syngas was also investigated over Co/SiO2/HZSM-5 by activity test and catalyst characterization, where H2 and CO2 content in the syngas were the main influence factors. And the whole route of biomass to liquid fuels(BTL) was roughly analyzed to optimize the efficiency of F-T synthesis from biomass. The results obtained are listed below 1. The high dispersion degree of cobalt particles resulted from high surface area of the supports, but the strong acidity of zeolite decreases this tendency. When the zeolite（USY、Hβ、HZSM-5）with different SiO2/Al2O3 ratio was used along with mesoporous SiO2 (9nm)as hybrid supports, the large surface area of SiO2 dispersed zeolite particles and reduced the acidity of zeolite without meso-pore structure destruction. The meso- and micro-pore structure of tailor-made Co/SiO2/Zeolite catalysts combined the advantage of quick diffusion rate and high shape selectivity to C5~C12, which increased the hydrocarbon yield to 150 g/Nm3. HZSM-5(38) was better than the other two zeolites during F-T synthesis. 2. Loading small amount of noble metal(Ru) increased the dispersion degree and reduction of Co/SiO2/HZSM-5 catalysts by H2 spillover. When Ru content was 1~2wt% on Co/SiO2/HZSM-5 catalyst, the increase degree of reduction degree at 150-400℃ was high. Although the hydrocarbon yield was increased when Ru loading amount was higher than 2wt%, the accelerated CO hydrogenation rate derived from high Co dispersion degree and reduction resulted in low space-time yield of C5-C12. The characterization of the used catalyst implied the carbon species deposited were hydrocarbons from F-T synthesis. And the decreased carbon depositing amount was due to the dissociative adsorption of H2 on Ru surface and Hads spillover from Ru to Co surface. 3. Proper amount of CO2 in biomass syngas increased CO2 conversion, but decreased CO conversion and total carbon conversion because of relatively slow hydrogenation rate of CO2 and the competing adsorption of Hads between CO and CO2. But CO2 conversion would be debased when quite amount of CO2 played as diluting gas without being catalyzed. While the product selectivity still showed typical F-T distribution model, resulted from CO hydrogenation in CO and CO2-containing biomass syngas. The proper H2/C ratio also affected the total synthesis results. 7.5% CO2 in the biomass syngas(C) inhibited WGS reaction and decreased the re-oxidation of Co-based catalysts, which kept the carbon usage and F-T performance at high level. The carbon species in the used catalysts were mainly hydrocarbons and carbon deposition. The favorable hydrocarbon yield and space-time yield of C5~C12 were achieved at T=250℃，P=2.0~2.5MPa， WHSV=6.27~12mg/gcat/h 4. For liquid fuel synthesis, the “Once-through” route combined with power generation from unconverted tail gas has higher efficiency with easier maintenance than 100% syngas conversion. And to increase H2 content is the primary task for stoichiometic adjustment of syngas composition and the key factor that affect efficiency of biomass to liquid technology. Both reformation and decarbonization of crude biomass gas can get fine BTL results.
语种	中文
公开日期	2011-07-14 ; 2011-07-15
页码	127
内容类型	学位论文
源URL	[http://ir.giec.ac.cn/handle/344007/5772]
专题	中国科学院广州能源研究所
推荐引用方式 GB/T 7714	李宇萍. 钴基催化剂制备及其催化合成汽油类烃的性能, Fischer-Tropsch synthesis of gasoline-range hydrocarbons from syngas over cobalt-based catalysts[D]. 广州能源研究所. 中国科学院广州能源研究所. 2008.

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