| Coal is the major energy resource in China for a long time. To realize high-efficiency energy utilization and the comprehensive value improvement of energy products, advanced processing and conversion technologies are needed to be developed and applied. Four projects on energy application technologies and demonstration plants had been determined as National Key Projects in the Twelfth Five-Year Plan for National Energy Technology Development, coal processing and conversion project is one of them. Nowadays, Coal-based technologies are facing new opportunities and challenges in China. F-T synthesis oil is the product of coal indirect liquefaction which is mainly processed through steam cracking and hydrogenation units. However, some research work on processing F-T synthesis oil through FCC technology also has been done in recent years.The previous laboratory research work had demonstrated that heavy F-T synthesis oil was suitable for producing gasoline. For the purpose of developing an effective way to increase the octane number of gasoline produced, the cracking performance of heavy F-T synthesis oil on different catalytic materials were investigated in this paper.The heavy F-T synthesis oil applied has a wide distillation range of250～706℃. It contains carbon mass fraction of84.75%and hydrogen mass fraction of14.51%; no sulfur and nitrogen; nor-paraffins and iso-paraffins account for64.1%and34.9%respectively.In order to investigate the cracking performance of heavy F-T synthesis oil on different materials, catalysts with three different zeolites, USY, Beta, and AMC zeolite, were employed in this work. The results showed that heavy F-T synthesis oil could be converted effectively on different zeolite catalysts with high conversion rate. The octane number of gasoline was the highest on AMC catalyst compared to the other two, while the olefins content in gasoline was as high as66.76%. For USY catalyst, the yield of gasoline reached the highest, the content of iso-paraffins in gasoline was as hign as39.87%, the olefins content of gasoline was the lowest and the gasoline octane barrels reached the highest. The yield of gasoline on catalyst with Beta zeolite was low, but the yield of LPG was high and the propylene concentration in LPG was high.The cracking performance of heavy F-T synthesis oil on USY catalysts with different rare earth content was investigated. The results revealed that rare earth in catalysts promoted over cracking of gasoline. The olefin content in gasoline decreased, while the iso-paraffins and aromatics content in gasoline increased, the octane number and octane barrels decreased.The cracking performance of heavy F-T synthesis oil on deactivated USY catalysts was also investigated and the results indicated that the feed conversion declined by using catalysts with small amount of carbon deposit or catalysts after hydrothermal treatment. The yields of dry gas, LPG and coke declined, while the gasoline increased for USY catalysts in both deactivation methods. The analysis of PONA revealed that the olefins content increased, but the iso-paraffins and aromatics declined. The RON and MON of gasoline were both improved on carbon deposited USY catalysts, while only RON of gasoline got increased on USY catalysts deactivated by hydrothermal treatment.The conversion of heavy F-T synthesis oil was almost unaffected by mixing a certain amount of shape-selective zeolite with USY catalyst. The yield of gasoline decreased while the RON and MON of gasoline increased. The octane barrels declined. The olefins and aromatics content in gasoline increased while the iso-paraffins decreased.The cracking results of heavy F-T synthesis oil under different reaction conditions showed that high reaction temperature, low feed rate and high catalyst to oil were in favor of enhancing the octane number of gasoline produced, while appropriate reaction temperature, high feed rate and low catalyst to oil were in favor of increasing octane barrels of gasoline. |
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