COKE FORMATION AND ITS INFLUENCE ON OLEFIN CONVERSION IN FCC NAPHTHA UPGRADING

Factors affecting the coke formation and olefins conversion during the upgrading of FCC naphtha,such as catalyst microactivity(MA),various narrow fractions of FCC naphtha,reaction temperature and MHSV,were studied by using a MAT-GC on-stream analysis system and a fixed fluidized bed device.Influences of feedstock preheated temperature and catalyst temperature on coke formation and olefins conversion in a continuous pilot riser-type FCC unit were also investigated and analyzed by kinetic method.The results showed that the initial coke formation was extremely fast,and the amount of coke increased with the catalyst microactivity(MA),reactant's activity and reaction temperature.The initial thermal cracking and the catalytic cracking reactions could be suppressed by the decrease of catalyst temperature and the increase of feedstock temperature.At the same time,the initial coke formation was reduced,and the catalyst activity was maintained in reaction process.As a result,the olefin content in the upgraded naphtha kept constant,despite of the change in carbon number distribution of olefins.