Propylene steaming of fluid catalytic cracking catalysts

Contaminant-Metal Deactivation and Metal-Dehydrogenation Effects During Cyclic Propylene Steaming of Fluid Catalytic Cracking Catalysts... 

The use of molecular sieve catalysts has also become more widespread in the past decade for the production and inter-conversion of olefins from feedstocks other than oxygenates. The addition of a modified ZSM-5 additive to the Y zeolite-based catalyst can substantially increase the amount of propylene produced in a conventional Fluid Catalytic Cracking (FCC) unit. This has become a very valuable modification, particularly in areas where propylene supplies are tight. More recently, a number of processes have been announced for the direct cracking of C4+ olefinic steams to propylene. These processes also use modified ZSM-5 based... 

Description The DCC process overcame the limitations of conventional fluid catalytic cracking (FCC) processes. The propylene yield of DCC is 3-5 times that of conventional FCC processes. The processing scheme of DCC is similar to that of a conventional FCC unit consisting of reaction-regeneration, fractionation and gas concentration sections. The feedstock, dispersed with steam, is fed to the system and contacted with the hot regenerated catalyst either in a riser-plus fluidized dense-bed reactor (for DCC-I) or in a riser reactor (for DCC-II). The feed is catalytically cracked. Reactor effluent proceeds to the fractionation and gas concentration sections for stream separation and further recovery. The coke-deposited catalyst is stripped with steam and transferred to a regenerator where air is introduced and coke on the catalyst is removed by combustion. The hot regenerated catalyst is returned to the reactor at a controlled circulation rate to achieve the heat balance for the system. 

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