Butane Oxidation in a Circulating Fluidized Bed

A significant technological advance was made by DuPont in 1986 when maleic anhydride was produced from n-butane in a circulating fluidized bed In this process, active catalyst reacts with bntene to give maleic anhydride, itself becoming reduced in the process. The overall reaction is  

Reduced catalyst is then reoxidized with air, in a separate regeneration reactor, to regenerate the active form. This innovation followed the snccessful introduction of conventional fluidized bed operation by Alusuisse and other companies in 1983. Physical circulation of a fluidized bed of catalyst particles, or microspheres, is an unusual technology and has been developed commercially only for the fluid catalytic cracking of heavy gas oils and the SASOL version of the Fischer-Tropsch Synthol process. Success depends not only on an active and selective catalyst but also on the resistance of the catalyst to attrition during the transfer from the reactor to the regenerator and back agaiir 

TABLE 4.9. Oxidation of butane to maleic anhydride in fluid beds 

Design Conventional fluid bed with Circulating fluid bed reaction 

The catalyst microspheres are approximately 40-150 m in diameter. Adequate strength for use in the circulating fluid bed is obtained by spray drying a slurry of srrrafl, 0.5-2 m, (VO 2P207 particles with 5% of polysilicic add at pH 3. During this process sihca forms a hard porous shell over the surface of the catalyst particles. 

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