Harold Saul Horowitz

A New Commercial Scale Process for n-Butane Oxidation to Maleic Anhydride Using a Circulating Fluidized Bed Reactor

Abstract DuPont has developed a new process for n-butane oxidation to maleic anhydride using a circulating fluidized bed (CFB) reactor. An extensive effort spanning a period of ten years has resulted in a successful demonstration of the process on a large demonstration plant. A novel approach to imparting attrition resistance to the catalyst for the process has been demonstrated on a commercial scale. The demonstration plant was used to activate the catalyst, optimize hydrodynamics of the CFB, confirm catalytic performance and attrition resistance, and generate data for the design of a very large commercial plant. Construction of the first commercial plant using this technology is scheduled to be completed in 1995.

The effects of steam on n-butane oxidation over VPO as studied in a riser reactor

Abstract The effects of steam, fed to the riser section of a laboratory recirculating solids reactor, on butane oxidation over a vanadyl pyrophosphate catalyst are reported. Gas red to the riser was either butane in inert or butane co-red with oxygen in inert. The catalyst regenerator-vessel was fluidized with air in all cases. It was observed that steam added to the riser competes for sites required for gas-phase oxygen activation, while catalyst lattice oxygen utilization is not affected. The competition for sites with oxygen causes a decrease in butane conversion and a corresponding increase in selectivity to maleic anhydride. The improvement in selectivity is more pronounced under anaerobic conditions, and an explanation for this result is offered. This study demonstrates the opportunity offered by a recirculating solids reactor to study various aspects of selective oxidation catalysis independent of the complicating effects of simultaneous catalyst reduction and oxidation reactions.

Butane Oxidation to Maleic Anhydride in A Recirculating Solids Reactor

Abstract Butane oxidation to maleic anhydride is currently commercially practiced in fixed bed reactors using a vanadium phosphate catalyst. Fluid bed reactors have been proposed, mainly due to more efficient heat removal for this highly exothermic reaction. Commercialization of fluid bed technology has been impeded by low yields and lack of adequate catalyst attrition resistance. We have solved the yield problem by use of a recirculating solids bed reactor concept. The vanadium phosphate is circulated between two reactors. In one, butane is oxidized by vanadium phosphate; in the other, the vanadium phosphate is reoxidized. Using this approach, selectivities to maleic anhydride higher than 90% have been achieved. We have discovered a novel method of imparting catalyst attrition resistance without loss of selectivity to maleic anhydride. The attrition resistance is provided using only small amounts (~10 wt%) of silica. The catalyst is synthesized through a spray drying step whereby a thin SiO 2 coating is produced which is physically protective but which also allows free passage of reactants and products. The active component, (VO) 2 P 2 O 7 , is prepared via a (VO) 2 H 2 O(PO 3 OH) 2 precursor for best selectivity. Both morphology and defect control of (VO) 2 P 2 O 7 appear to be important for the best catalytic properties.