27 April 2010 10:47 [Source: Chemical Report]
Maleic anhydride (MA) is produced commercially by the oxidation of benzene or butane. Although the butane-based process is considered to have superior economics and is the preferred route used by most producers, Lonza claims its fixed bed benzene route is competitive in low cost revamps and medium-size plants. However, when the cost of benzene is high, this route is much less attractive.
MA can be produced from butane in either fixed bed or fluidised bed processes. The fluid bed process is seen to have advantages over the fixed bed route, such as lower air-to-hydrocarbon concentration in the feedstock and no need for premixing, but has disadvantages including abrasion of the catalyst, conversion rates and by-product formation.
In the fixed bed route, air is mixed with superheated butane and fed to the reactor containing the catalyst which consists of vanadium-phosphorus oxide supported on silica. Oxidation is carried out at 400-430oC. The reaction gases are cooled and maleic anhydride is condensed. Further MA is recovered from the maleic acid in the water scrubber by dehydration. The crude anhydride is purified by distillation under reduced pressure.
Scientific Design has developed chloride-free catalysts for MA production in fixed bed reactors. The catalysts are being toll manufactured by Lonza.
BOC Gases and Mitsubishi Chemical have developed a new technology, Petrox, which has been operated on a large-scale pilot plant in ?xml:namespace>
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