GB754665A - Method and apparatus for catalytically converting vaporizable organic materials - Google Patents

Abstract

Undesired secondary reactions are avoided, in the catalytic treatment, e.g. oxidation, of organic compounds in vapour form, by passing the stream of vapour and conversion gas through a fluidized bed of solid catalytic material divided into two zones, usually by using baffles. The first of these zones contains a turbulent fluidized catalyst bed in which adequate heat-exchange facilities exist so that the stream can be cooled to end the reaction, before it leaves the zone. This is followed by a dilute catalytic disengaging zone where adequate heat exchange facilities are difficult to maintain due to the poor heat exchange. Specific reactions referred to are oxidation of naphthalene to phthalic anhydride or alpha naphthaquinone; ortho xylene to corresponding aldehydes, aldehydic acids, phthalic anhydride or maleic anhydride; alkyl naphthalenes and phenanthrenes to phthalic anhydride or maleic anhydride; oxidation of benzene, butadiene, phenol, furfural and terpenes to maleic anhydride; oxidation of meta and para xylenes or toluene to aldehydes or maleic anhydride; oxidation of anthracene to anthraquinone; oxidation of acenaphthene to acenaphthene quinone or naphthalic anhydride; methane or methanol to formaldehyde; and ethylene to ethylene oxide. In an example, a stream of naphthalene and air is passed through a fluidized bed of a vanadium/silica/potassium catalyst maintained at 320-410 DEG C. in the first part thereof and cooled to 210-270 DEG C. towards the end thereof so as to terminate the oxidation reaction. Phthalic anhydride is formed. In another example, anthracene is oxidized to anthraquinone by passing a stream of anthracene and air through a fluidized bed of a vanadium/iron/manganese/silica catalyst at 340-450 DEG C., the quench zone being maintained at 300 DEG C. Specification 626,455, [Group III], is referred to.ALSO:Undesired secondary reactions are avoided, in the catalytic treatment of organic materials in vapour form, by passing the stream of vapour and conversion gas through a fluidized bed of solid catalytic material divided into two zones, usually by using baflles. The zones are a turbulent fluidized catalyst bed in which adequate heat-exchange facilities exist so that the stream can be cooled to end the reaction, before it leaves the zone, followed by a dilute catalytic disengaging zone where adequate heat-exchange facilities <PICT:0754665/III/1> are difficult to maintain due to the poor heat-exchange. Specific reactions referred to are oxidation of naphthalene to phthalic anhydride or alpha naphthaquinone; ortho xylene to corresponding aldehydes, aldehydic acids, phthalic anhydride or maleic anhydride; alkyl naphthalenes and phenanthenes to phthalic anhydride or maleic anhydride; oxidation of benzene, butadiene, phenol, furfural and terpenes to maleic anhydride; oxidation of meta and para xylenes or toluene to aldehydes or maleic anhydride; oxidation of anthracene to acenaphthenequinone; oxidation of acenaphthene to acenaphthene; or naphthalic anhydride, methane or methanol to form aldehyde and ethylene to ethylene oxide. An apparatus which may be used in the oxidation of naphthalene consists of a cylindrical reactor 10 which is divided into three zones of fluidization R, Q and D. Oxidizing gas is admitted from inlet 12 and organic vapour from inlet 18 while the products pass through filter system 38. The reaction zone R is a dense turbulent bed of catalyst and kept at the desired reaction temperatures by heat-exchangers 26. A baffle 30 divides R from another dense phase bed Q which is the quench zone kept effectively at a temperature below the desired reaction temperature by heat-exchangers 28. In the disengaging space D the bulk of the catalyst is separated from the reaction mixture at a temperature below the normal conversion temperature. In order to maintain a dense bed from the bottom of the reactor up to the top of the quench zone a return pipe 32 is inserted with lip 34 inserted so that it is always submerged in the dense bed. Temperatures suitable for the reaction are 320 DEG -425 DEG C. preferably 350 DEG C. The preparation of silica for use as a catalyst support according to Specification 626,455 is described.