Bayer Aktiengesellschaft

Manfred Martin

Gerhard Scharfe

Wulf Schwerdtel

Johann Grolig

Norbert Schenk

Paul Losacker

Wolfgang Swodenk

Karl-Hermann Reissinger

Walter Schmidt

Kurt Halcourt

Bruno Engelhard

A process has been found for the preparation of anthraquinone by catalytic oxidation of naphthalene in the gas phase to provide a reaction product, obtained by quenching, cooling or quenching and cooling, containing naphthaquinone and phthalic anhydride, treating said reaction product directly with butadiene to provide tetrahydroanthraquinone, oxidation by means of molecular oxygen to the tetrahydroanthraquinone contained in this reaction product, to give anthraquinone, and separation of naphthalene, phthalic anhydride, anthraquinone and by-products by distillation, the gases produced in the quenching and/or cooling of the gases from the naphthalene oxidation and the gases from the oxidation of the tetrahydroanthraquinone to give anthraquinone being completely or partially recycled to the oxidation of naphthalene, in which a compound with an alkaline reaction is introduced between the reactor in which naphthalene is oxidized and the reactor in which the reaction with butadiene takes place, and/or into the gas streams which are recycled to the oxidation of naphthalene. The process of the invention reduces considerably the formation of higher-boiling products formed in the continuous preparation of anthraquinone from naphthalene and increases the selectivity of the conversion of naphthalene to anthraquinone. In addition, the process of the invention provides greater freedom in separation of the reaction products since the production of troublesome high-boilers is minimized; and the process results in a reduced formation of carbon dioxide in the oxidation of naphthalene.

Process for the preparation of anthraquinone

A process for removing 1,4-naphthoquinone from phthalic anhydride has now been found, which is characterized in that phthalic anhydride containing 1,4-naphthoquinone, or mixtures containing phthalic anhydride and also containing 1,4-naphthoquinone, are subjected to a heat treatment at temperatures from 200 .degree. to 300.degree. C. in the presence of 1,4,4a,9a-tetrahydroanthraquinone.

Process for removing 1,4-naphthoquinone from phthalic anhydride

Catalysts for the catalytic oxidation of organic compounds containing silicon, vanadium, sulfur, oxygen and at least one alkali metal element. The catalyst is prepared from a silicic acid which has an average particle size of less than 50 microns and an alkali metal content of less than 2% by weight, calculated as Na.sub.2 O and expressed relative to anhydrous silicic acid.

Silicon containing catalysts

1,4-Naphthoquinone is prepared by reacting naphthalene with molecular oxygen in a gaseous phase in the presence of a catalyst containing vanadium. Prior to reacting the naphthalene with oxygen, the catalyst is pre-treated with molecular oxygen at 300.degree. to 400.degree. C in the absence of organic compounds and immediately thereafter a gas mixture containing naphthalene and molecular oxygen is passed over the pretreated catalyst at temperatures in the range of 300.degree. to 400.degree. C. The catalyst pre-treatment can be carried out in the presence of water vapor and the subsequent reaction of naphthalene with molecular oxygen can also be carried out in the presence of water vapor.

Process for preparing 1,4-naphthoquinone

In the preparation of isopropyl chloride wherein propylene and hydrogen chloride are reacted at elevated temperature in the gaseous phase in the presence of aluminum oxide as catalyst, the improvement which comprises effecting the reaction at a pressure of about 3 to 8 atm, at a temperature of about 50.degree. to 200.degree. C and in the presence of aluminum oxide having an internal surface area of about 200 to 500 m.sup.2 /g.

Preparation of isopropyl chloride

Allyl alcohol is produced in simple and economical fashion from propylene and oxygen by reacting propylene, oxygen and acetic acid over a palladium-containing catalyst in the presence of water; condensing the reaction product to form a condensate containing allyl acetate, acetic acid and water; treating the condensate with an acid catalyst and separating the resulting product by distillation into a head product consisting essentially of an allyl acetate/allyl alcohol/water azeotrope and into a sump product consisting essentially of acetic acid, allyl alcohol and water; recycling the head product to the acid catalyst stage; separating the sump product in a second distillation into an allyl alcohol/water head product and into a second sump product consisting essentially of acetic acid and water and recycling this sump product to the initial reaction.

Growing community of inventors

Cologne, Germany

Manfred Martin