The present invention relates to a process for the preparation of halogenated carboxylic anhydrides, e.g. for the preparation of trifluoroacetic anhydride. The preparation is achieved by reacting a halogenated carboxylic acid, e.g. trifluoroacetic acid, with sulfuric acid, oleum and/or disulfuric acid.

Methods and systems for separating a desublimatable compound from hydrocarbons is disclosed. A feed fluid stream, consisting of a hydrocarbon and a desublimatable compound, is passed into an upper chamber of a vessel. The feed fluid stream is cooled in the upper chamber, thereby desublimating a portion of the desublimatable compound out of the feed liquid stream to form a product gas stream and a desublimatable compound snow which is collected in the lower chamber of the vessel. A lower portion of the desublimatable compound snow is melted to form a liquid desublimatable compound stream such that an upper portion of the solid desublimatable compound snow remains as an insulative barrier between the upper chamber and the liquid desublimatable compound stream. The liquid desublimatable compound stream is removed at a rate that matches a production rate of the solid desublimatable compound snow, thereby maintaining the insulative barrier.

The present invention concerns a process for the reduction of content of carboxylic acids and derivatives thereof in oleum, disulfuric acid or concentrated sulfuric acid. The invention further concerns a process for the manufacture of carboxylic acid anhydrides comprising the process for the reduction of content of carboxylic acids and derivatives thereof from oleum, disulfuric acid or concentrated sulfuric acid.

The present invention concerns a process for the reduction of content of carboxylic acids and derivatives thereof in oleum, disulfuric acid or concentrated sulfuric acid. The invention further concerns a process for the manufacture of carboxylic acid anhydrides comprising the process for the reduction of content of carboxylic acids and derivatives thereof from oleum, disulfuric acid or concentrated sulfuric acid.

The present invention concerns a process for the reduction of content of carboxylic acids and derivatives thereof in oleum, disulfuric acid or concentrated sulfuric acid. The invention further concerns a process for the manufacture of carboxylic acid anhydrides comprising the process for the reduction of content of carboxylic acids and derivatives thereof from oleum, disulfuric acid or concentrated sulfuric acid.

The present invention relates to a process for the preparation of halogenated carboxylic anhydrides, e.g. for the preparation of trifluoroacetic anhydride. The preparation is achieved by reacting a halogenated carboxylic acid, e.g. trifluoroacetic acid, with sulfuric acid, oleum and/or disulfuric acid.

The present invention relates to a process for the preparation of halogenated carboxylic anhydrides, e.g. for the preparation of trifluoroacetic anhydride. The preparation is achieved by reacting a halogenated carboxylic acid, e.g. trifluoroacetic acid, with sulfuric acid, oleum and/or disulfuric acid.

Continuous process for co-production of acetic acid and acetic anhydride by contacting carbon monoxide with a liquid reaction composition containing methyl acetate, dimethyl ether or a mixture thereof, a Group VIII metal catalyst, methyl iodide, acetic acid, acetic anhydride, and water in a concentration of 0.1 wt % or less, withdrawing liquid reaction composition from the reaction zone, introducing at least a portion thereof into a flash separation zone, and removing from the flash separation zone a vapor fraction containing acetic anhydride, acetic acid and methyl iodide and a liquid fraction containing acetic anhydride, and Group VIII metal catalyst. The liquid reaction composition and the withdrawn liquid reaction composition introduced into the flash separation zone contains a Group IA and/or Group IIA metal salt and the molar ratio of acetic acid to acetic anhydride in the vapor fraction removed from the flash separation zone is greater than or equal to 1.

Continuous process for co-production of acetic acid and acetic anhydride by contacting carbon monoxide with a liquid reaction composition containing methyl acetate, dimethyl ether or a mixture thereof, a Group VIII metal catalyst, methyl iodide, acetic acid, acetic anhydride, and water in a concentration of 0.1 wt % or less, withdrawing liquid reaction composition from the reaction zone, introducing at least a portion thereof into a flash separation zone, and removing from the flash separation zone a vapor fraction containing acetic anhydride, acetic acid and methyl iodide and a liquid fraction containing acetic anhydride, and Group VIII metal catalyst. The liquid reaction composition and the withdrawn liquid reaction composition introduced into the flash separation zone contains a Group IA and/or Group IIA metal salt and the molar ratio of acetic acid to acetic anhydride in the vapor fraction removed from the flash separation zone is greater than or equal to 1.

A process for continuous dissolution of a solid in a reaction medium includes: (a) providing a liquid by withdrawal of a portion of the reaction medium from a first reaction vessel; (b) contacting the liquid provided in (a) with the solid in a second reaction vessel to form a solution of the solid; and (c) recycling the solution formed in step b) into the first reaction vessel. The solid in the second reaction vessel is present in the form of a fixed bed which is traversed by the liquid.