The present invention is directed to using methyl acetate from a vinyl acetate -based or a vinyl-or ethylene-alcohol based polymer or copolymer process directly for use in a methanol carbonylation production process to produce acetic acid, acetic anhydride, or a coproduction of each. Methyl acetate is a by-product of commercial polyvinyl-alcohol or alkene vinyl alcohol copolymer-based processes. Generally, this material is processed to recover methanol and acetic acid. Discussed herein is a cost-saving scheme to by-pass the methyl acetate processing at production or plant facilities and utilize the methyl acetate in an integrated methanol carbonylation unit. The scheme discussed eliminates an expensive hydrolysis step often associated with the polymer process.

Integrated process for producing carbonylation acetic acid,acetic anhydride,or coproduction of each from a methyl acetate by-product stream

Design and control of acetic acid dehydration system via heterogeneous azeotropic distillation

Design and synthesis of heterogeneous azeotropic distillations—III. Column sequences

The minimum energy requirement of a distillation sets a lower, thermodynamically defined operating limit, which is increasingly important in practice due to growing interest in saving energy. During the conceptual design phase this energy information can also be used to quickly compare distillation configurations. This paper gives a summary of the most important methods published to date for the calculation of the minimum energy requirement. Firstly, the occurrence of so-called pinch zones will be systematically described. These are sections of the column in which at minimum reflux an infinite number of separation stages would be necessary. Then exact and approximating solutions of the problems both for ideal and for nonideal mixtures will be discussed. For ideal mixtures a rapid calculation is possible using the well-known Underwood equations, which can also be applied to complex columns (e.g., several feeds and side products, side stream strippers and enrichers). However, strongly nonideal multicomponent mixtures still require time-consuming simulations of columns having large numbers of plates. In such cases serious convergence problems must often be reckoned with. Recent developments aim at avoiding column simulations and at calculating pinch points directly.

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A review on minimum energy calculations for ideal and nonideal distillations

Provided is a method of removing carboxylic acids from effluent streams comprising the steps of pretreatment which may include chemical conditioning, clarification and filtering the effluent stream to remove suspended solid particles to provide a filtered stream. The filtered stream is subjected to membrane filtration to remove organic compounds having a molecular weight of greater than 150 while simultaneously permitting permeation of the membrane by the carboxylic acids to provide a membrane filtered stream. A reverse osmosis membrane is provided having a high pressure side and a low pressure side, and the membrane filtered stream is introduced to the high pressure side of the reverse osmosis membrane. The carboxylic acids are concentrated in the high pressure side of the reverse osmosis membrane. In a preferred embodiment, purified liquid (permeate) is neutralized and passed to the high pressure side of a second pass reverse osmosis membrane, producing a high-purity final permeate for plant reuse or discharge to surface water.

Recovery of carboxylic acids from chemical plant effluents

In an azeotropic distillation column, the rate of net flow and the composition of net flow for both stripping and rectifying sections can be calculated from the limiting conditions of the separation desired The pinch points are dotted on the radial lines starting from the point of net flow composition by trial and error, and locus of the pinch points are traced on the triangular diagram by the way of connecting the pinch points Each minimum reflux ratio of stripping and rectifying sections can be calculated from the quantitative ratio of vapor and liquid of the operating line passing the point of intersection of locus line and feed line, and the larger of the two values shall be defined as the minimum reflux ratio of the system For example, we illustrate the graphical calculation method for AcOH-H2O-BuOAc system and AcOH-H2O-EtOAc system

Graphical calculation method for minimum reflux ratio in azeotropic distillation

An alkenyl carboxylate having a higher value than, for ex­ample, vinyl acetate can be prepared by the ester-exchange reac­tion between a corresponding carboxylic acid and vinyl acetate in the presence of a catalyst system comprising (a) a palladium com­pound, (b) copper bromide or a combination of a copper compound other than copper bromide and an inorganic bromine compound and (c) a lithium compound selected from lithium carboxylates, lithium carbonate, lithium hydrogencarbonate and lithium hydr­oxide.

Method for the preparation of an alkenyl carboxylate

The invention provides a means for greatly saving the thermal energy consumption in the dehydrating distillation of an aqueous solution of a carboxylic acid such as acetic acid by use of an azeotropically distilling entrainer boiling at a lower temperature than the carboxylic acid and immiscible with water. The improvement proposed by the invention comprises taking at least a part of the entrainer phase separated from the condensate coming from the column top or at least a part of the side-cut fluid abstracted from the refluxing fluid inside the column, evaporating the thus taken fluid into vapor and introducing the vapor into the distillation column at a stage for the introduction of the starting feed or below.

Method for dehydrating distillation of an aqueous solution of carboxylic acid

A novel and effective catalyst system is provided for application in the preparation of alkenyl esters of carboxylic acids by transesterification reaction. The catalyst system consists of a palladium compound as the main ingredient and a cocatalyst formed of an alkali metal compound and a copper compound, at least one of which is a halide. The catalyst ingredients are adsorbed on a solid catalyst carrier, so that repeated use of the combined catalyst or a continuous operation of the reaction can easily be facilitated.

Shozo Tanaka

Papers

Graphical calculation method for minimum reflux ratio in azeotropic distillation

Method for the preparation of an alkenyl carboxylate

Method for dehydrating distillation of an aqueous solution of carboxylic acid

Method for the preparation of alkenyl esters of carboxylic acids

Verfahren zur herstellung eines alkenylesters von carbonsaeuren