Sulzer Chemtech Ag

Sulzer Management Ag

Peter Faessler

Manfred Stepanski

Oliver Bailer

Claudia Von Scala

Peter Moritz

Halbe Jansen

A plant for preparing a purified isomeric methylene diphenyl diisocyanate monomer from a mixture of different isomeric monomers is disclosed herein. The plant can comprise a distillation apparatus, which comprises: a) a distillation column including a structured packing, b) a source for a mixture of different isomeric methylene diphenyl diisocyanate monomers, c) an evaporator, d) an overhead vapor condenser, e) optionally, an overhead vacuum system and f) a flow-controlled reflux system. The overhead vapor condenser comprises a shell and tube arrangement and is embodied so as to directly subcool the condensate to less than 47&#xb0; C. The flow-controlled reflux system comprises a heater, which is embodied so as to reheat a partial stream of the condensate formed in the overhead vapor condenser up to 190&#xb0; C.

Plant and method for purifying an isomeric monomer

The present invention relates to a method for purifying a crude benzoic acid () containing 5 to 20% by weight of byproducts and 80 to 95% by weight of benzoic acid, by means of distillation, wherein the distillation is performed in a plant comprising a first distillation system (), which comprises a divided wall column (). Preferably, the divided wall column () comprises: an upper portion having an upper undivided section () for concentrating low-boiling components, wherein the low-boiling components have a lower boiling point than benzoic acid, and an outlet for removal of the low-boiling components from the column (), a lower portion having a lower undivided section () for concentrating high-boiling components, wherein the high-boiling components have a higher boiling point than benzoic acid, and an outlet for removal of the high-boiling components from the column (), and a central portion arranged between the upper portion and the lower portion having at least one vertical dividing wall () for dividing the central portion into at least one feed section () and at least one withdrawal section (), the feed section () having an inlet for the feed of crude benzoic acid () and the withdrawal section having a side draw outlet for the purified benzoic acid ().

Method for purification of benzoic acid

The apparatus for the esterification of a fatty acid F includes a column with a packing. In addition to functioning as a catalytic reactor, the packing functions as a stripping section. A heteregenous catalysis of a fatty acid is carried out with an alcohol used in the same molar ratio or in excess. A gaseous alcohol-rich counter-flow is produced in a sump of the column by vaporization. Water is removed from the reaction zone by means of the counter-flow acting as a stripping gas. The loaded stripping gas is at least partially liquefied at the head of the column. The head product is separated into a water-rich fraction as well as an alcohol-rich fraction. The alcohol-rich fraction is returned to the process as a starting material for the esterification and for the production of the stripping gas.

Apparatus for the esterification of a fatty acid

The method for the esterification of a fatty acid F is carried out in a column with a packing. In addition to functioning as a catalytic reactor, the packing functions as a stripping section. A heteregenous catalysis of a fatty acid is carried out with an alcohol used in the same molar ratio or in excess. A gaseous alcohol-rich counter-flow is produced in a sump of the column by vaporization. Water is removed from the reaction zone by means of the counter-flow acting as a stripping gas. The loaded stripping gas is at least partially liquefied at the head of the column. The head product is separated into a water-rich fraction as well as an alcohol-rich fraction. The alcohol-rich fraction is returned to the process as a starting material for the esterification and for the production of the stripping gas.

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Allschwil, Switzerland

Peter Faessler