Abstract: The invention relates to a method for thermally separating silane mixtures, which contain silanes, selected from alkylchlorosilanes and hydrochlorosilanes, in a distillation apparatus, in which at least part of the heat for heating the distillation apparatus is transferred by vapors of another distillation apparatus, and in which a silane product is obtained having impurities of no more than 200 ppm.

Abstract: The invention relates to a method for separating and purifying an aqueous mixture that mainly consists of acetic acid, formic acid and high-boiling substances by extraction with a solvent in a cyclic process. The inventive method is characterized in that the flow of raffinate is fed to a solvent stripping column (11) with the major part of the water in order to remove the water from the cycle. The flow of extract is fed to a solvent recovery distillation column (8). In a first step, a mixture (A) that consists of water and solvent, is separated by overhead distillation. A mixture (B) that consists of acetic acid, formic acid and high-boiling substances is separated via a sump. Once the formic acid is removed in a column (29), mixture (B) is separated in an acetic acid distillation column to give pure acetic acid and high-boiling substances.

Abstract: A method for the separation and purification of an aqueous mixture of main components, namely acetic acid and formic acid and non-volatiles by extraction, uses a solvent in a circulatory system. A raffinate stream is mixed with the larger proportion of water from a solvent stripper column (11) for the removal of water. The extraction stream is introduced into a solvent distillation column (8), from which in a first step involving the use of a mixture (A) containing a larger proportion of the solvent is separated out via a header and a mixture (B) of formic acid, water and solvent is separated out via a side offtake and a mixture (C) of acetic acid and non-volatiles is also separated out. A mixture (B) is introduced into a formic acid distillation column (4) for further processing, and a mixture (C) is introduced into an acetic acid distillation column (5), and purified acetic acid is subsequently isolated in the acetic acid distillation column (5) from the header.

Abstract: A process and an apparatus are for preparing saturated carboxylic acids having from one to four carbon atoms by gas-phase oxidation at a reaction temperature of from 100° C. to 400° C. and pressures of from 1.2×105 to 51×105 Pa in the presence of saturated or unsaturated C4-hydrocarbons and mixtures thereof. Also present in the reactor are an oxygen-containing gas and water vapor and in the presence of at least one catalyst, with part of the reactor outlet gas being recirculated in a reaction gas circuit. The acid concentration in the recirculated portion is reduced by means of a separation step, and the crude acid is separated from the reactor outlet gas by means of a countercurrent scrubber.