Abstract: A process for preparing saturated carboxylic acids having from one to four carbon atoms by gas-phase oxidation, includes reacting 2-butanone with oxygen over a coated catalyst which is an inert nonporous support body and a catalytically active mixed oxide composition comprising (a) one or more oxides selected from the group consisting of titanium dioxide, zirconium dioxide, tin dioxide and aluminum oxide, and (b) from 0.1% to 1.5% by weight, based on the weight of the component (a) and per m2/g of specific surface area of the component (a), of vanadium pentoxide, applied to the external surface of the support body.

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 is for producing monolithic substrate catalysts and for their use in the gas phase oxidation of hydrocarbons. The catalysts are obtained by coating the catalyst substrate with a suspension that includes a catalytically active compound and one or more surfactants of the general formula RnYmX. R represents the hydrophobic part of the surfactant, with n being 1, 2 or 3. Y represents the hydrophobic part of the surfactant, with m being 0, 1, 2, or 3 and X represents the hydrophilic head group of the surfactant.

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 for preparing saturated carboxylic acids having from 1 to 4 carbon atoms at a reaction temperature of from 100° C. to 400° C. and pressures of from 1.2×105 Pa to 51×105 Pa by gas phase oxidation of saturated and/or unsaturated C4-hydrocarbons, with an oxygen-containing gas and water vapor in the presence of at least one catalyst. The gas leaving the reactor is partly recirculated in a reaction gas circuit. This reaction gas circuit is configured such that part of the organic acids formed in the gas-phase oxidation is taken from the gas leaving the reactor so that the acid content of the recirculated part of the gas leaving the reactor is from 0.01% to 6.0% by volume.

Abstract: The invention relates to supported catalysts consisting of an active material on an inert support in the shape of rings, wherein the rings have one or more notches in the upper and/or lower flat side of the ring.

Abstract: A process for preparing saturated carboxylic acids having from 1 to 4 carbon atoms at a reaction temperature of from 100° C. to 400° C. and pressures of from 1.2×105 Pa to 51×105 Pa by gas phase oxidation of saturated and/or unsaturated C4-hydrocarbons, with an oxygen-containing gas and water vapor in the presence of at least one catalyst. The gas leaving the reactor is partly recirculated in a reaction gas circuit. This reaction gas circuit is configured such that part of the organic acids formed in the gas-phase oxidation is taken from the gas leaving the reactor so that the acid content of the recirculated part of the gas leaving the reactor is from 0.01% to 6.0% by volume.

Abstract: To provide a communication interface for a path measuring device which can be coupled between the path measuring device and a control device, wherein a path determination can be carried out by means of the path measuring device by way of a measurement of the propagation time of measurement signals and a measurement of the propagation time can be triggered by way of control signals on a control signal communication channel and a propagation-time signal communication channel is provided for propagation-time signals, by means of which a path measuring device may be used universally and in a simple manner, it is suggested that the communication interface be coupled to the control signal communication channel and/or to the propagation-time signal communication channel and that digital data be transmittable between the control device and the path measuring device in addition to control signals for the measurement of the propagation time and propagation-time signals.

Abstract: A process for preparing saturated carboxylic acids having from 1 to 4 carbon atoms at a reaction temperature of from 100° C. to 400° C. and pressures of from 1.2×105 Pa to 51×105 Pa by gas phase oxidation of saturated and/or unsaturated C4-hydrocarbons, with an oxygen-containing gas and water vapor in the presence of at least one catalyst. The gas leaving the reactor is partly recirculated in a reaction gas circuit. This reaction gas circuit is configured such that part of the organic acids formed in the gas-phase oxidation is taken from the gas leaving the reactor so that the acid content of the recirculated part of the gas leaving the reactor is from 0.01% to 6.0% by volume.

Abstract: A method is provided for producing catalysts useful for synthesizing maleic anhydride by oxidizing saturated and/or unsaturated C4 hydrocarbons. A vanadium (V) compound is reacted with a mixture of phosphorous and phosphoric acids in a particular ratio, in a solvent mixture containing a structure former, and an entrainer and where the water of reaction together with entrainer is distilled off and the resulting precursor is subjected to calcination.

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.

Abstract: A process for preparing acetic acid by gas-phase oxidation of saturated C4-hydrocarbons and their mixtures with unsaturated C4-hydrocarbons in a tube reactor using a coated catalyst comprising an inert nonporous support body and a catalytically active mixed oxide composition comprising (a) one or more oxides selected from the group consisting of titanium dioxide, zirconium dioxide, tin dioxide and aluminum oxide and (b) from 0.1% to 1.5% by weight, based on the weight of the component (a) and per m2/g of specific surface area of the component (a), of vanadium pentoxide applied to the outer surface of the support body, wherein a gas mixture comprising oxygen or oxygen-containing gas, one or more C4-hydrocarbons and water vapor and having a C4-hydrocarbon/air (oxygen) volume ratio of from 0.2/99.8 to 25/75 and a C4-hydrocarbon/water vapor volume ratio of from 1/1 to 1/60 is reacted over the coated catalyst at a temperature of from 100° C. to 400° C. and a gauge pressure of from 0.2 to 50 bar.

Abstract: The invention relates to a shell catalyst for producing acetic acid by gas-phase oxidation of unsaturated C4-hydrocarbons, comprising an inert non-porous carrier and a catalytically active mixed oxide material applied on the outer surface of the carrier, wherein said material contains (a) one or several oxides from the group titanium dioxide, zircon dioxide, stannic dioxide, aluminum oxide, and b) 0.1 to 1.5 wt. % vanadium pentoxide in relation to the weight of the constituent (a) and per m2/g of the specific surface of the constituent (a).

Abstract: There is a process for producing coated catalysts for the gas-phase oxidation of C.sub.4 hydrocarbons to maleic anhydride. A vanadyl phosphate catalyst precursor is prepared having a V/P ratio of from 1:0.5 to 1:2 and a mean vanadium oxidation state of from 3.9 to 4.5. The vanadyl phosphate precursor is then calcined by heating for a several hours at a temperature of from 200.degree. C. to 500.degree. C. before being applied, in an aqueous suspension to the support bodies. Furthermore, there is the use of these coated catalysts in processes for the gas-phase oxidation of saturated or unsaturated C.sub.4 -hydrocarbons to maleic anhydride.

Abstract: The invention relates to a supported catalyst for gas-phase reactions having an inert support body and a surface coating comprisinga) at least 5% by weight of silicon carbide,b) from 5 to 90% by weight, calculated as oxide, of one or more titanium dioxide or zirconium oxide components or mixtures thereof,c) from 1 to 50% by weight, calculated as V.sub.2 O.sub.5, of one or more vanadium oxide components,d) from 0 to 10% by weight, calculated as oxide, of one or more compounds of elements of the 1st and 5th main groups of the Periodic Table, and also a process for its preparation and its use.