PROCESS FOR HETEROGENEOUSLY CATALYZED GAS PHASE PARTIAL OXIDATION OF (METH)ACROLEIN TO (METH)ACRYLIC ACID

A process for preparing (meth)acrylic acid by heterogeneously catalyzed gas phase partial oxidation of (meth)acrolein over a multimetal oxide composition which comprises the elements Mo, V and W and is obtained by a hydrothermal preparation route, and the multimetal oxide composition obtainable by this preparation route. 1. A process , comprising heterogeneously catalyzing a partial oxidation of (meth)acrolein to (meth)acrylic acid in the gas phase over a catalytically active multimetal oxide composition of formula (I):{'br': None, 'sub': 12', 'a', 'b', 'c', 'd', 'c', 'f', 'g', 'n, 'sup': 1', '2', '3', '4', '5', '6, 'MoVXXXXXXO\u2003\u2003(I),'}wherein:{'sup': '1', 'Xrepresents W, Nb, Ta, Cr, Ce, or a mixture thereof;'}{'sup': '2', 'Xrepresents Cu, Ni, Co, Fe, Mn, Zn, or a mixture thereof;'}{'sup': '3', 'Xrepresents Sb, Te, Bi, or a mixture thereof;'}{'sup': '4', 'Xrepresents H, one or more alkali metals, or a mixture thereof;'}{'sup': '5', 'Xrepresents one or more alkaline earth metals;'}{'sup': '6', 'Xrepresents Si, Al, Ti, Zr, or a mixture thereof;'}a represents 1 to 6;b represents 0.2 to 8;c represents 0 to 18;d represents 0 to 40;e represents 0 to 4;f represents 0 to 4;g represents 0 to 40;n represents a number determined by the valency and frequency of the elements in the formula (I) other than oxygen;{'sup': '1', 'at least 50 mol % of a total molar amount of elements Xpresent in the multimetal oxide composition of formula (I) is the element W; and'}the multimetal oxide composition of formula (I) is prepared by hydrothermally treating a mixture of sources of elemental constituents in the presence of water in a pressure vessel, such that a newly forming solid is removed as a precursor composition which is converted to the catalytically active multimetal oxide composition of formula (I) by thermal treatment.2. The process according to claim 1 , wherein the catalytically active multimetal oxide composition satisfies formula (II):{'br': None, 'sub': 12', 'a', 'b', ...

Process for operating a plant for preparing an alkanesulfonic acid

The present invention relates to a process for operating a plant for preparing an alkanesulfonic acid, wherein said alkanesulfonic acid is prepared by oxidation of an alkylmercaptan, dialkydisulfide and/or dialkylpolysulfide and the one or more alkyl radicals of the alkylmercaptan, dialkydisulfide and/or dialkylpolysulfide are identical with the alkyl radical of the alkylsulfonic acid to be prepared, characterized in that the oxidation is performed in the presence of an at least stoichiometric amount of an oxoacid of nitrogen, e.g. nitric acid, relative to the amount of said alkylmercaptan, dialkyldisulfide and/or dialkylpolysulfide during the start-up phase of the plant of the plant, wherein the start up phase comprises the steps adding an oxoacid of nitrogen to the reactor, adding sulfur-containing reactant progressively so that it is converted to alkanesulfonic acid, filling up the compile volume of the reactor by adding progressively sulfur-containing reactant and if needed oxoacid of nitrogen to make sure that it is in excess, once the reactor is full, transitioning out of the start-up phase by adding an oxygen containing fluid, and during the running phase, keeping the reaction volume full by balancing the volume of product withdrawn with the volume of sulfur-containing reactant added.

Method for determining dimethyl disulphide

A method for determining dimethyl disulphide proceeds by carrying out a chromatographic separation of an analyte containing at least dimethyl disulphide and methanesulphonic acid, and determining the dimethyl disulphide by pulsed amperometric detection.

Process for preparing an alkanesulphonic acid

The present invention relates to a process for preparing alkanesulphonic acid by oxidizing an alkyl mercaptan, a dialkyl disulphide and/or a dialkyl polysulphide having three to nine sulphur atoms with an oxidizing agent, wherein additional oxidizing agentis fed into the oxidation if as yet unoxidized alkyl mercaptan and/or unoxidized dialkyl disulphide and/or at least one intermediate from the oxidation of the dialkyl disulphide and/or of the dialkyl polysulphide is present in the reaction output, and a corresponding apparatus for performance of oxidation reactions.

Catalyst for the synthesis of alkyl mercaptan and process for its preparation

Process for the preparation of alkyl mercaptan

Catalyst for the synthesis of alkyl mercaptan and process for its preparation

A catalyst may include a support and from 5 to 20 wt.-% of a promoter, based on the total weight of the catalyst, wherein the support may include titanium dioxide, zirconium dioxide, and/or a mixture thereof, and the promoter may be an alkali metal oxide. Processes for preparing such catalysts may include impregnating a support of titanium dioxide and/or zirconium dioxide with an aqueous solution including a preferably soluble alkali compound and calcining. Alkyl mercaptans may be prepared in the presence of such catalysts or catalysts obtained by such processes.