Abstract: Compositions of the formula IMo.sub.12 P.sub.a V.sub.b X.sub.c.sup.1 X.sub.d.sup.2 X.sub.e.sup.3 Sb.sub.f Re.sub.g S.sub.h O.sub.n (I),whereX.sup.1 is potassium, rubidium and/or cesium,X.sup.2 is copper and/or silver,X.sup.3 is cerium, boron, zirconium, manganese and/or bismuth,a is from 0.5 to 3.0,b is from 0.01 to 3.0,c is from 0.2 to 3.0,d is from 0.01 to 2.0,e is from 0 to 2.0,f is from 0.01 to 2.0,g is from 0 to 1.0,h is from 0.001 to 0.5 andn is a number determined by the valency and content of the elements different from oxygen in I, are used as catalysts for preparing methacrylic acid by gas-phase oxidation of methacrolein.

Abstract: Compositions of the formula IMO.sub.12 P.sub.a V.sub.b X.sup.1.sub.c X.sup.2.sub.d X.sup.3.sub.e Sb.sub.f Re.sub.g S.sub.h O.sub.n (I)whereX.sup.1 is potassium, rubidium and/or cesium,X.sup.2 is copper and/or silver,X.sup.3 is cerium, boron, zirconium, manganese and/or bismuth,a is from 0.5 to 3.0,b is from 0.01 to 3.0,c is from 0.2 to 3.0,d is from 0.01 to 2.0,e is from 0 to 2.0,f is from 0.01 to 2.0,g is from 0 to 1.0,h is from 0.001 to 0.5 andn is a number determined by the valency and content ofthe elements different from oxygen in I, are used as catalysts for preparing methacrylic acid by gas-phase oxidation of methacrolein.

Abstract: Methacrylic acid can be prepared with advantage by gas phase oxidation of methacrolein or isobutyraldehyde over Mo- and P-containing catalysts at from 250.degree. to 400.degree. C. with cooling of the hot reaction gas to below 100.degree. C., absorption of the methacrylic acid in a water-operated absorption column, at below 100.degree. C. and partial recycling into the oxidation reactor after admixture of methacrolein or isobutyraldehyde and oxygen by feeding a quantity of methacrolein or isobutyraldehyde equal to the quantity of methacrolein or isobutyraldehyde consumed in the reaction in liquid form together with a polymerization inhibitor into the reactor gas in the lower two-thirds of the absorber column and upstream of the feed point for the fresh methacrolein or isobutyraldehyde or down-stream of the absorption column splitting off the reactor off-gas a side stream which is washed in a wash column operated with water at <10.degree. C.

Abstract: Oxidation catalysts of the general formulaMo.sub.12 P.sub.a W.sub.b Sb.sub.c As.sub.d Cu.sub.e X.sub.f O.sub.xwhereX is Nb, Fe, Mn, Sn and/or Cr,a is 0.1-3,b is 0.1-4,c is <0-2,d is 0-1,e is 0-1,d+e is <0-2,f is 0-1.5,e+f is 0-2 andx is the number of oxygen atoms formally required to saturate the valencies of the other catalyst components,may be used particularly advantageously for the preparation of methacrylic acid by gas phase oxidation of methacrolein.

Abstract: A catalyst which is free from alkali metal compounds and alkaline earth metal compounds, contains palladium and lead as active constituents and is supported on a carrier which contains two or more of the oxides ZnO, Al.sub.2 O.sub.3, La.sub.2 O.sub.3 and TiO.sub.2, and the use of this catalyst for the preparation of methyl methacrylate from methacrolein, methanol and oxygen.

Abstract: Methanol is prepared by catalytic conversion of a synthesis gas mixture, containing hydrogen, carbon monoxide, carbon dioxide and/or water, at from 200.degree. to 320.degree. C. and under from 30 to 300 bar in adiabatic and/or isothermal reactions in the presence of a catalyst containing copper and zinc, by a process in which the fresh catalyst is reduced with a hydrogen-containing gas before the start-up of the process, and then the synthesis is started under conventional conditions and is continued until the formation of methanol in the reaction zone has declined substantially, after which the reaction is interrupted and the catalyst is regenerated.

Abstract: Oxidation catalysts of the general formulaW.sub.6 Mo.sub.a V.sub.b P.sub.c Cu.sub.d As.sub.e Sb.sub.f X.sub.g Y.sub.h O.sub.xwhere X is K, Rb and/or Cs, Y is Nb, Fe, Mn, Sn, Li, Na, Sr, Rh, Ce, Ti and/or Cr, a is from 2.0 to 6, b is from 0 to 3, c is from 0.1 to 3, d is from 0.01 to 1, e is from 0 to 1, f is from 0 to 2, g is from 0.01 to 3, h is from 0 to 1 and x is the number of oxygen atoms formally required to saturate the valencies of the catalyst components, give high conversions and particularly high selectivity in the oxidation of methacrolein in the gas phase to methacrylic acid.

Abstract: Catalysts for the preparation of carboxylates from an aldehyde and an alkanol in the presence of oxygen, which contain palladium and lead as active components, these being present on a carrier containing zinc oxide, and the palladium being applied as a palladium salt in a solution containing hydrochloric acid and then being liberated by reduction, and whose carrier consists solely of zinc oxide, are particularly active and selective.

Abstract: .alpha.-Alkylacroleins are prepared by a process wherein an alkanal is reacted with formaldehyde in the presence of a secondary amine and in the presence or absence, of an acid, in the liquid phase, under superatmospheric pressure and at above 150.degree. C., for not more than 25 minutes.The .alpha.-alkylacroleins obtainable by the process are useful starting materials for dyes, drugs and pesticides.

Abstract: To destroy phosgene contained in gases, the phosgene is decomposed catalytically in the presence of active carbon by hydrolysis with water vapor, in the absence of liquid water, at above the dew point of water.

Abstract: Acrolein and methacrolein are prepared advantageously by oxidizing propylene or isobutylene, respectively, with an oxygen-containing gas mixture under conventional conditions over a supported catalyst possessing a firmly adhering coating, from 150 to 1,500 .mu.m thick, which contains calcined catalytic material based on molybdenum oxide and has a carrier core with a surface area of less than 15 m.sup.2 /g and a diameter of more than 100 .mu.m, if a coated catalyst is used which has been prepared by applying calcined catalytic material having a particle size of from 0.1 to 300 .mu.m, in an amount of from 1 to 40 g/min/liter of carrier and water in a weight ratio of catalytic material to water of from 1:1 to 8:1, continuously and separately from one another, each at a constant speed, at below 100.degree. C.

Abstract: Catalysts which consist of a molded carrier, the surface of which is coated with an active catalyst composition of the general formula Mo.sub.12 A.sub.a B.sub.b C.sub.c D.sub.d O.sub.x, where A is V and/or W, B is Cu and/or Fe and/or Mn and/or Ni and/or Cr, C is Nb and/or Ta and/or Bi and/or Sb and/or Sn and/or Th and/or Ce and/or U, D is Li and/or Na and/or K and/or Rb and/or Cs and/or Tl and a is from 0.1 to 18, b is from 0 to 8, c is from 0 to 10, d is from 0 to 2 and x is from 36 to 135, which are particularly active and selective for the oxidation of acrolein and methacrolein with oxygen-containing gases to give acrylic acid and methacrylic acid, respectively, are obtained by first manufacturing the catalyst composition, before applying it to the carrier, from thermally easily decomposed salts of the components by mixing aqueous solutions, slurries or moist solid masses of the salts of the components, drying the mixture and calcining the dried composition at from 140.degree. to 600.degree. C.

Abstract: .gamma.-Butyrolactone is manufactured by hydrogenating maleic anhydride in the presence of butyrolactone as the solvent. The hydrogenated reaction mixture, which contains butyrolactone, succinic anhydride and succinic acid, is fractionated in a thin film evaporator.

Abstract: In the oxidation of propylene and/or acrolein, high-boiling or non-volatile byproducts are separated from the solvents used for absorbing the acrylic acid by treating the said solvents laden with byproducts with the hot reaction gases in such amounts that the major portion of the solvents evaporates, the residual solvent containing a high percentage of said byproducts then being discarded or worked up.

Abstract: In the oxidation of .alpha.-olefins in the gas phase to .alpha.,.beta.-olefinically unsaturated aldehydes and carboxylic acids with molecular oxygen in the presence of an inert gas using a catalyst containing molybdenum and bismuth with elements as oxides or mixed oxides at from 280.degree. to 450.degree. C a content of indium and/or aluminum and/or lanthanum and/or gallium as oxide or mixed oxide results in an improvement in the conversion and/or activity and/or life of the catalyst.

Abstract: In the oxidation of propylene to acrylic acid in the gas phase in two spatially separate oxidation stages, a part of the off-gas, which has been freed from condensable products, is fed to the oxidation stages in addition to freshly charged propylene and air, under the following conditions:A. The recycled off-gas and air are in part fed to the first oxidation stage and in part to the second oxidation stage,B. The molar ratio of propylene : oxygen : residual gases fed to the first stage is 1 : 1.5-2.3 : 11-19,C. The molar ratio of the total propylene fed in, to the total oxygen fed in, in the form of air or off-gas, before and after the first stage, and to the total residual gases fed in is 1 : 1.9-2.5 : 13-25, with the proviso thatD. The air and the recycled off-gas are divided between the two feed points in such a way that from 10 to 50% by volume of the total quantity of air and off-gas fed in are added after the first stage andE.

Abstract: Acrylic acid practically devoid of water, acrolein, formaldehyde and acetic acid is obtained at particularly low cost by countercurrent scrubbing and quenching of the reaction gas formed in the catalytic oxidation of propylene and/or acrolein with a high-boiling, extremely hydrophobic solvent followed by processing of the extract.