Basf Aktiengesellschaft

Badische Anilin- & Soda-fabrik Aktiengesellschaft

Fritz Thiessen

Richard Krabetz

Gerd Duembgen

Heinz Engelbach

Carl-Heinz Willersinn

Ulrich Lebert

Franz Merger

Ulrich Hammon

Walter Frey

Matthias Schwarzmann

Herbert Vogel

Karl-Heinz Boehning

Bernd Heida

Albrecht Dams

Norbert Scholz

Walter Herrmann

Gerd-Juergen Engert

Horst Egly

Gerhard Altinger

Hermann Spitzl

Herbert Vogal

Michael Jaeger

Rudolf Kaiser

Process for the separation of acrylic acid

Column tray for a mass transfer column, in particular one provided with a support ring at the circumference, which tray has support elements and tray plates arranged side by side on the support elements and having passages, in particular holes, valves or bubble caps, wherein the majority, preferably the total number, of tray plates are connected liquid-tight, preferably welded, to the support elements or the support ring, in particular in discrete area elements; the majority, preferably the total number, of support elements are connected liquid-tight, preferably welded, to one another and to the column wall or the support ring, in particular in discrete area elements; and in addition the majority, preferably the total number, of adjacent tray plates and support elements are separated from one another and from the column wall or the support ring by gaps having a width of from 1 to 15 mm, preferably from 1 to 7 mm.

Mass transfer in plate columns and apparatus for this purpose

Compositions of the formula Mo.sub.12 P.sub.a V.sub.b X.sup.1 c X.sup.2

Compositions of the formula MO.sub.12 P.sub.a V.sub.b X.sup.1.sub.c

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 &lt;10.degree. C. to remove unconverted methacrolein or isobutyraldehyde which is fed as an aqueous solution to the top of the absorption column.

Preparation of methacrylic acid

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., then milling it to a particle size of less than 150 .mu.m and thereafter applying it, as a mixture with water, as a layer from 10 to 1,500 .mu.m thick, to the premolded carrier, which has a rough surface.

Catalyst for the oxidation of acrolein and methacrolein to acrylic acid

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.

Method of separating high-boiling or non-volatile materials

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.

Catalytic oxidation of .alpha.-olefins

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 that D. 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 and E. The air and off-gas are admixed to the reaction gas mixture after the first stage, immediately after it leaves the catalyst zone, so that the mixture is rapidly cooled to a temperature of from 150.degree. to 320.degree. C.

Manufacture of acrylic acid by oxidation of propylene with

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.

Recovering anhydrous acrylic acid

Growing community of inventors

Ludwigshafen, Germany

Fritz Thiessen