SU738658A1 - Oxidation catalyst - Google Patents

Description

The invention relates to the production of catalysts for the oxidation of olefins, unsaturated sdedehydes, in particular for oxidation. NIN propylene to acrolein or iso-Sutylene to methyl acrolein, which is used for the synthesis, for example, methionine, glycerin, acrylic or methacrylic acid, and their esters.

Cobalt molybdenum oxide bismuth oxide catalysts for the oxidation of propylene to acrolein are known, on which the aldehyde stock reaches 70–75% {11.

Oxidic cobaltmolybdenum-bismuth-iron catalysts, modified by addition of an oxide compound of one or more alkali metal metals, are also known to oxidize propylene or isobutylene to o, {1-unsaturated aldehydes and acids. The conversion of the staples is 97-99%. The yield of acrolein or methylacrolein is 50-55% and 55-60%, respectively, the yield of acrylic acid is 28-3.0%, and methacrylic acid is 15-18% 2.

A common disadvantage of known catalysts is their low

selectivity in the oxidation of olefins to unsaturated aldehydes, not exceeding 60-75%, and a low yield of these. products (50-65%).

The closest to the proposed is an oxide magnesium-molybdenum-bismuth-iron catalyst for

10 oxidation of propylene or isobutylene to the corresponding unsaturated aldehydes and acids. At 380-420 ° C, the conversion of olefin reaches 96-99% when the output of acrolein is 50-55% and acry., Lovoic acid is 27-30% or methyl acryleine 50-60% and methacrylic acid 14-16% 3.

Disadvantage of this catalyst

20 is a low selectivity for unsaturated aldehyde (no more than 65%) and, as a result, its low yield (50-60%).

The purpose of the invention is to increase the catalyst selectivity.

This goal is achieved by the addition of alkali metal to the catalyst containing magnesium, molybdenum, bismuth, iron, and oxygen.

30 or a mixture of alkali metals and its

the composition corresponds to the empirical formula

MD "Mo 2 B 6 Fee,

where M is one or more alkali metals;

a 4-10;

b 0,2-2,0;

with 0.2-3.0;

d: 0, 5

X is the number of oxygen atoms corresponding to the number and valence of the metal atoms included in the catalyst

The proposed catalysts provide high conversion of propylene or isobutylene (92-95%). The selectivity of the formation of the corresponding unsaturated aldehyde is 80-90%. Moreover, their output reaches

70-75%. ..; -. /:::

Cataly 3 Ator is prepared in the following way. .

A finely milled molybdate pores or .11aram6 ammonium ammonium, molybdenum acid or molybdenum trioxide are added to a nitrated acidic solution of magnesium nitrate, rmmuth, iron, and one or more alkali metals (lithium; sodium, potassium, rubidium,

cesium) -; ... . -.

The catalyst can also be prepared by pouring out an aqueous solution of molybdate or paramolybdate, and ammonium with a; solvent; an aqueous solution of yttrate in magnesium; bismuth, iron, and one or more alkali metals (lithium, sodium, porridge, rubidium, cesium).

It is obvious in both of them that as salts or alkali metal compounds, oxides, hydroxides, carbonates, bicarbonates, organic salts, organic salts, oxalates, formates, etc. can be used. The mixture obtained by one of the methods is mixed thoroughly, dried to dryness under periodic stirring and calcined at 420

500 ° C .-: -.-. .;, - / .; :,; .

P and measures iV 21.2 p of ammonium paramolybdate are ground to powder and to it is added an aqueous solution containing 15.36 t of magnesium nitrate, 2.4 g a: bismuth zoate, 3.0 g iron nitrate and 0.035 g carb (ph.at potassium in 15 ml of water and 4 ml of concentrated nitric acid. The mixture is thoroughly mixed, dried to dryness at IO-120 C with occasional stirring and calcined at 450-480 C for 3 hours. The resulting catalyst is ground into powder, sifting through a sieve with a rum of 0.1-0.2 mm cells and tapped;

15 cm Md e MO 2 In about 5 Fe 0,7 5 in Catalyst load in flow

A stainless steel reactor with an internal diameter of 14 mm and pass a gas mixture containing, vol.%: isobutylene 8, air 72 and water vapor 20. At 390 ° C, and the duration of contact with 3 s isobutylene conversion is 92% with selectivity of formation methylarolein 80%, the yield of aldehyde 73.6%.

Example 2. 21.2 g of ammonium paramolybdate are dissolved in 30 ml of ditilated water and mixed with an aqueous solution containing 15.36 magnesium nitrate, 2.4 g bismuth nitrate, 3.0 g iron nitrate and 0.07 g potassium carbonate in 15 ml of water and 4 ml of concentrated nitric acid. The mixture is thoroughly stirred, dried to dryness at 110120 s with occasional stirring and calcined at 450-480 ° C for 3 hours. The resulting catalyst is ground to powder, sieved through a sieve with a size cells of 0.1-0.2 mmi are tableted.

3 Cm3Mo Mo ,,, Bit, e Feo ,, 5Ko, H Od ,,, the catalyst is loaded into a glass flow-free gradient-free reactor and the gas mixture containing about. % isobutylene 7 and air 93. At 3.95 ° C and a contact time of 1.5 with isobutylene conversion reaches 86% and with a selectivity of methyl acrolein formation of 84%, the aldehyde yield is 72%.

When a gas mixture containing 8% by volume of propylene and 92% by volume of air is passed over the same catalyst, at 395 ° C and a contact time of 3 s, the yield of a: cattle is 73% with an olefin conversion of 95%.

Example 3. The catalyst was prepared according to the method described in Example 2, but. use 0.35 g of potassium carbonate. Catalyst

MggMo Bio s is loaded into peaKTQp and the process is carried out under the conditions of Example 2 with a contact duration of 4 s. The isobutylene convex reaches 90%, the selectivity to meth-pakolane is 60%, the yield of aldehyde is 54%, and the yield of methacrylic acid is 12.%.

Example 4. The catalyst is th. T in the manner described in Example 2, but instead of potassium carbonate, 0.037 g of lithium carbonate is used. The MggMo B1O ,, 75 S catalyst is loaded into the reactor and the process is carried out under the conditions of Example 2 at 400 ° C and a contact duration of 4 s. The conversion of isobutylene reaches 81% with a selectivity of formation of methylacrolein 62%. The yield of aldehyde is 50%, methacrylic acid 8%. ,

Claims (1)

Claim A catalyst for the oxidation of olefins, including magnesium, molybdenum, bismuth, iron and oxygen, characterized in that, in order to increase the selectivity of the catalyst, it additionally contains an alkali metal or a mixture of alkali * metals and the composition of the catalyst corresponds to the empirical formula: , Μβό ^ ο ^ ΒίςΡβ ^ Οχ> M is an alkali metal or a mixture of alkali metals; a - 4-10 c - 0.2-2.0 s - 0.2-3.0 d - 0.05-0.5 x - the number of oxygen atoms corresponding to the number and valency of metal atoms that make up the catalyst.