DE926245C - Catalyst for the oxidation of olefins and process for their production - Google Patents

Description

Catalyst for the oxidation of olefins and process for their Manufacturing The invention relates to a catalyst used for the oxidation of olefins is very useful for the production of the corresponding unsaturated aldehydes, and it also includes the method of making the catalyst.

For the oxidation of olefins by means of molecular oxygen metal selenites and metal tellurites have already been proposed as catalysts, whereby copper oxide is also used as a stimulator and stabilizer for the mentioned catalysts has been. However, the effect of these catalysts is small and in the course of time limited, and the yields of unsaturated aldehydes achieved are unsatisfactory.

It has now been found that in such an oxidation process the best results in terms of the duration of the action of the catalyst and the yield of unsaturated aldehydes when a catalyst is used which consists of copper oxide distributed on silica gel as a carrier.

The subject of patent 877 450 is a method of manufacture of acrolein and methacrolein by the oxidation of propylene and isobutylene, respectively. This The process essentially consists in using a mixture of propylene or isobutylene and molecular oxygen-containing gases at elevated temperature over a such a catalyst is passed and the oxidation caused thereby obtained unsaturated aldehydes (acrolein or methacrolein) from the reaction mixture to be deposited.

This procedure can be carried out in a number of ways. In each case, however, the effect of the new catalyst was satisfactory and the effect significantly superior to the catalysts used so far.

This finding is surprising since the oxidation process when it under otherwise identical conditions, but using, for example, Pumice stone or asbestos as a carrier for the copper oxide is carried out to a almost complete combustion, for example of propylene to carbon dioxide and leads to the production of only very small amounts of the desired oxidation product.

The preparation of those particularly suitable for the process mentioned According to the invention, catalysts can be carried out, for example, in such a way that silica gel, preferably in granular form, impregnated with a copper nitrate solution, the mixture is dried and then annealed by slowly increasing the temperature to about 450 ° and held at this temperature for the required time. Will be expedient a stream of nitrogen or air is used to remove the nitrous Remove fumes. The cooled silica gel-cupric oxide mixture obtained in this way can be used directly as a contact material for the above-mentioned oxidation process will. However, the silica gel-cupric oxide mixture obtained by annealing to 450 "is useful a certain time, for example 1 to 2 hours, before it is used about 600 ", which can improve its effect. This effect can be increased even further if the catalyst is combined with elemental Selenium is used, which either precedes the copper oxide-silica gel catalyst or is switched alongside and the gas mixture to be processed then in its entirety or partly via the selenium heated to the desired temperature is sent away, before it is heated above the reaction temperature described and to the required temperature Copper oxide catalyst is passed away.

Example I Granular silica gel was heated to 200 " and then with an excess of a boiling mixture of 40 parts by weight: water and 100 parts of Cu (NO3) 2 .3 3 H20 added. The free liquid then became Poured off as much as possible and dried the mixture at 1000. It then became heated in an electric furnace while air is passed through, with the temperature was gradually increased to 450 "within 1112 hours.

The catalyst obtained in this way can be used directly or with concomitant use used by selenium for the oxidation reaction in question and causes high rates of conversion of the processed olefin to the corresponding one Aldehyde.

The reaction temperatures are between about 250 and 3500.

Example 2 It became a. ' Contact material made as in Example I, but after the decomposition of the copper nitrate at 450 "it was another 1 hour at 600" heated.

The -Catalyst obtained in this way can be used directly or with concomitant use of selenium can be used for the oxidation reaction in question.

Claims (3)

PATENT CLAIMS: I. Catalyst for the oxidation of olefins too unsaturated aldehydes by means of molecular oxygen, characterized that it consists of copper oxide distributed on silica gel as a carrier. 2. Catalyst according to claim I, characterized in that it is pre- or additionally contains metallic selenium. 3. Process for the preparation of the catalyst according to claim I, characterized characterized in that silica gel, preferably in granular form, with a solution a copper salt that can be decomposed into copper oxide, preferably a copper nitrate solution, soaked, the mixture dried and then heated to about 450 "for so long Annealing is carried out until the copper salt has been converted into copper oxide, whereupon the obtained silica gel-copper oxide mixture possibly for some time about 600 "is heated.