Process for the epoxidation of an olefin
In a process for the epoxidation of an olefin by continuously reacting the olefin with hydrogen peroxide in a methanol solvent on a fixed bed epoxidation catalyst comprising a titanium zeolite, the hydrogen peroxide is used as an aqueous hydrogen peroxide solution made by an anthraquinone process, the aqueous hydrogen peroxide solution is mixed with methanol to give a feed mixture and this feed mixture is filtered before being contacted with the fixed bed epoxidation catalyst.
1. A process for the epoxidation of an olefin by continuously reacting the olefin with hydrogen peroxide in a methanol solvent on a fixed bed epoxidation catalyst comprising a titanium zeolite, wherein:
a) hydrogen peroxide is used as an aqueous hydrogen peroxide solution made by an anthraquinone process;
b) the aqueous hydrogen peroxide solution is mixed with methanol to give a feed mixture; and
c) said feed mixture is filtered before being contacted with the fixed bed epoxidation catalyst.
2. The process of claim 1 , wherein the aqueous hydrogen peroxide solution is mixed with at least 50% of the methanol used for reacting the olefin with hydrogen peroxide.
3. The process of claim 1 , wherein the feed mixture is filtered through a filter medium having an average pore size of from 0.1 to 50 μm.
4. The process of claim 1 , wherein the filter medium is selected from aramid polymers, polyolefins, polyamides, fluorinated polymers and sintered metals.
5. The process of claim 1 , wherein the olefin is propene.
6. The process of claim 1 , wherein the filtered feed mixture is mixed with the olefin before being contacted with the fixed bed epoxidation catalyst.
7. The process of claim 1 , wherein the fixed bed epoxidation catalyst is placed in the tubes of a vertically arranged tube bundle reactor and the filtered feed mixture is distributed to the top of said tubes through orifices of a liquid distributor.
8. The process of claim 7 wherein the filtered feed mixture is combined with the olefin before being distributed to the top of the tubes.
9. The process of claim 7 , wherein the filtered feed mixture and the olefin are distributed to the top of said tubes through orifices of two separate liquid distributors.
10. The process of claim 1 , wherein the feed mixture is filtered with a filter comprising a filter medium and a gas separator upstream of said filter medium, and said gas separator is purged with an inert gas.
11. The process of claim 10 , wherein the filter comprises a temperature sensor, a pressure sensor and a safety valve connected with a dump vessel, and the safety valve is opened for emptying the filter when the temperature or the pressure in the filter exceeds a preset safety limit.