Process for the epoxidation of propene

A process for the epoxidation of propene by continuously reacting propene with hydrogen peroxide in a methanol solvent and in the presence of a shaped titanium silicalite catalyst;

• wherein:
• a) the reaction is in a tube bundle reactor comprising a multitude of parallel reaction tubes and a cooling jacket enclosing the reaction tubes;
• b) the catalyst is arranged as a fixed bed in the reaction tubes;
• c) the molar ratio of propene to hydrogen peroxide is in the range of from 2.5:1 to 6:1 at full load of the reactor;
• d) during start-up of the reaction with a fresh or a regenerated catalyst until full load of the reactor is reached:
• i) cooling medium is fed to the cooling jacket at a constant rate for full load of the reactor, the entry temperature of the cooling medium being kept essentially constant at a value in the range of from 20° C. to 50° C.;
• ii) methanol solvent is fed to the reaction tubes at a feeding rate of from 50 to 100% of a feeding rate for full load of the reactor;
• iii) hydrogen peroxide is fed to the reaction tubes at a feeding rate that starts with no more than 10% of a feeding rate for full load of the reactor and is increased continuously or stepwise to the rate for full load of the reactor, increasing the feeding rate for hydrogen peroxide to maintain a maximum temperature in the fixed bed of no more than 60° C. and a temperature difference between the maximum temperature in the fixed bed and the cooling medium entry temperature of no more than 20° C.;
• and
• iv) propene is fed to the reaction tubes at a feeding rate of from 20 to 100% of a feeding rate for full load of the reactor, increasing the feeding rate for propene when the molar ratio of propene to hydrogen peroxide reaches the molar ratio for full load of the reactor.