Method for producing methylamines in the gas phase with improved control of the reactor inlet temperature

Abstract

The invention relates to a process for producing methylamines by a gas phase reaction of methanol and ammonia as reactants, which is exothermic overall, in the presence of a heterogeneous catalyst at a pressure in the range from 15 to 35 bar. The reactants are evaporated in one or more heat exchangers and superheated before being fed to the reactor, where the heat exchangers are heated in turn with the hotter product gas stream from the reactor. In addition to methylamines (monomethylamine, dimethylamine and trimethylamine), the product gas stream also comprises unconverted reactants, water and any other reaction by-products. In order to control and limit the reactor inlet temperature to a temperature in the range from 350° C. to 410° C., a suitable quench liquid is introduced into the hot product gas stream before it is fed to the heat exchangers for the heating of the reactants. Evaporation and superheating of the added quench liquid removes the corresponding amount of energy is extracted from the hot product gas stream, as a result of which it is cooled efficiently and quickly. As a result, the temperature differential between the cold and hot sides of the heat exchangers is smaller, which means that less energy is transferred to the reactant stream and hence the reactor inlet temperature thereof can be adjusted or limited.

Dependencies are inferred from the claim text.