BigPatents India

A process for the production of lower aliphatic esters said process comprising reacting ethylene, propylene or mixtures thereof with a saturated C1 to C4 aliphatic mono-carboxylic acid in the vapour phase in the presence of a heteropolyacid catalyst of the kind known, wherein the vapours of the reactant olefins and ac ids are passed over the catalyst at a GHSV in the range from 100 to 5000 per hour, the addition reaction is carried out at a temperature in the range from 150 to 200oC, and the reaction pressure is 400Kpa or more, depending upon the relative mole rations of olefin to acid reactant and the amo8nt of water used, characterised in that the reaction is carried out in a plurality of reactors set up in series such that the gases exiting from a first reactor are fed as the feed gas to a second reactor and those exiting from the second reactor are fed as the feed gas to a third reactor and so on for the subsequent reactors, and an aliquot of the reactant monocarboxylic acid is introduced into the feed gas to the second and subsequent reactors so as to maintain the olefin to monocarboxylic acid ratio in the feed gas to each of the second and subsequent reactors within a pre-determined range, and wherein the mole ratio of olefin to the lower monocarboxylic acid in the reactant gases fed to the first reactor is in the range from 1:1 to 18:1. (FIG.)nil