Procedure for the production of alkyl carbonates

A process for the continuous preparation of dimethylcarbonate consisting essentially of:

• (a) feeding methanol, hydrochloric acid, carbon monoxide and oxygen into a reaction mixture containing a liquid mixture of methanol, dimethylcarbonate, water and a catalyst based on cuprous chloride;
• (b) removing a flow of vapours composed of methanol, water, dimethylcarbonate from the reaction mixture, said flow being present together with a gaseous flow containing carbon monoxide;
• and
• (c) recovering the vaporized water and dimethylcarbonate from the reaction mixture in a quantity substantially equal to that formed during the reaction and recycling the other components to the reaction environment;
• wherein the composition and volume of the liquid mixture, contained in the reaction mixture, are substantially kept constant over a period of time, with a concentration of methanol equal to or higher than 30% by weight and a concentration of water equal to or lower than 10% by weight in the mixture and wherein the hologenidric acid is fed in such quantities as to maintain in the catalyst a ratio of halogen/copper of about 1 and the productivity is higher than 20 grams of dialkyl carbonate per liter of reactor volume per hour, which remains substantially constant over an indefinite period of time.

A process of making dialkylcarbonates consisting essentially of:

• (a) dispersing a cuprous halide catalyst in a reaction medium comprising a C.sub.1 -C.sub.4 alcohol to obtain a dispersion;
• (b) reacting the dispersion with a mixture including CO and O.sub.2 in the presence of HX, where HX is hydrochloric acid, to obtain a dialkylcarbonate;
• (c) recovering the dialkylcarbonate wherein said dialkylcarbonate is dimethylcarbonate;
• wherein the amount of HX present is the amount necessary to maintain in the catalyst an overall ratio of X:Cu of about 1:1 and wherein said ratio is maintained by regulating the amount of said hydrochloric acid introduced into the reactor, and wherein the productivity is higher than 20 grams of dialkyl carbonate per liter of reactor volume per hour, which remains substantially constant over an indefinite period of time.