Patent ID: 7314947

Claim:
A process for the production of dimethyl carbonate comprising the steps of: (a) feeding a stream containing urea, methanol, water and ammonium carbamate to a first distillation column reactor: (b) concurrently in said first distillation column reactor, (i) reacting a portion of said urea with a portion of said methanol to produce methyl carbamate, (ii) reacting water with urea to form ammonium carbamate, (iii) decomposing the ammonium carbamate in the feed and the ammonium carbamate from the reaction of water with urea into ammonia and carbon dioxide, and (iv) separating the ammonia, carbon monoxide and methanol from the urea and methyl carbamate by distillation; (c) removing ammonia, carbon dioxide and methanol from said first distillation column reactor as a first overheads; (d) removing urea and methyl carbamate from said distillation column reactor as a first bottoms; (e) feeding said first bottoms and methanol to a second distillation column reactor; (f) concurrently in said second distillation column reactor, (i) reacting methanol and urea in the presence of a homogeneous catalyst comprising an organotin complex compound of dialkylmethoxide in a high boiling solvent to form dimethyl carbonate and (ii) separating dimethyl carbonate and ammonia from the homogeneous catalyst by distillation; (g) removing dimethyl carbonate and methanol from said second distillation column reactor as a second overheads; (h) removing homogeneous catalyst from said second distillation column reactor as a second bottoms; (i) separating the dimethyl carbonate from the methanol in said second overheads by extractive distillation; and (j) feeding a first portion of said second bottoms to said first distillation column reactor; (k) feeding a second portion of said second bottoms to a third distillation column reactor where the catalyst is regenerated and cleaned up of heavies; and (l) recycling a third portion of said second bottoms to said second distillation column reactor.