Method of producing high-concentration alkyl carbonates using carbon dioxide as feedstock

摘要

Two methods of producing high purity dimethyl carbonate through the reaction of carbon dioxide and methanol are provided. In the ammonia-based method ammonia and carbon dioxide react to produce urea. The urea is mixed with methanol for further reaction to produce dimethyl carbonate. Ammonia released in the process is recycled as a reactant to produce more urea. In the ethylene-oxide process carbon dioxide reacts with ethylene oxide to produce ethylene carbonate. It is then reacted with methanol to produce dimethyl carbonate with ethylene glycol as byproduct. An integrated reactive distillation process using side reactors is used for facilitating catalytic reaction in these two methods for producing high purity dimethyl carbonate. The process is further enhanced by enclosing multiple side reactors into a pressure vessel and incorporating thermal heat pump for recovery and reuse of latent heat within the process.

主权项

1. A method of producing a concentrated dimethyl carbonate composition and an ethylene glycol byproduct including the steps of:
(a) reacting carbon dioxide and ethylene oxide in a reaction chamber to produce an ethylene carbonate composition; (b) charging at least a first a methanol side reactor with said ethylene carbonate composition to produce a composition containing dimethyl carbonate, ethylene glycol, unreacted methanol and ethylene carbonate; (c) inserting said composition into a distillation column in an upper section thereof said distillation column being divided into a plurality of descending sections; (d) removing a portion of dimethyl carbonate and unreacted methanol from the upper section of said distillation column; (e) purifying said dimethyl carbonate and unreacted methanol composition to produce a dimethyl carbonate rich composition whereby said dimethyl carbonate and unreacted methanol compositions are separated into a dimethyl carbonate rich composition and a methanol rich composition; (f) returning said dimethyl carbonate rich composition to said distillation column; (g) charging at least a second methanol side reactor with said methanol rich composition to produce a further dimethyl carbonate rich composition; (h) inserting said further dimethyl carbonate rich composition into said distillation column into a section of said distillation column below said upper section: (i) removing the purified dimethyl carbonate composition from said upper section of said distillation column; (j) accumulating ethylene glycol and ethylene carbonate in a lower section of said distillation column; (k) purifying said ethylene glycol and unreacted ethylene carbonate in reboilers for insertion into said distillation column to produce an ethylene glycol rich composition by vaporizing dimethyl carbonate and methanol; and (l) recovering latent heat from vapor condensation in at least one overhead condenser and upgrading by using a thermal heat pump for reuse in the distillation process.