Method for preparing a dialkyl carbonate, and its use in the preparation of diaryl carbonates and polycarbonates
AssigneePolimeri Europa S.p.A.
InventorsDaniele Delledonne, Franco Rivetti, Eugene Boden, Ignacio Fernandez
Life of this patent
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Abstract
Unexpected corrosion of downstream sections of a dialkyl carbonate manufacturing apparatus has been traced to alkyl chloroformate impurities, which slowly decompose to yield hydrochloric acid. An improved process and apparatus for dialkyl carbonate synthesis reduce corrosion by physically removing or chemically decomposing the alkyl chloroformate impurities within the corrosion-resistant upstream sections of the apparatus.
Claims42
A method of preparing a dialkyl carbonate, comprising:
- reacting an alkanol, oxygen, carbon monoxide, and a catalyst to form a mixture comprising a dialkyl carbonate, an alkyl chloroformate, hydrochloric acid, water, carbon dioxide, and carbon monoxide;
- and removing alkyl chloroformate from said mixture.
A method of preparing a dialkyl carbonate, comprising:
- reacting an alkanol, oxygen, carbon monoxide, and a catalyst to form a mixture comprising a dialkyl carbonate, an alkyl chloroformate, hydrochloric acid, water, carbon dioxide, and carbon monoxide;
- reducing the concentration of said alkyl chloroformate in said mixture to less than about 500 parts per million by weight while removing less than about 10% of said dialkyl carbonate;
- and removing hydrochloric acid from said mixture.
A method of preparing a dialkyl carbonate, comprising:
- reacting an alkanol, oxygen, carbon monoxide, and a catalyst to form a first mixture comprising a dialkyl carbonate, an alkyl chloroformate, hydrochloric acid, water, carbon dioxide, and carbon monoxide;
- removing alkyl chloroformate from said first mixture to form a second mixture;
- and removing hydrochloric acid from said second mixture.
A method of preparing a dialkyl carbonate, comprising:
- reacting an alkanol, oxygen, carbon monoxide, and a catalyst to form a first mixture comprising a dialkyl carbonate, an alkyl chloroformate, hydrochloric acid, water, carbon dioxide, and carbon monoxide;
- removing hydrochloric acid from said first mixture to form a second mixture;
- and removing alkyl chloroformate from said second mixture.
A method of preparing dimethyl carbonate, comprising:
- combining methanol, oxygen, carbon monoxide, and a copper catalyst to form a first mixture comprising a vapor of dimethyl carbonate, a vapor of methyl chloroformate, hydrochloric acid, water, carbon dioxide, and carbon monoxide;
- removing a portion of said carbon dioxide and a portion of said carbon monoxide from said first mixture to form a second mixture;
- at least partially condensing said vapor of dialkyl carbonate and said vapor of alkyl chloroformate to form a third mixture;
- removing at least about 90% of said methyl chloroformate and less than about 1% of said dimethyl carbonate from said third mixture to form a fourth mixture;
- and removing hydrochloric acid from said fourth mixture.
Dependencies are inferred from the claim text.