Removal of Carbon Dioxide from Process Streams

Removal of Carbon Dioxide from Process Streams 

Carbon dioxide is produced in petrochemical process streams by reactions with oxygenates (mainly oxygen or water). In steam cracking, hydrocarbons (e.g. methane) and carbon react with steam, forming initially carbon monoxide which is then converted into carbon dioxide by the water-gas-shift reaction  

Gases containing carbon dioxide enter the bottom of an absorption tower and ascend against the flow of a descending solvent which preferentially absorbs carbon dioxide. The cracked gases, devoid of carbon dioxide, exit the top of the column. The carbon dioxide rich solvent exits the bottom of the tower and is passed to a regenerating column where typically the solvent is boiled to expel the carbon dioxide and regenerate the solvent which is passed back to the absorption tower. 

Carbon dioxide is also produced as a by-product to oxidation processes. For example, as the by-product to the production of ethylene oxide by oxidation of ethylene with supported silver catalysts  

A similar process can be used to separate the carbon dioxide from unconverted ethylene and product. 

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