Several methods are known for the separation of selected organics from gaseous mixtures, including cryogenic distillation, liquid adsorption, membrane separation and pressure swing adsorption. Of these methods, cryogenic distillation and liquid adsorption are most commonly known. However, cryogenic distillation is energy- intensive and is associated with high cost, while liquid separation methods for separation are not easily adaptable for commercial use. More recently, molecular sieve zeolites have been investigated to selectively adsorb carbon monoxide and hydrocarbons from gaseous mixtures. To date, these zeolites have shown only moderate capacity for recovery of the targeted compound, with limited selectivity for olefins.
Researchers at the University of Michigan have developed adsorbents for use in the separation of unsaturated hydrocarbons from a mixture of gases. The preferred adsorbents comprise of metal compounds, usually silver or copper, supported on high surface area carriers with a plurality of pores. These adsorbents are usable in pressure swing adsorption or temperature swing adsorption processes; when pressure and/or temperature is changed, the silver or copper compound releases the alkene-rich component from the adsorbent. The new adsorbents are very effective for selective adsorption of alkenes such as ethylene, propylene, and mixtures of these from gaseous mixtures.
Applications and Advantages
- Separation of selected organics from gaseous mixtures, in particular for separating olefins from paraffins
- More effective and economical process than prior methods
- Enhanced selectivity for alkenes