Separation of Hydrocarbon Gas Mixtures

Shortly after World War 1, activated carbon was employed to recover gasoline from natural gas. The plants were operated manually 

Although many aspects of a solvent-vapor system apply to gasoline recovery, there are some fundamental differences. The recovery of a solvent is a relatively simple process in which an adsorbable vapor is removed from non-adsorbable air whereas the recovery of gasoline involves a selective separation of ingredients that are more adsorbable from ingredients that are less adsorbable. Because of this, the arrangement and design of the equipment and the operational procedure must be modified to fit the needs of the individual operation. The operation can be adjusted to include the recovery of propane, butane, pentane. 

The recovery plants include a desiccant to dry the gas and prevent the formation of hydrate in the transmission lines. The desiccant is used in the same adsorber with the carbon on the inlet side or two adsorbers are used in series, one containing the desiccant and the other, activated carbon. The desiccant also adsorbs the higher-boiling-point hydrocarbons so that the total adsorption is a combined effect of the two. Operating cycles are fairly fast, the adsorption period varying from 20 to 45 minutes. 

Studies have been made of continuous systems. In the hypersorption process, a vertical column contains a bed of carbon that continuously moves downward. Raw gas enters at a point midway in the column. As the smaller hydrocarbon molecules are less adsorbable they flow upward to be collected and recovered at the top of the column whereas the larger hydrocarbon molecules are adsorbed and are carried with the carbon to the discharge at the bottom. The adsorbed hydrocarbons are recovered at a heating station and the denuded carbon is returned to the top of the column to repeat the cycle.25 

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Centeno TA, Fuertes AB (2001) Carbon molecular sieve membranes derived from a phenolic resin supported on porous ceramic tubes. Sep Purif Technol 25 (1-3) 379-384 Fuertes AB, Menendez 1 (2002) Separation of hydrocarbon gas mixtures using phenolic resin-based carbon membranes. Sep Purif Technol 28 (1) 29-41... 

Euertes AB, Menendez I (2002) Separation of hydrocarbon gas mixtures using phenolic resin-based earbon membranes. Sep Purif Tech 28 (1) 29-41... 

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