Separation of Hydrogen Sulfide and Hydrocarbons

As mentioned earlier, hydrogen sulfide is present in some natural gases as a non-combustible impurity. In addition, hydrogen sulfide is toxic. Therefore, the purpose of natural gas treatment which is best performed at the wellhead is to remove hydrogen sulfide along with carbon dioxide. 

Effect of temperature on separation performance of poly[bis(phcnoxy)phosphazene] membranes for removing carbon dioxide from methane 

Effect of temperature on permeability of hydrogen sulfide in a 10% H2S/CH4 gaseous mixture through various polyphosphazene membranes 

Note PPOP poly[bis(phenoxy)phosphazene] pressure 1.4 bars [Peterson et al., 1993] 

The permeability data in Table 7.10 and other data show that the polarity of the substituent group on the polymer backbone (such as poly[bis(phenoxy)phosphazene] or PPOP) has a significant impact on the membrane permeability. The more polar gas (i.e. S02) the more easily it permeates a polar polymer (i.e., m-F-PPOP) and a less polar gas (i.e., CO2) exhibits a lower permeability through a more polar membrane (i.e., SO3-PPOP). This seems to provide a vast opportunity for chemically designing an inorganic polymer membrane for a particular separation application [Peterson et al., 1993]. 

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