**Abstract**

Natural gas can contain significant amounts of impurifies, including CO2, H2S, N2, He, and C3+ hydrocarbons. These C3+ hydrocarbons are valuable chemical feedstocks and can be used as a liquid fuel for power generation. Membrane-based separation technologies have recently emerged as an economically favorable alternative due to reduced capital and operating cost. Polymeric membranes for the separation and removal of C3+ hydrocarbons from natural gas have been practiced in chemical and petrochemical industries. Therefore, these industries can benefit from membranes with improved C3+ hydrocarbon separation. This chapter overviews the different gas processing technologies for C3+ hydrocarbon separation and recovery from natural gas, highlighting the advantages, research and industrial needs, and challenges in developing highly efficient polymer-based membranes. More specifically, this chapter summarizes the removal of C3H8 and C4H10 from CH4 by prospective polymer architectures based on reverse-selective glassy polymers, rubbery polymers, and its hybrid mixed matrix membranes. In addition, the effect of testing conditions and gas compositions on the membrane permeation properties (permeability and selectivity) is reviewed.

**Keywords:** glassy polymers, rubbery polymers, membrane separation, C3+ hydrocarbons, permeation property, C3+/CH4 separation
