Separation of gasoline vapor from nitrogen by hollow fiber composite membranes for VOC emission control

This study deals with removal of volatile organic compounds (VOCs) from nitrogen by membranes for emission control. Hollow fiber composite membranes comprising of a thin layer of poly(ether block amide) supported on microporous poly(vinylidene fluoride) substrate were prepared for this purpose. The membranes were initially examined for the removal of representative VOCs from binary VOC/nitrogen mixtures. Then the separation of actual gasoline vapors, with and without gasoline additives, from nitrogen using the composite hollow fiber membranes was investigated. The separation performance of the membranes at various operating conditions (e.g. feed composition, operating temperature) was evaluated. It was found that the hollow fiber composite membranes were effective for the recovery of gasoline vapors from nitrogen. At ambient temperature, an overall permeate VOC concentration as high as 95 wt% was obtained, and the overall VOC flux was in the range of (2–4) × 10−2 g/(m2 s). The composition profile of the recovered gasoline was different from the gasoline vapor in the feed gas, and blending reformulation may be needed for the recovered gasoline to meet certain volatility and octane ratings. The membrane was found to be stable for gasoline vapor recovery during a 10-month period of testing.