A method and system for capturing hydrogen gas in a refinery is disclosed. The system comprises a first membrane and pre-reformer. The membrane is suitable for separating a refinery fuel gas feed, which includes hydrogen gas and hydrocarbon gases, into a hydrogen gas depleted retentate stream and a hydrogen gas enriched permeate stream. The pre-reformer receives the retentate stream from the first membrane and catalytically converts the retentate stream into an outlet stream of hydrogen and methane gases. The system may further include a reformer which receives at least a portion of the outlet stream and catalytically converts the methane gas into hydrogen and carbon oxides. A second membrane may be used for separating the outlet stream into a second hydrogen depleted retentate stream and second hydrogen enriched permeate stream. The reformer, in this case, receives the second hydrogen depleted retentate stream to provide methane for steam reforming. Because hydrogen is removed from the original refinery fuel gas feed fed to the pre-reformer and/or the outlet stream fed to the reformer, additional hydrocarbons can be fed to the pre-reformer and/or reformer, in place of the removed hydrogen gas, to increase the overall hydrogen gas production from the system.
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