A system and method for removing sulfur contaminants from an air stream prior to feeding the air stream to an autothermal reformer. The system includes an air inlet, a first desulfurization reactor, and the autothermal reformer. The air inlet is adapted to allow atmospheric air to enter therethrough to form the air stream. The first desulfurization reactor includes a first fixed bed. The first fixed bed includes one or more metal oxides adapted to remove sulfur dioxide from the air stream to create a desulfurized air stream. The sulfur dioxide is removed from the air stream as the air stream moves through the first desulfurization reactor. The autothermal reformer is adapted to receive the desulfurized air stream and a desulfurized natural gas/steam stream and convert the received desulfurized air stream and the received desulfurized natural gas/steam stream into a synthesis gas stream substantially free of sulfur contaminants.