SBIR Phase I: Synergistic Combinations of New Materials&Systems for Scalable Desulfurization of Distributed Biogas Resources

This Small Business Innovation Research Phase I project proposes a fundamentally new means for biogas (landfill gas) desulfurization that produces less waste, allows recycle of recovered sulfur, and provides annualized operating costs a fraction of current practice. Inexpensive biogas cleanup is required for subsequent combustion, fuel cell usage, or conversion to liquid fuels. The costs of gas clean up and spent sorbent disposal currently dictate the cost of biogas conversion to clean energy. The proposed two-stage process is a synergistic combination of: a novel Oxidative Sulfur Removal (OSR) catalyst formulation producing elemental sulfur; a wide temperature range regenerable downstream polishing sorbent; and a unique in situ sensor permitting optimal adsorbent bed operation and cycling. Current technology produces 125 tons of spent adsorbent for a 500kWe biogas combustor. Ironically, this adsorbent must be landfilled. The proposed process could reduce adsorbent waste 7-20 times and yields elemental sulfur that can be recycled into the fertilizer industry. The OSR catalyst is anticipated to be contaminant-tolerant in practice. Major innovations of the proposed approach include: long-life OSR catalyst, high selectivity to elemental sulfur, high activity and low-cost catalyst, real-time in situ adsorbent capacity monitoring to maximize material utilization and further reduce costs. The broader impact/commercial potential of this project includes the greatly enhanced ability to utilize biogas for alternative and renewable energy production facilities with significantly reduced carbon and waste footprints and process costs. The proposed process is thermodynamically efficient and readily scalable to a variety of locations and capacities. The proposed process has the ability to remove sulfur contaminants to very low levels thereby enabling catalytic conversion of biogas to higher value liquid fuels and chemicals. Recovered elemental sulfur can be utilized directly as a fertilizer additive. In short, the proposed innovation permits biogas desulfurization and subsequent usage in a more economic and environmentally friendly manner than current approaches. The proposed process is also capable of cleaning biogas and other gas sources with high sulfur contents (ca. 1-3%) without a significant increase in process costs. Besides biogas, other gas streams including natural gas, frac gas, petroleum gas, and syngas from a variety of sources can be desulfurized. Therefore, BTL, CTL, GTL, and renewable electric power generation can be impacted by the success of this innovation.