Effects of a Real Syngas On PdCu-Alloy Hydrogen Separation Membranes

摘要

Gasification is generally recognized as a viable near-term approach for addressing national fuel security and economic sustainability concerns, while simultaneously addressing the control of greenhouse gas emissions. The gasification process can utilize a variety of carbon-based feed stocks such as coal and biomass to produce synthesis gas (syngas). Integrating a water-gas shift reactor with simultaneous hydrogen separation (a WGS membrane reactor) can enhance CO-conversion beyond that attainable in conventional reactors decreasing the necessity for multiple reactors, added catalysts, and large quantities of steam, while maximizing H2 yield and producing a highly concentrated, high pressure stream of carbon dioxide ready for co-sequestration. Dense metal membranes are a promising technology for the separation of H2 from these other product gases due to their high permeability and high selectivity for H2. However, impurities typically contained in coal derived syngas can have adverse effects on metal-based separation membranes. Sulfur compounds, particularly hydrogen sulfide, are probably the most detrimental to metal membrane technologies. H2S is well known to severely impact the performance of dense metal membranes. These effects include catalytic poisoning and corrosion which can result in severe performance degradation and mechanical failure. In laboratory studies, the effects of minor contaminants such as As and Se compounds are not often considered. Therefore, developing a thorough understanding of the effects of syngas constituents, especially H2S but including minor components, on metal membrane-based H2 separation membranes is imperative to facilitate the acceptance and deployment of membranes in gasification technoloqies.