Hydrogen from hydrogen sulfide: towards a more sustainable hydrogen economy

The decomposition of hydrogen sulfide (H2S) with simultaneous hydrogen (H2) generation offers a sustainable energy production option and an environmental pollution abatement strategy. H2S is both naturally occurring and human-made. In the future, H2S production is expected to increase due to increased heavy oil refining. Currently, H2S is largely converted to sulfur and water using industrial processes such as the Claus process, however, it would be more useful and economical to convert H2S to sulfur and H2 instead. H2 currently comes from the steam reforming of natural gas, which is an energy-intensive process. Because H2 is a valued commodity and global consumption is expected to increase, alternative sources of H2 and hydrogen conservation have become topics of active research. Alberta is an especially large consumer of H2 due to its oil sands processing. H2 from petroleum-based H2S sources could be reused in petroleum upgrading, as a partial replacement of steam methane reforming. This review paper highlights some of the methods of H2S utilization, such as partial oxidation, reformation and decomposition techniques and approaches that convert H2S to sulfur, water and, more importantly, H2. To date, almost no technologies exist that are suitable for converting H2S to sulfur and H2 for industrial-scale applications. Here, we survey the literature to identify the most promising approach.