Catalytic conversion of H2S to H2: Challenges and Catalyst Limitations

H2S, a highly toxic chemical, is produced in massive quantities worldwide as a by-product. Environmental regulations require >99% sulfur recovery, which is currently met using sulfur recovery units based on the Claus process, where H2S is converted to sulfur and water. Ideally, hydrogen in H2S is recovered as H2. Despite much effort to achieve this objective, especially in thermal catalysis, an industrial application remains distant. A fundamental factor is the lack of an effective catalyst. In this work, we employ density functional theory (DFT) to illustrate the main limitations in existing catalysts. We use pure metals to explain this by studying the full elementary steps in H2S decomposition. We find that many catalysts, though capable of decomposing H2S, are limited due to sulfur poisoning. We conclude by outlining the ideal properties of a catalyst for this process.