From gray to blue hydrogen: Trends and forecasts of catalysts and sorbents for unit process

Achieving Net Zero 2050 through decarbonization and securing next-generation clean energy have become the most important challenges. One of the pathways that make these possible is the paradigm shift to the hydrogen economy society. "Blue hydrogen" production controls CO2 emissions by applying carbon capture, utilization and storage (CCUS) technology to the existing gray hydrogen process. Performance improvement by identifying key performance-influencing factors of materials for each unit can be a valid approach to effectively solve the aforementioned issues. This review highlights the recent relevant research on materials applied to each unit process of blue hydrogen production (catalysts for reforming, water-gas shift, preferential oxidation, sorbents and oxygen carriers for desulfurization, pressure swing adsorption, CCUS) and deals with key performanceinfluencing factors and acceptable performance criteria for integration with CCUS. For desulfurization, PSA, and CCUS sorbents, maintaining pore structure is crucial. Performance can be improved by combining liquid and solid adsorbents, as well as using specific molecular sieves and porous supports. In reforming, water-gas shift, and preferential oxidation, achieving high metal dispersion is crucial. Enhancing metal-support interaction through proper support application prevents sintering and boosts catalytic performance.