Improvement strategies for Ni-based alcohol steam reforming catalysts

Steam reforming (SR) of fossil methane is already a well-known, documented and established expertise in the industrial sector as it accounts for the vast majority of the global hydrogen production. From a sustainable development perspective, hydrogen production by SR of biomass-derived feedstock represents a promising alternative that could help to lower the carbon footprint of the traditional process. In this regard, bio-alcohols such as methanol, ethanol or glycerol are among the attractive candidates that could serve as green hydrogen carriers as they decompose at relatively low temperatures in the presence of water compared to methane, allowing for improved H2 yields. However, significant challenges remain regarding the activity and stability of nickel-based catalysts, which are most widely used in alcohol SR processes due to their affordability and ability to break C–C, O–H and C–H bonds, yet are prone to rapid deactivation primarily caused by coke deposition and metal particle sintering. In this state-of-the-art review, a portfolio of strategies to improve the performance of Ni-based catalysts used in alcohol SR processes is unfolded with the intent of pinpointing the critical issues in catalyst development. Close examination of literature reveals that the efforts tackling these recurring issues can be directed at the active metal, either by tuning Ni dispersion and Ni-support interactions or by targeting synergistic effects in bimetallic systems, while others focus on the support, either by modifying acid-base character, oxygen mobility, or by embedding Ni in specific crystallographic structures. This review provides a very useful tool to orient future work in catalyst development.