Alkaline-Etched NiMgAl Trimetallic Oxide-Supported KMoS-Based Catalysts for Boosting Higher Alcohol Selectivity in CO Hydrogenation

The acidity/alkalinity and structural properties of NiMgAl trimetallic oxides (MMOs) can be effectively modulated by the alkaline-etching process with various etching times, which are further used as a support to prepare KMoS-based catalysts through the cetyltrimethylammonium bromide-encapsulated Mo-precursor strategy. The enriched surface anion groups in alkaline-etched MMO affect the textural properties, metal-support interaction, and sulfidation degree of the as-synthesized KMoS-based catalysts. As a result, KMoS-based catalysts using alkaline-etched MMO as supports effectively enhance the reducibility and dispersion of Mo species, which exert a positive influence on higher alcohol synthesis (HAS) performance in CO hydrogenation. A proper balance between acidity/alkalinity and structural properties in K, Mo/MMO-x catalysts can significantly enhance the alcohol selectivity in HAS from 55 to 65% (carbon selectivity). The formation of C₂⁺ alcohols can be boosted by adol condensation with optimal acidic/basic properties via suppressing the acidity and increasing the amount of basic sites. The alkaline-etching process also significantly improves the space time yield of C₂⁺ alcohols over unit mass of molybdenum.