Catalytic valorization of C1-C4 alcohols: an integrated comparative analysis and future perspectives

초록

As the global transition toward carbon neutrality and a sustainable chemical economy accelerates, technologies converting biomass- and diverse carbon-source-derived C1-C4 lower alcohols into high-value fuels and chemical feedstocks play a pivotal role. Although conversion technologies for individual alcohols are well established, a unified framework for comparing catalytic valorization pathways across the C1-C4 spectrum has yet to be clearly defined. This review critically examines the impact of the carbon chain length and structural characteristics of feedstock alcohols on reaction mechanisms and catalyst design. For methanol (C1), which lacks C-C bonds, an indirect C-C bond-forming pathway via the Hydrocarbon Pool (HCP) mechanism within zeolite catalysts (e.g., HZSM-5, SAPO-34) predominates, where pore architecture governs product selectivity. In contrast, C2+ alcohols inherently possess C-C bonds and undergo direct chain growth via Guerbet condensation or dehydrationoligomerization pathways. Specifically for propanol (C3) and butanol (C4), steric hindrance and isomeric structures (iso- vs. n-) significantly determine pathway selectivity and catalyst deactivation. Furthermore, this review provides an in-depth analysis of universal catalyst deactivation issues, including coke deposition, hydrothermal degradation, and active site poisoning. To mitigate these challenges, advanced catalytic engineering strategies are presented, including hierarchical porous structures, nanocrystallization, precise modulation of active sites, and hybrid catalyst design. Conclusively, this review presents a unified catalytic overview by systematically contrasting the indirect HCP-mediated C1 pathways with the direct chain-growth mechanisms of C2+ alcohols, providing a strategic roadmap for engineering structure-optimized catalysts that overcome universal deactivation barriers in next-generation valorization technologies.

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