Not all CO2 is equal: Source-specific constraints and viability trade-offs in methanol synthesis from industrial emissions

Methanol synthesis from captured CO 2 is widely regarded as a promising pathway for carbon utilization, yet its feasibility depends heavily on the characteristics and constraints of the CO 2 source. This review evaluates four industrial point sources—biogas, steel plants, cement kilns, and waste-to-energy facilities—highlighting key differences in CO 2 purity, contaminant load, hydrogen integration, and catalyst stability. We propose a five-axis viability framework, developed through a synthesis of current literature, to structure source-specific comparison and guide system-level evaluation. The framework includes CO 2 usability, hydrogen vulnerability, contaminant burden, integration potential, and policy exposure. By applying this structured lens, the review identifies key performance-limiting trade-offs, techno-economic constraints, and integration barriers across point sources. Results show that biogas and steel off-gases offer favourable trade-offs (scores of 15–18/25), while cement and waste-to-energy streams face major integration and degradation challenges (≤9/25). Reforming pathways, gas conditioning requirements and modular deployment considerations are also discussed. This review concludes that effective CO 2 -to-methanol deployment requires source-specific process design, improved contaminant-tolerant catalysts, and better alignment of infrastructure and policy to the heterogeneous nature of industrial CO 2 sources.