Significance and influence of various promoters on Cu‐based catalyst for synthesizing methanol from syngas: a critical review

Methanol synthesis from syngas is an effective method for producing fuel additives, oxygenated fuels, and other chemicals. Several promoted catalytic systems have been tested for the synthesis of methanol. Catalysts based on noble metals are extremely active in generating methanol from syngas. However, sintering, poisoning, and related expenses accounted for the switch to Cu‐based catalysts. The promotion of Cu‐based catalysts, even with small doses of an effective promoter, resulted in a considerable change in product selectivity. A suitable promoter is required for Cu‐based catalysts used in the synthesis of methanol because it significantly impacts the electronic, geometric, or acid/base surface properties, which in turn affect the catalyst's activity and selectivity. It also significantly impacts the interactions between the catalyst's active ingredients. However, the interactions between the active component and the promoter can be adjusted or influenced by appropriate support. The present paper primarily focuses on several promoters in the copper‐based catalyst for synthesizing methanol from syngas. We briefly deliberated on the need for copper‐based catalysts for methanol synthesis, their reaction and mechanism, the reasons for promoter addition concerning their role and influence, the importance of CO2 addition in feed synthesis gas and their impact on the catalyst. This paper mainly highlights the selectivity and activity of various promoted Cu‐based catalysts, although different reaction parameters are the cause of promotion and inhibition in the catalyst. The effects of reaction conditions, including pressure, temperature, gas hourly space velocity (GHSV), and syngas composition, are briefly reported. This paper also comprehensively compares the effects of adding various promoters in small amounts to copper‐based catalysts. This review intends to be illustrative rather than exhaustive. © 2023 Society of Chemical Industry (SCI).