We present a comprehensive mean-field microkinetic model for the methanol synthesis and water-gas-shift (WGS) reactions that includes novel reaction intermediates, such as formic acid (HCOOH) and hydroxymethoxy (CH3O2) and allows for the formation of formic acid (HCOOH), formaldehyde (CH2O), and methyl formate (HCOOCH3) as byproducts. All input model parameters were initially derived from periodic, self-consistent, GGA-PW91 density functional theory calculations on the Cu(111) surface and subsequently fitted to published experimental methanol synthesis rate data, which were collected under realistic conditions on a commercial Cu/ZnO/Al2O3 catalyst. We find that the WGS reaction follows the carboxyl (COOH)-mediated path and that both CO and CO2 hydrogenation pathways are active for methanol synthesis. Under typical industrial methanol synthesis conditions, CO2 hydrogenation is responsible for ∼2/3 of the methanol produced. The intermediates of the CO2 pathway for methanol synthesis include HCOO*, HCOOH*, C...

Mechanism of Methanol Synthesis on Cu through CO2 and CO Hydrogenation

FTIR Study of the Adsorption of Methanol on Clean and Ca-Promoted Pd/SiO2 Catalysts

Forty years of applied catalysis research at Xiamen University and its interaction with fundamental catalysis research

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). 

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

Effects of small amounts of formic acid and/or CO 2 on methanol yield in CO hydrogenation to methanol over Cu/ZnO, Cu/ZrO 2 , and Cu/MgO catalysts and the in-situ FT-IR spectra of the chemisorbed species have been investigated. Formate adspecies appears to be a chemisorbed intermediate in CO hydrogenation to methanol over the three copper-based catalysts; CO hydrogenation over Cu/MgO is inhibited by even very small proportion of CO 2 ; over Cu/ZnO, the inhibit on by CO 2 becomes apparent at slightly higher CO 2 proportion, while over Cu/ZrO 2 it is unaffected by small amounts of CO 2 . The inhibition is probably due to carbonation of the basic MgO site and the slightly basic ZnO site. The nature of the active site and mechanism of synergistic catalysis in CO hydrogenation to methanol over copper-based catalysts is discussed.

H. Chen

Papers

Effects of Formic Acid and CO2 in CO Hydrogenation to Methanol Over Copper-Based Catalysts and Nature of Active Sites