What are the chemical reactions for synthesizing methanol?

CO + 2H2 → CH3OH. When carbon dioxide is present among the reactants, it is converted into methanol through the following reaction: CO2 + H2 → CO + H2O. The overall reaction equation for these two steps is: CO2 + 3H2 → CH3OH + H2O. The side reactions that occur can be further divided into parallel side reactions and sequential side reactions. The parallel side reactions are: CO + 3 H2 → CH4 + H2O; 2CO + 2 H2 → CH4 + CO2; 4CO + 8 H2 → C4H9OH + 3 H2O; 2CO + 4 H2 → CH3OCH3 + H2O. When metals such as iron, cobalt, and nickel are present, reactions that produce carbon may also occur. The series of side reactions that occur in 2CO = CO2 + C are as follows: 2CH3OH = CH3OCH3 + H2O; CH3OH + nCO + 2nH2 = CnH2n+1; CH2OH + nH2O; CH3OH + nCO + 2(n–1)H2 = CnH2n+1; COOH + (n–1)H2O. The products of these side reactions can further undergo dehydration, condensation, acylation, or other reactions to yield by-products such as alkenes, esters, and similar compounds. When alkali compounds are present in the catalyst, these compounds are formed more rapidly. By-products not only consume raw materials but also affect the quality of methanol and the lifespan of the catalyst. In particular, the reaction that produces methane is a highly exothermic reaction, which makes it difficult to control the reaction temperature. Moreover, the methane produced does not condense along with the product; instead, it circulates within the circulation system, further compromising the chemical equilibrium and reaction rate of the main reaction. The main equations for synthesizing methanol from syngas (CO, CO2, and H2) are: CO + 2H2 = CH3OH, ΔH298℃ = -9018 kJ/mol; CO2 + 3H2 = CH3OH + H2O, ΔH298℃ = -4916 kJ/mol

1) Main reactions: CO + 2H2 = CH3OH + Q; CO2 + 3H2 = CH3OH + H2O + Q. (2) Side reactions: 2CO + 4H2 = CH3OCH3 + H2O + Q; CO + 3H2 = CH4 + H2O + Q; 4CO + 8H2 = C4H9OH + 3H2O + Q; CO2 + H2 = CO + H2O – Q; nCO + 2nH2 = (CH2)n + nH2O + Q

CO + 2H2 → CH3OH. When carbon dioxide is present among the reactants, it is converted into methanol through the following reaction: CO2 + H2 → CO + H2O. The overall reaction equation for these two steps is: CO2 + 3H2 → CH3OH + H2O. The side reactions that occur can be further divided into parallel side reactions and sequential side reactions. The parallel side reactions are: CO + 3 H2 → CH4 + H2O; 2CO + 2 H2 → CH4 + CO2; 4CO + 8 H2 → C4H9OH + 3 H2O; 2CO + 4 H2 → CH3OCH3 + H2O. When metals such as iron, cobalt, and nickel are present, reactions that produce carbon may also occur. The series of side reactions that occur for 2CO = CO2 + C are as follows: 2CH3OH = CH3OCH3 + H2O; CH3OH + nCO + 2nH2 = CnH2n; CH2OH + nH2O; CH3OH + nCO + 2(n – 1)H2 = CnH2n+1; COOH + (n – 1)H2O