Experimental and kinetic study of methanol reforming and methanol-syngas co-oxidation at high pressure

Abstract

Using engine exhaust heat to partially convert methanol to syngas and then co-combust is a favored strategy to optimize combustion in methanol engines. In the present work, experiments of methanol pyrolysis and methanol-syngas oxidation were conducted using flow reactors at 1.0–5.0 MPa. The substitution ratio of syngas to methanol varied from 0 to 50%. Experimental results show that high pressure slightly promotes methanol pyrolysis and reduces CH2O generation; syngas inhibits methanol oxidation and reduces CH2O generation. Otherwise, experimental results were used to validate the recently published methanol model, and Mech15.34 captures the experimental data well. The kinetic analysis revealed the effects of substitution ratio on methanol-syngas co-oxidation can be divided into dilution and chemical effects. The dilution effect refers to the reduction of methanol, which directly decreases the CH2O generation. The chemical effect refers to the competition of H2 and CO for OH radicals, which decelerates the CH3OH oxidation. Meanwhile, the reaction H2O2 + H = H2 + HO2 proceeds in reverse direction with H2 blending, generating more H radicals, which enhances the CH2O consumption through the reaction CH2O + H = HCO + H2.