Investigating influential effect of methanol-phenol-steam mixture on hydrogen production through thermodynamic analysis with experimental evaluation

Abstract

Thermodynamic analysis for methanol-phenol mixture steam reforming (M-PSR) for H2 production together with experimental evaluation has been carried out in this study. Firstly, a number of possible reactions were evaluated using Gibbs free energy and equilibrium rate constants to determine its feasibility and nature over the temperature of 100 to 1200°C. Then, the Gibbs free energy minimization method was used to carry out the thermodynamic analysis of the M-PSR system. A comprehensive thermodynamic analysis was used to study the effect of different parameters on product distribution. Temperature is an important parameter that significantly affects product distribution. Within the range of 100 to 400°C, a high CH4 production was obtained due to phenol decomposition and methanol methanation reaction. With further increase in temperature in the range of 300 to 600°C the CH4 production was dropped drastically, where in the reforming reactions, reverse methanation reactions gradually produce CO2 gas. However, as the temperature rises beyond 600°C, the predominant reactions for the M-PSR reaction for H2 production include the phenol steam reforming and methanol steam reforming reactions, where there is an obvious increase in H2 evolution. The feed ratio also affects H2 production, where a high steam feed is beneficial for the reforming reaction, and at the same time, it suppresses the formation of carbon species. Low pressure is also favourable for the M-PSR H2 production, which is in accordance with Le-Chatelier's principle. The optimum operating parameters were determined to be; the temperature of 700°C, atmospheric pressure and methanol-phenol-steam feed molar ratio of 0.1:0.9:20, where H2 production is maximized with minimal side products (CO, CO2, CH4) and coke formation. The comparative analysis of thermodynamics with phenol steam reforming and methanol steam reforming experimental studies complement current thermodynamic results. This research elucidates that thermodynamics analysis using the Gibbs free energy minimization method is immensely helpful in providing insight into the complexity of methanol-phenol steam reforming reaction.