Characteristics of the Synthesis of Methanol Using Biomass-Derived Syngas

The characteristics of methanol synthesis from biomass-derived syngas were studied in a high-pressure microreactor with a commercial Cu/ZnO/Al2O3 catalyst. A series of experiments was conducted at a temperature range of 215−270 °C, with three different pressures of 2.6, 3.6, and 4.6 MPa and space velocities of 4000−12 000 h-1. Four model bio-syngases with different H2/CO/CO2/N2 ratios, which were configured according to the results of biomass gasification, were used in the studies. The effect of temperature, pressure, and space velocity on the space-time yield and selectivity of methanol was explored. The sensitivity analysis of the yield and selectivity of methanol with different H2/(CO + CO2) and CO2/CO ratios was investigated. Results show that both yield and selectivity of methanol are affected by the operating parameters, and optimum conditions exist within the tested range. The yield of methanol is sensitive to the H2/(CO + CO2) ratio, whereas the selectivity of methanol is more sensitive to the CO2/CO ratio. It is concluded that the yield of methanol from the syngas derived from air−steam gasification is lower than that from catalytic gasification, whereas the selectivity of methanol is the reverse. With a partial removal of CO2, both yield and selectivity of methanol can be improved.