Determination Of Gas-Liquid Mass Transfer Coefficient For Methanol Synthesis Under Supercritical Condition

Gas-liquid mass transfer coefficient for methanol synthesis was determined and laws for gas-liquid mass transfer coefficient was studied under the condition of different stirring speed in a mechanically agitated slurry reactor with paraffin oil as the inert liquid medium and n-hexane as the supercritical medium. The ratio of gas-liquid mass transfer resistance to reaction resistance increased with the increasing of catalyst concentration under the reaction condition of the temperature238℃, the syngas pressure3.7MPa, and the space velocity2744h-1. When gas-liquid mass transfer was the control step, the gas-liquid mass transfer coefficients were obtained with extrapolation method. The results show that the catalyst concentration has a much bigger effect on the gas-liquid mass transfer of CO than that of the CO2. The gas-liquid mass transfer coefficients of CO and CO2in the liquid-phase reaction were0.161s-1and0.030s-1respectively, while they were0.199s-1,0.042s-1under the supercritical condition. It indicates supercritical fluid is conductive to gas-liquid mass transfer in the three-phase methanol synthesis process. The decrease of gas-liquid mass transfer coefficient between supercritical reaction and liquid-phase reaction got smaller with the increasing of stirring speed, and supercritical fluid has a smaller effect on the gas-liquid mass transfer, the volumetric mass transfer coefficient was affected by stirring speed together with supercritical fluid.