110th Anniversary: Characterization of a Condensing CO2 to Methanol Reactor

A novel condensing reactor for conversion of CO2 to methanol is characterized under forced convective conditions, both experimentally and by modeling. The goal of the study is to optimize the operation conditions and identify limitations of the reactor concept. Experimental results show that productivity is limited by reaction equilibrium and mass transport at high temperature (>250 °C), while reaction kinetics limit productivity at low temperature (<220 °C). Further analysis of the liquid out/gas in concept is performed by an adiabatic 1D-reactor model in combination with an equilibrium flash condenser model. To enable autothermal operation, internal heat exchange is required. It was found that a condenser temperature below 70 °C is required to avoid excessive heat exchange areas. Increasing the length of the catalyst section, and with this the overall reactor size, will increase the conversion per pass, until equilibrium is reached. On the other hand, the internal recycle ratio is decreased and thus less heat exchange and condenser area is required, decreasing overall reactor size. With the model developed, overall reactor performance can be optimized by finding the most optimal combination of reactor and condenser conditions in the recycle system.