Study of Temporal and Oscillatory Behavior during Methanol Synthesis Using a Cu/ZnO/Al2O3 (60:30:10) Catalyst

This paper reports, on marked deviations in the rate of CH3OH synthesis from the CO2/H2 feed over a Cu/ZnO/Al2O3 (60:30:10) catalyst observed using gas chromatographiy (GC) analysis of the product. The rate of Methanol synthesis over a Cu/ZnO/Al2O3 (60:30:10) catalyst has been measured using CO2/H2 (10:90) and CO/CO2/H2 (10:10:80) streams at 433,443,453, 463 and 473K. Using the CO2/H2 stream, it requires 12x103s to achieve steady state performance; this time reduces to 5.4x103s on increasing the temperature to 463K. Using the CO/CO2/H2 stream, steady State performance is not achieved even after 14.4x103s at 433K but is achieved after 9x103s at 463K. Significant deviations from steady state behavior (~40% of steady state) are observed only at 453K and only using the CO2/H2 feed when gas chromatography (GC) is the analysis system. Oscillations are observed when the reactor output is directly connected to a flame ionisation detector (FID) at all temperatures studied using a CO2/H2 stream. Injecting CO into the CO2/H2 stream that is synthesising methanol at 473K causes a sharp spike in the rate of methanol synthesis, followed by an oscillatory relaxation to steady state behaviour. At 433 and 443K the injection of CO into the CO2/H2 stream again produce the sharply spiked increase in the rater of methanol synthesis, which returns to the baseline value without oscillations.