Temporal and Oscillatory Behavior Observed during Methanol Synthesis on a Cu/ZnO/Al&sub&&span style="font-family:Verdana;"&2&/span&&/sub&&span style="font-family:Verdana;"&O&/span&&sub&&span style="font-family:Verdana;"&3&/span&&/sub&&span style="font-family:Verdana;"& (60:30:10) Catalyst

摘要

The rate of Methanol synthesis over a Cu/ZnO/Al_( 2 ) O _( 3 ) (60:30:10) catalyst has been measured using CO _( 2 ) /H _( 2 ) (10:90) and CO/CO _( 2 ) /H _( 2 ) (10:10:80) streams at 433, 443, 453, 463 and 473 K. Using the CO _( 2 ) /H _( 2 ) stream, it requires 12 × 10 ~( 3 ) s to achieve steady - state performance; this time reduces to 5.4 × 10 ~( 3 ) s on increasing the temperature to 463 K. Using the CO/CO _( 2 ) /H _( 2 ) stream, steady State performance is not achieved even after 14.4 × 10 ~( 3 ) s at 433 K but is achieved after 9 × 10 ~( 3 ) s at 463 K. Significant deviations from steady state behavior (~40% of steady state ) are observed only at 453 K and only using the CO _( 2 ) /H _( 2 ) feed when gas chromatography (GC) is the analysis system. When the reactor output is connected directly into a flame ionization detector (FID), oscillation is observed at all temperatures studied using a CO _( 2 ) /H _( 2 ) stream. Injection of CO into the CO _( 2 ) /H _( 2 ) stream, which is synthesizing methanol at 473 K, produces a sharply spiked increase in the rate of methanol synthesis followed by an oscillatory relaxation to steady state behavior. At 433 and 443 K , the injection of CO into the CO _( 2 ) /H _( 2 ) stream again produce s the sharply spiked increase in the rater of methanol synthesis, which returns to the baseline value without oscillations.