PROMOTED ZINC CHROMITE CATALYSTS FOR HIGHER ALCOHOL SYNTHESIS

During this reporting period, a ''zinc chromite'' catalyst promoted with 6 wt.% cesium (Cs) was evaluated at the following operating conditions: Temperature - 375 C and 400 C; Total Pressure--13.6 MPa (2000 psig); Gas Hourly Space Velocity (GHSV) - 5000 standard liters/kg(cat)-hr; and H{sub 2}/CO feed ratio--0.5, 1.0 and 2.0 mole/mole. Decahydronaphthalene (DHN) was used as the slurry liquid. The experiment lasted for twelve days of continuous operation. Unpromoted zinc chromite catalyst then was re-examined under the same operating conditions. Reproducible data was achieved with a continuous liquid make-up. Compared with unpromoted zinc chromite catalyst, 6 wt.% Cs-promoted catalyst shifted the product distribution from methanol to higher alcohols, even though methanol was still the major product. The effect of operating conditions was less important than the addition of promoter. However, it was observed that higher temperature favors higher alcohol synthesis, and that a higher H{sub 2}/CO ratio leads to lower oxygenates selectivity and higher hydrocarbons selectivity. These trends showed clearly with the Cs-promoted catalyst, but were not as prominent with the unpromoted catalyst. The slurry liquid did not decompose or alkylate to a measurable extent during either continuous, 12 - day experiment, even with the higher reactor temperature (400 C). There was a relatively significant loss of catalyst surface area during the experiment with the promoted catalyst, but not with the unpromoted catalyst