An efficient catalyst for the production of isobutanol and methanol from syngas. XI. K- and Pd-promoted Zn/Cr/Mn spinel (excess ZnO)

A 2.25 wt% K‐ and 6.0 wt% Pd‐promoted Zn/Cr/Mn spinel (excess ZnO) higher alcohol synthesis (HAS) catalyst has been tested for the production of isobutanol and methanol at 440°C and 1500 psig. An isobutanol production rate of 179 g kg−1 h−1, a methanol‐to‐isobutanol mole ratio of 1.3 and a total alcohol rate of 304 g kg−1 h− are attained. This ratio is slightly higher than the desired value of 1.0 for MTBE production. These results are superior to others presented in the literature thus far. Surface characterization data indicate that the near‐surface region of the catalyst consists primarily of ZnO and K. Pretreating the catalyst in a reductive environment similar to that given to the catalyst before reaction tests, causes an enrichment of the K promoter at the surface. The product stream composition does not significantly change during five days of testing.