Effect of Potassium on the Regulation of C1 Intermediates in Isobutyl Alcohol Synthesis from Syngas over CuLaZrO2 Catalysts

The important role of alkali additives in the CO hydrogenation process is related to their high promotion effect. However, the wide application of alkali additives does not reflect a thorough understanding of the mechanism of their promotional abilities. Here, we have investigated the effect of potassium (K) on the isobutyl alcohol formation over CuLaZrO2 catalysts. It was found that K addition had a great effect on the C-C chain growth in spite of the occurrences of decreased surface area and increased CuO reduction temperature. Probe molecule experiments and in situ diffuse reflectance infrared Fourier transform spectroscopy revealed that K addition enhanced the formation of C-1 intermediates needed for isobutyl alcohol synthesis under high reaction temperature. Among the adsorbed species, bicarbonate species showed moderate adsorption intensity and benefitted from isobutyl alcohol synthesis. Meanwhile, K addition promoted the adsorption of linear CO, which was considered as another important intermediate for alcohols synthesis, thus accelerating the C-C chain growth.