Isobutanol synthesis from syngas over K–Cu/ZrO2–La2O3(x) catalysts: Effect of La-loading

• Cu/ZrO2 catalysts promoted by K have good performance for isobutanol synthesis.
• Addition of La facilitates the dispersion of CuO and improves Cu–Zr interaction.
• Under relative low reaction temperature and high H2/CO ratio (2.5), high selectivity of isobutanol (32.8%) is obtained.

A series of K–Cu/ZrO2 catalysts with different La loadings for isobutanol synthesis from CO hydrogenation were prepared by a co-precipitation method. The catalysts were characterized by XRD, reactive N2O adsorption, XPS, H2-TPR, in situ IR and Raman techniques, and then tested for isobutanol synthesis from CO hydrogenation at the conditions of 360 °C, 10.0 MPa, GHSV = 3000 h−1 and H2/CO = 2.5. These characterization results showed that incorporation of La into the K/Cu–Zr catalyst resulted in increase of BET surface area and dispersion of catalyst particles. Especially, medium La addition facilitated the synergistic effect between Cu–Zr interactions, improved the reducibility of catalyst and increased the amounts of dispersed copper. An enrichment of C1 intermediates on catalyst surface related to high dispersed CuO is better for chain growth. In the isobutanol synthesis reaction, the conversion of CO and selectivity of isobutanol increased first and then decreased as the increase of La concentration. Among these La-promoted K/Cu–Zr catalysts, the 3% La/Cu/Zr catalyst exhibited the highest alcohol selectivity of 32.8 wt%, which can be radically attributed to the highest Cu surface area.

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