Boosting CO2 hydrogenation efficiency for methanol synthesis over Pd/In2O3/ZrO2 catalysts by crystalline phase effect

The crystalline phases of support have great influence on their surface and structure properties. Therefore, adjusting the crystalline structure of heterogeneous catalysts imposes a significant impact on the catalytic performance. Herein, a suite of Pd/In 2 O 3 /ZrO 2 catalysts with different crystalline phases of ZrO 2 were prepared and evaluated for CO 2 hydrogenation to CH 3 OH using the same amount of metal loading. The activity data showed the distinct superior reactivity of Pd/In 2 O 3 /ZrO 2 catalyst used mixed monoclinic and tetragonal phases ZrO 2 (Mix-ZrO 2 ) as support as compared to respective single phase of monoclinic ZrO 2 (m-ZrO 2 ) and tetragonal ZrO 2 (t-ZrO 2 ). The catalysts are extensively characterized through BET, XRD, HRTEM, UV–vis, H 2 -TPR, CO 2 /H 2 -TPD and XPS. Combining the characterization results and activity data, the superior activity of Pd/In 2 O 3 /Mix-ZrO 2 catalyst can be correlated with large particle size of Pd nanoparticles, the concentration of oxygen vacancies, and the abundant medium basic sites, which were essential for activation of H 2 and inert CO 2 and enhancement of catalytic performance. The best-performing Pd/In 2 O 3 /Mix-ZrO 2 catalyst exhibited a remarkable reactivity with space time yield (STY) of 0.54 g methanol ·h −1 ·g cat −1 at 573 K and 5 MPa, and stability without noticeable deactivation after 100 h of time on stream, demonstrating its potential as catalyst used in CH 3 OH synthesis from CO 2 hydrogenation.