Innovative Carbon-Al2O3 Composite Supports for Catalysts in CO2-to-Methanol Hydrogenation

The increase in CO2 emissions contributes massively to the aggravation of climate change. The hydrogenation of CO2 to methanol is a possible approach for reducing this gas emissions by converting emitted CO2 into a value-added product. Therefore, the development of efficient catalysts for this reaction is fundamental. In this study, CuZn bimetallic catalysts supported on composites of AC-Al2O3 and CNT-Al2O3 were synthesized, and their catalytic performance was assessed. The catalytic experiments were conducted at 250 degrees C and 30 bar for 15 h, under a H-2:CO2 ratio of 3. The catalysts CuZn/AC-Al2O3 (50:50) and CuZn/AC-Al2O3 (70:30) demonstrated an overall improved catalytic performance when compared to the catalyst supported on pristine AC, indicating that the increased presence of mesopores and the synergistic effect between AC and Al2O3 are beneficial. The catalyst CuZn/CNT-Al2O3 (90:10) performed similarly to the catalyst supported on pristine CNT. CuZn/CNT-Al2O3 (50:50) and CuZn/CNT-Al2O3 (70:30) displayed reduced CO2 conversion but enhanced methanol selectivity compared to the reference catalyst, CuZn/Al2O3, suggesting that the presence of CNT is advantageous for methanol selectivity. The catalyst CuZn/CNT presented the highest methanol yield, and was stable for over 80 h on a TOS experiment.