Researchers have considered CO2
as a mild oxidant that can overcome over-oxidation and low propylene selectivity that are typically associated with the current synthesis routes. Oxidative dehydrogenation of propane to propylene with CO2
(ODPC) is an attractive method for catalytic method for propylene production compared to oxidative dehydrogenation with oxygen (ODHE), as it manufactures a valuable product and mitigates anthropogenic emissions.1,2
Herein, we report the rapid synthesis of customized metal-doped zeolite monoliths with various compositions and hierarchical porosity (macro-meso-micro) by 3D printing. To enhance catalytic activity and propylene selectivity in OPDC, single- and mixed metal oxide of Ga, Zr, V, and Cr (5-35 wt.%) were synthesized by directly incorporated commercial oxides into the printing pastes. The monolithsâ physical and chemical characteristics were studied through XRD, N2
physisorption, FTIR, SEM-EDS, CO2
-TPR, and NH3
-TPD. Their performances were evaluated for OPDC at 500-650 Â°C for 6 h of reaction time. The reaction experiments revealed that the vanadium-containing samples exhibited the best performance, where 40% propane conversion and 97% propylene selectivity were observed in the presence of CO2
. Moreover, the monoliths produced by direct oxide printing did not produce any BTX and showed less than 2% coking after 6 h reaction time. Because of these properties, this new method of direct printing was concluded to be superior to pre-dissolution of nitrate salts for the production of catalytic monoliths. Overall, this study represents a novel way of manufacturing structured catalysts and demonstrates materials which outperform the state-of-art for ODPC propane conversion.
 M.A. Atanga et al. Oxidative dehydrogenation of propane to propylene with carbon dioxide, Appl. Catal. B Environ. 220 (2018) 429â445.
 F. Magzoub et al. 3D-printed ZSM-5 monoliths with metal dopants for methanol conversion in the presence and absence of carbon dioxide, Appl. Catal. B Environ. 245 (2019) 486â495.