Mechanism of norbornadiene dimerization promotion by Co‐species‐modified alkali‐treated zeolite

Abstract Norbornadiene (NBD) dimer is one of the most important high‐energy‐density fuels for aerospace propulsion, but it is difficult to synthesize with high efficiency. Herein, we fabricated nano‐cobalt loaded alkali‐treated HY zeolite, which significantly promotes the NBD dimerization reaction with a conversion of 73.5% and a selectivity of 84.7%, which is a 20% higher yield than previously reported catalysts. The characterizations confirm that the mild alkali treatment expands the zeolite pore size, providing more reaction space and enhancing the NBD conversion. The in situ Fourier‐transform infrared spectra demonstrate that alkali‐treated zeolites can adsorb more NBD, and the incorporation of Co species enhances the adsorption of double bonds to form a stable transition state with a three‐center two‐electron configuration, thereby promoting the reaction. The dimerization product after hydrogenation has a high density (1.06 g/mL at 20°C) and high volumetric neat heat of combustion (45.3 MJ/L), which is very promising for practical application.