Superior performance of K/Co2AlO4 catalysts for the oxidative dehydrogenation of ethylbenzene to styrene with N2O as an oxidant

• N 2 O-ODEB was an effective method for greenhouse gas elimination and styrene production. • The K/Co 2 AlO 4 exhibited 62.0% of EB conversion and 85.1% of styrene selectivity at 500 °C. • The K modification changed the electronic properties of active metal and weakened the bond energy of Co 3+ -O − . • The K modification reduced the coke deposition on the catalyst surface. This study explored the feasibility of coupling N 2 O decomposition with ethylbenzene (EB) oxidative dehydrogenation, as an alternative approach for greenhouse gas elimination and styrene (ST) production, on the Co-Al mixed oxides and K-modified catalysts. It was found that N 2 O could decompose completely over the K/Co 2 AlO 4 catalyst, accompanied with 62.0% of EB conversion and 85.1% of styrene selectivity, which were much better than the existing catalyst systems for EB oxidative dehydrogenation. Characterization results showed that despite the decreased specific surface area of the catalysts with increasing the Co/Al molar ratio, the improved reducibility, the reduced acid properties as well as the higher ratio of Co 3+ /Co 2+ were responsible for the enhanced performance. The K modification not only changed the electronic properties of active metal, resulting from the charge transfer from K cation to the Co species, but also weakened the binding energy of Co 3+ -O − , leading to the complete decomposition of N 2 O. Furthermore, the optimized strong acid properties inhibited the dealkylation or ring-opening reactions and significantly reduced the coke deposition on the catalyst surface, thus improving the ST selectivity.