Tuning the anti-coking and reusability properties of Al2O3 coating grown by low-temperature atomic layer deposition

Using passivation coating to inhibit coking is key for applying active cooling technology in high-speed aircraft. However, the anti-coking performance of coatings during the repeated fuel pyrolysis and decoking processes is the focus of research. Herein, Al 2 O 3 coatings prepared by atomic layer deposition were characterized to explore the improvement effect of anti-coking and reusability. These properties were analyzed via repeated use of n -decane pyrolysis and coke oxidation removal experiments. The dense and smooth coatings obtained by adjusting the number of deposition cycles exhibit an amorphous Al 2 O 3 crystal structure at 200 °C, which can prevent contact between the coking precursors and metal active sites, achieving the anti-coking rate of about 90 %. The characterization results reveal that coating maintains the integral structure after the decoking treatment. The partial transformation of Al 2 O 3 crystalline phase into intermediate phases under high-temperature conditions leads to an increase in surface acidic sites, accelerating the catalytic cracking and promoting the formation of filamentous coke with higher graphitization degree. However, the coking inhibition efficiency of coating remains above 80 % after several coking and decoking cycles. The present work provides new insights into the application of anti-coking coating prepared at low temperatures in the reusable coking and decoking process.