The Unique Role of CaO in Stabilizing the Pt/Al2O3 Catalyst for the Dehydrogenation of Cyclohexane

Coke-induced deactivation is one of the major challenges in the field of heterogeneous catalysis. Herein, the performance of the Pt/Al2O3 catalyst for the hydrogen-free dehydrogenation of cyclohexane was improved by doping with a small amount of Ca. The Ca-modified Pt/Al2O3 catalyst exhibited a cyclohexane conversion of 97.0?% and maintained a conversion above 75?% after 48 h, whilst the unmodified catalyst was deactivated from 87.0 to 2.7?% under the same conditions. Characterization techniques, including in situ DRIFT, XPS, thermal analysis, and temperature-programmed techniques, revealed that the presence of Ca effectively suppressed the deep dehydrogenation of H-rich carbonaceous components and promoted coke desorption by increasing the H/C ratio of H-deficient coke. This promotion effect of Ca was also associated with neutralizing the residual Cl ions and promoting immediate dehydrogenation.