Modifying α-Al 2 O 3 with cerium, zirconium, and sulfate for catalytic removal of C 4 F 8

Modification of α-Al O (A) with cerium (C), zirconium (Z), and sulfate (S) for effective C F removal is evaluated at temperatures ≤ 650 °C. Catalytic hydrolysis of C F is conducted to compare the performance of catalysts prepared (namely, A, AC, AZ, AS, ACS, and AZS). The interplay between rare earth element, acid amount, and surface area is further investigated. An investigation was carried out by characterization of catalysts by using XRD, BET, and NH -TPD. XRD pattern of the modified α-Al O catalyst shows that the average grain size is 37 nm. BET analysis indicates that the surface area increases with the addition of Ce and Zr, while NH -TPD analysis shows the improvement of acid sites after the addition of Ce, Zr, and SO . The experimental results indicate that C F conversion over A catalyst reaches 14.81% at 550 °C with the addition of 38% H O . Under the same operating condition, C F conversion efficiencies achieved with AC and AZ catalysts increase to 42.03% and 50.1%, respectively. Furthermore, the efficiencies over AS, ACS, and AZS catalysts increase to 49.85%, 86.94%, and 87.18%, respectively. Stability tests show that the performances of the catalysts for C F conversion are with the order of AZS > ACS > AZ > AC > AS > A at 650 °C during 24 h. The activation energy of the AZS catalyst in catalytic hydrolysis of C F is 60.49 kJ/mol. The products of C F conversion mainly include CO , CO, and COF and small amounts of CHF and C F . This study has confirmed that the AZS catalyst shows the best activity, acidity, and stability on C F removal.