| dc.description.abstract | The effectiveness of alumina-based catalysts modified by cerium, zirconium, sulfate, and ethanol in the catalytic hydrolysis of C4F8 at temperatures ≤ 650oC is evaluated. Modification of catalysts enhances the acid amount and surface area. The interplay among rare earth elements, acid amount, and surface area is further investigated. Thereafter, a stability test was carried out to evaluate the performance of ASE (sulfate-modified-Al2O3 catalysts), ACSE (cerium-modified-Al2O3 catalysts), and AZSE (zirconium-modified-Al2O3 catalysts) for C4F8 destruction. Ethanol was used to modify catalysts and is designated with the symbol (E). The results of the stability test show that the performances ACSE>AZSE>ASE for C4F8 conversion at 650oC during 24 h reaction. Coupling effects of water and oxygen content have been evaluated. Overall, the ACSE catalyst shows good performance at 650oC. The highest conversion by catalytic pyrolysis was 9.56 % at 650oC in the absence of water vapor. The highest conversion by catalytic hydrolysis was 100% at 550oC with 38% H2O(g). Furthermore, the highest conversion by catalytic oxidation was 95% at 650oC with 21% oxygen. Coupling of catalytic hydrolysis and oxidation achieves 91% C4F8 conversion at 450oC. The activation energies of ACSE catalysts in catalytic hydrolysis, pyrolysis, and oxidation are 67.2, 60.1, and 79.9 kJ/mol, respectively. The major products from C4F8 conversion include CO2, CO, and COF2. Small amounts of CHF3, C2F4, C3F6O were also identified as products. This study has confirmed that modifying alumina-based catalysts with cerium, sulfate, and ethanol improves the activity and stability of alumina-based catalysts for C4F8 conversion. | en_US |