The Effect of Catalyst Calcination Temperature on Catalytic Decomposition of HFC-134a over γ-Al2O3

Abstract

This paper explores the thermal and catalytic pyrolysis of HFC-134a over γ-Al2O3 calcined at temperatures of 550 °C (A550), 650 °C (A650), 750 °C (A750), and 850 °C (A850). The physicochemical properties of catalysts were studied through thermogravimetric analysis (TGA), Brunauer–Emmett–Teller equation for nitrogen physisorption analysis (BET), X-ray diffraction (XRD), and temperature-programmed desorption of ammonia (NH3-TPD). The non-catalytic pyrolysis of HFC-134a showed less than 15% decomposition of HFC-134a. Catalysts increased the decomposition as A650 revealed the highest decomposition efficiency by decomposing more than 95% HFC-134a for 8 h followed by A750, A850, and A550. The larger surface area and pore volume paired with a low amount of strong acidic sites were considered as the main contributors to the comparatively longer catalytic activity of A650.

Construction of intimate Lewis acid and basic sites on an Al2O3–NC composite catalyst with enhanced performance in transfer hydrogenation of cinnamaldehyde

“…Higher temperatures resulted in changes of the surface nitrogen functional groups derived from dopamine hydrochloride, but had little effect on the surface acidity which primarily originates from Al 2 O 3 . 49 The acidity and basicity of the catalysts prepared at different thermal treatment temperatures are presented in Table 2. These data indicated that 10-Al 2 O 3 -NC (550) possessed the largest amount of basic sites on its surface and the highest ratio of basic to acid sites.…”