IN-SITU DRIFTS STUDIES OF THE ACTIVATION OF GA H-ZSM-5 CATALYSTS FOR THE AROMATIZATION OF PROPANE/

An in-situ diffuse reflectance IR fourier transform spectroscopy study of the reduction/activation of Ga/H-ZSM-5 and variants thereof has be en performed. These studies have shown a synergy between acidic suppor ts (zeolitic and non-zeolitic) and Ga2O3, which leads to the reduction of the latter in either a H-2 or propane stream, as evidenced by the loss in intensity of the nu Ga-O band. No reduction of Ga2O3 was obser ved when it was unsupported or supported upon non-acidic supports. In all cases the reduction process was accompanied by loss of Bronsted ac id groups due to reaction between the acidic site and gallium suboxide . Moreover, the appearance of a strong sharp band coincident with the known frequency of the nu Ga-O band was also recorded and is presumed to indicate the presence of Ga2O. Reduction of Ga/H-ZSM-5 using propan e as a reductant was accompanied by side reactions and coke deposition and appeared to be a less effective means of activating the catalyst.