TG AND DSC STUDY OF THE PROPERTIES OF COKED MOLECULAR-SIEVE CATALYST

A cracking catalyst designated SRNY was manufactured from a commercial SRNY molecular sieve (M.S.). The support consisted of kaolin, clay an d SiO2. The coking behaviour of the SRNY M.S., the support and the cat alyst were examined with light diesel oil (LDO) as feedstock in a micr oreactor. The physico-chemical properties of both fresh and aged sampl es, subjected to or not subjected to the cracking reaction of LDO, wer e sequentially characterized by means of pore structure determination and thermal analysis. The pore structure included the specific surface area and the pore volume or porosity. Thermal analysis methods used i ncluded TG and DSC. The results indicated that all coked samples exhib ited obvious changes in surface pore structure and acidity in comparis on with non-coked samples. Their specific surface area and acid amount decreased with increase in the coke content of the samples. The appar ent activation energy data obtained from decoking samples in an air fl ow, using the temperature-programmed oxidation (TPO) method, showed th at the kinetic parameters of the SRNY M.S. differed from those of the SRNY catalyst and its support.