Structural Characteristics And Performance For N-Pentane Cracking Of Hydrothermal Stable Rehy

In this paper, two HY zeolites dealed with homothermal calcinating (HY) and fractional temperature programmed calcinating (HY-N) were studied based on the usual four-exchanged-four-calcinated method. Three kinds of REHY zeolites were obtained by rare earth (RE) ions modified. The structrual performance of these two kinds of HY zeolites, three kinds of REHY before and after hydrothermal aging were characterized by XRD、XRF、NH3-TPD and BET. The pentane cracking catalytic performance of REHY was evaluated by micro fixed bed reactor. The results indicated that the Na content of Y zeolite treated by loading RE first followed by ammonium exchanging is much lower than that of Y zeolite treated by ammonium exchanging for twice. In result, the Na2O content of the sample dealed with fractional temperature programmed calcinated method was as low as0.07wt%, and the crystaline of the Y zeolite was87.44%, the total acidity was1.24mmol/g, and the specific surface area was514.2m2/g, which is exhibited that the fractional temperature programmed calcinated method was better than the usual homothermal calcinated method to prepare the HY zeolites. The structure of the Y zeolites hadn’t been changed after those three RE ion-exchange methods, but the extra ammounium ion-exchange would waste a lot of rare earth. The Na2O content of6.8%REHY4-N zeolite was0.02wt%, the crystaline was87.44%, the total acidity was1.07mmol/g, the mediate strong acidity was0.543mmol/g, and the specific space area was666.4m2/g. It had a better structure after hydrothermal aging and the performance of the6.8%rare earth content of REHY4-N in catalytic cracking reaction of n-pentane had the selectivity of ethene and propene were30.4%and24.3%, respectively, and the conversion of the n-pentane was91.9%.