Authors: Jiangyin Lu Zhen Zhao Chunming Xu Aijun Duan Xiaoning Wang Pu Zhang
Publish Date: 2007/05/30
Volume: 15, Issue: 2, Pages: 213-220
Abstract
Several systems of HZSM5 FeHZSM5 and CrHZSM5 zeolite catalysts with different ratios of SiO2/Al2O3 25385080 and 150 were prepared and they were characterized by means of Xray diffraction XRD UV–Vis NH3TPD and BET techniques The results indicated that compared with uncalcined HZSM5 zeolites the total acid amounts acidic site density and acidic strength of HZSM5 FeHZSM5 and CrHZSM5 zeolite catalysts obviously decreased while those of weak acid amounts obviously enhanced with the decrease of SiO2/Al2O3 molar ratio When the ratio of SiO2/Al2O3 is less than 50 the three systems of HZSM5 FeHZSM5 and CrHZSM5 zeolite catalysts with same ratio of SiO2/Al2O3 gave similar and high isobutane conversions However when the ratio of SiO2/Al2O3 was equal to or greater than 80 these three systems of catalysts possessed different altering tendencies of isobutane conversions thus their isobutene conversions were different High yields of light olefins were obtained over the FeHZSM5 and CrHZSM5 zeolite catalysts with high ratio of SiO2/Al2O3 ≥80 The ratio of SiO2/Al2O3 has large effects on the surface area and acidic characteristics of HZSM5 FeHZSM5 and CrHZSM5 zeolites catalysts and thus further affect their catalytic performances for isobutane cracking That is the nature of SiO2/Al2O3 ratio effect on the catalytic performancesThe authors would like to thank the financial support from the National Basic Research Program of China grant No 2004CB 217806 and 2005CB221402 the Young Scientists Innovation Foundation of CNPC NO 04E7025 the National Natural Science Foundation of China Grant No 20373043 and the Scientific Research Key Foundation for the Returned Overseas Chinese Scholars of State Education Ministry
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