Olefin reduction of FCC gasoline via hydroisomerization aromatization over modified HMOR/HZSM-5/Hβ composite carriers Original Research Article

To develop a novel catalyst system that has excellent olefin control for FCC gasoline without loss in octane number, we prepared different catalysts supported on composite carriers consisting of Hβ, HMOR and HZSM-5 and assessed their catalytic performance for FCC gasoline upgrading in the present investigation. The influence of the ratios of Hβ to HMOR and HZSM-5 contents in catalysts on hydroisomerization and aromatization performance was studied. The XRD patterns of the catalysts showed that metal components were highly dispersed on zeolites. Acidity determined by pyridine-adsorbed FT-IR spectra and NH3-TPD measurements showed that hydroisomerization and aromatization activities were closely related both to the acid types and to the ratios of medium acid amount and strong acid amount to total acid amount. The Hβ content in triple-zeolite carriers was found to be an important factor affecting the acid properties, pore structure, and hence hydroisomerization and aromatization activities of the catalysts. When the ratio of Hβ to HMOR was 2.5, the highest activity could be achieved. The increase of HZSM-5 content was confirmed to degrade the overall performance of catalysts. Compared to the binary-zeolite HMOR/HZSM-5 and Hβ/HZSM-5 supported catalysts, the triple-zeolite HMOR/HZSM-5/Hβ supported catalysts offered much higher activity and selectivity to arene, which played an important role in preserving gasoline octane number.