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Catalytic Performance of Pt/Al2O3/WO3/ZrO2 Catalyst for Isomerization of n-Hexane
DU Yuqiao, CHEN Xiaorong, CHEN Changlin*, XU Nanping
2006, 27 (5):
397-402.
A series of Pt/Al2O3/WO3/ZrO2 catalyst samples were prepared by the impregnation method. The structure and redox properties of the catalyst samples were characterized by X-ray powder diffraction, temperatrue-programmed reduction of H2, and FT-IR spectroscopy. The catalytic performance of the samples for the n-hexane isomerization under different conditions was studied. The results showed that the addition of Pt has a great effect on the redox properties of tungstated zirconia. Owing to the presence of Pt, the n-hexane isomerization is catalyzed by metal and acid sites, and the selectivity for 2,2-dimethyl butane is significantly increased. The addition of Al2O3 can promote the interaction between tungsten oxide and zirconia and to increase the Lewis acidity. Under the conditions of n(H2)/n(n-C6H14)=1.5, WHSV=0.7 h-1, m(cat)=2.0 g, p=1.0 MPa, θ=220 ℃, and t=3 h, the conversion of n-hexane is 84.9%, the selectivity for 2,2-dimethyl butane reaches 22.9%, and the cracking yield of C4- is less than 1.5%. The stability of the Pt/Al2O3/WO3/ZrO2 catalyst for the n-hexane isomerization was further investigated. The catalyst exhibits excellent stability, and no deactivation after 1?000 h operation was detected.
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