Pt/HL和Pt/KL沸石在异丙醇分解反应中的不同催化行为

Ｐｔ／ＫＬ沸石在异丙醇分解反应中具有很高的脱氢活性,而Ｐｔ／ＨＬ沸石具有明显的缺电子性,在此反应中难以显示出脱氢活性,通过加氢作用,可使沸石的酸位免受积炭覆盖,从而可增强Ｐｔ／ＨＬ沸石的酸性催化作用。

DIFFERENT CATALYTIC BEHAVIOUR OF Pt/HL AND Pt/KL ZEOLITES FOR ISOPROPANOL DECOMPOSITION

he catalytic property of Pt dispersed on acidic HL zeolite was totally different from that on basic KL zeolite. In isopropanol decomposition, Pt/KL accelerated acetone formation due to the dehydrogenation by Pt cluster. Pt/HL, however, did not show obvious dehydrogenation property, but enhanced the conversion of isopropanol to form H2O and propene. The FTIR spectra of CO adsorbed on the zeolites revealed that the Pt cluster on HL was "electron deficiency". In alkylation of toluene with methanol at 693 K, the xylene yield on Pt/HL was 5. 7% and that on HL only 1. 3%. It was proved that the acidic catalysis of Pt/HL was enhanced. The results of IR showed that, however, the amount of Bronsted acid sites on Pt/HL was smaller than that on HL. It was found that Pt loaded on HL protected acid sites on the zeolite against deactivation by carbonaceous overlay. This was one of the factors causing the enhancement of acidic catalysis of Pt/HL zeolite.