EFFECT OF KCL ADDITION METHOD ON THE PT KL CATALYST FOR THE AROMATIZATION OF HEXANE

Citation
Lx. Dai et al., EFFECT OF KCL ADDITION METHOD ON THE PT KL CATALYST FOR THE AROMATIZATION OF HEXANE, Journal of catalysis, 147(1), 1994, pp. 311-321
Citations number
27
Categorie Soggetti
Engineering, Chemical","Chemistry Physical
Journal title
ISSN journal
00219517
Volume
147
Issue
1
Year of publication
1994
Pages
311 - 321
Database
ISI
SICI code
0021-9517(1994)147:1<311:EOKAMO>2.0.ZU;2-9
Abstract
The influence of the method for loading platinum precursor and adding KCl, KCl loading content, calcination temperature, KCl addition proced ure, various additives, and water washing on the activity and selectiv ity of Pt/KL catalysts for hexane reforming reaction has been investig ated. The catalyst preparation methods involve ion exchange (IE), inci pient wetness impregnation (IWI), and coimpregnation with KCl (IWI-KCl ). The Pt/KL catalysts PrePared by ion ''Change with [Pt(NH3)4]Cl2 fol lowed by impregnation with KCl (EE-KCl) gave much higher activity and selectivity for benzene formation than the catalysts prepared by coimp regnation of KL zeolite with [Pt(NH3)4]Cl2 and KCl. The IE-KCl catalys t with KCl/Pt molar ratio of 4.5 showed 100.0% conversion of hexane an d 89.3% yield of benzene at 743 K and 0.2 MPa. The IE-KCl catalysts ex hibited lower H/Pt ratios than the IE catalyst. The KCl addition proce dures markedly affected the activity and selectivity of the Pt/KL cata lyst; the addition of KCl to the IE sample prior to calcination and re duction was necessary for the catalyst to exhibit the high activity in benzene formation. It has also been found that the performance of Pt/ KL catalysts is markedly affected by the calcination temperature. With the IE-KCl catalysts, however, the decrease in the benzene yield caus ed by high-temperature calcination was not as serious as with the IE c atalyst. In contrast, with the IWI and IWI-KCl catalysts, the activity for benzene production was highly sensitive to the calcination at hig h temperature, drastically decreasing by calcination at 823 K. The Cl species on the IE-KCl catalysts may have existed in the state of KCl. (C) 1994 Academic Press, Inc.