Effects of heavy rare earth addition on properties of KL zeolite-supported platinum reforming catalyst Original Research Article

A series of Ptsingle bondREsingle bondKL catalysts, which containing 0.8 wt% platinum and 0.2 wt% RE (REdouble bond; length as m-dashGd, Tb, Dy, Tm, Yb, Lu), have been prepared by impregnation of the L-type zeolite support with corresponding RE nitrate aqueous solutions. The reforming reactions of n-hexane, cyclohexane and methylcyclopentane (MCP) on Ptsingle bondREsingle bondKL catalysts have been investigated with a plus microcatalytic apparatus. The surface properties and the active sites of these catalysts have also been studied with TPD, TPR and plus-CS2 poisoning test. Our results reveal that those heavy rare earth elements added to Ptsingle bondKL catalyst have effect of electronic donation to Pt particles and blocking the accumulation of active Pt particles, and thus can remarkably increase the ability of resistant sulfur poisoning and the aromatic selectivity of n-hexane or MCP conversion on the Ptsingle bondKL catalyst. Studies on the relationship between the magnetic properties of catalysts and the activities as well as selectivity of catalysts show that after addition of the RE, the magnetic susceptibilities of Ptsingle bondREsingle bondKL catalysts decrease dramatically compared with that of Ptsingle bondKL catalyst, while catalytic properties of Ptsingle bondREsingle bondKL catalysts are improved, which suggests that the unpaired electron numbers of Pt particles are decreased by RE2O3ʹs giving electrons to Pt particles, therefore electronic property of catalysts is one of the most important factors affecting the activity of Ptsingle bondREsingle bondKL catalysts.