Enhanced catalytic performance of isobutane direct dehydrogenation over Pt-In catalysts: Effect of different fluorides modified hydrotalcite-like derivatives

A series of MgF 2 -modified hydrotalcite-like (HT) derivatives supported Pt-In catalysts PtInHTR-X (X = NH 4 F, NaF and KF, R = reduced catalyst) were prepared by combination of hydrothermal method, alkali-etching and impregnation strategy and applied to direct dehydrogenation of isobutane to isobutene. The catalysts and precursors were characterized by XRD, SEM, TEM, XPS, TG, O 2 -TPO and low temperature N 2 adsorption-desorption isotherms. The formation of MgF 2 phase as dopant to modify the catalyst can influence the pore structure and even the surface acid properties of catalysts. Especially, compared with the three catalysts, PtInHTR-KF catalyst had better stability of isobutene selectivity of over 95% after 9 h reaction, and PtInHTR-NH 4 F and PtInHTR-NaF catalysts exhibited more stable isobutane activity of 60%. One of the reasons for this catalytic performance is that small particles of MgF 2 and unsaturated MgF 2 can provide weak acidic sites which can inhibit coke deposition. And it was found the improved catalytic performance was also related to the appropriate In 3+ /In 0 ratio, well-dispersed Pt species and the excellent anti-sintering ability of catalysts modified MgF 2 .