Effects of alumina phases on the structure and performance for selective propane dehydrogenation of PtFeSn/Al2O3 catalysts

By the analysis of the catalytic performance and the characterizations of the PtFeSn/x-Al2O3 (x = α, θ, δ, γ), it is found that the less electron depletion of the Pt species, appropriate surface acidities and higher B/L acid ratio are beneficial to the catalytic performance. [Display omitted] •Illuminating the phase effects of the Al2O3 on the PtFeSn/x-Al2O3 in the PDH process.•Less electron depletion of the Pt species is beneficial to the initial catalytic activity.•Higher total surface acidity is beneficial to the initial catalytic activity.•Higher B/L acid ratio is beneficial to the catalytic stability. Supported Pt-based catalysts are extensively employed in the propane dehydrogenation (PDH) industry, though the effect of the support remains a problem. Herein, wet impregnation method is employed to generate samples with highly dispersed PtFeSn clusters supported by x-Al2O3 (x = α, θ, δ, γ). According to the catalytic test, the PtFeSn/θ-Al2O3 exhibits better catalytic performance (>49 % initial propane conversion and > 95 % initial propylene selectivity, and better stability. In comparison, the PtFeSn/x-Al2O3 (x = α, δ, γ) samples exhibit faster deactivation. Based on the systematic characterization of the materials, the phase transformation is observed to affect the surface acid properties and PtFeSn-support interactions, which exert great influence on the activity and coking behavior of catalysts. Moreover, the experiments and theoretical calculations for mechanism analysis illuminate that there is a strong correlation between the catalytic activity of PtFeSn/x-Al2O3 (x = α, δ, γ) samples in the PDH process and electron depletion of Pt species, which is influenced by the PtFeSn-supports interaction. Additionally, appropriate surface acidities and higher B/L ratio which is influenced by both supports and PtFeSn clusters, can enhance the initial catalytic activity and inhibit the generation of carbon deposited by inhibiting deep dehydrogenation of propylene. This study can make contribution to the fundamental principle for tailoring the performance of Pt-based PDH catalysts.