Selective hydrogenation of 1-hexyne using Pd-Mn on alumina catalysts

Abstract

Mixed C4 hydrocarbon is one of the product streams from the naphtha cracking processes. This stream contains vinylacetylene, butadiene, isobutylene, butyne, butene, butane, etc. The selective catalytic hydrogenation process is an alternative for mixed C4 hydrocarbons upgrading. In this research, 1 -hexyne was chosen as a model compound for unsaturated mixed C4 hydrocarbons. The activity and selectivity of hydrogenation were investigated by using low loaded Pd (0.3 wt %) and Mn doped Pd on alumina catalysts. The atomic ratios of Pd/Mn were varied at 0.5, 0.75, 1.0, 1.5, 2.0, and 5.0. The experimental conditions were 40 ℃ and H2 partial pressure of 1.5 bar. Temperature program reduction (TPR), hydrogen chemisorption and surface area analysis were applied for catalyst characterization. It is interesting to find that the activity was significantly improved when Mn was doped on the Pd/Al2O3 catalysts (Pd/Mn ≤ 1). The selectivity of the Pd-Mn/ Al2O3 catalysts also increased from the Pd/ Al2O3 catalyst when Mn is added.