Influence of Support Structural Characteristics on Long-term Performance of Pd-Ag/α-Al₂O₃ Catalyst for Tail-end Acetylene Selective Hydrogenation

Abstract

The selective hydrogenation of acetylene to ethylene in acetylene/ethylene mixture over Pd-Ag/α-Al 2 O 3 catalysts prepared by sequential impregnation method was studied. The α-Al 2 O 3 support was prepared by thermal treatment of γ-Al 2 O 3 in temperature range of 1,090-1,100°C. The samples were characterized for their structural properties and coke deposition. They showed egg-shell structure with penetration depth increasing with sintering temperature of the support. A kinetic model based on 1st order in acetylene and 0.5th order in hydrogen for the main reaction and 2nd order independent decay law for catalyst deactivation was used to fit the conversion-time data and to obtain quantitative assessment of catalyst performances. Fair fits were observed from which the reaction and deactivation rate constants were evaluated. The highest selectivity to ethylene, and therefore best performance, was obtained for the highest calcination temperature which was attributed to its lower acidity and larger pore diameters.

Harnessing strong metal–support interactions via a reverse route

“…In general, the reaction order varies from ~0.5 (refs. 42,43 ), ~1 (refs. 44,45 ), and up to ~1.6 (ref.…”

Modification of Pd Nanoparticles with Lower Work Function Elements for Enhanced Formic Acid Dehydrogenation and Trichloroethylene Dechlorination

“…A recent study elucidated that the surrounding Cu surface could receive the spillover H atom transferred from the Pd island reaction sites and then selectively hydrogenated specific alkynes to alkenes rather than alkanes, consistent with the accumulation of ethene in the Fe@C–Pd–Ag system. One possible reason was that the incorporation of Ag decreased the adsorption energy of ethene, some of which tended to be desorbed from the surface before being fully hydrogenated. − On the basis of the discussion above, a mechanistic basis for FA dehydrogenation and TCE dechlorination on the modified Pd-based NPs was proposed in Figure S13.…”

Synthetic Strategies of Supported Pd-Based Bimetallic Catalysts for Selective Semi-Hydrogenation of Acetylene: A Review and Perspectives

“…Gas-phase catalytic hydrogenation has been the focus of scientists and industrial engineers because the vast majority of ethylene purification plants are using this strategy [ 15 , 16 ]. It is typically carried out in multi-bed adiabatic high-pressure reactors via two different scenarios depending on feed condition, namely front-end and tail-end configurations [ 17 , 18 , 19 ]. In the tail-end process, the lighter components, such as CH 4 , CO, as well as excess hydrogen, are removed from the feed before entering the reaction systems.…”