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This research investigates how alkaline-earth promotion affects acetylene hydrogenation for enhanced ethylene selectivity in polymer production.

April 16, 2026Scientific Reports0 citationsOpen Access

Alkaline-earth-promoted Pd–Ag/Al2O3 for selective acetylene hydrogenation: green-oil mitigation, ethylene selectivity, and implications for hydrogen spillover

FSFarnaz Rahbar Shamskar SMSajad Mobini MRMehran Rezaei

Key Points

This research investigates how alkaline-earth promotion affects acetylene hydrogenation for enhanced ethylene selectivity in polymer production.
Utilized eggshell Pd-Ag/θ-Al2O3 catalysts promoted with alkaline-earth additives.
Conducted fixed-bed tests at 10 bar and 40-60 °C after H2 prereduction.
Employed multiple analytical techniques like XRD, H2-TPR, and SEM-EDS to establish structure-property relationships.
Achieved over 96% acetylene conversion with improved ethylene selectivity across all promoted catalysts.
Demonstrated reduction in carbon deposition due to promoter effects.
Noted enhanced surface area and mesoporosity linked to promoter stabilization of θ-Al2O3.

Abstract

Removing trace acetylene from ethylene streams is critical to protect Ziegler-Natta polymerization. Eggshell Pd-Ag/θ-Al2O3 spheres (0.03 wt% Pd, 0.13 wt% Ag) were promoted with 1 wt% alkaline-earth additives to suppress green oil and improve ethylene selectivity. XRD, N2 physisorption, H2-TPR, NH3/CO2-TPD, TPO, SEM-EDS, and ICP-OES established structure-property links. Fixed-bed tests (10 bar, 40-60 °C) after H2 prereduction showed promoter-stabilized θ-Al2O3, higher surface area and mesoporosity and stronger metal-support interactions. All promoted catalysts achieved ≳ 96% acetylene conversion with higher ethylene selectivity and reduced carbon deposition. A possible contribution from hydrogen spillover is discussed qualitatively based on indirect evidence.

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