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Selective hydrogenation of acetylene in excess ethylene using Ag- and Au–Pd/SiO2 bimetallic catalysts prepared by electroless deposition

Paper ID Volume ID Publish Year Pages File Format Full-Text
40194 45845 2014 8 PDF Available
Title
Selective hydrogenation of acetylene in excess ethylene using Ag- and Au–Pd/SiO2 bimetallic catalysts prepared by electroless deposition
Abstract

•Electroless deposition used to deposit Ag (or Au) onto Pd particles with coverages ranging from 0.2 to 0.9.•Catalysts have been evaluated for selective hydrogenation of acetylene to ethylene in excess ethylene streams.•Selective formation of ethylene linked to small Pd ensembles.•Kinetic analysis of reaction supports above bimetallic ensemble effect.

Selective hydrogenation of acetylene in excess ethylene has been investigated for a series of Ag- and Au–Pd/SiO2 bimetallic catalysts having incremental surface coverages of Ag and Au on the Pd surface. The catalysts were prepared by electroless deposition and characterized by atomic absorption spectroscopy and selective chemisorption. Both Ag- and Au–Pd/SiO2 catalysts showed increased selectivity of acetylene conversion to form ethylene, rather than ethane, at high coverages. The catalyst performance results suggest that at high coverages of Ag or Au on Pd, that result in small ensembles of Pd sites, acetylene is adsorbed as a π-bonded species that favors hydrogenation to ethylene. At low coverages, where ensemble sizes of contiguous Pd surface sites are much larger, acetylene is strongly adsorbed as a multi-σ-bonded species which preferentially forms ethane, lowering the selectivity to ethylene. Both kinetic analyses and the calculated turnover frequencies of acetylene conversion and ethane formation were consistent with the above explanation. The similar performance trends for Ag- and Au–Pd/SiO2 suggest that the bimetallic effect for these catalysts is geometric and not electronic in nature.

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Keywords
Hydrogenation; Acetylene; Bimetallic catalysts; Ag–Pd; Au–Pd; Electroless deposition; Kinetics
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Selective hydrogenation of acetylene in excess ethylene using Ag- and Au–Pd/SiO2 bimetallic catalysts prepared by electroless deposition
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 469, 17 January 2014, Pages 419–426
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us