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Title: Selective Hydrogenation of Acetylene in the Presence of Ethylene on K+ -beta-Zeolite Supported Pd and PdAg Catalysts

Abstract

The selective hydrogenation of acetylene in the presence of ethylene has been studied on K+ exchanged {beta}-zeolite supported Pd and PdAg catalysts. Results from batch reactor studies with Fourier transform infrared spectroscopy (FTIR) have shown that the K+-{beta}-zeolite support is more selective than the Al2O3 or Na+-{beta}-zeolite supports toward the hydrogenation of acetylene. The rate and equilibrium constants for Pd/K+-{beta}-zeolite and PdAg/K+-{beta}-zeolite were determined using a Langmuir-Hinshelwood model. The selectivity of the PdAg bimetallic catalyst is twice of that of the Pd catalyst. Results from flow reactor studies show that the PdAg/K+-{beta}-zeolite catalyst has higher selectivity but lower activity toward acetylene hydrogenation than the Pd/K+-{beta}-zeolite catalyst. The selectivity to the undesirable ethane by-product is inhibited on the bimetallic catalyst. Extended X-ray absorption fine structure (EXAFS) studies and transmission electron microscope (TEM) analysis confirm the formation of Pd-Ag bimetallic bonds in the PdAg/K+-{beta}-zeolite catalyst.

Authors:
; ; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
959635
Report Number(s):
BNL-82621-2009-JA
TRN: US201016%%779
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Catalysis A: General; Journal Volume: 333
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ABSORPTION; ACETYLENE; BY-PRODUCTS; CATALYSTS; ELECTRON MICROSCOPES; ETHANE; ETHYLENE; FINE STRUCTURE; HYDROGENATION; SPECTROSCOPY; ZEOLITES; national synchrotron light source

Citation Formats

Huang,W., Pyrz, W., Lobo, R., and Chen, J. Selective Hydrogenation of Acetylene in the Presence of Ethylene on K+ -beta-Zeolite Supported Pd and PdAg Catalysts. United States: N. p., 2007. Web. doi:10.1016/j.apcata.2007.09.017.
Huang,W., Pyrz, W., Lobo, R., & Chen, J. Selective Hydrogenation of Acetylene in the Presence of Ethylene on K+ -beta-Zeolite Supported Pd and PdAg Catalysts. United States. doi:10.1016/j.apcata.2007.09.017.
Huang,W., Pyrz, W., Lobo, R., and Chen, J. Mon . "Selective Hydrogenation of Acetylene in the Presence of Ethylene on K+ -beta-Zeolite Supported Pd and PdAg Catalysts". United States. doi:10.1016/j.apcata.2007.09.017.
@article{osti_959635,
title = {Selective Hydrogenation of Acetylene in the Presence of Ethylene on K+ -beta-Zeolite Supported Pd and PdAg Catalysts},
author = {Huang,W. and Pyrz, W. and Lobo, R. and Chen, J.},
abstractNote = {The selective hydrogenation of acetylene in the presence of ethylene has been studied on K+ exchanged {beta}-zeolite supported Pd and PdAg catalysts. Results from batch reactor studies with Fourier transform infrared spectroscopy (FTIR) have shown that the K+-{beta}-zeolite support is more selective than the Al2O3 or Na+-{beta}-zeolite supports toward the hydrogenation of acetylene. The rate and equilibrium constants for Pd/K+-{beta}-zeolite and PdAg/K+-{beta}-zeolite were determined using a Langmuir-Hinshelwood model. The selectivity of the PdAg bimetallic catalyst is twice of that of the Pd catalyst. Results from flow reactor studies show that the PdAg/K+-{beta}-zeolite catalyst has higher selectivity but lower activity toward acetylene hydrogenation than the Pd/K+-{beta}-zeolite catalyst. The selectivity to the undesirable ethane by-product is inhibited on the bimetallic catalyst. Extended X-ray absorption fine structure (EXAFS) studies and transmission electron microscope (TEM) analysis confirm the formation of Pd-Ag bimetallic bonds in the PdAg/K+-{beta}-zeolite catalyst.},
doi = {10.1016/j.apcata.2007.09.017},
journal = {Applied Catalysis A: General},
number = ,
volume = 333,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • In the production of ethylene from the steam cracking of natural gas, small amounts of acetylene and butadiene are produced. Downstream, acetylene can present a hazard in a cryogenic separation process while nonselective hydrogenation removes acetylene as well as valuable ethylene and butadiene. With the aid of adsorption measurements, a selective hydrogenation catalyst has been designed. Small-pore zeolites, which serve as catalytic supports and provide reactant selective control, were ion-exchanged with Ni{sup 2+} and subsequently reduced. Compared to a commercial catalyst in which 60% of butadiene and all of the acetylene are hydrogenated, these new catalysts totally hydrogenate acetylene withmore » only 10-20% hydrogenation of the butadiene and almost no hydrogenation of ethylene. To achieve selective hydrogenation, poisoning of the metal sites on the external zeolite surface is essential in order to obtain a product spectrum dominated by catalytic sites within the zeolite framework.« less
  • Per-hydrogenation of naphthalene produces both cis-decalin (c-DeHN) and trans-decalin (t-DcHN). Huang and Kang reported the rate data shown in Scheme 1 for this reaction catalyzed by Pt/Al{sub 2}O{sub 3}. Isomerization of c-DeHN was treated as irreversible, and it was assumed that dehydrogenation of DeHN could be neglected. We have found it possible to achieve high selectivity for one DeHN isomer by appropriate catalyst selection. For example, PYHY gives 100% naphthalene conversion to decalins with 80% selectivity for c-DeHN. There numerous potential industrial applications for c-DeHN; such as, the production of sebacic acid which can be used in the manufacture ofmore » Nylon 6, 10 and softeners. Conversely, catalysts that promote the thermodynamically favored c-DeHN to t-DeHN isomerization can be made to give nearly 96% t-DeHN. This reaction can be used in fuel upgrading applications, to increase the thermal stability of the fuel.« less
  • ESCA and ESR spectroscopic studies of 18 and 50Vertical Bar3< rhodium-exchanged Y zeolites, activated under vacuum at 100/sup 0/-600/sup 0/C, and activity tests for ethylene hydrogenation and dimerization and acetylene hydrogenation in a static reactor at 20/sup 0/C and 76-100 mm Hg provided evidence that during reduction under vacuum of the rhodium(III) in the zeolite, part of the rhodium formed stable rhodium(I) ions, possibly partly associated with residual chlorine or hydride ions. The bare rhodium(I) cations were coordinatively unsaturated, were more stable at the lower rhodium exchange levels, and were active in ethylene hydrogenation and dimerization. The formation of atomicallymore » dispersed and clustered rhodium(0) was also observed during the heat treatment; it was active for acetylene hydrogenation and ethylene dimerization. The results were similar to results obtained with chloro tris(triphenylphosphine) rhodium(I) and various other homogeneous catalysts, and similar mechanisms apparently apply to the two types of catalysts.« less
  • Pd-Based catalysts are used for the selective hydrogenation of alkynes and alkadienes to the corresponding alkenes on a large scale. Addition of Pb and Zn (Lindlar type catalysts) to Pd, and alloying of Pd with Ag, Cu, Pb improve the selectivity of alkyne hydrogenation. The presence of organic bases organic sulfides, or CO in the reaction mixture is known to inhibit hydrogenation of the alkene formed. Although structure sensitivity in alkene hydrogenation has been systematically investigated, only a few studies have been devoted to the effect of metal dispersion on the selectively of hydrogenation of an alkyne-alkene mixture. The workmore » described in this article aimed to investigate the effect of Pd dispersion on the competitive hydrogenation of a mixture containing 0.3% C/sub 2/H/sub 2/, 0.5% H/sub 2/ balanced by C/sub 2/H/sub 4/ over Pd/alumina as catalyst. In particular, attempts have been made to clarify the extent of ethane formation produced directly from acetylene (intrinsic selectivity of the ethane formation) and that from ethylene in the presence of acetylene with the use of (/sup 14/C)C/sub 2/H/sub 2/. Isotopic labeling techniques have unambiguously demonstrated that ethane is generally formed from both acetylene and ethylene. 30 references.« less