Features of deposit formation from 1,3-butadiene over Pd catalysts |
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Authors: | A Sárkány |
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Institution: | (1) Institute of Isotope and Surface Chemistry, Chemical Research Center, Hungarian Academy of Sciences, H-1525 Budapest, P.O. Box 77, Hungary |
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Abstract: | Formation of carbonaceous deposits from 1,3-butadiene has been investigated over a group of Pd catalysts. Hydrogen generated
in decomposition of diene at 473–523 K participates in diene hydrogenation, resulting in the formation ofn-butenes. XRD measurements have confirmed formation of dissolved carbon (PdCx) phase. DRIFT measurements over 0.06 wt.%Pd/γ-Al2O3 have revealed bands at 1575 and 1464 cm−1, suggesting formation of carboxylate structures. Selectivity of the competitive hydrogenation in 1,3-butadiene and propene
mixture R(BD)/R(Pr) has been measured on “fresh” and poisoned samples. Accumulation of deposits has decreased the R(BD)/R(Pr)
ratio. The results have been interpreted by transport hindrance and a greater prevalence of non-selective low coordination
sites on the poisoned surface. Measurements over Pd, Cu, Pt and Rh catalysts have shown that the highn-butane selectivity over Pt and Rh is also accompanied with low R(BD)/R(Pr) values, suggesting that thermodynamic and mechanistic
factors are not entirely separable.
Dedicated to Professor Pál Tétényi on the occasion of his 70th birthday |
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Keywords: | Carbonaceous deposit dissolved carbon transport hindrance competitive hydrogenation |
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