Alumina-supported bimetallics of palladium alloyed with germanium, tin, lead, or antimony from organometallic precursors. II. Gas-phase hydrogenation of 2-methyl-1-buten-3-yne (valylene) and 2-methyl-1,3-butadiene (isoprene)

Journal Article · Wed May 01 00:00:00 EDT 1991 · Journal of Catalysis; (USA)

DOI:https://doi.org/10.1016/0021-9517(91)90008-R· OSTI ID:5721317

Aduriz, H R; Bodnariuk, P ^[1]; Coq, B; Figueras, F ^[2]

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1. UNS-CONICET, Bahia Blanca (Argentina)
2. CNRS ENSCM, Montpellier (France)

A series of PdGe, PdSb, PdSn, and PdPb/{alpha}{minus}Al{sub 2}O{sub 3} catalysts, prepared by the controlled surface reaction (CSR) technique from organometallic precursors have been tested in the gas-phase hydrogenation of 2-methyl-1-buten-3-yne (valylene) and 2-methyl-1,3-butadiene (isoprene). On catalysts reduced at 573 K, the turnover frequencies for valylene (TON{sub v}) and isoprene (TON{sub 1}) hydrogenation were not modified by addition to the 0.09wt% Pd/{alpha}{minus}Al{sub 2}O{sub 3} base catalyst of Ge, Sb, Sn, or Pb, up to0.1 wt% (at 293 K: TON{sub v}= 20 s{sup {minus}1} and TON{sub 1} = 33 s{sup {minus}1}). Pd/{alpha}{minus}Al{sub 2}O{sub 3} reduced at 773 K was severely sintered (d{sub TEM} increased from 2.8nm to 12.4nm) and TON{sub v} and TON{sub 1} at 293 K increased to 190 and 283 s{sup {minus}1}, respectively, as a result of an apparent crystal size effect: the reactants adsorb more strongly on the smaller Pd particles. Upon alloying with Ge, Sb, Sn, or Pb and a subsequent reduction at 773 K, a modest decrease of both TON{sub v} (by a factor of 2) and TON{sub 1} (by a factor of 2{minus}5) was observed. At high conversion, both the selectivity to isoprene (S{sub I}) in valylene hydrogenation, and to olefins (S{sub 0}) in isoprene hydrogenation on Pd/{alpha}{minus}Al{sub 2}O{sub 3} were improved upon alloying with Sb, Sn, or Pb (Ge had no effect). In addition, the isomerization of 2-methyl-1-butene and 3-methyl-1-butene (double bond migration reaction) during isoprene hydrogenation was partially suppressed on PdSn and PdPb/{alpha}{minus}Al{sub 2}O{sub 3}. The improvement in selectivities was interpreted in terms of a change in the relative adsorption strength of the reactants and intermediate products over the new bimetallic sites.

• OSTI ID: 5721317
• Journal Information: Journal of Catalysis; (USA), Vol. 129:1; ISSN 0021-9517
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
ALKYNES
HYDROGENATION
ANTIMONY
CATALYTIC EFFECTS
GERMANIUM
ISOPRENE
LEAD
PALLADIUM
TIN
ADSORPTION
ALKENES
ALLOYS
ALUMINIUM OXIDES
BIMETALS
BUTENES
CATALYST SUPPORTS
CATALYSTS
CHEMICAL PREPARATION
CRACKING
CRYSTAL STRUCTURE
INTERMETALLIC COMPOUNDS
ISOMERIZATION
PETROCHEMICALS
PETROLEUM PRODUCTS
QUANTITY RATIO
SORPTIVE PROPERTIES
SYNTHESIS
ALUMINIUM COMPOUNDS
CHALCOGENIDES
CHEMICAL REACTIONS
DECOMPOSITION
DIENES
ELEMENTS
HYDROCARBONS
METALS
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PLATINUM METALS
POLYENES
PYROLYSIS
SORPTION
SURFACE PROPERTIES
THERMOCHEMICAL PROCESSES
TRANSITION ELEMENTS
020400* - Petroleum- Processing