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Activity Enhancement by the Support in the Hydrogenation of C=C Bonds over Polymer‐Supported Palladium Catalysts
Author(s) -
Zecca Marco,
Fišera Roman,
Palma Giancarlo,
Lora Silvano,
Hronec Milan,
Králik Milan
Publication year - 2000
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/1521-3765(20000602)6:11<1980::aid-chem1980>3.0.co;2-z
Subject(s) - palladium , comonomer , catalysis , chemistry , sodium borohydride , styrene , cyclohexene , divinylbenzene , polymer chemistry , ion exchange resin , methanol , nuclear chemistry , polymer , organic chemistry , inorganic chemistry , copolymer , ethylene
Four synthetic ion‐exchange resins (AH, BH, CH, DH) of different hydrophilic/hydrophobic properties were used as supports for heterogeneous palladium catalysts (A, B, C, D). The resins contained styrene (STY) and 2‐(methacryloxy)ethylsulfonic acid (MESA) as the comonomers. Either divinylbenzene (DVB: CH, DH resins) or N , N ′‐methylenebisacrylamide (MBAA: AH, BH resins) were used as the cross‐linker. AH contained also N , N ‐dimethylacrylamide (DMAA) as the third comonomer. The catalysts (Pd 0.25‐0.45 % w / w ) were obtained by ion‐exchanging the acidic forms of the resins with [Pd(OAc) 2 ] and reducing palladium( II ) with excess sodium borohydride. The use of NaBH 4 also ensured the neutralization of the acidic sites of the supports. No effect of the hydrophilic/hydrophobic properties of the supports was observed in the hydrogenation of cyclohexene and 2‐cyclohexen‐1‐one in methanol, at 25 °C and 0.5, 1, and 1.5 MPa, respectively. However, catalysts A and B, containing amido groups provided by either DMAA or MBAA, proved to be more active than C and D. The observed activity enhancement was directly proportional to the nitrogen/palladium molar ratio in the catalysts. This finding suggests that amido groups promote palladium through a direct interaction with the metal surface.