ISSN 1070-4272, Russian Journal of Applied Chemistry, 2007, Vol. 80, No. 9, pp. 1523!1528. + Pleiades Publishing, Ltd., 2007.
Original Russian Text + L.B. Belykh, N.I. Skripov, L.N. Belonogova, V.A. Umanets, F.K. Shmidt, 2007, published in Zhurnal Prikladnoi Khimii, 2007,
Vol. 80, No. 9, pp. 1489!1494.
Preparation of High-Performance Nanosized Palladium
Hydrogenation Catalysts Using White Phosphorus
L. B. Belykh, N. I. Skripov, L. N. Belonogova, V. A. Umanets, and F. K. Shmidt
Irkutsk State University, Irkutsk, Russia
Received November 20, 2006
Abstract-The nature and properties of nanosized palladium hydrogenation catalysts modified with elemental
phosphorus and phosphine (PH
) were studied.
Previously were studied the nature of particles
active in hydrogenation that were formed by treatment
with different reducing agents of palladium(II) com-
plexes with organic phosphines [13 4]. Microhetero-
geneous nature of these catalysts was revealed, and
the key steps of their formation was determined. In
particular, the main reactions of palladium(II) phos-
phine complexes with hydrogen are reduction of
Pd(II) to Pd(0) by hydrogenolysis of the Pd3X bonds
(X is an acido ligand); degradation of phosphine
ligands in the coordination sphere of Pd(0) by oxida-
tive addition of organophosphorus ligands to Pd(0),
followed by hydrogenolysis of the Pd3C bond with
hydrogen and formation of polynuclear palladium
phosphine and phosphinidene complexes (in the limit-
ing case, palladium phosphides, Pd
P and Pd
and formation of Pd(0) clusters [2, 3]. Active in hy-
drogenation are Pd(0) clusters or cluster palladium
] immobilized on polynucliear palla-
dium complexes with phosphide and posphinidene
ligands or on palladium phosphides. Since formation
of Pd(II) phosphine complexes involves stepwise
degradation of organophosphorus ligands to form
a heterophase system containing in the limiting case
palladium phosphides of different composition and
Pd(0) clusters, we suggested that phosphine (PH
white phosphorus (P
) can be used to modify the cata-
lyst. This approach can simplify preparation of nano-
sized palladium hydrogenation catalysts. The aim of
this study was to examine the nature and catalytic
properties of the systems prepared by treatment with
molecular hydrogen of mixtures of palladium bis-
acetylacetonate with white phosphorus or phosphine.
The solvents and chemicals were purified by stan-
dard procedures used in handling of organometallic
compounds . Benzene was additionally dried by
distillation from LiAlH
on a column and was stored
in an argon atmosphere in sealed ampules over 4A
To remove water and amine impurities, dimethyl-
formamide was kept over anhydrous copper sulfate
until a green solution was formed. Then the solvent
was double-distilled in a vacuum (3 mm Hg) at tem-
perature no higher than 42oC.
Palladium bisacetylacetonate was prepared by
the procedure described in patent .
d(CH) = 5.04 ppm (s, 1H), d(CH
) = 1.76 ppm (s, 6H).
To prepare phosphine, a solution of 25 g of KOH
in 25 ml of water was added dropwise to a suspension
of 10 g of red phosphorus in 30 ml of toluene, pre-
heated to ~110oC . The liberating gas was succes-
sively passed through a Tishchenko bottle filled with
a 50% solution of an alkali in an H
O + DMSO mix-
ture to remove diphosphine impurities and then
through columns packed with NaOH and P
move water traces. Phosphine was collected by dis-
solution in benzene placed in a finger-like vessel.
The phosphine concentration in the benzene solution
was determined by
P NMR spectroscopy using
as external reference;
P NMR: d
3238 ppm (q, J
= 188 Hz).
To remove surface oxidation products of white
phosphorus, it was washed with anhydrous benzene.
A benzene solution of white phosphorus was prepared