316
J. A. Delgado and C. Godard
+
220ºC
Ni NPs
6 bar H 2
Dioxane, 85 ºC
Ni(acac) 2
Oleylamine
R
X ,% S C=C , %
NO 2
3
4 3
NH 2
24
78
Br
72
96
Cl
95
100
P
7 3
Toluene, 220ºC
P 4
Ni 2 P NPs
R
R
TOP
0.01 eq.
Fig. 10.8 Preparation of Ni 2 P NPs and semi-hydrogenation of substituted phenylacetylenes
(20 bar H 2 , 100 °C), and moderate to good alkene selectivities were observed. DFT
calculations suggested that the relatively low adsorption energy of the alkene on
Ni 3 N (vs. pure Ni) might contribute to the high selectivity for alkene.
Similarly, Zhao et al. reported the preparation of palladium phosphide NPs
by chemical reduction of Pd(acac) 2 in the presence of triphenylphosphine and
trioctylphosphine as phosphorus source [93]. ICP and XRD analysis suggested the
formation Pd 75 P 25 NPs with an alloyed structure. The NPs evidenced high activity but
addition of quinoline was necessary to prevent excessive over-hydrogenation. Higher
alkene selectivities were reported by the same author using a trimetallic palladium
copper nickel phosphide catalyst (Pd-Cu-Ni-P) [94]. The authors attributed this result
to synergistic effects of the electron deficiency of Pd and the amorphous phase.
For the semi-hydrogenation of acetylene in ethylene-rich mixtures, Williams et al.
studied the application of PdAg and PdAu/SiO 2 bimetallic catalysts prepared by
electroless deposition. This synthetic method favoured the formation of core@shell
NPs [96]. NPs with different degree of M-coverage (M = Ag or Au) were prepared
by controlling the stoichiometry of the Pd and Ag/Au solutions. In catalysis, the
selectivity towards ethylene was enhanced with the Au or Au coverage. Interestingly, similar activity and selectivity trends were observed for both Ag- and Au–
Pd/SiO 2 thus suggesting that the bimetallic promotion for these particular catalysts
was geometric and not electronic in nature. In this line, the bimetallic PdCu/CNTs
catalyst reported by Godard et al. was also tested in the semi-hydrogenation of acetylene in ethylene-rich mixtures [62]. Excellent stability was observed even after 40 h
of reaction with moderate to good ethylene selectivity (ca. 60%). The performance
of the bimetallic catalyst was superior to that observed for a commercial pure Pd
J. A. Delgado and C. Godard
+
220ºC
Ni NPs
6 bar H 2
Dioxane, 85 ºC
Ni(acac) 2
Oleylamine
R
X ,% S C=C , %
NO 2
3
4 3
NH 2
24
78
Br
72
96
Cl
95
100
P
7 3
Toluene, 220ºC
P 4
Ni 2 P NPs
R
R
TOP
0.01 eq.
Fig. 10.8 Preparation of Ni 2 P NPs and semi-hydrogenation of substituted phenylacetylenes
(20 bar H 2 , 100 °C), and moderate to good alkene selectivities were observed. DFT
calculations suggested that the relatively low adsorption energy of the alkene on
Ni 3 N (vs. pure Ni) might contribute to the high selectivity for alkene.
Similarly, Zhao et al. reported the preparation of palladium phosphide NPs
by chemical reduction of Pd(acac) 2 in the presence of triphenylphosphine and
trioctylphosphine as phosphorus source [93]. ICP and XRD analysis suggested the
formation Pd 75 P 25 NPs with an alloyed structure. The NPs evidenced high activity but
addition of quinoline was necessary to prevent excessive over-hydrogenation. Higher
alkene selectivities were reported by the same author using a trimetallic palladium
copper nickel phosphide catalyst (Pd-Cu-Ni-P) [94]. The authors attributed this result
to synergistic effects of the electron deficiency of Pd and the amorphous phase.
For the semi-hydrogenation of acetylene in ethylene-rich mixtures, Williams et al.
studied the application of PdAg and PdAu/SiO 2 bimetallic catalysts prepared by
electroless deposition. This synthetic method favoured the formation of core@shell
NPs [96]. NPs with different degree of M-coverage (M = Ag or Au) were prepared
by controlling the stoichiometry of the Pd and Ag/Au solutions. In catalysis, the
selectivity towards ethylene was enhanced with the Au or Au coverage. Interestingly, similar activity and selectivity trends were observed for both Ag- and Au–
Pd/SiO 2 thus suggesting that the bimetallic promotion for these particular catalysts
was geometric and not electronic in nature. In this line, the bimetallic PdCu/CNTs
catalyst reported by Godard et al. was also tested in the semi-hydrogenation of acetylene in ethylene-rich mixtures [62]. Excellent stability was observed even after 40 h
of reaction with moderate to good ethylene selectivity (ca. 60%). The performance
of the bimetallic catalyst was superior to that observed for a commercial pure Pd