212
R. V. Jagadeesh
Table 6.3 Cobalt nanoparticles surrounded by N-doped carbon prepared by the pyrolysis of Cophenanthroline complex on different supports and their catalytic applications
Entry Ratio of
Co-phenanthroline
Support Pyrolysis
conditions
(t, Ar, t)
Nature of cobalt
particles
Catalytic
applications
1
1:2
Carbon 800 °C,
Ar, 2 h
Co 3 O 4 nanoparticles
surrounded by
N-doped graphene
Hydrogenation of
nitro compounds
and reductive
amination
2
1:2
Carbon 800 °C,
Ar, 2 h
Co 3 O 4 nanoparticles
surrounded by
N-doped graphene
Synthesis of esters
and nitriles form
alcohols
3
1:2
α-Al 2 O 3
Co, Co 3 O 4
nanoparticles
surrounded by
N-doped graphene
Hydrogenation of
quinlaines, nitriles
and carbonyl
compounds
4
1:2
SiO 2
Co, CoO and Co 3 O 4
nanoparticles
encapsulated in
N-doped graphitic
shells
Semi-hydrogenation
of alkynes to alkenes
5
1:7 or 1:10
Carbon
Cobalt single atoms
with CoNx centers
Dehydrogenation of
formic acid for the
generation of
hydrogen
(or hydrogenation) of N-heterocycles to store H 2 , using formic acid or external
hydrogen as a hydrogen source (Scheme 6.16) [27]. Several tetrahydroquinolines
and indolines were selectively dehydrogenated producing quinolines and indoles in
up to 99% yields [27].
In addition to nitrogen ligated metal complexes, in recent years, nitrogen-based
metal organic frameworks (MOFs) were conveniently used as suitable procures
for the preparation of N-doped carbon supported nanoparticles-based catalysts by
pyrolytic processes [28–31]. Notably, MOFs prepared using different metal ions and
organic linkers represent a stable class of porous compounds, which can be assembled in a highly modular manner [32, 33]. Due to their structural tunability, different
MOFs can be obtained, which can serve as desired precursors to prepare active and
selective nanoparticle-based catalysts.
In general, nitrogen-based MOFs can be directly pyrolyzed [28–30], which act
as self-sacrifying templates or can be immobilized/assembled on heterogeneous
supports followed by pyrolysis [31] to generate metal nanoparticles supported on
nitrogen doped carbons (Scheme 6.17).
Li et al. [30] have shown that direct pyrolysis of Co-DABCO-TPA-TPA (DABCO
= 1,4-diazabicyclo[2.2.2]octane; triethylenediamine. TPA = terephthalic acid; 1,4benzenedioic acid, BDA) at 900 °C under an inert atmosphere produced bifunctional N-doped cobalt nanoparticle (Co@NC-900)-based catalysts. On pyrolysis, this
R. V. Jagadeesh
Table 6.3 Cobalt nanoparticles surrounded by N-doped carbon prepared by the pyrolysis of Cophenanthroline complex on different supports and their catalytic applications
Entry Ratio of
Co-phenanthroline
Support Pyrolysis
conditions
(t, Ar, t)
Nature of cobalt
particles
Catalytic
applications
1
1:2
Carbon 800 °C,
Ar, 2 h
Co 3 O 4 nanoparticles
surrounded by
N-doped graphene
Hydrogenation of
nitro compounds
and reductive
amination
2
1:2
Carbon 800 °C,
Ar, 2 h
Co 3 O 4 nanoparticles
surrounded by
N-doped graphene
Synthesis of esters
and nitriles form
alcohols
3
1:2
α-Al 2 O 3
Co, Co 3 O 4
nanoparticles
surrounded by
N-doped graphene
Hydrogenation of
quinlaines, nitriles
and carbonyl
compounds
4
1:2
SiO 2
Co, CoO and Co 3 O 4
nanoparticles
encapsulated in
N-doped graphitic
shells
Semi-hydrogenation
of alkynes to alkenes
5
1:7 or 1:10
Carbon
Cobalt single atoms
with CoNx centers
Dehydrogenation of
formic acid for the
generation of
hydrogen
(or hydrogenation) of N-heterocycles to store H 2 , using formic acid or external
hydrogen as a hydrogen source (Scheme 6.16) [27]. Several tetrahydroquinolines
and indolines were selectively dehydrogenated producing quinolines and indoles in
up to 99% yields [27].
In addition to nitrogen ligated metal complexes, in recent years, nitrogen-based
metal organic frameworks (MOFs) were conveniently used as suitable procures
for the preparation of N-doped carbon supported nanoparticles-based catalysts by
pyrolytic processes [28–31]. Notably, MOFs prepared using different metal ions and
organic linkers represent a stable class of porous compounds, which can be assembled in a highly modular manner [32, 33]. Due to their structural tunability, different
MOFs can be obtained, which can serve as desired precursors to prepare active and
selective nanoparticle-based catalysts.
In general, nitrogen-based MOFs can be directly pyrolyzed [28–30], which act
as self-sacrifying templates or can be immobilized/assembled on heterogeneous
supports followed by pyrolysis [31] to generate metal nanoparticles supported on
nitrogen doped carbons (Scheme 6.17).
Li et al. [30] have shown that direct pyrolysis of Co-DABCO-TPA-TPA (DABCO
= 1,4-diazabicyclo[2.2.2]octane; triethylenediamine. TPA = terephthalic acid; 1,4benzenedioic acid, BDA) at 900 °C under an inert atmosphere produced bifunctional N-doped cobalt nanoparticle (Co@NC-900)-based catalysts. On pyrolysis, this