257
Bimetallic MOF-Derived Catalysts
The MOF catalysts suffer from low hydrothermal and chemical stability, which can
be addressed by MOF-derived carbon-based metal and metal oxides. The carbon
material has high stability for the chemical and hydrothermal environment. A
bimetallic catalyst (CuNi@C), prepared by impregnation of nickel nitrate onto
Cu-based MOFs, was utilized for conversion of furfural to cyclopentanone at
130 °C, 5 MPa for 5 h. As a result, a 96.9% yield of the product was obtained.
Cyclopentanone has wide applications in insecticide, medicine, and perfume
industries. It can also be used as a solvent in the electronics industry [67]. In another
work, the CuCo 0.4 /C-873 catalyst is tested for the conversion of furfural to furfuryl
alcohol. The catalyst is derived from Co-doped Cu-BTC MOF by thermolysis in a
nitrogen environment at a temperature ranging from 773 K to 1073 K.; the doping
of the cobalt helped inefficient dispersion of Co and Cu nanoparticles. The
thermolysis temperature has an effect on the chemical state of the catalyst. At the
best catalytic performance, 98.7% furfural was converted with high selectivity of
furfural alcohol (97.7%) [68].
The Ni nanoparticle catalyst generated in situ with the help of MOF precursor
(MIL-77(Ni)) is used for hydrotreatment of lignocellulosic biomass to avoid the
disadvantages of supported catalysts such as metal leaching, coke deposition,
polymerization of unstable species, less water tolerance, etc. The catalyst was found
to be ten times more active than a conventional catalyst, i.e., Ni/SiO 2 -Al 2 O 3 . The
higher activity is attributed to high purity and crystallinity due to in situ generation
and the robust MOF network [69].
Overall, MOFs are a good alternative to microporous zeolites, mesoporous silica, and carbon-based catalysts. It offers numerous advantages such as reduced
mass transfer resistance, improved surface properties, and efficient immobilization
of functional groups. However, its uses as a catalyst get restricted due to high synthesis cost, leaching of active species, and low hydrothermal stability. Thus, directed
efforts are required toward the structure-activity analysis of MOFs to be widely
accepted as a catalyst for biomass conversion [5].
2.3.3 Solid-Phase Ionic Liquid (IL)-Based Catalyst
Ionic liquids (ILs) are generally in the liquid state at room temperature and have a
melting point below 100 °C. They are organic salts and are increasingly used as an
alternative solvent to conventional volatile solvents. They consist of organic cation
and inorganic or organic anions. The advantages of ILs are their extremely low
vapor pressure and high thermal stability, which are helpful in developing the
greener technologies and sometimes referred to as green solvents [70]. Additionally,
ILs possess tunable physical properties by virtue of the different combination of
cations and anions. The properties of ILs, such as viscosity, density, melting point,
solubility, and acidity, can be tuned. Theoretically, it is possible to synthesize 10
18
Sustainability of the Catalytic Process for Biomass Conversion: Recent Trends and…
Bimetallic MOF-Derived Catalysts
The MOF catalysts suffer from low hydrothermal and chemical stability, which can
be addressed by MOF-derived carbon-based metal and metal oxides. The carbon
material has high stability for the chemical and hydrothermal environment. A
bimetallic catalyst (CuNi@C), prepared by impregnation of nickel nitrate onto
Cu-based MOFs, was utilized for conversion of furfural to cyclopentanone at
130 °C, 5 MPa for 5 h. As a result, a 96.9% yield of the product was obtained.
Cyclopentanone has wide applications in insecticide, medicine, and perfume
industries. It can also be used as a solvent in the electronics industry [67]. In another
work, the CuCo 0.4 /C-873 catalyst is tested for the conversion of furfural to furfuryl
alcohol. The catalyst is derived from Co-doped Cu-BTC MOF by thermolysis in a
nitrogen environment at a temperature ranging from 773 K to 1073 K.; the doping
of the cobalt helped inefficient dispersion of Co and Cu nanoparticles. The
thermolysis temperature has an effect on the chemical state of the catalyst. At the
best catalytic performance, 98.7% furfural was converted with high selectivity of
furfural alcohol (97.7%) [68].
The Ni nanoparticle catalyst generated in situ with the help of MOF precursor
(MIL-77(Ni)) is used for hydrotreatment of lignocellulosic biomass to avoid the
disadvantages of supported catalysts such as metal leaching, coke deposition,
polymerization of unstable species, less water tolerance, etc. The catalyst was found
to be ten times more active than a conventional catalyst, i.e., Ni/SiO 2 -Al 2 O 3 . The
higher activity is attributed to high purity and crystallinity due to in situ generation
and the robust MOF network [69].
Overall, MOFs are a good alternative to microporous zeolites, mesoporous silica, and carbon-based catalysts. It offers numerous advantages such as reduced
mass transfer resistance, improved surface properties, and efficient immobilization
of functional groups. However, its uses as a catalyst get restricted due to high synthesis cost, leaching of active species, and low hydrothermal stability. Thus, directed
efforts are required toward the structure-activity analysis of MOFs to be widely
accepted as a catalyst for biomass conversion [5].
2.3.3 Solid-Phase Ionic Liquid (IL)-Based Catalyst
Ionic liquids (ILs) are generally in the liquid state at room temperature and have a
melting point below 100 °C. They are organic salts and are increasingly used as an
alternative solvent to conventional volatile solvents. They consist of organic cation
and inorganic or organic anions. The advantages of ILs are their extremely low
vapor pressure and high thermal stability, which are helpful in developing the
greener technologies and sometimes referred to as green solvents [70]. Additionally,
ILs possess tunable physical properties by virtue of the different combination of
cations and anions. The properties of ILs, such as viscosity, density, melting point,
solubility, and acidity, can be tuned. Theoretically, it is possible to synthesize 10
18
Sustainability of the Catalytic Process for Biomass Conversion: Recent Trends and…