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catalyst. The results were even better with hexitol yield up to 53.2% and 54.2%, respectively, for Pd-Ni and Ru-Ni catalyst at 100% conversion of glucose.
2.4.2 Hemicellulose Conversion Using the Bimetallic Catalyst
Hemicellulose is a polymer with C 5 sugars, mainly xylose. Xylose is converted to
xylitol by hydrogenation using a different metal catalyst. The catalyst Ru-Ni is
commonly used to produce xylitol. For catalyst deactivation due to leaching,
deposition is a common issue. Xylitol is a common sweetener used in the food
industry. A platform chemical, furfural, can be obtained by dehydration of xylose
and further hydrogenated to 2-methylfuran, furfural alcohol, and furan. The
Cu-chromite is the most widely used commercial catalyst for hydrogenation [87].
The other bimetallic catalysts used for hemicellulose conversion are Cu/C, Cu/
MgO, NiCu/SiO 2 , CuCO/SiO 2 , etc. Furfural yield of 98% was reported at 473 K
over Cu/MgO and CuCo/SiO 2 catalyst [6].
2.4.3 Lignin Conversion Using the Bimetallic Catalyst
Lignin is a significant fraction of biomass, and its effective utilization will ensure
the economic feasibility of the biomass conversion. Commercially, lignin is used in
a very inefficient manner as 98% of it is burned to fulfill energy demand in pulp
mills, whereas only 2% is utilized toward chemical production. So for the sustainable
operation of biorefinery, lignin conversion to chemicals through technological
advancement is necessary [88, 89]. Lignin possesses aromatic functionality, and
products like benzene, phenol, and cyclohexanes can be made from it through
cracking via hydrogenation and hydrodeoxygenation (HDO). Bimetallic catalysts
such as sulfide, CoMo, and NiMo are used for lignin hydrogenation and HDO. The
catalysts PtSn and PtRh are also reported to be used for lignin conversion. Among
the catalysts, at a lower temperature (<673 K), all Rh-based catalysts are active than
sulfide, CoMo, and NiMo catalysts. Owing to its complexity, model components
such as phenol, cresol, anisole, etc. are used to study the conversion of lignin. Zhang
et al. (2014) [90] conducted the catalytic hydrogenolysis of lignin using NiRu
(Ni = 85% and Ru = 15%) to obtain aromatic chemicals and fuel-grade hydrocarbons.
The results with bimetallic catalysts show better performance than monometallic Ni
and Ru. The best result for pinene transformation was obtained using bimetallic
Au-Cu/TiO 2 catalyst with higher selectivity for verbenone product due to the
synchronized effect between bimetals and their support [91].
2.4.4 Catalytic Conversion of Glycerol Using the Bimetallic Catalyst
Bimetallic catalysts are used for the conversion of biomass-derived glycerol to valuable chemicals. Glycerol can be valorized through hydrogenolysis, hydrogenation,
and oxidation reactions. Hydrogenolysis involves breaking of bonds with the help
R. Bhoi et al.
catalyst. The results were even better with hexitol yield up to 53.2% and 54.2%, respectively, for Pd-Ni and Ru-Ni catalyst at 100% conversion of glucose.
2.4.2 Hemicellulose Conversion Using the Bimetallic Catalyst
Hemicellulose is a polymer with C 5 sugars, mainly xylose. Xylose is converted to
xylitol by hydrogenation using a different metal catalyst. The catalyst Ru-Ni is
commonly used to produce xylitol. For catalyst deactivation due to leaching,
deposition is a common issue. Xylitol is a common sweetener used in the food
industry. A platform chemical, furfural, can be obtained by dehydration of xylose
and further hydrogenated to 2-methylfuran, furfural alcohol, and furan. The
Cu-chromite is the most widely used commercial catalyst for hydrogenation [87].
The other bimetallic catalysts used for hemicellulose conversion are Cu/C, Cu/
MgO, NiCu/SiO 2 , CuCO/SiO 2 , etc. Furfural yield of 98% was reported at 473 K
over Cu/MgO and CuCo/SiO 2 catalyst [6].
2.4.3 Lignin Conversion Using the Bimetallic Catalyst
Lignin is a significant fraction of biomass, and its effective utilization will ensure
the economic feasibility of the biomass conversion. Commercially, lignin is used in
a very inefficient manner as 98% of it is burned to fulfill energy demand in pulp
mills, whereas only 2% is utilized toward chemical production. So for the sustainable
operation of biorefinery, lignin conversion to chemicals through technological
advancement is necessary [88, 89]. Lignin possesses aromatic functionality, and
products like benzene, phenol, and cyclohexanes can be made from it through
cracking via hydrogenation and hydrodeoxygenation (HDO). Bimetallic catalysts
such as sulfide, CoMo, and NiMo are used for lignin hydrogenation and HDO. The
catalysts PtSn and PtRh are also reported to be used for lignin conversion. Among
the catalysts, at a lower temperature (<673 K), all Rh-based catalysts are active than
sulfide, CoMo, and NiMo catalysts. Owing to its complexity, model components
such as phenol, cresol, anisole, etc. are used to study the conversion of lignin. Zhang
et al. (2014) [90] conducted the catalytic hydrogenolysis of lignin using NiRu
(Ni = 85% and Ru = 15%) to obtain aromatic chemicals and fuel-grade hydrocarbons.
The results with bimetallic catalysts show better performance than monometallic Ni
and Ru. The best result for pinene transformation was obtained using bimetallic
Au-Cu/TiO 2 catalyst with higher selectivity for verbenone product due to the
synchronized effect between bimetals and their support [91].
2.4.4 Catalytic Conversion of Glycerol Using the Bimetallic Catalyst
Bimetallic catalysts are used for the conversion of biomass-derived glycerol to valuable chemicals. Glycerol can be valorized through hydrogenolysis, hydrogenation,
and oxidation reactions. Hydrogenolysis involves breaking of bonds with the help
R. Bhoi et al.