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whenever heterogeneous catalysts are used. The energy density of biomass can be
increased through the removal of oxygen and can be achieved through various conversion processes mentioned earlier. Thermal processes are nonselective, whereas chemical processes are selective such as dehydration, hydrogenolysis, decarboxylation, and
decarbonylation. The catalyst then affects the conversion rates and the selectivity of
the products but suffers from deactivation. Many catalysts for biomass conversion
have been tested, but few found suitable on the basis of stability, selectivity, and reusability. Most of the catalysts are tested with model components, and the problem
appears when real feedstocks with impurities are used. Bimetallic catalysts seem to be
promising as the catalyst properties can be modified to handle real feedstocks [6].
The porosity of the catalysts plays a vital role in biomass conversion. Porous materials with mixed pores (micro, meso, and macro), compared with single-mode pores,
are more suitable for biomass conversion [7]. As an important step in processing,
biomass is converted to platform chemicals through various routes. There are five
platforms reported in the literature. They are the sugar platform, thermochemical or
syngas platform, biogas platform, carbon-rich chain platform, and plant product platform. The sugar platform focuses on the fermentation of sugar extracted from biomass; the thermochemical platform focuses on the gasification/pyrolysis of biomass
feedstock; the biogas platform decomposes the biomass through anaerobic digestion
with the help of microorganism, carbon-rich platform converts oil and fats via etherification/transesterification; and plant product platform is the biorefinery operations in
a plant kingdom itself rather than in an industrial plant. Sometimes, the plant strains
are genetically modified to produce more feedstock or chemicals than it does naturally. Presented below is the list of top 12 chemical products that form the building
blocks of the biorefinery by evaluating their potential market, their derivatives, and the
technical complexity of the synthesis pathways [8]; these are:
• 1,4- Succinic, 1,4-fumaric, and 1,4-malic acids
• 2,5-Furandicarboxylic acid
• 3-Hydroxy propionic acid
• Aspartic acid
• Glucaric acid
• Glutamic acid
• Itaconic acid
• Levulinic acid
• 3-Hydroxybutyrolactone
• Glycerol
• Sorbitol
• Xylitol/arabinitol
2.1 Catalytic Processes for Lignocellulosic
Biomass Conversion
In this section, the various catalytic processes for the conversion of biomass into
fuels and valuable chemicals are discussed. The chemical processes for biomass
conversion are sensitive to reaction conditions and nature of solvents and catalysts
and produce a complex mixture of products requiring further separation and
Sustainability of the Catalytic Process for Biomass Conversion: Recent Trends and…
whenever heterogeneous catalysts are used. The energy density of biomass can be
increased through the removal of oxygen and can be achieved through various conversion processes mentioned earlier. Thermal processes are nonselective, whereas chemical processes are selective such as dehydration, hydrogenolysis, decarboxylation, and
decarbonylation. The catalyst then affects the conversion rates and the selectivity of
the products but suffers from deactivation. Many catalysts for biomass conversion
have been tested, but few found suitable on the basis of stability, selectivity, and reusability. Most of the catalysts are tested with model components, and the problem
appears when real feedstocks with impurities are used. Bimetallic catalysts seem to be
promising as the catalyst properties can be modified to handle real feedstocks [6].
The porosity of the catalysts plays a vital role in biomass conversion. Porous materials with mixed pores (micro, meso, and macro), compared with single-mode pores,
are more suitable for biomass conversion [7]. As an important step in processing,
biomass is converted to platform chemicals through various routes. There are five
platforms reported in the literature. They are the sugar platform, thermochemical or
syngas platform, biogas platform, carbon-rich chain platform, and plant product platform. The sugar platform focuses on the fermentation of sugar extracted from biomass; the thermochemical platform focuses on the gasification/pyrolysis of biomass
feedstock; the biogas platform decomposes the biomass through anaerobic digestion
with the help of microorganism, carbon-rich platform converts oil and fats via etherification/transesterification; and plant product platform is the biorefinery operations in
a plant kingdom itself rather than in an industrial plant. Sometimes, the plant strains
are genetically modified to produce more feedstock or chemicals than it does naturally. Presented below is the list of top 12 chemical products that form the building
blocks of the biorefinery by evaluating their potential market, their derivatives, and the
technical complexity of the synthesis pathways [8]; these are:
• 1,4- Succinic, 1,4-fumaric, and 1,4-malic acids
• 2,5-Furandicarboxylic acid
• 3-Hydroxy propionic acid
• Aspartic acid
• Glucaric acid
• Glutamic acid
• Itaconic acid
• Levulinic acid
• 3-Hydroxybutyrolactone
• Glycerol
• Sorbitol
• Xylitol/arabinitol
2.1 Catalytic Processes for Lignocellulosic
Biomass Conversion
In this section, the various catalytic processes for the conversion of biomass into
fuels and valuable chemicals are discussed. The chemical processes for biomass
conversion are sensitive to reaction conditions and nature of solvents and catalysts
and produce a complex mixture of products requiring further separation and
Sustainability of the Catalytic Process for Biomass Conversion: Recent Trends and…