616
into a valuable product, the use of strong acid/alkali is substantial, but there are
certain limitations. For instance, in a conventional viscose process on cellulose
regeneration, CS 2 with strong alkalis and mineral acid is used, which releases H 2 S
and SO 2 into the environment leading to air pollution. To overcome environmental
problems and achieve better dissolution with high reactivities, a variety of new solvents have been employed. N-Methylmorpholine-N-oxide,N,N- dimethylformamide/
dinitrogen tetroxide (DMF-N 2 O 4 ), molten salt hydrates (LiClO 4 ·3H 2 O,
LiSCN·2H 2 O),
N,N-dimethylacetamide/lithium
chloride
(DMA- LiCl),
N-methylmorpholine-N-oxide (NMMO), and dimethyl sulfoxide tetrabutylammonium (DMSO/TBAF) are few examples. However, some serious drawbacks such as
the requirement of harsh conditions, low dissolving power, high processing cost due
to difficult solvent recovery, and comparatively higher toxicity are still existing,
which limits the overall applicability for industrial uses. It is to note that converting
sugars like mono- and disaccharides into HMF/fur requires less energy than the
lignocellulose due to the absence of lignin and strong H-bonding network within the
structure. For further understanding about the trends in HMF production from sugar
molecules, readers may refer previously published literature [8, 13, 24]. Since the
focus of this chapter is the utilization of raw biomass for chemicals and fuels, discussion on mono- and disaccharide-mediated HMF production has been avoided.
This chapter is aimed to summarize the recent developments in raw biomass conversion over the use of various catalysts, including ionic liquids under mild thermal
conditions. Further, discussion proposed a progressive pathway toward HMF/Fur
production starting from raw biomass and the need for combined bio- and chemocatalytic approach for producing high-value molecules for fuel and chemical
industries.
2 Transformation of Lignocellulosic Biomass
With the increasing demand for food, energy, and materials, the United Nations has
estimated the global population to increase from 7.7 billion to 9.1 billion by 2050
[25]. One compound that has attracted attention from both academic and industrial
researchers is Fur, a triple dehydration product (furanic heterocycle molecule with
aldehyde functionality). The furfural is directly derived from hemicellulosic biomasses by hydrolysis and subsequent dehydration of pentose sugars in suitable acid
catalysts under the desired solvent medium. It is an inefficient, high-cost production
of furfural and non-scalability. The focus is yet to be established on the future possibilities for economically and environmentally feasible technologies based on
recyclable solvent catalysts to minimize the use of high boiling solvents and mineral
acid. In this direction, the conversion of hemicellulosic biomass into furfural via
hydrolysis followed by dehydration would create a high impact in furfural synthesis. Further valorization in such a scalable quantity can be used as a future platform
chemical to produce second-generation biofuels and build block chemicals.
M. I. Alam
into a valuable product, the use of strong acid/alkali is substantial, but there are
certain limitations. For instance, in a conventional viscose process on cellulose
regeneration, CS 2 with strong alkalis and mineral acid is used, which releases H 2 S
and SO 2 into the environment leading to air pollution. To overcome environmental
problems and achieve better dissolution with high reactivities, a variety of new solvents have been employed. N-Methylmorpholine-N-oxide,N,N- dimethylformamide/
dinitrogen tetroxide (DMF-N 2 O 4 ), molten salt hydrates (LiClO 4 ·3H 2 O,
LiSCN·2H 2 O),
N,N-dimethylacetamide/lithium
chloride
(DMA- LiCl),
N-methylmorpholine-N-oxide (NMMO), and dimethyl sulfoxide tetrabutylammonium (DMSO/TBAF) are few examples. However, some serious drawbacks such as
the requirement of harsh conditions, low dissolving power, high processing cost due
to difficult solvent recovery, and comparatively higher toxicity are still existing,
which limits the overall applicability for industrial uses. It is to note that converting
sugars like mono- and disaccharides into HMF/fur requires less energy than the
lignocellulose due to the absence of lignin and strong H-bonding network within the
structure. For further understanding about the trends in HMF production from sugar
molecules, readers may refer previously published literature [8, 13, 24]. Since the
focus of this chapter is the utilization of raw biomass for chemicals and fuels, discussion on mono- and disaccharide-mediated HMF production has been avoided.
This chapter is aimed to summarize the recent developments in raw biomass conversion over the use of various catalysts, including ionic liquids under mild thermal
conditions. Further, discussion proposed a progressive pathway toward HMF/Fur
production starting from raw biomass and the need for combined bio- and chemocatalytic approach for producing high-value molecules for fuel and chemical
industries.
2 Transformation of Lignocellulosic Biomass
With the increasing demand for food, energy, and materials, the United Nations has
estimated the global population to increase from 7.7 billion to 9.1 billion by 2050
[25]. One compound that has attracted attention from both academic and industrial
researchers is Fur, a triple dehydration product (furanic heterocycle molecule with
aldehyde functionality). The furfural is directly derived from hemicellulosic biomasses by hydrolysis and subsequent dehydration of pentose sugars in suitable acid
catalysts under the desired solvent medium. It is an inefficient, high-cost production
of furfural and non-scalability. The focus is yet to be established on the future possibilities for economically and environmentally feasible technologies based on
recyclable solvent catalysts to minimize the use of high boiling solvents and mineral
acid. In this direction, the conversion of hemicellulosic biomass into furfural via
hydrolysis followed by dehydration would create a high impact in furfural synthesis. Further valorization in such a scalable quantity can be used as a future platform
chemical to produce second-generation biofuels and build block chemicals.
M. I. Alam