514
efforts on the development of sustainable chemical catalytic processes for the conversion of bioethanol to 1-butanol via classical Guerbet chemistry [73, 74]. A number of reviews covering in detail the development of both homogeneous and
heterogeneous processes and catalysts for the conversion of ethanol to 1-butanol
have been published [56, 75–77]. Several types of heterogeneous catalysts, based on
MgO, Mg−Al-O mixed oxides, Cu/CeO 2 , basic zeolites, hydroxyapatite, solid acidsupported Cu and alumina- and carbon-supported metal catalysts, in batch and continuous-flow mode, under different reaction conditions, have been explored [77].
1-Butanol yields in the range 20–30% could be obtained with heterogeneous catalysts [77] along with the formation of C 4+ alcohols. With Ru-based homogeneous
catalysts, n-butanol selectivity as high as 94%, but at very low ethanol conversion of
22% (21% yield of butanol), has been reported [78]. Thus, achieving high yields of
1-butanol remains a challenge. Increase in demand for 1-butanol has led to the
revival of one of the oldest known fermentation processes, ABE (acetone- butanolethanol) process for production of 1-butanol, using different strains of Clostridium
sp. with glucose, starch, molasses, corn stover, rice straw and cranny grass as feedstocks [79–81]. Different types of biomass feedstocks, microorganisms, biomass
pretreatment methods, extraction methods, genetic engineering techniques like cell
recycle and cell immobilization and strategies to minimize product inhibition have
been adopted to improve butanol yield [82–84]. Using starch-based packing peanuts
as substrate for continuous production with C. beijerinckii BA101strains, 18.9 g/L
of butanol could be produced from 80.0 g/L of the substrate within 110 h, indicating
the crucial role played by the selection of substrate and microbial strain [85].
C 2 , C 3 and C 4 diols are highly useful chemical intermediates which can be transformed into a number of value-added products. Mono ethylene glycol (MEG) is
manufactured by hydrolysis of ethylene oxide, which in turn is produced by catalytic oxidation of ethylene. Major application of MEG is as the monomer in the
manufacture of polyester fibre and polyethylene terephthalate (PET), PTA being the
other monomer. Other minor applications include anti-freeze and coolants, solvents
and chemical intermediates (Fig. 8).
With the growing emphasis on sustainable products, bio-based PET is being
manufactured, using bio-MEG produced using ethylene obtained by dehydration of
bioethanol. PlantBottle, made from PET using bio-MEG and PTA, was introduced
by Coca Cola [56, 87] in 2009. Global market for bio-based PET (containing 30%
bio-MEG and 70% PTA) is expected to touch 5.8 million tons by 2020 and consequently help in moving towards sustainable packaging applications. Global sustainable packaging market on the same lines is expected to grow from US$ 200.00
billion in 2014 to US$ 267.00 billion in 2020, with a CAGR of 4.9%.
C 3 diols, namely, 1,2 and 1,3 propane diols are valuable monomers for the production of polyesters, polycarbonates and polyurethanes, besides having applications as anti-freezing agents, additive in nutrition products, solvents and component
of hydraulic fluids [56]. 1,3-Propane diol (1,3 PDO) on polymerization with terephthalic acid yields commercial polyesters, SORONA
®
(from DuPont) and
CORTERRA
®
(from Shell), which are used in the manufacture of high-quality carpet and textile fibres. While 1,2-PDO is produced by selective hydrolysis of
R. Vinayagamoorthi et al.
efforts on the development of sustainable chemical catalytic processes for the conversion of bioethanol to 1-butanol via classical Guerbet chemistry [73, 74]. A number of reviews covering in detail the development of both homogeneous and
heterogeneous processes and catalysts for the conversion of ethanol to 1-butanol
have been published [56, 75–77]. Several types of heterogeneous catalysts, based on
MgO, Mg−Al-O mixed oxides, Cu/CeO 2 , basic zeolites, hydroxyapatite, solid acidsupported Cu and alumina- and carbon-supported metal catalysts, in batch and continuous-flow mode, under different reaction conditions, have been explored [77].
1-Butanol yields in the range 20–30% could be obtained with heterogeneous catalysts [77] along with the formation of C 4+ alcohols. With Ru-based homogeneous
catalysts, n-butanol selectivity as high as 94%, but at very low ethanol conversion of
22% (21% yield of butanol), has been reported [78]. Thus, achieving high yields of
1-butanol remains a challenge. Increase in demand for 1-butanol has led to the
revival of one of the oldest known fermentation processes, ABE (acetone- butanolethanol) process for production of 1-butanol, using different strains of Clostridium
sp. with glucose, starch, molasses, corn stover, rice straw and cranny grass as feedstocks [79–81]. Different types of biomass feedstocks, microorganisms, biomass
pretreatment methods, extraction methods, genetic engineering techniques like cell
recycle and cell immobilization and strategies to minimize product inhibition have
been adopted to improve butanol yield [82–84]. Using starch-based packing peanuts
as substrate for continuous production with C. beijerinckii BA101strains, 18.9 g/L
of butanol could be produced from 80.0 g/L of the substrate within 110 h, indicating
the crucial role played by the selection of substrate and microbial strain [85].
C 2 , C 3 and C 4 diols are highly useful chemical intermediates which can be transformed into a number of value-added products. Mono ethylene glycol (MEG) is
manufactured by hydrolysis of ethylene oxide, which in turn is produced by catalytic oxidation of ethylene. Major application of MEG is as the monomer in the
manufacture of polyester fibre and polyethylene terephthalate (PET), PTA being the
other monomer. Other minor applications include anti-freeze and coolants, solvents
and chemical intermediates (Fig. 8).
With the growing emphasis on sustainable products, bio-based PET is being
manufactured, using bio-MEG produced using ethylene obtained by dehydration of
bioethanol. PlantBottle, made from PET using bio-MEG and PTA, was introduced
by Coca Cola [56, 87] in 2009. Global market for bio-based PET (containing 30%
bio-MEG and 70% PTA) is expected to touch 5.8 million tons by 2020 and consequently help in moving towards sustainable packaging applications. Global sustainable packaging market on the same lines is expected to grow from US$ 200.00
billion in 2014 to US$ 267.00 billion in 2020, with a CAGR of 4.9%.
C 3 diols, namely, 1,2 and 1,3 propane diols are valuable monomers for the production of polyesters, polycarbonates and polyurethanes, besides having applications as anti-freezing agents, additive in nutrition products, solvents and component
of hydraulic fluids [56]. 1,3-Propane diol (1,3 PDO) on polymerization with terephthalic acid yields commercial polyesters, SORONA
®
(from DuPont) and
CORTERRA
®
(from Shell), which are used in the manufacture of high-quality carpet and textile fibres. While 1,2-PDO is produced by selective hydrolysis of
R. Vinayagamoorthi et al.