714
Although the gaseous-phase hydrogenation in the presence of copper (Cu) catalyst
of furfural is the favoured route for conversion of FUR to biofuels, in this report we
tried to explore the field of liquid-phase hydrogenation which is much more feasible
from lab-scale perspective. From economical perspective, the liquid-phase hydrogenation requires much less as compared to the gas-phase process. In the gaseousphase hydrogenation of FUR, the use of an evaporator system for FUR feeding,
which consists of a packed column, in addition to that a circulating pump, heaters,
and supply of continuous H 2 gas under high pressure must be maintained.
Hydrogenation of 2-furaldehyde was initially started in year 1928 by a company
called the Quaker Oats Company, by using bimetallic catalyst of nickel (Ni) supported on magnesium oxide (MgO) which required absolute control to prevent total
conversion of FUR and to prevent side-step reactions forming tetrahydrofurfuryl
alcohol as product [2]. One of the most widely catalyst was reduced copper (Cu)
and chromite (Cr), which was used under high temperature and pressure, yielding
more than 90% of furfuryl alcohol production from FUR. Further addition of basic
metal oxides as calcium oxide (CaO) and barium oxide (BaO) resulted in an
improved furfuryl alcohol yield and high selectivity even at low H 2 pressures. From
industrial perspective, the use of chromium catalysts was very much feasible and
successful. But from the environmental concern, the main drawback being excess
toxicity of chromium led to more research in the field of catalysts for designing a
catalyst which is cost-effective, environmentally safe and environmentally friendly.
It was seen that the hydrogenation of furfural was producing chemicals like furfuryl
alcohol and subsequent furanic chemicals with selectivity close to 100%. But the
use of high hydrogen pressure adds to the risk of operation. Hence various metals
like nickel (Ni) and copper (Cu) were mostly under different experimental conditions. By using these multicomponent systems, almost full conversion of furfural to
furfuryl alcohol was attained [24].
With the current effort focussed on developing economically viable, inexpensive
and environmentally sustainable new technologies, H 2 O-organic solvent biphasic
systems such as poly(styrene sulphonic) acid for xylose dehydration to furfural
were used [23]. The mechanism behind such an approach was to utilise the coefficient of partition of FUR between the organic solvent and H 2 O. Due to the absence
of a catalyst in the inhibition phase of degradation reaction, FUR exhibits higher
affinity towards the organic phase. A large variety of catalysts such as sulfonated
metal oxides, sulfonic ion-exchange resins, zeolites and zeotypes, sulfonic acidmodified mesoporous silicas, Keggin heteropoly acids, mesoporous niobium phosphate, etc. have been tried and tested in the recent years. Reaction kinetics of the
liquid-phase selective hydrogenation have been also studied with catalysed synthesised by platinum metal doped over carbon (Pt/C) [25]. The Langmuir-Hinshelwood
dual-site mechanism is adequately followed which have separate active sites associated with hydrogen adsorption and for furfural and furfuryl alcohol. Furfural and
hydrogen adsorption together forms the rate determining step. The copper (Cu)doped catalysts are deactivated, and by atomic layer deposition via sintering and
leaching, it is used for selective liquid-phase hydrogenation [26]. Reducing an aldehyde by oxidising it in the presence of a secondary alcohol, which is also known as
N. J. Mazumdar et al.
Although the gaseous-phase hydrogenation in the presence of copper (Cu) catalyst
of furfural is the favoured route for conversion of FUR to biofuels, in this report we
tried to explore the field of liquid-phase hydrogenation which is much more feasible
from lab-scale perspective. From economical perspective, the liquid-phase hydrogenation requires much less as compared to the gas-phase process. In the gaseousphase hydrogenation of FUR, the use of an evaporator system for FUR feeding,
which consists of a packed column, in addition to that a circulating pump, heaters,
and supply of continuous H 2 gas under high pressure must be maintained.
Hydrogenation of 2-furaldehyde was initially started in year 1928 by a company
called the Quaker Oats Company, by using bimetallic catalyst of nickel (Ni) supported on magnesium oxide (MgO) which required absolute control to prevent total
conversion of FUR and to prevent side-step reactions forming tetrahydrofurfuryl
alcohol as product [2]. One of the most widely catalyst was reduced copper (Cu)
and chromite (Cr), which was used under high temperature and pressure, yielding
more than 90% of furfuryl alcohol production from FUR. Further addition of basic
metal oxides as calcium oxide (CaO) and barium oxide (BaO) resulted in an
improved furfuryl alcohol yield and high selectivity even at low H 2 pressures. From
industrial perspective, the use of chromium catalysts was very much feasible and
successful. But from the environmental concern, the main drawback being excess
toxicity of chromium led to more research in the field of catalysts for designing a
catalyst which is cost-effective, environmentally safe and environmentally friendly.
It was seen that the hydrogenation of furfural was producing chemicals like furfuryl
alcohol and subsequent furanic chemicals with selectivity close to 100%. But the
use of high hydrogen pressure adds to the risk of operation. Hence various metals
like nickel (Ni) and copper (Cu) were mostly under different experimental conditions. By using these multicomponent systems, almost full conversion of furfural to
furfuryl alcohol was attained [24].
With the current effort focussed on developing economically viable, inexpensive
and environmentally sustainable new technologies, H 2 O-organic solvent biphasic
systems such as poly(styrene sulphonic) acid for xylose dehydration to furfural
were used [23]. The mechanism behind such an approach was to utilise the coefficient of partition of FUR between the organic solvent and H 2 O. Due to the absence
of a catalyst in the inhibition phase of degradation reaction, FUR exhibits higher
affinity towards the organic phase. A large variety of catalysts such as sulfonated
metal oxides, sulfonic ion-exchange resins, zeolites and zeotypes, sulfonic acidmodified mesoporous silicas, Keggin heteropoly acids, mesoporous niobium phosphate, etc. have been tried and tested in the recent years. Reaction kinetics of the
liquid-phase selective hydrogenation have been also studied with catalysed synthesised by platinum metal doped over carbon (Pt/C) [25]. The Langmuir-Hinshelwood
dual-site mechanism is adequately followed which have separate active sites associated with hydrogen adsorption and for furfural and furfuryl alcohol. Furfural and
hydrogen adsorption together forms the rate determining step. The copper (Cu)doped catalysts are deactivated, and by atomic layer deposition via sintering and
leaching, it is used for selective liquid-phase hydrogenation [26]. Reducing an aldehyde by oxidising it in the presence of a secondary alcohol, which is also known as
N. J. Mazumdar et al.