Furfural

In this work, the desorption of furfural, which is a competitive intermediate during the production of biofuel and valuable aromatic compounds, was studied using pure alumina, as well as alumina impregnated with iron and platinum oxides both individually and in combination, using thermogravimetric analysis (TGA). The bimetallic sample exhibited the lowest desorption percentage for furfural. High-resolution transmission electron microscopy (HRTEM) imaging revealed the intimate connection between the iron and platinum oxide species on the alumina support. The mechanism of furfural desorption from the Pt-Fe/Al2O3 0.5%-0.5% sample was determined using physisorbed furfural instead of chemisorbed furfural; this mechanism involved the oxidation of the C=O group on furfural by the catalyst. The oxide nanoparticles on γ-Al2O3 support helped to stabilize the furfural molecule on the surface.

For the synthesis of important platform chemicals such as sugars (xylose and arabinose) and furans (furfural and 5-hydroxymethylfurfural (HMF)) from carbohydrates (hemicellulose and fructose) solid acid catalysts are employed. Similarly, over solid acid catalysts, conversion of lignin into aromatic monomers is performed. It is observed that in the dehydration of fructose, because of higher hydrothermal stability, silicoaluminophosphate (SAPO) catalysts give better activity (78% HMF yield) compared with other solid acid cata-
lysts (<63% HMF yield) at 175o C. Particularly, SAPO-44 catalyst can be reused at least 5 times with marginal decrease in the activity. Zeolite, HUSY (Si/Al = 15) is active in the conversion of isolated (pure) hemicellulose to produce 41% C5 sugars in water. The catalyst is also active in the selective conversion of hemicellulose from bagasse to yield 59% C5 sugars. It is possible to obtain high yields of furfural (54%) directly from bagasse if instead of water, water+toluene solvent system is used. Depolymerization of lignin using HUSY catalyst produced aromatic monomers with 60% yield at 250o C. A detailed catalyst characterization study is performed to understand the correlation between catalyst activity and morphology. To understand the effect of impurities present in the substrate over solid acid catalysts, metal-exchange study is carried out.

We have synthesized ordered Ni x Sn y nano-particles separated by Al 2 O 3 as highly efficient catalysts for the vapor phase hydrogenation of furfural. The Ni x Sn y-Al 2 O 3 composite catalysts with different chemical compositions (Ni 3 Sn 4 , Ni 3 Sn, Ni 1.5 Sn, Ni 3 Sn 2 , Ni) were prepared through the layered double hydroxide (LDH) route by annealing at 800 °C in the presence of H 2. Ni x Sn y nanoparticles were well dispersed throughout the Al 2 O 3 matrix indicating the high thermal stability of these materials. The effect of different concentration of Ni, Sn, and Al in the formation of Ni x Sn y-Al 2 O 3 catalyst was investigated. The X-ray diffraction, transmission electron microscopy, and X-ray absorption fine structure analyses indicate the formation of intermetallic phases with spherical particles having an average size of 30−160 nm. The nanoparticles with different compositions were tested toward the hydrogenation of furfural, and it was found that crystal structure, atomic ordering and composition play crucial roles in the catalytic activity. DFT calculations indicate that the adsorption energy and the geometrical orientation of furfural on the surface of different Ni x Sn y-Al 2 O 3 compounds play crucial role in the hydrogenation of furfural. Ni 3 Sn 2 −Al 2 O 3 was found to be the most efficient catalyst with high furfural conversion (∼65%) and selectivity (57−62%) for furfuryl alcohol.

In recent studies, importance has been given to the use of natural products from renewable resources due to the decrease in the supply and price escalations of petroleum raw materials. Cardanol-based resole type phenolic resin has been synthesized by condensing cardanol with furfural in a  particular mole ratio using a dicarboxylic acid catalyst such as phthalic acid.  Polyurethane sheets were prepared by treating cardanol furfural resin with  4,41–methylene bis(cyclohexyl  isocyanate)    and  the  catalyst  dibutyltin  dilaurate.    Natural fibers are prospective reinforcing materials and their use until now has been more traditional than technical.    Among the various fibers, sisal is of particular interest in that its composites have high impact strength besides having moderate tensile and flexural properties compared to other fibers.    Fiber-reinforced polyurethane composites have been prepared by treating sisal fiber (10%)  into  polyurethane.  The physicochemical, spectral, and thermal properties of polyurethane and fiber-reinforced polyurethane composites have been studied

Energy demand is ever increasing, fossil fuels are depleting at faster rate and
emission of green house gases by fossil fuels are increasing, this scenario forced the
researchers to investigate alternate fuel. Biomass energy is a viable option as an
alternative due to reduced CO2 emissions. Biomass from food crops not a good option
due to demand of food. Lignocellulosic feed stocks are residues of food crop and
forestry waste. This makes researchers to focus on the conversion of feed stock to
useful green fuels and other flat form chemicals. This present paper briefly reviews the
conversion of lignocellulosic material conversion to furfural and furfuryl alcohol by
hydrolysis process

The results of a study on the preparation of furfural, an important industrial chemical, from rice hulls, an abundantly available agricultural waste, are presented. Furfural has been obtained in satisfactory yield by the hydrolysis of the hulls with dilute sulphuric acid. The optimum conditions worked out for getting maximum yield of furfural (53,4% on the basis of the pentosans present in rice hulls) are: Conc. of sulphuric acid, 6% ; reaction temp., 150°C; and reaction period, 2 hr.

Development of stable, reusable, and water-tolerant solid acid catalysts in the conversion of polysaccharides to give value-added chemicals is vital because catalysts are prone to undergo morphological changes during the reactions. With the anticipation that silicoaluminophosphate (SAPO) catalysts will have higher hydrothermal stability, those were synthesized, characterized, and employed in a one-pot conversion of hemicellulose. SAPO-44 catalyst at 170° C within 8 h could give 63% furfural yield with 88% mass balance and showed similar activity up to at least 8 catalytic cycles. The morphological studies revealed that SAPO catalysts having hydrophilic characteristics are stable under reaction conditions.

Levulinic acid (LA) can be produced from lignocellulosic materials via hydroxylation followed by an acid-catalyzed conversion of hexoses. Inorganic homogeneous catalysts are mostly used, in particular sulphuric acid, yielding a mixture of LA with sulphuric acid, formic acid (FA) and furfural. Significant attention has been paid to optimization of the yield, but purification of the LA is a challenge too. This work focuses on the separation of LA from the complex aqueous mixtures by liquid-liquid extraction. Two aqueous product feeds were considered, reflecting two different processes. One aqueous product stream contains sulphuric acid and LA, while the second product stream also contains formic FA and furfural. Furfural could be removed selectively via liquid-liquid extraction with toluene. For selective extraction of LA and FA without co-extracting sulphuric acid, 30 wt.% of trioctylphosphine oxide (TOPO) in methylisobutylketone (MIBK) was found most suitable, showing a high selectivity over sulphuric acid, and a high equilibrium partitioning of LA. When instead of MIBK, 1-octanol was applied as diluent, the co-extraction of FA was enhanced, while hexanoic acid suppressed the acid extraction. To obtain the LA pure, eventually a distillation is required, and the potential of temperature swing back extraction (TSBE) at 90 °C to pre-concentrate the acid solutions was evaluated for 30 wt.% TOPO in MIBK. This pre-concentration step increased the concentrations of LA and FA by a factor of 2.45 and 2.45 respectively, reducing the distillation reboiler duty from roughly 31.5 to 11.3 GJ per ton LA, at a cost of roughly 4.5 GJ heating duty per ton produced LA.

Japanese cedar (Cryptomeria japonica) was treated with hot-compressed water and as
decomposed products, the following compounds were recovered: furfural, 5-hydroxymethyl
furfural, levoglucosan, lactic acid, glycolic acid, coniferyl alcohol, coniferyl aldehyde and
vanillin. The impacts and fermentability of these compounds were studied on acetic acid
fermentation by the co-culture of Clostridium thermocellum and Moorella thermoacetica. It was
Low
concentration
High
concentration
Hydrolyzate Saccharides
Decomposed
products:
furfural, 5-HMF,
coniferyl alcohol,
coniferyl
aldehyde, vanillin
etc.
0 40 80 120
0
2
4
6
8
Co-immobilized
cells
Free cells
Fermentation time (h) Acetic acid (g/L)
Theoretical max.
Inhibitory
Not inhibitory to free
C. thermocellum and M. thermoacetica
Co-immobilization
 Enhanced tolerance
to inhibitors
 Increased acetic
acid production
from total
hydrolyzate
3
found that furfural, 5-HMF and lignin-derived products strongly limited acetic acid production.
Co-immobilization of C. thermocellum and M. thermoacetica successfully removed the negative
effects of these decomposed products and provided acetic acid corresponding to 93 % of the
theoretical maximum from Japanese cedar hydrolyzates.

The impact of furfural on hydrogen production and microbial growth kinetics was assessed using mixed anaerobic cultures at mesophilic and thermophilic conditions. Mesophilic experiments showed a hydrogen yield of 1.6 mol H 2 /mol initial sugars at 1 g/L furfural which is a 45% enhancement from the control (0 g/L furfural) at a substrate-to-biomass ratio (S /X) of 4 gCOD/gVSS. On the other hand, thermophilic experiments showed no enhancement at 1 g/L furfural but rather a 53% decrease in hydrogen yield from its control. Furfural inhibition threshold limit was observed to be greater than 1 g/L for mesophilic experiments and less than 1 g/L for thermophilic experiments. In both cases, 4 g/L was the most recalcitrant furfural concentration, with propionate and lactate the most predominant soluble metabolites in the mesophilic and thermophilic experiments respectively. It was also noted that in the presence of furfural, hydrogen-producers in both mesophilic and thermophilic mixed cultures were inactivated as no hydrogen was produced until furfural was completely degraded irrespective of sugars degradation. This study also presents the kinetics of microbial growth and substrate degradation obtained using the Monod model on MATLAB ® , ignoring an inhibition term. IC 50 of the mesophilic and thermophilic experiments were 1.03 g/L and 0.5 g/L respectively indicating that the thermophilic hydrogen producers were more strongly affected by furfural than the mesophilic cultures.

There were investigated grape marc spirits regarding their safety on consumers. Major volatile compounds which present risk to human health (such as methanol, furfural, and acetaldehyde) and ethyl alcohol content were compared to European Union Regulation and other values found in previous studies.  The aim of our study was to evaluate the safety of grape marc spirits considering their content in major volatile compounds by comparison with the requirements of European Union Regulation. We investigated the ethyl alcohol content by electronic densimetry and 10 major volatile compounds (acetaldehyde, ethyl acetate, methanol, 1-propanol, 1-butanol, 2-butanol, isobutyl alcohol, isoamyl alcohol, amyl active alcohol and furfural) by Gas Chromatography coupled with Flame Ionization Detector. We used reference chemicals to identify these compounds and 3-pentanol as internal standard to quantify the volatiles. Results were compared with the requirements of European Union Regulation. All major...

In this work, we assessed the potential of southern cattail (Typha domingensis) as a lignocellulosic material for producing furfural in some regions. Also, we modeled and optimized the process involving autohydrolysis of the raw material, and its subsequent separation by liquid–liquid extraction and simple distillation. The process is based on biorefining principles and aimed at preserving the integrity of other polymer fractions of the raw material for subsequent use. The autohydrolysis liquor and furfural were characterized by Fourier-transform infrared spectroscopy (FTIR), ultraviolet–visible spectroscopy, and high pressure liquid chromatography (HPLC). Also, a central composite factor design was used to model and optimize the autohydrolysis/liquid–liquid extraction process for conversion of hemicellulosic materials into furfural. Based on the results, southern cattail is a suitable material for extracting hemicellulose to be converted into furfural while preserving other fractions of use for other purposes. The optimum operating ranges for the autohydrolysis conditions were found to be 177–189 °C and 30–45 min. Under such conditions, 20–25% of all xylan in the raw material was converted into furfural with little simultaneous production of degradation products. Furfural in the autohydrolysis liquor was separated virtually quantitatively by extraction with chloroform and subsequent simple distillation.

In this work, we assessed the potential of southern cattail (Typha domingensis) as a lignocellulosic material for producing furfural in some regions. Also, we modeled and optimized the process involving autohydrolysis of the raw material, and its subsequent separation by liquid-liquid extraction and simple distillation. The process is based on biorefining principles and aimed at preserving the integrity of other polymer fractions of the raw material for subsequent use. The autohydrolysis liquor and furfural were characterized by Fourier-transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy, and high pressure liquid chromatography (HPLC). Also, a central composite factor design was used to model and optimize the autohydrolysis/liquidliquid extraction process for conversion of hemicellulosic materials into furfural. Based on the results, southern cattail is a suitable material for extracting hemicellulose to be converted into furfural while preserving other fractions of use for other purposes. The optimum operating ranges for the autohydrolysis conditions were found to be 177-189°C and 30-45 min. Under such conditions, 20-25% of all xylan in the raw material was converted into furfural with little simultaneous production of degradation products. Furfural in the autohydrolysis liquor was separated virtually quantitatively by extraction with chloroform and subsequent simple distillation.

Green, inexpensive, and robust copper-based heterogeneous catalysts achieve 100 % conversion and 99 % selectivity in the conversion of furfural to furfuryl alcohol when using cyclopentyl-methyl ether as green solvent and microwave reactors at low H2 pressures and mild temperatures. The utilization of pressurized microwave reactors produces a 3-4 fold increase in conversion and an unexpected enhancement in selectivity as compared to the reaction carried out at the same conditions using conventional autoclave reactors. The enhancement in catalytic rate produced by microwave irradiation is temperature dependent. This work highlights that using microwave irradiation in the catalytic hydrogenation of biomass-derived compounds is a very strong tool for biomass upgrade that offers immense potential in a large number of transformations where it could be a determining factor for commercial exploitation.

India has agro-based economy and agriculture accounts for a large share of GDP and employment. Besides, a number of useful products, a large quantity of agro-wastes are also produced which is not properly used at present. These agro-wastes are either burnt as fuel or improperly disposed off causing the problem of waste treatment and environmental pollution. Furfural is derived from the pentosan in the cellulose of plant tissues, the most prominent sources of which are corn cobs, saw dust, rice husk, bagasse, pea nut shell. Most furfural that is being produced today is derived from corncobs. In the process we used two different concentrations of sulphuric acid was taken as 14% and 16%. For 16% acid concentration we get maximum conversion of Pentoses to furfural. The hydrolysis process was carried out in simple distillation set up; in distillate we get hydrolysed solution which contained mixture of water, furfural and some light fractions like as methanol acetone etc. After hydrolysis...