Abstract:In this work, two catalytic systems combining Lewis and Brønsted acids (ZnCl 2 /HCl and AlCl 3 /HCl) were applied in a tetrahydrofuran (THF)/NaCl aq biphasic system to produce furan compounds from plant polysaccharides. The following cellulosic matrices were applied for this purpose: α-cellulose, microcrystalline cellulose and both native and steam-exploded sugarcane bagasse. The AlCl 3 /HCl catalytic system afforded the best yields for α-cellulose conversion to furan compounds (hydrolysis followed by dehydrat… Show more
“…The experimental matrix and the EL yields (%) are presented in Table . The factors evaluated were temperature ( T : 160–190 °C), time ( t : 20–60 min), and IL quantity (1–10 equiv), and their levels were selected according to previous works. ,− As can be seen in Table , the highest EL yield (81%) from MCC was achieved when all factors were at the upper level: 190 °C, 60 min, and 10 equiv of [TauIm][HSO 4 ] (entry 8).…”
In this work, a novel renewable taurine-based ionic liquid (IL), [TauIm][HSO 4 ], was synthesized via the Debus− Radziszewski reaction. The synthesized IL was then used to produce ethyl levulinate (EL) from several lignocellulosic substrates under microwave irradiation. Experimental conditions (temperature, time, and IL quantity) for EL production from a model substrate (microcrystalline cellulose, MCC) were first investigated by design of experiment (DoE) using a central composite design (CCD). The highest EL yields (over 80%) in MCC were achieved at the upper limits of all factors (190 °C; 60 min; 10 equiv of IL). Computational studies revealed that the IL−cellobiose interaction is stronger than the IL itself at the reaction temperature (190 °C), indicating the efficiency of the IL in interacting with cellulose in the optimal reaction conditions. Moreover, the formation of the IL− cellobiose complex was mediated by the hydrogen sulfate anion, while the cation worked as a spacer. Optimized conditions from DoE were also applied to sugarcane bagasse and straw, elephant grass leaves and stems, rice husks and straw, and corn biomass. EL production yields from 12 to 59% were obtained from these biomasses using this novel imidazolium IL, with the highest EL yields obtained with raw sugarcane bagasse (SCB) without any pretreatments. The superior performance of SCB was associated with the higher content of hemicelluloses in its composition compared to that of the other biomasses. Together, these results presented herein open new possibilities for increasing biomass valorization using renewable and straightforward routes.
“…The experimental matrix and the EL yields (%) are presented in Table . The factors evaluated were temperature ( T : 160–190 °C), time ( t : 20–60 min), and IL quantity (1–10 equiv), and their levels were selected according to previous works. ,− As can be seen in Table , the highest EL yield (81%) from MCC was achieved when all factors were at the upper level: 190 °C, 60 min, and 10 equiv of [TauIm][HSO 4 ] (entry 8).…”
In this work, a novel renewable taurine-based ionic liquid (IL), [TauIm][HSO 4 ], was synthesized via the Debus− Radziszewski reaction. The synthesized IL was then used to produce ethyl levulinate (EL) from several lignocellulosic substrates under microwave irradiation. Experimental conditions (temperature, time, and IL quantity) for EL production from a model substrate (microcrystalline cellulose, MCC) were first investigated by design of experiment (DoE) using a central composite design (CCD). The highest EL yields (over 80%) in MCC were achieved at the upper limits of all factors (190 °C; 60 min; 10 equiv of IL). Computational studies revealed that the IL−cellobiose interaction is stronger than the IL itself at the reaction temperature (190 °C), indicating the efficiency of the IL in interacting with cellulose in the optimal reaction conditions. Moreover, the formation of the IL− cellobiose complex was mediated by the hydrogen sulfate anion, while the cation worked as a spacer. Optimized conditions from DoE were also applied to sugarcane bagasse and straw, elephant grass leaves and stems, rice husks and straw, and corn biomass. EL production yields from 12 to 59% were obtained from these biomasses using this novel imidazolium IL, with the highest EL yields obtained with raw sugarcane bagasse (SCB) without any pretreatments. The superior performance of SCB was associated with the higher content of hemicelluloses in its composition compared to that of the other biomasses. Together, these results presented herein open new possibilities for increasing biomass valorization using renewable and straightforward routes.
“…The maximum yield of furfural and HMF obtained were 720 and 200 g kg –1 , respectively, at 190 °C, 1% H 2 SO 4 , and 10 min . Gomes et al reported the production of furfurals from dehydration of steam exploded sugar cane bagasse using AlCl 3 /HCl. The highest yield of HMF and furfural were 440 and 922 g kg –1 , respectively, at 180 °C .…”
Section: Resultsmentioning
confidence: 99%
“…Gomes et al reported the production of furfurals from dehydration of steam exploded sugar cane bagasse using AlCl 3 /HCl. The highest yield of HMF and furfural were 440 and 922 g kg –1 , respectively, at 180 °C . In this study, the maximum yields of HMF and furfural obtained from pretreatment of sugar cane bagasse using IPEG200 at 120 °C were 460 and 140 g kg –1 , respectively, which is comparable with the literature.…”
In this study, rice
straw and sugar cane bagasse were pretreated
using a novel imidazole:poly(ethylene glycol) (IPEG) solvent at temperatures
between 120 and 200 °C for 1 h. The pretreatment using IPEG with
molecular weight of PEG of 200 g/mol (IPEG200) resulted in 83% and
92% of xylan from rice straw and bagasse, respectively, being converted
to furfural. The solubility of xylan was highest in IPEG200, which
had higher hydrogen bonding acidity, hydrogen bonding basicity, and
polarizability. The yield of glucose from pretreated residues via
enzymatic hydrolysis was highest for rice straw treated with IPEG200
(27%) compared to the untreated sample (9%). Pretreatment of sugar
cane bagasse using IPEG200 resulted in higher yield of furan derivatives
(600 g/kg) compared to that from rice straw. The pyrolysates from
the enzymatic hydrolysis residues contained a significantly lower
amount of carboxylic acid and furan derivatives due to the removal
of hemicellulose during the pretreatment process.
“…In H 2 O/THF biphasic system, Fang et al (2019) obtained 76 and 81% yields of HMF and furfural from corn stover, respectively, using H 2 SO 4 /Na 2 SO 4 as catalyst. In combination of Lewis acid with Brønsted acids in NaCl-H 2 O/THF biphasic system, the yields of HMF and furfural was 44.0 and 92.2% catalyzed by AlCl 3 /HCl and 36.5 and 81.4% by the catalysis of ZnCl 2 /HCl, respectively (Gomes et al, 2018). As high as 71% yield of furfural and 30% yield of HMF could be simultaneously produced from wheat straw in NaCl-H 2 O/THF biphasic system catalyzed by SnCl 2 -PTA/β (Phosphotungstic acid) catalyst (Xu et al, 2019).…”
Section: The Co-production Of Hmf and Furfuralmentioning
Lignocellulosic biomass as a potential alternative to fossil resource for the production of valuable chemicals and fuels has attracted substantial attention, while reducing the recalcitrance of lignocellulosic biomass is still challenging due to the complex and cross-linking structure of biomass. Solvent system plays important roles in the pretreatment of lignocellulose, enabling the transformation of solid biomass to liquid fluid with better mass and heat transfer, as well as in the selective formation of target products. In particular, H 2 O/tetrahydrofuran (H 2 O/THF) system has recently been widely applied in lignocellulose valorization, which has been proved to exhibit outstanding efficiency for the conversion of lignocellulose, solubilization of the intermediates and products, and shifting reaction equilibrium, thereby significantly improving the yield and selectivity of target products, as well as the full utilization of lignocellulose. In addition, THF shows low toxicity, and is known as a renewable solvent which can be produced from bio-derived chemicals. Herein, this review concentrates on the advances of H 2 O/THF system in lignocellulose valorization in recent years. Several aspects relative to the roles of H 2 O/THF system are discussed as follows: the pretreatment of lignin, conversion of hemicellulose and cellulose components in lignocelluloses, and the promoting formation of valuable chemicals like furfural, 5-hydroxymethyl furfural (HMF), levulinic acid, and so on, as well as the inhibiting role in humins formation. This review might provide useful information for the design of effective solvent system in full utilization of lignocellulosic biomass.
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