Direct chemical conversion of xylan into furfural over sulfonated graphene oxide

Furfural production from xylan using a Pueraria Residues carbon-based solid-acid catalyst

BACKGROUND

The conversion of biomass into high value-added platform compounds is an important method of biomass utilization. The conversion of hemicellulose represented by xylan into furfural can not only reduce the consumption of fossil fuels, but also promotes the development and utilization of non-edible biomass resources. In this study, a bifunctional solid-acid catalyst prepared from agricultural and forestry waste Pueraria (P. eduli) Residues was used to convert xylan into furfural in a biphasic system.

RESULTS

In this study, P. eduli Residues was used as raw material to prepare a P. eduli Residues-based carbon solid-acid catalyst (PR/C-SO3H-Fe) by one-step sulfonation carbonization and impregnation. The catalyst catalyzes the conversion of xylan to furfural in a biphasic system (2-methyltetrahydrofuran/water). The physicochemical properties of the catalysts were characterized by X-ray powder diffraction, scanning electron microscopy, differential thermogravimetric analysis, Brunauer-Emmett-Teller surface area, Fourier transform infrared spectroscopy and ammonia temperature-programmed desorption. Subsequently, the experimental conditions were studied and optimized, such as metal species, iron ion concentration, reaction time and temperature, volume ratio of organic phase to water phase and ratio of substrate to catalyst. The results showed that under conditions of 160 °C, 50 mg catalyst, 100 mg xylan and 7 mL reaction solvent, the yield of furfural could reach 78.94% after 3 h of reaction.

CONCLUSION

This study provides an effective research method for the conversion of xylan into furfural, and provides a reference for the catalytic conversion and utilization of hemicellulose in agricultural and forestry biomass. It also provides a feasible method for the resource utilization of agricultural and forestry waste. © 2024 Society of Chemical Industry.

Synthesis of ZIF-8/ZnFe2O4/GO-OSO3H nanocomposite as a superior and reusable heterogeneous catalyst for the preparation of pyrimidine derivatives and investigation of their antimicrobial activities

In this report, we synthesized some pyrimidine derivatives by multi-component reaction of urea, benzaldehydes, and 1,3-indandione in the presence of ZIF-8/ZnFe2O4/GO-OSO3H nanocomposite under reflux conditions. Initially, graphene oxide was prepared from graphite, and then it was sulfonated using ClOSO3H. Next, GO-OSO3H nanosheets were used to support ZIF-8/ZnFe2O4 nanostructure. The construction of the synthesized structure was established using different spectral techniques such as X-ray crystallography (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX/Mapping), Fourier transform infrared (FTIR), thermal gravimetric analysis (TGA), vibrating sample magnetometer (VSM), and Brunauer-Emmett-Teller (BET). The present method provides various benefits including the efficiency of outcomes, easy separation of the catalyst, and excellent yield of the products within short reaction times. Moreover, the antibacterial activities of pyrimidine derivatives were investigated via the agar-well diffusion method on gram-negative (Escherichia coli) and gram-positive (Staphylococcus aureus) bacteria and the obtained results illustrated reasonable effects.

Recent progress in direct production of furfural from lignocellulosic residues and hemicellulose

Furfural is a vital biomass-derived platform molecule, which can be used to synthesize a wide range of value-added chemicals. Furfural and its derivatives are promising alternatives to conventional petroleum chemicals. However, recent industrial production of furfural existed some thorny problems, including low efficiency, energy waste, and environmental pollution. Therefore, tremendous and continuous efforts have been made by researchers to develop novel furfural production processes with high economic viability, production efficiency, and sustainability. This review summarized the merits and shortcomings of disparate catalytic systems for the synthesis of furfural from biomass and biomass pretreatment hydrolysate on the basis of recently published literature. Furthermore, the suggestions for furfural production research were put forward.

Facile preparation protocol of magnetic mesoporous carbon acid catalysts via soft-template self-assembly method and their applications in conversion of xylose into furfural

Furfural is a valuable dehydration product of xylose. It has a broad spectrum of industrial applications. Various catalysts containing SO₃H have been reported for the conversion of xylose into furfural. Nevertheless, the multi-step preparation is tedious, and the catalysts are usually fine powders that are difficult to separate from the suspension. Novel magnetic mesoporous carbonaceous materials (Fe/MC) were successfully prepared via facile self-assembly in a single step. A facile subsequent hydrothermal sulfonation of Fe/MC with concentrated H₂SO₄ at 180°C gave mesoporous carbon bearing SO₃H groups (SO₃H@Fe/MC) without loss of the magnetic properties. Various techniques were employed to characterize the SO₃H@Fe/MC as a candidate catalyst. It showed strong magnetism due to its Fe particles and possessed a 243 m² g^-1 BET-specific surface area and a 90% mesopore volume. The sample contained 0.21 mmol g^-1 of SO₃H and gave a high conversion and an acceptable furfural yield and selectivity (100%, 45% and 45%, respectively) when used at 170°C for 1 h with γ-valerolactone as solvent. The catalyst was easily separated after the catalytic tests by using a magnet, confirming sufficient magneticstability. This article is part of the theme issue 'Bio-derived and bioinspired sustainable advanced materials for emerging technologies (part 2)'.

pH-Controlled Efficient Conversion of Hemicellulose to Furfural Using Choline-Based Deep Eutectic Solvents as Catalysts

The valorization of hemicellulose isolated from lignocellulosic biomass (wheat straw, rice husk, and bagasse) to furfural was achieved by pH-controlled acid catalysis using choline-based Brønsted acidic (BA) and natural acidic (NA) deep eutectic solvents (DES) serving both as catalyst and solvent. The effect of pH variation on the catalytic activity of various BADES and NADES prepared in 1 : 1 molar ratio was observed, and choline chloride/p-toluene sulfonic acid (ChCl/p-TSA) was found to be the best with lower pH value of 1.0. The yield of furfural decreased from 85 to 51 % with increase in pH from 1.0 to 3.0. The molar ratio of hydrogen bond donor to acceptor components was varied from 1 : 1 to 1 : 9 to achieve the lowest possible pH values of the DESs and to increase the furfural yield. Further optimization of reaction conditions was also done in terms of DES loading, time of reaction, and temperature using the model DES to achieve higher furfural yield. The best results were obtained using 5 mmol DES at pH 1.0 in 1.5 h at 120 °C. ChCl/p-TSA and ChCl/oxalic acid among BADES and ChCl/levulinic acid among NADES investigated in this work yielding 85 % furfural were found to be most efficient. The reported methodology is advantageous in terms of using bio-based green solvents, mild reaction conditions, and efficient scale-up of the reaction. The DESs were found to be efficiently recyclable up to five consecutive runs for the process.

Magnetically Recyclable Graphene Oxide Demulsifier Adapting Wide pH Conditions on Detachment of Oil in the Crude Oil-in-Water Emulsion

In the present work, an amphiphilic and magnetically recyclable graphene oxide (MR-GO) demulsifier was devised and synthesized by graft of magnetic nanoparticles (Fe₃O₄@SiO₂-APTES) and ethylenediamine on the GO surface. The wettability and surface charges of MR-GO under various pH conditions can be regulated via adjusting the contents and species of surface functional groups (such as amino, carboxyl, and hydroxyl). In the demulsificaition test, MR-GO displayed favorable demulsification performance for crude oil-in-water (O/W) emulsion under pH of 2.0-10.0, thusly greatly improving the application scope of common demulsifier. The optimal dosage of MR-GO was 200 mg/L and the demulsification efficiency attained a maximum value of 99.7% for crude O/W emulsion with pH of 6.0. What's more, owing to its magnetic response performance, the MR-GO can be reused and the demulsification efficiency remained above 91.0% after six cycles. Based on the strong interfacial activity, MR-GO can arrive to the crude oil-water interface. With the synergy effects of interfacial adsorption (π-π/n-π) interactions and electrostatic attraction of demulsifier and interfacial films, and the aid of external mechanical forces, the interfacial films stabilized the emulsion were disrupted. Therefore, the oil droplets coated on the water droplets were gathered rapidly to form oily flocs and then migrated to the water surface to accomplish the demulsification of crude O/W emulsion.

Investigation of heterogeneous sulfonated graphene oxide to hydrolyze cellulose and produce dark fermentative biohydrogen using Enterobacter aerogenes

The main aim of this work was investigating the potential of sulfonated graphene oxide (sGO) for hydrolysis of cellulosic substrates and dark fermentative hydrogen production from obtained hydrolysates using E. aerogenes. Sulfonation of graphene oxide was performed using chlorosulfonic acid which showed a high acid density of 4.63 mmol/g. Influence of the reaction time (1-5 h), temperature (90-180 °C) and sGO dosage (62.5-500 mg in 25 mL reaction volume) on the hydrolysis of pretreated microcrystalline cellulose was experimented. It revealed that the yield of glucose and total reducing sugars and selectivity can reach 454.4 ± 22.20 mg/g, 682.6 ± 30.67 mg/g and 95.5%, respectively, at 150 °C for 3 h using 250 mg sGO. The maximum hydrogen efficiency of 150.0 ± 5.65 mL/g was achieved under optimized conditions, which was 2.2-fold higher than that from the pretreated MCC substrate as control in the absence of sGO (67.3 ± 8.84 mL/g).