
==== Front
Heliyon
Heliyon
Heliyon
2405-8440
Elsevier

S2405-8440(24)13843-1
10.1016/j.heliyon.2024.e37812
e37812
Research Article
Boron-doped sulfonated graphitic carbon nitride as a highly efficient catalyst for the production of 5-hydroxymethylfurfural from carbohydrates
Le Diep Dinh ab1
Nguyen Trinh Hao ab1
Nguyen Luc Tan ab
Le Nguyen Dao Anh ab
Thi Le Mai Ngoc ab
Nguyen Khoa Dang ab
Phan Ha Bich abc
Tran Phuong Hoang thphuong@hcmus.edu.vn
ab⁎
a Department of Organic Chemistry, Faculty of Chemistry, University of Science, Ho Chi Minh City, Viet Nam
b Vietnam National University, Ho Chi Minh City, Viet Nam
c Institute of Public Health, Ho Chi Minh City, Viet Nam
⁎ Corresponding author. Department of Organic Chemistry, Faculty of Chemistry, University of Science, Ho Chi Minh City, Viet Nam. thphuong@hcmus.edu.vn
1 The authors contributed equally.

11 9 2024
30 9 2024
11 9 2024
10 18 e3781221 4 2024
7 9 2024
10 9 2024
© 2024 Published by Elsevier Ltd.
2024

https://creativecommons.org/licenses/by-nc-nd/4.0/ This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
The presence of humins during the conversion of concentrated fructose presents a major obstacle in the large-scale production of 5-hydroxymethylfurfural (HMF) from fructose. Herein, we reported a boron-doped graphitic carbon nitride sulfonated (BGCN-SO3H) as an excellent catalyst for the synthesis of HMF from fructose. The BGCN-SO3H catalyst structures were analyzed using various characterization techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), energy-dispersive X-ray spectroscopy (EDX), elemental mapping analysis, and Fourier-transform infrared spectroscopy (FT-IR). The BGCN-SO3H catalyst was evaluated for the synthesis of HMF from fructose. We investigated the influence of catalyst performance, including solvent reactions, catalyst loading, substrates, and volume of solvent to optimize reaction conditions. As a result, the yield of HMF was obtained at 88 % within 5 h when using 30 mg of catalyst. The study of catalyst activity involved examining reactions that allowed recovery and reuse. The research findings offer a method for producing HMF with exceptional efficiency using solid catalysts.

Highlights

• The BGCN-SO3H catalyst was easily synthesized and characterized using various characterization techniques.

• The BGCN-SO3H catalyst was evaluated for synthesis of HMF from fructose.

• A high HMF yield of 88 % was achieved within a 5-h timeframe by employing a catalyst dosage of 30 mg.

• The BGCN-SO3H catalyst can be recovered and reused.

Keywords

5-Hydroxymethylfurfural
Graphitic carbon nitride
Fructose
Solid catalysts
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pmc1 Introduction

The global dependence on petroleum as the predominant supplier of chemicals and energy has experienced substantial growth [1]. However, with diminishing reserves and increasing demand, it is crucial to explore new, sustainable alternatives for both fuels and bulk chemicals [2]. Biomass emerges as the most promising substitute due to its wide availability, making it the only viable option besides oil and coal [[3], [4], [5]]. Within the various forms of biomass, carbohydrates play a vital role as they can be converted into valuable chemicals. 5-Hydroxymethylfurfural (HMF) and furfural are pivotal compounds in the field of organic chemistry, owing to their remarkable potential for conversion into a diverse range of valuable chemicals [6,7]. These compounds exhibit exceptional efficiency, rendering them highly desirable for various applications [8]. As an illustration, HMF has the potential to undergo conversion processes leading to the production of platform chemicals, namely 2,5-dimethylfuran and 2,5-diformylfuran (DFF) [9]. Furthermore, the conversion of HMF can yield ethyl levulinate, γ-valerolactone, and liquid alkanes, which possess significant potential for diverse industrial applications (Scheme 1) [10]. HMF has been widely recognized as a pivotal link connecting carbohydrates and the petroleum sector in the context of organic chemistry [11]. Hence, the pursuit of proficient synthetic methodologies to achieve optimal HMF yield from carbohydrates has garnered significant scholarly interest [12].Scheme 1 Main domains of practical applications of HMF and its derivatives.

Scheme 1

Hexose sugars, including fructose and glucose, have extensively been employed as substrates for the conversion of carbohydrate into HMF [13]. Hongyu Tian et al. created coprecipitation-based hafnium-aluminum bimetallic oxide (Al-HfOx) andpoly (ionic liquid)s-silica spheres (PIL@SiO2) catalysts that convert glucose or fructose to HMF. The study proposes a heterogeneous bimetallic oxide and silica-based core-shell synergistic catalyst approach for carbohydrate-to-HMF conversion [14,15]. Yang al et. reported the transformation of biomass into HMF using solid acid catalyst, resulting in the yield of the reaction obtained about 89 % and 54 % from fructose and inulin, respectively [16]. It is significant to highlight that numerous catalytic methodologies have been devised for fructose dehydration to HMF employing diverse homogeneous and heterogeneous acid catalysts [17]. However, the specific removal of water from fructose to produce HMF is significantly influenced by different factors in the reaction, such as the catalyst employed, the medium in which the reaction takes place, and the temperature at which the reaction occurs, which made the reaction yield became low and not selectivity [18]. Notably, the solvent effects have a significant impact on various undesired side reactions, such as the formation of soluble or insoluble polymers like humin, through condensation or polymerization reactions during the reaction of fructose. Various catalysts, such as different types of acids, metal salts, and metal oxides, have been widely used in the production of HMF from fructose. These catalysts can be used in aqueous or biphasic water/organic solvent systems, as well as in ionic liquids [19]. Nevertheless, the production of HMF in an aqueous environment has been found to result in relatively low yields [20]. One possible explanation for this phenomenon is the unwanted rehydration of a compound known as HMF, which results in the formation of levulinic acid and formic acid. In contrast, polar aprotic solvents, such as dimethyl sulfoxide (DMSO), exhibit a higher propensity for dehydrating fructose by effectively mitigating side reactions and enhancing the production of HMF [21,22].

Graphitic carbon nitride (GCN) is a highly suitable material for catalytic applications. It is composed of abundant elements, namely carbon and nitrogen, and possesses excellent stability and non-toxic properties [23,24]. The GCN nanosheets are a fascinating material with a unique structure that gives it inherent basic properties. This is due to the existence of certain groups within its ring structure [25]. In a recent study, Jiang and Han presented an innovative approach to synthesizing phenol from benzene. They utilized a catalyst called vanadium-doped graphitic carbon nitride (V–g-C3N4) and hydrogen peroxide as the oxidant, achieving selective results [26]. In a recent study, Sanny et al. explored the functionalization of GCN nanosheets with a sulfonic group (S-GCN). This alteration rendered the nanosheets more acidic in nature. The researchers then investigated the use of S-GCN as a catalyst in an aqueous environment within a sealed tube to transform glucose into levulinic acid and fructose into HMF [27]. For example, Chen and colleagues developed the MXene/g-C3N4 composite (MX/CN) for photocatalytic HMF to DFF oxidation, achieving over 90 % selectivity and yield above 6 % MX/CN [28]. Wenlei Xie et al. conducted a study on the grafting copolymerization of a combination of two acidic ionic liquids onto a core-shell structured magnetic silica material, with the aim of using it for biodiesel generation [29].

Nevertheless, the use of heterogeneous catalysis for biomass conversion may face several constraints and problems, such as catalyst deactivation, variations in feedstock composition, reaction conditions, selectivity, and yield [30]. To achieve more efficient, sustainable, and economically feasible processes, the field of heterogeneous catalysis for biomass transformation must tackle these issues and focus on these research areas.

In this study, the BGCN-SO3H catalysts were synthesized using a 4-step procedure. The structural analysis of the catalyst is conducted through contemporary techniques such as Fourier Transform Infrared Spectroscopy (FTIR), Energy-Dispersive X-ray Spectroscopy (EDX), and Scanning Electron Microscopy (SEM). Additionally, the thermal stability of the catalyst is assessed utilizing the Thermogravimetric Analysis (TGA) method. The catalysts synthesized in this study were subjected to a range of characterization techniques to assess their properties. These catalysts were then utilized in the dehydration of fructose to produce HMF in a solvent of dimethyl sulfoxide (DMSO). The BGCN-SO3H catalyst has a significant impact on the acid properties and catalytic performance, as observed in our study. We also examined various reaction parameters, such as the temperature and duration of the reaction, the selection of solvent, and the potential for reusing the catalyst.

2 Experimental

2.1 Chemicals and equipment

2.1.1 Chemical

Maltose (99 %), fructose (99 %), glucose (99 %), sucrose (99 %), cellulose (99 %) was obtained from Sigmal-Aldrich. Melamine (99 %) was collected from Oxford. Boric acid (99 %), sulfuric acid (98 %, H2SO4), nitric acid (63 %, HNO3), and dimethyl sulfoxide (99 %, DMSO) were obtained from Fisher. Butanol (99 %), sulfolane (99 %), ethyl acetate (99 %), and hexane (99 %) were purchased from ChemSol-Vietnam. (3-mercaptopropyl) triethoxysilane (99 %, MPTES) was obtained from Macklin. 5-Hydroxymethylfufuran (99 %, HMF), 2,5-diformylfruan (99 %, DFF) were collected from Merck.

2.2 Equipment

The FT-IR analysis was conducted using a JASCO- FT/IR-6600 instrument from 600 to 4000 cm−1. An evaluation of the catalyst's thermal stability was carried out using a Toledo TGA/DSC instrument. The catalyst was subjected to calcination, with the temperature gradually increasing from ambient to 800 °C at a scanning rate of 10 Kpm. The morphologies of samples were studied using the SEM-equipped EDX on a JSM-IT200, JEOL, Japan. The crystallinities of the samples were evaluated using XRD on a Bruker D8 Advance powder X-ray diffraction machine with X-ray with wavelength Kα = 0.154178 nm, voltage 40 kW, current intensity 40 mA, scanning angle from 3 to 30°, scanning speed 0.02°/s. Raman spectra were measured by the Horiba Xplora Plus Raman instrument, a laser source with a wavelength of 532 nm.

The quantification of HMF was conducted using an HPLC system, namely Agilent Technologies 1260 Infinity, equipped with a Diode Array Detector operating at wavelengths of 285 nm. The constituents of the reaction mixture were isolated utilizing the InertSustain C18 column (5 μm, 4.6 × 150 mm). The temperature of the column was held constant at 25–30 °C. A methanol solution containing sulfuric acid (2.5 mM) was utilized as the eluent, operating at 0.7 mL min−1 flow rate. The elution process followed a gradient pattern as outlined below: During the time interval of 0–2.50 min, the composition of the solution was 100 % B. From 2.50 to 2.51 min, the composition was 85 % B. This composition was maintained from 2.51 to 17.00 min. From 17.00 to 17.01 min, the composition is not specified. Finally, from 17.01 to 25.00 min, the solution consisted of 100 % B. The sample was injected with a volume of 10 μL, and the detection was performed at a wavelength of 285 nm. The equation utilized for determining HMF yield (1) is expressed as follows:(1) Yield of HMF (%) = (molar amount of HMF produced/ molar amount of substrate initially charged) x100

2.3 Preparation of catalyst

2.3.1 Preparation of boron-doped graphitic carbon nitride

The synthesis of boron-doped graphitic carbon nitride (BGCN) was performed according to the following our procedure [31]. First, a mixture of 4.25 g melamine and 0.75 g boric acid was added to 20 mL of deionized water. The mixture was heated at 90 °C until the water completely evaporated. Next, the dried mixture was placed into an alumina crucible and heated at 550 °C for 4 h. The heating rate during this step was set at 2.5 °C per minute. The process was carried out in a furnace with still air. After the heating process, a pale yellow powder was obtained. To eliminate any residual boric acid, the powder was rinsed with a mixture of hot water and ethanol. Finally, the powder was dried in an oven at 70 °C for 8 h to remove any remaining solvent, resulting in a dried BGCN powder.

2.3.2 Preparation of boron-doped graphitic carbon nitride sulfonated (O-BGCN)

The next step in the synthesis process involved adding the synthesized BGCN powder (1.0 g) to a mixed solution of concentrated H2SO4 (98 %) and HNO3 (69 %) in a 1:1 ratio (20 mL). The resulting mixture was heated at 40 °C while being sonicated for 2 h. Afterward, a 6 % H2O2 solution (5 mL) was added dropwise, and the reaction mixture was sonicated for an additional 3 h.

The resulting product was an opaque white substance. To further process it, ice-cold deionized water (100 mL) was added to the reaction mixture. A dilute suspension of oxidized graphitic carbon nitride (O-BGCN) was then obtained by filtering the mixture and washing it alternately with deionized water and acetone. The material was finally dried in a furnace at 80 °C for 12 h, resulting in a white O-BGCN catalyst.

2.3.3 Synthesis of BGCN-SH using (3-mercaptopropyl) triethoxysilane

BGCN was activated with (3-mercaptopropyl) triethoxysilane (MPTES) to form BGCN-SH. In a 100 mL flask, O-BGCN (1.0 g) was dispersed in toluene (50 mL) by ultrasound for 15 min, and at the same time, MPTES (1 mL) was dissolved separately in toluene (10 mL). Next, the MPTES solution was slowly introduced to O-BGCN under ultrasonic conditions. The reaction mixture was carried out under reflux conditions with N2 atmosphere for 24 h. After reflux, the catalyst was filtered, washed with ethanol, and dried at room temperature.

2.3.4 Synthesis of BGCN-SO3H

To synthesize BGCN-SO3H, BGCN-SH (1.0 g) was dispersed in 30 % H2O2 solution (30 g) and stirred at room temperature for 24 h. The material was then filtered, washed three times with deionized water, and dried in a vacuum oven at 80 °C for 12 h (Scheme 2).Scheme 2 The procedure of synthesis of BGCN-SO3H.

Scheme 2

2.4 General procedure of synthesis of HMF using BGCN-SO3H

A mixture of fructose (1 mmol, 180 mg), BGCN-SO3H (30 mg), DMSO (3 mL) were heated with a magnetic field. An extensive experimental study was conducted to assess the various factors affecting the conversion of carbohydrates into HMF. The study involved investigating the influence of reaction time, reaction temperature, choice of solvent, catalyst dosage, substrate type, and volume of solvent. The reaction times tested ranged from 0.5 to 7 h, while the reaction temperatures varied from 80 °C to 140 °C. Different solvents, including butanol, DMSO, sulfolane, DMF, and water, were examined for their impact on the reaction. Catalyst dosages of 5 mg, 10 mg, 30 mg, 50 mg, and 100 mg were tested to determine their effect on the conversion process. Additionally, different carbohydrate substrates such as glucose, fructose, cellulose, maltose, and sucrose were also investigated. The volume of solvent used in the reaction was also varied, with quantities of 1, 3, 5, and 10 mL being tested. This comprehensive study aimed to evaluate the influence of these reaction conditions on the conversion of carbohydrates into HMF. After the reaction, the sample was weighed at different times and diluted with deionized water (10 mL) and filtered with 0.45 μm nylon. The HMF yield was determined by HPLC with a DAD detector.

3 Results and discussion

3.1 Characterization of catalyst

The FTIR spectrum seen in Fig. 1a attested evidence of the successful surface alteration of BGCN-SO3H. Tri-s-triazine units are represented by the absorption peak at 795 cm−1, and the peaks in the range of 1200–1700 cm−1 confirm the production of C-N bonds in graphitic carbon nitride [32]. However, because of the overlapping signals, it is difficult to distinguish between peaks in the 1200–1700 cm−1 range, namely B-N and C-N bonds [33]. The N-H vibration modes and the adsorbed water molecules are responsible for the broad absorption signal observed in the 2900-3400 cm−1 region. A structural difference between BGCN and O-BGCN is indicated by the tiny absorption peak at 2170 cm−1, and this difference is present in both BGCN-SH and BGCN-SO3H. The -OH of -SO3H group forms a unique signal range between 2500 and 3500 cm−1. The stretching vibration of the Si-O bond is observed at 1090 and the nearby region around 795 cm−1 shows absorption changes compared to BGCN with a typical tri-s-triazine structure. The butyl groups of the salivating agent's C-H bond stretching vibrations are responsible for the absorption peaks at 2850 and 2930 cm−1. Furthermore, the successful grafting of propylsulfonic acid groups onto BGCN through the salinization process of the O-H surface groups is shown by a large absorption range of -OH (3300 cm−1). Because the C-N and Si-O-Si bonds produce overlapping absorption bands in the 1000-1200 cm−1 region, it is difficult to distinguish the distinctive signals of sulfonic acid [34]. Fig. 1b illustrated the thermogravimetric analysis that was conducted on BGCN-SO3H within the temperature range of 50–800 °C. BGCN-SO3H undergoes a relatively early thermal degradation process, with a decrease of 5.7 % at 100 °C, mostly because of water molecules breaking down. In the following range, the breakdown of water molecules that form hydro bonds with -SO3H causes BGCN-SO3H to lose weight by about 3.92 % as the temperature rises from 100 to 200 °C. On the TGA curve of BGCN-SO3H, weight loss in the 200–500 °C region is ascribed to the breakdown of sulfonic groups connected to the silica surface, which accounts for 14.83 % of the mass loss. A further mass loss was noted because of the tri-s-triazine structure breaking down when the temperature was increased above 500 °C. This may be explained by the strong thermal stability that is produced when amine groups combine to form hydrogen bonds.Fig. 1 FTIR spectra (a), TGA curve (b), Raman spectroscopy (c), EDX analysis of BGCN-SO3H (d).

Fig. 1

The structural characterizations of BGCN-SO3H were conducted using powder X-ray diffraction (XRD) analysis, with the pattern displayed in Fig. 1c. The highest peak is observed at 2θ = 27°, indicating an interplanar spacing of 002. This indicates an arrangement of the aromatic system that resembles a structure similar to graphite [35]. There is a less prominent peak at 2θ = 13°, indicating a slight tilt in the cyclic structure of the tri-s-triazine framework. The observed low intensity peak is indicative of the structural pattern within the sample [36].

Using EDX, the elemental composition of the catalyst was confirmed (Fig. 1d). The results indicate that the catalyst contains C, N, O, S, Si, and B, indicating that surface modification on a catalyst was effective; the presence of Si indicates that surface silane wiring has been completed. Additionally, the following elemental weight percentages were confirmed: C (11.89 ± 0.09), N (45.61 ± 0.19), B (11.89 ± 0.04), O (8.90 ± 0.11), Si (0.24 ± 0.03), and S (1.43 ± 0.04). The C (34.87 ± 0.10), N (42.71 % 18.), B (14.432 ± 0.05), O (7.30 ± 0.09), Si (0.11 ± 0.01), and S (0.58 ± 0.02) comprise the elemental percentages. The SEM mapping image demonstrates the uniform distribution of elements across the surface of the catalyst. Additionally, it captures the layer structure, which exhibits an uneven surface (Fig. 2).Fig. 2 EDX mapping and SEM with different magnification of BGCN-SO3H.

Fig. 2

3.2 Carbohydrate conversion

3.2.1 Effect of solvent

In this part, the effect of solvent reaction was investigated to evaluate the yield of HMF. The experiment was conducted with the combination of fructose (180 mg), BGCN-SO3H (30 mg), 5 h at 120 °C with various solvents (butanol, DMSO, sulfolane, DMF, water). Fig. 3 presented the results of the findings. The reaction efficiency reached about 5 % HMF when using butanol as solvent, meanwhile, with sulfolane solvents, the efficiency was improved, reaching about 12 % HMF within 5 h at 120 °C. In previous studies, butanol and sulfolane solvents were often unfavorable for the preparation of HMF [37]. In addition, we also investigated the effects of the solvent dimethylformamide (DMF) and water. However, the reaction efficiency was not as high as expected, reaching about 8 % HMF and 4 % HMF when used DMF and water as a solvent, respectively. Interestingly, the yield of the desired product was dramatically increased when using DMSO solvent and obtained at about 55 % HMF within 5 h. In prior research, it was shown that the DMSO solvent is the most effective solvent for biomass conversion [38].Fig. 3 Effect of solvent on the yield of HMF. Experiment set: An experiment was conducted using specific quantities of fructose, a catalyst, and DMSO at elevated temperature and for a specific duration.

Fig. 3

DMSO is ideal for synthesizing HMF from fructose due to its high polarity, intermediate stabilization, heat stability, and side reaction inhibition. It often outperforms water, alcohol, and ionic liquids [39]. Based on the findings of our academic research on the impact of solvents, it can be inferred that DMSO is a widely used and appropriate solvent for the reaction involved in the production of HMF from carbohydrates.

3.2.2 Effect of temperature

The reaction kinetics, yield, selectivity, and by-products of HMF synthesis from fructose depend on the temperature (Fig. 4). The experiment commenced at a temperature of 80 °C, and as time progressed, the yield showed a slight increase. The maximum yield achieved was approximately 20 % HMF after 7 h. By raising the temperature from 80 °C to 100 °C, the HMF production reached approximately 30 % in a mere 7 h. The most compelling evidence is raised reaction temperature led to an increase in the production of HMF; the yield was 0 % HMF, 11 % HMF, 15.3 % HMF, 51 % HMF, and 68 % HMF within 0.5, 1, 3, 5, and 7 h, respectively, at 120 °C. However, the yield of HMF declined with a long-time reaction. Without any doubt, the reason for increasing HMF has formed humins and created by-products [40]. The reaction was obtained at about 7.1 % HMF, 16.9 % HMF, 64.9 % HMF, 88.7 % HMF, 95.4 % HMF from 0.5 h to 7 h. In this work, we successfully synthesized HMF form fructose using BGCN-SO3H as a catalyst, the yield of the reaction was obtained about 88.7 % HMF within 5 h at 140 °C.Fig. 4 The impact of temperature on the production of HMF. Experiment set: 1 mmol of fructose (180 mg), BGCN-SO3H (30 mg), solvents (DMSO, 3 mL) with different temperatures from 80 °C to 140 °C.

Fig. 4

3.2.3 Effect of catalyst loading

Our study focused on examining the effects of catalyst loading and time on the production of HMF from fructose (Fig. 5). In an academic context, it is observed that a higher catalyst loading has the potential to enhance the dehydration of fructose. However, it is essential to note that this can also increase side reactions. These side reactions involve the polymerization of HMF with sugars, resulting in the formation of humins. Additionally, the rehydration of HMF can occur, leading to levulinic and formic acid formation [41]. As shown in Fig. 5, at 5 mg of catalyst, the yield of HMF was 19.5 % HMF, 44.4 % HMF, 70.0 % HMF, 71.8 % HMF, and 69.2 % HMF with increasing time reaction (0.5, 1, 3, 5, and 7 h). When the catalyst loading increased to 10 mg, the yield of HMF increased to 72 % in 5 h. When the catalyst loading was further evaluated to 30 mg, the yield of HMF increased quickly to 88 % at the initial 5 h. Besides, the reaction was increased time led to decrease the yield of the reaction, because of formation by-products. At 140 °C, when highly using weight of catalyst (100 mg), the HMF yield was slowly obtained about 30 % in 7 h. Thus, 30 mg of catalyst was chosen for the next investigation.Fig. 5 Exploring the influence of catalyst loading on HMF production. Experiment set: 1 mmol of fructose (180 mg), BGCN-SO3H, solvent (DMSO, 3 mL) with different catalyst's weight.

Fig. 5

At 140 °C, the formation of HMF and its conversion to HMF versus time with six loadings of BGCN-SO3H were depicted in Fig. 6. The yield of the reaction was obtained about 37 % without catalyst at 5 h. By increasing the amount of catalyst, the yield of HMF reached approximately 71 % and 73 % when using 5 mg and 10 mg of catalyst, respectively. Interestingly, the yield of the reaction was dramatically increased, resulting in about 88 % HMF within 5 h. The high catalyst loading led to a decline in the yield of the reaction, which accounted for about 43 % HMF. Besides, using 100 mg of catalyst, the HMF was slightly increased when compared to 50 mg of catalyst, reaching at about 20 % HMF.Fig. 6 The impact of catalyst loading on the production of HMF at 5 h. Experiment set: 1 mmol of Fructose (180 mg), BGCN-SO3H, solvent (DMSO, 3 mL) with different catalyst's weight, 140 °C.

Fig. 6

3.2.4 Effect of substrates

During this phase, the impact of different substrates on the overall reaction yield was carried out. The experiment was conducted with carbohydrates (1 mmol), BGCN-SO3H (30 mg), DMSO (3 mL), 5 h, 140 °C (Fig. 7). With fructose as substrates, the yield was reached at about 89 % within 5 h. Fructose dehydrated with the help of Brønsted acid on the catalyst to form HMF. Next, when we investigated the glucose substrate, the reaction efficiency was not as expected, less than 10 % HMF was formed. When using sucrose as substrate, the reaction efficiency reached about 68 % HMF in 5 h. Sucrose is made up of glucose and fructose, so in the presence of a catalyst, the reaction is carried out easily on a sucrose substrate. For cellulose, the reaction does not occur, no HMF was obtained. Because cellulose required a catalyst with a strong acid center to perform the hydrolysis process and break the bond chains [42].Fig. 7 The impact of substrates on the production of HMF at 5 h. Experiment set: 1 mmol of carbohydrates (glucose, fructose, sucrose, maltose, and cellulose), BGCN-SO3H (30 mg), solvents (DMSO, 3 mL), 140 °C.

Fig. 7

3.2.5 Effect of volume of solvent

Following an in-depth analysis of the variables impacting reaction efficiency, our study delved into the correlation between solvent volume and the effectiveness of HMF formation. Various quantities of solvent were used in the experiment, ranging from 1 mL to 7 mL of DMSO (Fig. 8). Upon analysis of 1 mL of DMSO solvent, the reaction efficiency was found to be approximately 83 %. However, when using larger volume in DMSO solvent (3 mL), the reaction efficiency slightly increased to around 89 %. The reaction efficiency reached about 60 % of HMF when increasing the volume of DMSO to 5 mL and reached about 43 % when using 7 mL of DMSO. From there it can be seen that the effect of solvent volume plays a critical role and directly affects the efficiency of forming HMF.Fig. 8 The impact of volume of solvent on the production of HMF at 5 h. Experiment set:1 mmol of fructose (180 mg), BGCN-SO3H (30 mg), DMSO (3 mL) with different volume DMSO (1, 3, 5, and 7 mL), 140 °C.

Fig. 8

3.2.6 Reusability test

The recovery ability of BGCN-SO3H was investigated and is illustrated in Fig. 9. After optimizing the reaction conditions, the reusability of catalyst test was investigated with fructose (1 mmol), BGCN-SO3H (30 mg) in DMSO (3 mL) at 140 °C for 5 h. The ratio of ethyl acetate to diethyl ether used to extract the reaction mixture was 95:5 (5 × 5 mL). Then, diethyl ether was used to wash the catalyst several times and dried under a vacuum for the next run. The HPLC-DAD method was used to determine the yield of HMF. After the initial trial, there was a small decline in the DFF yield, going from 88 % to 76 % HMF. The lack of efficiency in converting fructose into HMF resulted from the depletion of active sites on the catalyst surface after each run, particularly the -SO3H group. Despite a decline in HMF yields after four reuses, the efficiency of the desired product remained consistently above 60 %.Fig. 9 Reusability test of BGCN-SO3H. Experiment set: 1 mmol of Fructose (180 mg), BGCN-SO3H (30 mg), solvent (DMSO, 3 mL), 5 h, 140 °C.

Fig. 9

3.2.7 The comparison of this study to previous studies

In recent years, there has been extensive research conducted on the synthesis of HMF from fructose using a variety of catalyst systems (Table 1). Besides investigation of activity of many types of catalyst, the effect of temperature, time reaction, solvent, or method was also tested. Zhao et al. performed the efficiency of transformation of fructose to HMF using heating method with NH4Cl as Brønsted acid catalyst in isopropanol at 100 °C (Table 1, entry 1). The yield of desired product was obtained at 56 % after 12 h. The other studies of Hu and Liu et al. were also carried out at 100 °C, employing CrCl2 as catalyst in [Emim]Cl and SnCl4 in [Emim]BF4, respectively. However, the yield performance of HMF attained higher at shorter reaction time (3 h) (entries 2 and 3). In addition, the use of continuous flow can increase the yield of HMF in a short time. Sonsiam et al. got 61 % yield in 13 min at lower temperature (80 °C) using HCl/MIBK – [ChCl][3 EG] (3:1) catalyst system (entry 4). Ruan and co-workers developed another catalyst system (HCl/MIBK and 2–butanol) to enhance the performance of converting fructose into HMF, gaining the yield of 80 % in 3 min but the higher temperature (180 °C) was required (Table 1, entry 5). Overall, the catalyst system of this study has higher yield compared with others. Although utilizing this catalyst obtained insignificantly higher yield of HMF than HCl/MIBK and 2–butanol catalyst system, our catalyst has high reusability.Table 1 The comparison of this work to previous work for conversion of fructose into HMF.

Table 1Entry	Catalyst systems	Reaction condition	HMF (%)	Method	
1	NH4Cl/Isopropanol [43]	12 h/100 °C	56	Heating	
2	CrCl2/[Emim]Cl [44]	3 h/100 °C	68	Heating	
3	SnCl4/[Emim]BF4 [44]	3 h/100 °C	60	Heating	
4	HCl/MIBK-[ChCl][3 EG] (3:1) [45]	13 min/80 °C	61	Continuous flow	
5	HCl/MIBK and 2-butanol [46]	3 min/180 °C	80	Continuous flow	
6	BGCN-SO3H/DMSO (this work)	5 h/140 °C	88	Heating	

4 Conclusion

In conclusion, we presented a BGCN-SO3H catalyst as a highly effective catalyst for converting fructose into HMF. The structures of the BGCN-SO3H catalyst were analyzed using a range of characterization techniques. This included X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), energy-dispersive X-ray spectroscopy (EDX), elemental mapping analysis, and Fourier-transform infrared spectroscopy (FTIR). An evaluation was conducted on the performance of the BGCN-SO3H catalysts in converting fructose into HMF. We explored the impact of catalyst performance, such as solvent reactions, catalyst loading, substrates, and volume of solvent, to determine the most favorable reaction conditions. Consequently, an impressive 88 % yield of HMF was achieved in just 5 h by employing a mere 30 mg of catalyst. Investigating catalyst activity required analyzing reactions that enabled the recovery and subsequent reuse of materials. This process offers numerous advantages, including its user-friendly operation, efficient recovery, and impressive catalytic efficiency even after recovery. Additionally, it boasts a high yield of HMF. Our next objective is to enhance the durability and reliability of the catalyst.

Data availability statement

Data will be made available on request.

CRediT authorship contribution statement

Diep Dinh Le: Writing – original draft, Resources, Methodology, Investigation, Formal analysis, Data curation. Trinh Hao Nguyen: Writing – original draft, Resources, Methodology, Investigation, Formal analysis, Data curation. Luc Tan Nguyen: Methodology, Investigation, Data curation. Dao Anh Le Nguyen: Methodology, Investigation, Data curation. Mai Ngoc Thi Le: Methodology, Investigation, Data curation. Khoa Dang Nguyen: Methodology, Investigation, Data curation. Ha Bich Phan: Formal analysis. Phuong Hoang Tran: Writing – review & editing, Supervision, Resources, Methodology.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Appendix A Supplementary data

The following is the supplementary data to this article:Multimedia component 1

Multimedia component 1

Acknowledgements

This research was funded by 10.13039/100015548 Vietnam National University Ho Chi Minh City - University of Science (VNUHCM University of Science) under Grant number U2022-08 .

Appendix A Supplementary data to this article can be found online at https://doi.org/10.1016/j.heliyon.2024.e37812.
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References

1 Tekin K. Karagöz S. Bektaş S. A review of hydrothermal biomass processing Renew. Sust. Energ. Rev. 40 2014 673 687
2 Antar M. Biomass for a sustainable bioeconomy: an overview of world biomass production and utilization Renew. Sust. Energ. Rev. 139 2021 110691
3 Besson M. Gallezot P. Pinel C. Conversion of biomass into chemicals over metal catalysts Chem. Rev. 114 3 2014 1827 1870 24083630
4 Xie W. Wan F. Immobilization of polyoxometalate-based sulfonated ionic liquids on UiO-66-2COOH metal-organic frameworks for biodiesel production via one-pot transesterification-esterification of acidic vegetable oils Chem. Eng. J. 365 2019 40 50
5 Xie W. Wang H. Immobilized polymeric sulfonated ionic liquid on core-shell structured Fe3O4/SiO2 composites: a magnetically recyclable catalyst for simultaneous transesterification and esterifications of low-cost oils to biodiesel Renew. Energy 145 2020 1709 1719
6 Hu L. Biocatalytic transformation of 5-hydroxymethylfurfural into high-value derivatives: recent advances and future aspects ACS Sustainable Chem. Eng. 6 12 2018 15915 15935
7 Nguyen T.H. Highly efficient and recyclable chromium/nitrogen-doped carbon nanotube catalysts with unexpected active sites for conversion of fructose into 5-hydroxymethylfurfural Energy 305 2024 132317
8 Slak J. A review of bio-refining process intensification in catalytic conversion reactions, separations and purifications of hydroxymethylfurfural (HMF) and furfural Chem. Eng. J 429 2022 132325
9 Davidson M.G. Production of HMF, FDCA and their derived products: a review of life cycle assessment (LCA) and techno-economic analysis (TEA) studies Green Chem. 23 9 2021 3154 3171
10 Chen S. How catalysts and experimental conditions determine the selective hydroconversion of furfural and 5-hydroxymethylfurfural Chem. Rev. 118 22 2018 11023 11117 30362725
11 Wang H. Recent advances in catalytic conversion of biomass to 5-hydroxymethylfurfural and 2, 5-dimethylfuran Renew. Sust. Energ. Rev. 103 2019 227 247
12 Mika L.T. Cséfalvay E. Németh Á. Catalytic conversion of carbohydrates to initial platform chemicals: chemistry and sustainability Chem. Rev. 118 2 2018 505 613 29155579
13 Iglesias J. Advances in catalytic routes for the production of carboxylic acids from biomass: a step forward for sustainable polymers Chem. Soc. Rev. 49 16 2020 5704 5771
14 Zhao C. Effective synergistic hafnium-aluminum bimetallic oxides catalysts for the synthesis of 5-hydroxymethylfurfural from glucose and fructose Mol. Catal. 547 2023 113407
15 Zhu N. Poly (ionic liquid)s-silica spheres as effective core-shell catalysts for the conversion of glucose and fructose into 5-hydroxymethylfurfural Mol. Catal. 546 2023 113244
16 Yang F. Conversion of biomass into 5-hydroxymethylfurfural using solid acid catalyst Bioresour. Technol. 102 3 2011 3424 3429 21036606
17 Zhang T. Advance in constructing acid catalyst-solvent combinations for efficient transformation of glucose into 5-Hydroxymethylfurfural Mol. Catal. 498 2020 111254
18 Eblagon K.M. The influence of the surface chemistry of phosphorylated carbon xerogel catalysts on the production of HMF from fructose in water Fuel 334 2023 126610
19 Deng W. Catalytic conversion of lignocellulosic biomass into chemicals and fuels Green Energy Environ. 8 1 2023 10 114
20 Weingarten R. Selective conversion of cellulose to hydroxymethylfurfural in polar aprotic solvents ChemCatChem 6 8 2014 2229 2234
21 Chen P. Efficient continuous dehydration of fructose to 5-hydroxymethylfurfural in ternary solvent system Fuel 334 2023 126632
22 Nguyen T.H. Highly efficient, rapid, and practical conversion of carbohydrate into 5-hydroxymethylfurfural using a continuous-flow reactor with 1-(4-sulfobutyl)-3-methylimidazolium bromide ionic liquid as a catalyst Fuel 354 2023 129399
23 Choudhary P. Kumar A. Krishnan V. Nanoarchitectonics of phosphorylated graphitic carbon nitride for sustainable, selective and metal-free synthesis of primary amides Chem. Eng. J. 431 2022 133695
24 Kong X. Graphitic carbon nitride-based materials for photocatalytic antibacterial application Mater. Sci. Eng. R Rep. 145 2021 100610
25 Majdoub M. Anfar Z. Amedlous A. Emerging chemical Functionalization of g-C3N4: covalent/noncovalent Modifications and applications ACS Nano 14 10 2020 12390 12469 33052050
26 Ding G. Highly selective synthesis of phenol from benzene over a vanadium-doped graphitic carbon nitride catalyst ChemCatChem 5 1 2013 192 200
27 Baig R.B.N. Room temperature synthesis of biodiesel using sulfonated graphitic carbon nitride Sci. Rep. 6 1 2016 39387
28 Wang X.-X. 2D/2D MXene/g-C3N4 for photocatalytic selective oxidation of 5-hydroxymethylfurfural into 2,5-formylfuran Catal. Commun. 147 2020 106152
29 Xie W. Wang H. Grafting copolymerization of dual acidic ionic liquid on core-shell structured magnetic silica: a magnetically recyclable Brönsted acid catalyst for biodiesel production by one-pot transformation of low-quality oils Fuel 283 2021 118893
30 Walker T.W. Fundamental catalytic challenges to design improved biomass conversion technologies J. Catal. 369 2019 518 525
31 Le D.D. Efficient conversion of carbohydrates into 5-hydroxymethylfurfural using graphitic carbon nitride bearing brönsted acid sites Energy Fuels 38 5 2024 4203 4216
32 Xu G. Facile hydrothermal preparation of graphitic carbon nitride supercell structures with enhanced photodegradation activity Diam. Relat. Mater. 97 2019 107461
33 Chhabra T. Influence of Lewis and Brønsted acidic sites on graphitic carbon nitride catalyst for aqueous phase conversion of biomass derived monosaccharides to 5-hydroxymethylfurfural Carbon 183 2021 984 998
34 Kohns R. In situ synthesis and characterization of sulfonic acid functionalized hierarchical silica monoliths J. Sol. Gel Sci. Technol. 96 1 2020 67 82
35 Sagara N. Photoelectrochemical CO2 reduction by a p-type boron-doped g-C3N4 electrode under visible light Appl. Catal., B 192 2016 193 198
36 Wang X. A metal-free polymeric photocatalyst for hydrogen production from water under visible light Nat. Mater. 8 1 2009 76 80 18997776
37 Wang T. Nolte M.W. Shanks B.H. Catalytic dehydration of C6 carbohydrates for the production of hydroxymethylfurfural (HMF) as a versatile platform chemical Green Chem. 16 2 2014 548 572
38 Lu Q. Ultrasound-NATDES/DMSO system for corn straw biomass conversion into platform compounds Renew. Energy 190 2022 675 683
39 Hao Nguyen T. One-Pot effective approach to 2,5-diformylfuran from carbohydrates using MoS2-decorated carbonaceous sugarcane bagasse ChemSusChem 2024 e202400657
40 Chien Truong C. Sustainable catalytic transformation of biomass‐derived 5‐hydroxymethylfurfural to 2, 5‐bis (hydroxymethyl) tetrahydrofuran ChemSusChem 15 13 2022 e202200178
41 Wang J. Promotion effect of molten salt hydrate on co-esterification of biomass-derived levulinic and formic acids Fuel 321 2022 124077
42 Hu L. Chemocatalytic hydrolysis of cellulose into glucose over solid acid catalysts Appl. Catal., B 174–175 2015 225 243
43 Zhao H. Metal chlorides in ionic liquid solvents convert sugars to 5-hydroxymethylfurfural Science 316 5831 2007 1597 1600 17569858
44 Hu S. Efficient conversion of glucose into 5-hydroxymethylfurfural catalyzed by a common Lewis acid SnCl4 in an ionic liquid Green Chem. 11 11 2009 1746 1749
45 Ruan C. Heeres H.J. Yue J. 5-Hydroxymethylfurfural synthesis from fructose over deep eutectic solvents in batch reactors and continuous flow microreactors J. Flow Chem. 2023 1 14 37359287
46 Liu J. Conversion of fructose into 5-hydroxymethylfurfural (HMF) and its derivatives promoted by inorganic salt in alcohol Carbohydr. Res. 350 2012 20 24 22264628
