Carbon-based Solid Acid Catalyst Research Articles

Sulfonated P-W modified nitrogen-containing carbon-based solid acid catalysts for one-pot conversion of cellulose to ethyl levulinate under water-ethanol medium

Sulfonated P-W modified nitrogen-containing carbon-based solid acid catalysts for one-pot conversion of cellulose to ethyl levulinate under water-ethanol medium

Efficient and selective conversion of xylose to furfural over carbon-based solid acid catalyst in water-γ-valerolactone

Hydrothermal liquefication of biomass to produce high-quality chemicals and liquid fuels is considered as a renewable and sustainable technology. Herein, a one-step hydrothermal method was used to prepare microcrystalline cellulose supported carbon-based catalyst PTA-BC with the activation factor of phosphotungstic acid. It was demonstrated by Py-FTIR, NH3-TPD and XPS that PTA-BC is not only rich in functional groups but also contains Brønsted acid sites (hydroxyl groups) and Lewis acid sites (CC, carboxyl groups). After experimental optimization, the optimum yield of furfural obtained from xylose catalyzed by PTA-BC was 81.02% at the reaction temperature of 180 °C and the reaction time of 20 min. The results show that PTA-BC contains –COOH, –OH and CC as catalytic sites and that the synergistic effect of these functional groups. The nature of the reaction solvent, appropriate reaction temperature and residence time are the main reasons for the good catalytic performance. This work provides a promising way for the synthesis of solid acid catalyst, which has a wide application prospect for the production of furfural.

Influence of Brönsted Acid Sites on Activated Carbon-Based Catalyst for Acetylene Dimerization.

Activated carbon (AC) has been widely used as a support material with both tunable acidity and abundant functional groups for solid acid catalysts in various chemical processes such as acetylene dimerization. A facile, mild acid modification method that directly activates AC to generate rich defects and oxygen functional group surface structures with Brönsted acid sites and an enhanced conductivity is presented here. Impressively, the catalyst with optimized Brönsted acid sites and an enhanced dispersion of active components exhibited a superior acetylene dimerization catalytic activity. Moreover, theoretical calculations indicated that an increase in hydrogen concentration could inhibit the formation of coke. This research offered a feasible potential way to devise and construct a carbon-based solid acid catalyst with an excellent catalytic performance.

The cellulose hydrolysis into glucose with carbon-based solid acid catalyst via machine learning, life cycle assessment and bibliometric analysis

The cellulose hydrolysis into glucose with carbon-based solid acid catalyst contributes to sustainable and low-carbon development. Determining the quantitative impact of key variables on glucose yield and environmental sustainability is a notoriously time-consuming and labor-intensive process. In this study, a bibliometric analysis was carried out to examine the current research on cellulose hydrolysis into glucose using solid acid catalyst. The application of machine learning (ML) has demonstrated that the random forest (RF) model possesses optimal predictive performance concerning the glucose yield (Training R2 = 0.89, Testing R2 = 0.80, MAE = 6.52, RMSE = 8.29). The SO3H acid densities was emerged as a most crucial influential parameter. The interactions relationship of influenced factors for glucose production was clarified by the partial dependence plot analysis (PDPs). Furthermore, the life cycle assessment (LCA) further indicated that the carbon solid acid catalysts used in cellulose hydrolysis to produce glucose have lower emissions of CO2, NOx, and SO2 compared to traditional acid catalysts, which is 85.5 kg ep of CO2, 0.17 kg ep of NOx, 0.23 kg ep of SO2 for carbon solid acid catalysts, while 91.84 kg ep of CO2, 0.24 kg ep of NOx, 0.61 kg ep of SO2 emission for acid hydrolysis. Thus, carbon solid acid catalysts have a comparably lower negative environmental impact than traditional acid hydrolysis. This study provides crucial insights into improving the prediction accuracy of ML models and reducing the carbon footprint involved in glucose production.

Lignin-derived carbon-based solid acid catalyst for the conversion of Pueraria cellulose to lactic acid

Lignin-derived carbon-based solid acid catalyst for the conversion of Pueraria cellulose to lactic acid

Cellulose hydrolysis reactor incorporating stirring apparatus for use with carbon-based solid acid catalyst

A highly efficient reactor with a stirring device was specially designed with the intent of performing the hydrolysis of pure crystalline cellulose using a carbon-based solid acid catalyst. This catalyst comprised an amorphous carbon-based material bearing –SO3H, –COOH and –OH groups. The stirring apparatus had seven blades coated with polytetrafluoroethylene and arranged axially at regular intervals with a 60° offset. This design proved highly effective, providing double the glucose yield compared with conventional stirring systems. The basic properties of this novel reactor were investigated and analyzed and are discussed herein.

Structure and Catalytic Performance of Carbon-Based Solid Acids from Biomass Activated by ZnCl2

In the current investigation, carbon-based solid acid catalysts were synthesized from peanut shells (PSs) and rice straw (RS) using ZnCl2 activation and concentrated sulfuric acid sulfonation. These catalysts were then employed for the hydration of pinene to produce terpineol. The research findings suggest that the natural porous structure of RS is more amenable to ZnCl2 activation compared to PSs. Furthermore, the catalysts prepared from fully activated RS by ZnCl2 (RSA-C-S) had a higher SBET and higher density of oxygen-containing groups (–COOH) in comparison with unactivated RS-based solid acids (RSC-S). The characterization outcomes revealed that RSA-C-S possesses a specific surface area of 527.0 m2/g, significantly outperforming RSC-S, which has a surface area of 420.9 m2/g. Additionally, RSA-C-S registered a higher –COOH density of 1.37 mmol/g, as opposed to RSC-S’s, with 1.07 mmol/g, attributable to the partial oxidation of internal –OH groups during activation. Experimental data from hydration tests confirmed that the catalyst’s superior performance is largely attributed to its elevated specific surface area and a high density of –COOH functional groups. Under optimal reaction parameters, RSA-C-S demonstrated unparalleled catalytic efficiency in the synthesis of α-terpineol via hydration of α-pinene, achieving conversion and selectivity rates of 87.15% and 54.19%, respectively.

A novel carbon-based solid acid catalyst with high acidity for the hydration of α-pinene to α-terpineol: Effect of graphite crystallite size and synergistic effect of defects

This work, for the first time, highlights that small-sized graphite crystallite and highly defective carbon-based catalysts can effectively increase the −SO3H density of the catalysts and modulate the surface electronic properties of the catalysts, which further facilitates the α-pinene hydration reaction. Hydrothermal phosphoric acid modulation of graphite crystallite size and defects in carbon-based catalysts systematically revealed the correlation between −SO3H density, catalytic activity, graphite crystallite size, and defects in biomass carbon. The characterization results demonstrate that small-size graphite crystallites and high structural defects provide more sp2 hybridized carbon edges, contributing to the catalyst's increase of −SO3H density. The −SO3H group density of the catalyst increased from 0.89 to 1.20 mmol/g after hydrothermal phosphoric acid treatment. The catalyst has the highest efficiency in the α-pinene hydration to α-terpineol among the reported catalysts, in which 87.06 % of α-pinene was converted and reached a maximum α-terpineol selectivity (55.38 %) time only 22 h. Density functional theory calculations show that the lattice defects of graphite crystallites in catalysts lead to the polarization of the electron cloud around the catalyst, which further leads to the reduction of electrostatic resistance between α-pinene and the active catalytic sites. The apparent activation energy of hydration by the catalyst is 1.74 times lower than that of conventional biomass carbon-based solid acids. The reduction of graphite crystallite size is considered a critical step in improving the selectivity of α-terpineol attributed to the effective reduction of α-terpineol adsorbed on the catalyst.

Powder properties of carbon-based solid acid catalyst for designing cellulose hydrolysis reactor with stirring apparatus

The powder properties of a carbon-based solid acid catalyst, an amorphous carbon material bearing SO3H, COOH and OH groups, were investigated for the hydrolysis of cellulose. The Carr flowability and floodability indices, the angle of internal friction (adherence), and the particle size distribution and shape for the powder catalyst were determined. The need to develop a special reactor with a stirring apparatus for the hydrolysis of cellulose was determined based on the Carr flowability index. Insight into the interaction or adherence between the catalyst and crystalline cellulose during the hydrolysis process was gained by measuring the internal friction angle. The optimum moisture content in the catalyst to achieve the maximum adherence was investigated.

H2SO4 assisted hydrothermal conversion of biomass with solid acid catalysis to produce aviation fuel precursors

With hydrothermal reaction, lignocellulosic biomass can be efficiently converted into furfural (FF) and levulinic acid (LA), both of which are key platform compounds that can be used for the subsequent preparation of aviation fuels. In order to reduce the acid concentration in traditional hydrolysis and provide a reaction system with good catalytic activity, we propose a biomass conversion route as dilute acid hydrolysis coupled with solid acid catalysis. Firstly, at different temperatures, the hemicellulose and cellulose in corn stover were step-hydrolyzed by sulfuric acid solution with a concentration of 0.9 wt.% to produce xylose and glucose, with conversion reaching 100% and 97.3%, respectively. Subsequently, a new resin-derived carbon-based solid acid catalyst was used to catalyze the aforementioned saccharide solutions to obtain FF with yield of 68.7 mol% and LA of 70.3 mol%, respectively. This work provides a promising approach for the efficient production of bio-aviation fuel precursors.

Preparation of Carbon-Based Solid Acid Catalyst from High-Sulfur Petroleum Coke with Nitric Acid and Ball Milling, and a Computational Evaluation of Inherent Sulfur Conversion Pathways.

A series of petroleum coke (petcoke)-derived solid acid catalysts were prepared via nitric acid treatment with or without ball milling pretreatment. The inherent sulfur in petcoke was converted to sulfonic groups, which were active sites for the esterification of octanoic acid and methanol at 60 °C, with ester yields of 14-43%. More specifically, samples without ball milling treated at 120 °C for 3 h had a total acidity of 4.67 mmol/g, which was 1.6 times that of the samples treated at 80 °C, despite their -SO3H acidities being similar (~0.08 mmol/g). The samples treated for 24 h had higher -SO3H (0.10 mmol/g) and total acidity (5.25 mmol/g) but not increased catalytic activity. Ball milling increased the defects and exposed aromatic hydrogen groups on petcoke, which facilitated further acid oxidation (0.12 mmol -SO3H/g for both materials and total acidity of 5.18 mmol/g and 5.01 mmol/g for BP-N-3/120 and BP-N-8/90, respectively) and an increased ester yield. DFT calculations were used to analyze the pathways of sulfonic acid group formation, and the reaction pathway with NO2• was the most thermodynamically and kinetically favourable. The activities of the prepared catalysts were related to the number of -SO3H acid sites, the total acidity, and the oxygen content, with the latter two factors having a negative impact.

A remarkable bifunctional carbon-based solid acid catalyst derived from waste bio-tar for efficient synthesis of 5-hydroxymethylfurfural from glucose

A remarkable bifunctional carbon-based solid acid catalyst derived from waste bio-tar for efficient synthesis of 5-hydroxymethylfurfural from glucose

Development of sulfonated carbon-based solid-acid catalysts derived from biorefinery residues and biomass ash for xylan hydrolysis

In this study, biorefinery residues and biomass ash were used to develop sulfonated carbon-based solid-acid catalysts to enhance xylan hydrolysis. Metals extracted from the biomass ash were impregnated into a carbon support prepared from biorefinery residues to synthesize sulfonated ash-impregnated carbon-based catalyst. Metals present in the ash most probably are responsible for the increased acid density in the catalyst. Using this catalyst, 11.4 % xylose yield was produced, an increase of 171 % over the yield obtained from a catalyst without ash impregnation. Using a xylan-to-catalyst ratio of 1:2, 72.9 % xylose yield was obtained, comparable to using 0.5 wt% sulfuric acid under the same reaction condition. Moreover, this catalyst significantly inhibited xylose dehydration, only forming 11.3 % furfural compared to that generated using dilute acid. Hence, these results show the potential for using biomass ash as a metal source to increase the number of acid sites in solid-acid catalysts used for biomass pretreatment.

Valorization of lignocellulosic wastes for low-cost and sustainable algal biodiesel production using biochar-based solid acid catalyst

Recently, carbon-based solid acid catalysts have come into prominence among different types of catalyst for production of biodiesel. Solid acid catalysts can be produced from carbon based materials such as biomass wastes by reducing the cost. Utilization of these wastes to prepare solid acid catalyst provides solid waste management and the potential greenhouse gas emissions decreases. Since algal biodiesel production is not so economical and needs to be improve, using these catalysts produced from waste biomass can be promising for making the process more cost effective and a low cost applicable zero-waste biorefinery approach can be put forth. In this study, walnut shell, olive stone and macroalgae were utilized to produce biochar based solid acid catalyst to be evaluated in microalgal biodiesel production. Walnut shell carbonized at 500 °C and then sulfonated by sulfuric acid was selected for biodiesel production due to having higher sulfonic acid density (0.35 mmol/g) and preferable structural properties. The statistical evaluation of transesterification parameters effect on microalgal biodiesel yield were evaluated and yield of 82% was found as the highest which was obtained by using 5 wt% catalyst, 12:1 methanol/oil molar ratio at the reaction time of 60 min. Stability test also showed the catalyst can be re-used up until the 5th cycle. Low cost feedstock and reusability of the catalyst presented a simple, cost-effective and environment-friendly process. At last, lignocellulosic wastes can be suggested for not only as biochar production also can be evaluated as solid acid catalyst and provide a cost-efficient biodiesel production.

A highly efficient, green, and straightforward approach for 2,5-diformylfuran synthesis from carbohydrates using carbonized sugarcane bagasse and KBr

2,5-Diformylfuran (DFF) is an important chemical that is utilized to synthesize several valuable chemicals. Direct preparation of DFF from plentiful and inexpensive carbohydrates in a one-pot approach is highly desired. Here, we report the development of a heterogeneous sulfonated amorphous carbon-derived sugarcane bagasse combined with KBr as a catalyst system to convert fructose to DFF in a short time and high yield in DMSO. Several reaction conditions, such as the effect of metal bromide, the effect of KBr and carbon-based solid acid catalyst loading, the effect of temperature, the effect of solvent, the effect of substrate, reusability test, and scale-up synthesis, have been investigated. The optimized yield of DFF was 90 ± 3% at 140 °C in DMSO solvent for 5 h. The approach has several outstanding features, including high chemo-selectivity, high yield, low cost, and recyclable catalyst.

Performance and deactivation mechanism of a carbon-based solid acid catalyst in the esterification of soybean saponin acid oil

In this study, a bamboo charcoal-based solid acid catalyst (BC) was generated by one-step carbonization and sulfonation at 150 °C for 4 h in the presence of sulfuric acid. The BC was characterized by Fourier transform infrared spectrometry, elemental analysis, X-ray powder diffraction, and Brunauer-Emmet-Teller specific surface area analysis. The BC had a specific surface area of 4.54 m2/g, pore volume of 0.0142 cm3/g, and acid density of 1.476 mmol/g. Subsequently, the catalytic activity and deactivation mechanism of the BC in the esterification of soybean saponin acid oil (SAO) and methanol were investigated. The results showed that the conversion yield of esterification reached 98.28% under optimal reaction conditions (i.e., catalyst addition of 10 wt%, methanol/oil molar ratio of 10:1, temperature of 65 °C, and time of 8 h). The conversion yield decreased as reuse batches increased, and was below 80% after three batches. The loss of sulfonic acid groups from the BC occurred mainly in the first esterification batch, caused by residual sulfuric acid leaching and chemical derivatization of sulfonic acid groups. In the second to fourth esterification batches, chemical derivatization was the main reason for deactivation, where the generation of sulfonate esters and exchange of metal cations with hydrogen ions accounted for more than 75% of the chemical derivatization loss. Therefore, without impurity purification of SAO, reducing the amount of sulfonate ester generated on the catalyst was found to be essential for increasing the reuse performance of the BC and reducing the cost of biodiesel production.

Reduced surface sulphonic acid concentration Alleviates carbon-based solid acid catalysts deactivation in biodiesel production

In this study, esterification of oleic acid with methanol using solid acid catalysts synthesised from different waste biomasses (bamboo, wheat straw, and peanut shells) using the carbonisation–sulphonation method was investigated. The results showed that biomass with higher lignin content had a lower optimum carbonisation temperature and the corresponding catalyst contained more acidic groups. All three catalysts catalyzed esterification reactions under optimum reaction conditions (10 wt% catalyst loading, 8:1 methanol/oleic acid, at 75 °C for 8 h) with >96% conversion. The oleic acid conversion decreased with catalyst cycles, reaching approximately 80% after four cycles. In addition to the leaching of active groups during the reaction, the reaction of the sulphonic acid on the catalyst surface with excess methanol (i.e., sulphonic ester formation) is an important cause of catalyst deactivation. The high concentration of sulphonic acid groups on the catalyst surface was the major cause of sulphonic ester formation during esterification. Therefore, reducing the concentration of sulphonic acid groups by increasing the catalyst volume and specific surface area is an effective way to avoid reduction in the catalyst activity while maintaining a constant total number of sulphonic acid groups.

Green biodiesel production from Jatropha curcas oil using a carbon-based solid acid catalyst: A process optimization study

Biodiesel production from low cost, inedible oil represents an increasingly important target for reasons of both sustainability and cost. In this work, we comprehensively verify the batch reproducibility of a sulfonic acid functionalized carbonaceous material (SAFACAM) as catalyst for biodiesel production from inedible feedstock Jatropha curcas oil (JCO). The current catalyst benefits the environment through its atom-efficient, one-pot preparation from an abundant natural biomass derivative (glucose) and has the potential to reduce the overall biodiesel production cost by converting inexpensive raw materials. In this context, JCO has emerged as a crop of interest to the energy sector, potentially providing a reliable and renewable energy source for many countries. Through a central composite design (CCD) approach using response surface methodology (RSM), a 98.7 ± 0.6% conversion of biodiesel is achieved (methanol-to-oil molar ratio 20:1, reaction time 50 min, reaction temperature 120 °C and catalyst loading 9 wt % (with respect to oil)). The chemically satisfactory composition of the biodiesel product has been verified, the reusability of catalyst has been tested, and a significant enhancement in performance when using microwave heating demonstrated. An 83.0 ± 0.8% conversion of JCO is reported in the fifth cycle of reuse.

Substitution of liquid methanol with methanol vapour increases the activity and stability of carbon-based solid acid catalysts in biodiesel production process

The effect of methanol vapour esterification (MVE) on the catalyst activity and reusability was investigated using methanol vapour (MV) instead of liquid methanol for the esterification reaction of oleic acid catalysed by a carbon-based solid acid catalyst (CSAC) S150-4. The conversion yield for the MVE was 98.8 % at a catalyst loading of 4 wt%, methanol/oleic acid molar ratio of 40:1, reaction temperature of 76 °C and reaction time of 4 h. When the catalyst loading is increased to 10 wt%, S150-4 repeatedly catalysed MVE up to the eighth batch, while still achieving 83.4 % conversion. The turnover frequency and number of catalyst reuses were twice as high for MVE as in liquid methanol esterification (LME) under the optimal esterification conditions for both modalities. When compared to LME, MVE achieved a combination of a large amount of methanol and oleic acid in a short time, increasing the conversion yield while reducing the average contact time between methanol and the acidic groups on the surface of the CSAC, resulting in less leaching and chemical derivatization of the sulphonic acid groups from the catalyst in MVE. The production cost of methyl oleate in MVE was 19.1 % lower than that for LME. Therefore, the application of MVE as an alternative to conventional esterification is an effective way to extend the life of CSACs.

Efficient conversion of biomass derivatives to furfural with a novel carbon-based solid acid catalyst

The novel carbon-based solid acid catalyst (S-800-CG) was synthesized by high-temperature carbonization of calcium gluconate followed by sulfonation with 4-diazoniobenzene sulfonate at room temperature. The catalyst was characterized by TEM, SEM, N2 adsorption-desorption, TGA, FT-IR, and XPS to reveal its physical and chemical properties. The S-800-CG was used as a catalyst for converting xylose or corncob into furfural via a one-step process. Furthermore, the effects of calcination temperatures of the carbon support, reaction temperature, residence time, catalyst loading, and substrate concentration were investigated. It was demonstrated that S-800-CG is an efficient solid acid catalyst for furfural production from xylose in 1,4-dioxane. 85.9% furfural yield can be achieved from 50 mg xylose at 140 °C in 40 min by using 100 mg catalyst. Moreover, 52.9% furfural yield was obtained from 200 mg corncob at 190 °C in 70 min using 100 mg catalyst.