Solid Acid Catalyst Research Articles

Methyl ester production process from palm fatty acid distillate using hydrodynamic cavitation reactors in series with solid acid catalyst.

This study aims to optimize the reduction of free fatty acids (FFAs) in palm fatty acid distillate (PFAD) using hydrodynamic cavitation reactors (HCRs) in series and a solid acid catalyst for biodiesel production. Hydrodynamic cavitation is used to accelerate the esterification of FFAs using a heterogeneous acid catalyst. There are three HCRs units, and each HCR composed of a 3D-printed rotor and stator, is separated by flanges and equipped with a basket for holding Amberlyst-15 catalyst. Through response surface methodology (RSM), the esterification process is optimized by adjusting its optimal parameters, namely, methanol (2-12 wt%), circulation time (30-170min), and rotor speed (1000-3000rpm). The optimal conditions for achieving a maximum methyl ester purity of 89.76 wt% in converting FFA in first-step esterified oil are 9 wt% methanol (molar ratio of methanol to oil of 4:1), 133min of circulation time, and 2000rpm of rotor speed. An 82.48 wt% biodiesel yield is achieved from the HCRs in series under the optimal conditions. Scanning electron microscope images reveal that after the esterification process, there are minor cracks and defects on the catalyst's resin surface, indicating the presence of residual reactants. Further examination of the catalyst after the esterification process, reveals an average absorption pore diameter of 341.41 Å and BET surface area of approximately 41.68 m2/g. Although there were slight physical changes in the catalyst, HCRs technology offers a viable FFA reduction process that could enhance biodiesel production efficiency. Moreover, the optimized conditions achieved in this study contribute to the advancement of biodiesel production processes and provide insights into the performance of the catalyst used.

Tungstic Acid-Functionalized Natural Zeolite as a Solid Acid Catalyst for Levulinic Acid Esterification

Tungstic Acid-Functionalized Natural Zeolite as a Solid Acid Catalyst for Levulinic Acid Esterification

Synergistic Effects of Nonthermal Plasma and Solid Acid Catalysts in Thermo-Catalytic Glycerol Dehydration

To enhance the bio-based synthesis of acrolein from glycerol, a hybrid approach combining in situ nonthermal plasma (NTP) with thermo-catalytic dehydration was employed. This study investigated the impact of the reaction temperature and NTP discharge field strength on glycerol conversion, acrolein selectivity, byproduct formation, and coke deposition using two catalysts of silicotungstic acid supported on mesoporous alumina and silica. The results revealed that, while the reaction temperature and NTP field strength exhibited complex interactions, the in situ application of NTP markedly improved both glycerol conversion and acrolein selectivity when optimized for specific temperature–NTP field strength combinations. Additionally, the reaction mechanisms of glycerol dehydration with the two catalysts, in the presence and absence of NTP, were systematically analyzed and discussed based on the experimental data.

Solid acid-catalyzed green synthesis of bis-Schiff bases: Spectroscopic, DFT, molecular docking, and ADMET studies

This research examines the green synthesis of bis-Schiff bases with benzyl substitutions at 3,4-dimethoxy and 3,4,5-trimethoxy positions through solvent-free microwave-assisted condensation between para-phenylenediamine and 3,4-dimethoxybenzaldehyde (I) and 3,4,5-trimethoxybenzaldehyde (II), using sulfated-TiO2 as a solid acid catalyst. The structures were confirmed through various physicochemical and spectroscopic techniques, including IR, ¹H NMR, ¹³C NMR, and SC-XRD. The compound II crystallized in the monoclinic system (space group of P-21/c). The primary objective was to explore the geometry using both experimental methods and density functional theory (DFT) with the B3LYP/6–311 G (d,p) level. A comparison of experimental (FT-IR, NMR, SC-XRD) and simulated data showed strong agreement. Additionally, Hirshfeld analysis, ELF, LOL, and RDG topological studies were performed. Docking simulations on the 2V54 monkeypox target protein revealed binding affinities, with compounds I and II. The target protein had a binding energy of 4.83 and −4.98 kcal/mol with I and II. ADMET predictions further demonstrated the pharmacological profile of the synthesized compounds.

Towards Photothermal Acid Catalysts Using Eco-Sustainable Sulfonated Carbon Nanoparticles—Part II: Thermal and Photothermal Catalysis of Biodiesel Synthesis

The main goal of this work is to evaluate the ability of sulfonated carbon nanoparticles (SCNs) to induce photothermal catalysis of the biodiesel synthesis reaction (transesterification of natural triglycerides (TGs) with alcohols). Carbon nanoparticles (CNs) are produced by the carbonization of cross-linked resin nanoparticles (RNs). The RNs are produced by condensation of a phenol (resorcinol or natural tannin) with formaldehyde under ammonia catalysis (Stober method). The method produces nanoparticles, which are carbonized into carbon nanoparticles (CNs). The illumination of CNs increases the temperature proportionally (linear) to the nanoparticle concentration and exposure time (with saturation). Solid acid catalysts are made by heating in concentrated sulfuric acid (SEAr sulfonation). The application of either light or a catalyst (SCNs) (at 25 °C) induced low conversions (<10%) for the esterification reaction of acetic acid with bioethanol. In contrast, the illumination of the reaction medium containing SCNs induced high conversions (>75%). In the case of biodiesel synthesis (transesterification of sunflower oil with bioethanol), conversions greater than 40% were observed only when light and the catalyst (SCNs) were applied simultaneously. Therefore, it is possible to use sulfonated carbon nanoparticles as photothermally activated catalysts for Fischer esterification and triglyceride transesterification (biodiesel synthesis).

Post-functionalized cellulose/metal-organic framework composite with sulfonic acid: An efficient, rapid and recyclable bio-based solid acid catalyst for the synthesis of 5-hydroxymethylfurfural

A new acid catalyst derived from renewable sources was developed using an ultrasound-assisted approach. This involved the formation of a metal-organic framework called MIL-88(Fe) in the presence of carboxymethylated-cellulose (CMC). Subsequently, the catalyst underwent a post-synthetic modification to introduce further acidic –SO3H groups into the structure of the CMC/MIL-88(Fe) composite. Various examinations were carried out that validated the successful creation of the CMC/MIL-88(Fe)-SO3H catalyst. The effectiveness of the catalyst was assessed in the process of solid acid catalysis, specifically in the dehydration of fructose to produce 5-hydroxymethylfurfural (HMF). Through the employment of Response Surface Method (RSM) optimization, it was determined that utilizing 34 wt% of the catalyst at a temperature of 90 °C for 30 min resulted in a remarkable 98 % HMF yield. The catalyst exhibited good reusability, as it retained its catalytic effectiveness throughout four consecutive cycles. Comparative catalytic investigations involving CMC and CMC/MIL-88(Fe) composite without sulfonation revealed the superior activity of CMC/MIL-88(Fe)-SO3H catalyst, emphasizing the collaborative effect of CMC, MIL-88(Fe), and the impact of post-functionalization with -SO3H on the performance of the catalyst.

Alkylsulfonic acid functionalized aluminoborate: A highly efficient and regioselective solid acid catalyst for ring-opening addition of epoxide under solvent-free condition

Functionalized solid acid material has more accessible active surface and therefore is usually considered as an important substitute for conventional liquid mineral acid. In this work, a novel alkylsulfonic acid functionalized porous aluminoborate molecular sieve (PKU-1) has been prepared through 3-step post-synthetic method, and the high-density acidic sites were tailored and comprehensively characterized by various measurements. These acidity-controllable active sites exhibit high activity and specific regioselectivity towards alcoholysis reaction for the solvent-free production of methoxyl alcohol, and turnover frequency reaches ∼1000 h–1, which is much superior to previous reports. Comprehensive characterizations indicate catalytic centers exclusively come from –SO3H acid sites, rather than other type of Brönsted or Lewis acid sites. A plausible reaction mechanism was proposed to interpret the key role of –SO3H active sites on alcoholysis reaction based on the related experimental results. This work offers a promising solution to generate the controllable acidity and provides an available candidate in the environmentally benign catalysis for selective synthesis of some value-added compounds.

Influence of pH on the synthesis of carbon spheres and the application of carbon sphere-based solid catalysts in esterification

Abstract Size uniformity is a key challenge in the preparation of hydrothermal carbon spheres and a prerequisite for size effect research and many applications of carbon spheres. To solve the scientific problem of low uniformity due to the slow carbonization in traditional preparation of glucose carbon spheres, we propose to add acid/base catalysts to accelerate nucleation, shorten the nucleation time, and improve the size uniformity of carbon spheres. The carbon spheres prepared under base conditions versus acid conditions have higher uniformity and smaller particle size (particle size = 503 nm). This result is due to the faster accumulation of aromatic clusters, shorter nucleation time, and larger number of carbon spheres in alkaline systems. The NaOH-HCSs-based solid acid catalyst as-prepared exhibits excellent catalytic activity, and the esterification rates of levulinic acid and n-butanol maximize to 96.36%.

Process Intensification and Reaction Kinetics for Synthesis of 5‐Hydroxymethyl Furfural Using DICAT‐1 Solid Acid Catalyst in a Batch Reactor

Abstract5‐HMF is a potential platform multifaceted molecule for various industrial applications and can be produced from biomass‐based hexose sugars. In the present study, the indigenously prepared catalyst DICAT‐1 (an acronym derived from DBT‐ICT Center for Energy Biosciences Catalyst #1) has been explored for fructose dehydration, using isopropyl alcohol (IPA) as a green and low boiling point (LBP) organic solvent. The exploration of heterogeneous DICAT‐1 adds specific advantages for 5‐HMF synthesis in terms of high yield, conversion, selectivity, catalyst separation, recycle, reuse, and so forth. Different variants of DICAT‐1, such as DICAT‐1A, DICAT‐1B, DICAT‐1C, and DICAT‐1D, having variable surface acidity were tested for fructose dehydration in the presence of IPA. Of the tested variants, DICAT‐1C provides good yield and selectivity of 5‐HMF. Thus, further process optimization study was conducted to obtain maximum yield, conversion, and selectivity using DICAT‐1C. The intensified process provides maximum 78% yield of 5‐HMF with 83% fructose conversion and 94% selectivity. The catalyst recyclability study showed the consistency in 5‐HMF yield, conversion, and selectivity for five consecutive recycle runs. The study of reaction kinetics showed the first‐order kinetics with an activation energy of 13.16 kJ/mole by using DICAT‐1C catalyst. Thus, the use of easily recyclable and robust catalyst provides an efficient route for production of 5‐HMF in presence of green solvent.

Niobium Pentoxide as an Acid Catalyst: An Overview

The global chemical industry is under increasing pressure to adopt more sustainable practices, as most chemical products exceed environmental safety limits. Given that chemical production largely relies on catalytic processes, the development of solid acid catalysts has become crucial for more sustainable production. Among these catalysts, niobium pentoxide stands out due to its strong acid sites, which remain active in the presence of water, and its stability under hydrothermal conditions. Recent studies have demonstrated that these solids maintain their catalytic activity even in the presence of strong bases, making them unique catalysts. This review explores the potential of niobium pentoxide as an acid catalyst, addressing advances in synthesis techniques, surface modifications, and combinations with other materials to enhance its catalytic performance in sustainable applications, such as biomass conversion and biofuel production, opening new pathways for the production of greener chemicals. Finally, the future perspectives of niobium pentoxide - based catalysts in green chemistry are discussed.

Heteropolyacids combined with Y zeolite as superior solid acid catalysts to accelerate lactic acid esterification

AbstractBACKGROUNDEthyl lactate produced via esterification between lactic acid and ethanol can be used in plastics, polymers and food industries and renowned for its biodegradability and low toxicity. However, lactic acid self‐catalyzed esterification presents a slow reaction process, and acid catalysts are needed to improve the catalysis. Homogeneous acid catalysts like H2SO4 are corrosive, as well as being difficult to be seperated from the reaction media; therefore, advanced heterogeneous catalysts are more ideal. In this study, two kinds of heteropolyacid–zeolite catalysts, involving loading silicotungstic acid and phosphotungstic acid onto Y zeolite, were synthesized, characterized using X‐ray diffraction, NH3 temperature‐programmed desorption and scanning electron microscopy and analyzed for their catalytic efficiency in the catalytic esterfication.RESULTSResults showed that the Keggin structures of heteropolyacids were retained during the preparation process and strong acid sites of Y zeolite were enriched, which made the main contribution to the esterification of lactic acid and ethanol. Furthermore, the initial‐stage reaction rate of esterification was significantly enhanced. During the first hour of esterification, the conversion of lactic acid increased from 18% to 65%. Exp Dec1 index model was employed to determine the activation energies of 60HSiW‐Y and 60HPW‐Y, which exhibit values of 29.3 and 28.2 kJ mol−1, respectively.CONCLUSIONThis study indicates that Keggin structures of heteropolyacids play a key role in the esterification and heteropolyacid–zeolite catalysts can effectively catalyze the esterification. Meanwhile, the results of the kinetic experiments can be of reference significance for large‐scale industrial processes involving esterification. © 2024 Society of Chemical Industry (SCI).

Facile construction of a stable biomass-derived carbon-supported Al[sbnd]Zr composite with crystalline solid solution and Brønsted–Lewis dual acidity for efficient catalytic conversion of cellulose

Exploiting cellulose-derived levulinic acid (LA) in biorefinery has potential application prospects, and the development of efficient and stable catalysts is crucial yet challenging. In this study, a bimetallic synergy strategy was proposed to construct an efficient and durable solid acid catalyst with crystalline solid solution by a totally solid-phase method. Mechanical activation (MA)-treated precursor (metal salts, starch, and urea) was calcined to obtain a stable biomass-derived carbon (BC)-supported AlZr (MA-AZ/BC) composite, which was applied for catalytic conversion of cellulose to LA in aqueous-phase system. The results indicate that the synergistic effect of bimetallic crystalline solid solution and the existence of Brønsted–Lewis dual-acid sites in the MA-AZ/BC catalyst contributed to a cellulose conversion efficiency of 97.5 % and a LA yield of 67.1 %. Benefiting from the strong bimetal–support interaction, the MA-AZ/BC catalyst exhibited favorable stability and recoverability. On the basis of comprehensive analysis, a reaction mechanism of Brønsted–Lewis dual-acid sites for synergistic catalytic conversion of cellulose was proposed. This study provides a new idea for the rational design and environmentally friendly fabrication of functional BC-based catalysts for efficiently producing platform compounds derived from biomass.

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

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. 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. 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.

Efficient conversion of xylose and corncob to furfural using a novel carbon-based solid acid derived from black liquor lignin-tin complexes

The novel carbon-based solid acid catalyst was prepared by carbonizing the mixture of metal salts and black liquor, followed by sulfonating. The physicochemical properties of the catalysts were characterized by SEM, FTIR, BET, NH3-TPD, Py-IR, XPS, ICP, and elemental analysis. The catalytic ability of the catalyst was explored by converting xylose and corncob to furfural via a one-step process. The effects of solvent types and water contents, catalyst dosage, substrate concentration, reaction temperature, and reaction time on furfural yield were evaluated. 93.4 % of furfural yield was achieved using 200 mg xylose at 170 °C for 120 min with 150 mg catalysts. Moreover, the furfural yields of 82.5 % were obtained from corncob. This work provides a promising strategy for synthesizing carbon-based solid acid catalysts from pulp waste black-liquid resources, which has a potential application for producing furfural from hemicellulose.

Corn Stover Lignin as a Solid Acid Catalyst for the Esterification of Oleic Acid

AbstractThe catastrophic ramifications of fossil fuels on the environment have prompted the search for renewable energy sources. Over the recent decades, biodiesel has garnered attention as a promising direct alternative to diesel fuel; however, reliance on homogeneous catalysts and the requirement for refined vegetable oil feedstocks present financial and sustainability concerns. Thus, there exists a need for the development of sustainable and cost‐effective catalytic solutions. Herein, the application of lignin, an abundant and renewable biomass, as an effective heterogeneous catalyst is reported for biodiesel production via the esterification of oleic acid. Lignin is extracted from corn straw using sulfuric acid, which endows sulfonic acid groups (0.85 mmol g−1) to its structure allowing it to act as an acid catalyst without additional post‐treatments. Conversion of oleic oil to biodiesel is achieved at 97% using a 1:3 oleic acid to methanol molar ratio with a 5 wt.% catalyst loading at 90 °C after only 30 min. Moreover, the catalyst exhibits a remarkable turnover frequency of 2.61 min−1 proving its efficiency. These findings demonstrate that heterogeneous catalysts can be prepared from biomass waste offering a significantly cheaper and less intensive synthesis process and allowing for a paradigm shift to non‐edible and waste cooking oils.

Bioinspired Synthesis of Novel Different Nanoparticles and its Utility in Biodiesel and Animals Applications

Because of its ability to speed up the reaction, the catalyst is critical to its success. Most catalysts are either homogeneous or heterogeneous. It has been shown that utilizing a heterogeneous catalyst, which is easier to remove from the product after the reaction has been finished. Because of the large surface area of the Nano-catalyst results in high catalytic efficiency. To enhance the performance of catalysts a range of various types of support materials have been used. SO42--ZnO and So42-/TiO active acid catalyst was prepared and characterized. ZnO nanoparticles catalyst synthesized by precipitation of zinc nitrate for comparison with supported catalyst. Sulphated zinc oxide (SO42--ZnO) and sulphated titania (SO42-/TiO) catalysts were synthesized using impregnation methods, to test their efficacy in biodiesel production. Various waste oils from different wastes such as mutton or beef tallow, chicken fat, and methanol are preferred to use during the esterification of waste animal fat oils using solid acid catalysts to produce biodiesel. Biodiesel synthesis generates a substantial amount of glycerol as a byproduct. Effect of optimum parameters such as temperature 60 degree centigrade (°C) shown 90% yield, time 1 hour resulted in 85% yield, catalyst dose 2wt% resulted in 80% yield, stirring speed 250rpm resulted in 80% yield, methanol to oil ratio12:1 resulted as 85.5% yield for transesterification of waste fat oil. It is valuable that the supported acid catalysts showed more yield than simply synthesized ZnO nanocatalyst similarly sulphated zinc oxide showed more FAME yield than sulphated titania.

Investigation of hydrolysis of sugarcane bagasse into glucose over solid acid HSO3-ZSM-5 zeolite for fermentation to bioethanol

ABSTRACT In the pursuit of sustainable energy sources, biomass has emerged as a promising alternative to fossil fuels due to its renewability and carbon neutrality. This current work presents the application of solid acid zeolite catalyst for biomass hydrolysis into reducing sugar for fermentation. Sulfonated ZSM-5 zeolite was prepared by grafting sulfonic acid group on the surface and/or into the pores of porous ZSM-5 zeolite and characterized by several analyses. The as-synthesized HSO3-ZSM-5 zeolite was then investigated as a solid acid catalyst for the hydrolysis of alkaline pretreated sugarcane bagasse (SB). Containing sulfonic acid groups – a very strong acid – on the surface, HSO3-ZSM-5 zeolite presented high catalytic activity and high efficiency in the hydrolysis of SB biomass. When the hydrolysis was carried out under optimal conditions, approximately 106.8 g/L of reducing sugar including of glucose, xylose, arabinose, and cellobiose was recovered. 86.65% fermentable sugars could be achieved after catalytic hydrolysis, and 48.7% of SB in total was converted to reducing sugar and others. Moreover, this solid acid catalyst can be reused impressively several times with no significant loss in catalytic activity. The sugar hydrolyzate could be used for fermentative production of bio-ethanol. Results indicated the possibility of using solid acid zeolite in the hydrolysis of lignocellulose to generate sugars that can be further applied in biofuel or chemical manufacturing.

Conversion of Cellobiose to Formic Acid as a Biomass-Derived Renewable Hydrogen Source Using Solid Base Catalysts.

Formic acid is considered a promising hydrogen carrier. Biomass-derived formic acid can be obtained by oxidative decomposition of sugars. This study explored the production of formic acid from cellobiose, a disaccharide consisting of d-glucose linked by β-glycosidic bonds using heterogeneous catalysts under mild reaction conditions. The use of alkaline earth metal oxide solid base catalysts like CaO and MgO in the presence of hydrogen peroxide could afford formic acid from cellobiose at 343 K. While CaO gave 14 % yield of formic acid, the oxide itself was converted to a harmful metal peroxide, CaO2 after the reaction. In contrast, MgO could produce formic acid without the formation of the metal peroxide. The difficulty in selectively synthesizing formic acid from cellobiose using these solid base catalysts was due to the poor conversion of cellobiose to glucose. Using a combination of solid acid and base catalysts, a high formic acid yield of 33 % was obtained under mild reaction conditions due to the quantitative hydrolysis of cellobiose to glucose by a solid acid followed by the selective decomposition of glucose to formic acid by a solid base.

Efficiently Catalyzing Xylose to Furfural by Synthesizing Solid Acid Catalysts from Lignocellulosic Residues

AbstractThe utilization of biomass as a carbon source for the synthesis of renewable solid acid catalysts (SA) has emerged as a prominent research direction in the field of heterogeneous catalysis. Based on the challenges associated with reusing residues from lignocellulosic biorefining, the biomass‐based SA (BCSA) were prepared using poplar sawdust (PS), hydrothermally pretreated PS (PPS), and the residue of PPS's enzymatic hydrolysis (ER). The characterization revealed that all three types of BCSA were loaded with catalytic groups, and the BCSA synthesized using ER rich in lignin components exhibited a highly efficient catalytic structure. Furthermore, the catalysis of a 20 g/L xylose solution with BCSA‐ER as SA also achieved the highest furfural yield (89.3%) and furfural selectivity (90.3%). The findings of this study suggested that lignin holds significant potential as a carbon carrier for SA, thereby offering a viable solution for utilizing by‐products from lignocellulosic biorefining.

Catalytic synthesis of DHHB using solid acids

Abstract DHHB (Diethylamino hydroxybenzoyl hexyl benzoate) is a widely regarded UV absorber with a high degree of safety, excellent efficiency and good solubility characteristics. In the conventional method of DHHB synthesis, H2SO4 is not effective as a catalyst. To address this drawback, we synthesized solid acid (sulfonic acid group-modified ion exchange resin) catalysts to replace H2SO4 by suspension polymerization modification and optimized the process. The experimental results showed that the yield of DHHB could reach 85% at 110 °C for 10 h, and the conversion of DHHB could be maintained above 90% after 10 cycles of the catalyst. SEM, FT-IR characterization and analysis of the solid acid catalysts before and after use revealed that the catalysts did not show any significant changes. The use of solid acid not only improves the yield of DHHB and reduces the energy consumption in the experimental process, but also the solid acid is simple to recover, recycled and has less waste acid. This experiment successfully explored a green and economic synthesis method for synthesizing DHHB.