Solid Acid Catalyst Research Articles

One-pot synthesis of highly substituted dihydro-2-oxopyrols using nano-SnCl4/γ-Al2O3 as a mild solid lewis acid catalyst

In this paper, highly substituted dihydro-2-oxopyrol derivatives were synthesized through a three component reaction of dialkylacetylenedicarboxylate, formaldehyde and aniline derivatives in the presence of nano-SnCl4/γ-Al2O3. The reaction was proceeded in ethanol as the solvent under reflux conditions. Nano-SnCl4/γ-Al2O3 was prepared via the reaction of SnCl4 with nano-γ-Al2O3 and characterized by FT-IR, XRD, FE-SEM, TEM, EDS,EDS-mapping, BET and TGA. Reusability of nano-SnCl4/γ-Al2O3 was examined in five runs, successfully. Short time of the reactions, good to excellent yield of products, heterogeneous conditions and reusability of the nano-catalyst are some of advantages of this green and environmental methodology.

Hydrogen Bonding Promotes 1-Butanol-3-Carbocation to 4-Methyl-1,3-Dioxane in Prins Condensation of Formaldehyde with Propene on Solid Acid Catalysts

Hydrogen Bonding Promotes 1-Butanol-3-Carbocation to 4-Methyl-1,3-Dioxane in Prins Condensation of Formaldehyde with Propene on Solid Acid Catalysts

Efficient synthesis of some [1,3]-oxazine derivatives in the presence of solid acid nano catalyst based on ferrierite and study on their activity against breast cancer through molecular docking calculation

In this research, the magnetic solid acid nanocatalyst based on ferrierite has been prepared and used as catalyst for the green synthesis of some [1,3]-oxazine derivatives in water at room temperature. The synthesized compounds were obtained in high to excellent yields after short reaction times and the structure of synthesized products were investigated by spectroscopic methods such as: FT-IR, 1H NMR and 13C NMR. The prepared magnetic solid acid catalyst was characterized using XRD, FT-IR, FE-SEM, EDX, elemental mapping, TGA and VSM analysis methods. Magnetic catalyst has easy separation ability, which leads to better and easier recycling. The preparation and synthesis of [1,3]-oxazine derivatives were carried out at room temperature in the presence of M-FER/TEPA/SO3H. Easy workup, green solvent (water) and also short reaction times with high to excellent yield of products, are some of advantageous of presented method. Docking calculations on the structure of the synthesized compounds proved their medicinal properties against breast cancer cells.

Boosting catalytic performance of Amberlyst‐15 by modulating surface properties for synthesis of 5-hydroxymethylfurfural from high-concentration fructose

The large-scale production of 5-hydroxymethylfurfural (HMF), a “sleeping giant” in sustainable chemistry, is frequently hampered by the severe formation of humins during the acid-catalyzed dehydration of high-concentration fructose. In this work, we demonstrate that the HMF yield could be remarkably enhanced by boosting the catalytic performance of a commercially used Amberlyst-15 solid acid organocatalyst, wherein the formation of humins could be effectively inhibited. We show that the modification of Amberlyst-15 with a typical cationic surfactant (i.e., cetyltrimethylammonium bromide (CTAB)) via charge interaction between sulfonic acid groups and quaternary ammonium cations led to an improved surface hydrophobicity and a reduced Brønsted acid density on the modified catalyst, thereby contributing to a complete suppression of HMF rehydration and remarkable suppression of humin formation via paths of both etherification-dehydration-condensation and degradative-condensation of fructose and/or HMF. As a result, the catalytic conversion of fructose over the CTAB-modified Amberlyst-15 catalyst in a low-boiling mixed solvent composed of 1,4-dioxane and H2O at 140 °C within 2 h led to high HMF yields in range of 53.3 ∼ 63.1 mol% in converting high-concentration fructose (10.0 ∼ 50.0 wt%), wherein an average enhancement of 20 mol% in product yield was achieved when compared with that over un-modified Amberlyst-15. Moreover, the adsorption of humins on solid catalyst was significantly reduced due to the enhanced surface hydrophobicity and alleviated formation of humins, which accounted for a stable catalytic performance of the modified Amberlyst-15 catalyst for at least five runs. This work highlights the rational adjustment of the surface wettability of a commercial solid acid catalyst to suppress the undesired humin formation for future HMF biorefinery.

Conversion of sugars into methyl lactate over poly (ionic liquid)s functionalized Sn/beta zeolites

Methyl lactate (MLA) is a versatile high value platform chemical prepared from biomass carbohydrates, with widely application in the pharmaceutical, food, pesticide, and cosmetics. The current study presented a one-pot catalytic conversion of sugars to MLA over poly (ionic liquid)s functionalized Sn/Beta zeolites under mild conditions. The Sn/Beta zeolites were prepared by an impregnation method, followed by modification with poly (vinyl imidazole) ([PVIM]) via an in-situ free radical polymerization method. Dosages of polymer and Sn, calcination temperature, reaction temperature, catalyst amount, substrate concentration, and reaction times were optimized. Results showed that an MLA yield of 61.4 % was obtained over 3[PVIM]-Sn/Beta with complete conversion of fructose at 140 °C for 8 h. The physicochemical properties were characterized by XRD, BET, FTIR, CO-DRIFTS, NH3-TPD and pyridine-FTIR analysis, indicating the coexistence of Lewis and Brønsted acid sites. Finally, a possible reaction mechanism was proposed that the weak Lewis acidity of imidazole rings of [PVIM] effectively regulated the local microenvironment of active sites, thus promoting the interaction of the active sites with electronegative oxygens of sugars. This study can provide as a reference for the development of solid acid catalysts for the catalytic conversion of biomass to platform chemicals.

3D simulation in a fixed bed coupled pervaporation reactor for biodiesel production

In this study, a solid acid catalyst SO42−/TiO2/ZSM-5 (STZ) was prepared. Biodiesel was synthesized from tall oil fatty acid (TOFA) by the ethanol esterification. The fixed bed and pervaporation (PV) coupling increased the esterification conversion of TOFA and ethanol by about 16 %. The spherical STZ catalyst’s appearance, composition, and catalytic activity were assessed through TGA, XRD, SEM, BET, FTIR, NH3-TPD and XPS analyses. The reaction parameters of ethanol/TOFA molar ratio (10:1–20:1), reaction temperature (75–85 ℃), catalyst dosage (6–12 g) and flow rate (0.3–0.9 mL/min) were optimized by the response surface method (RSM). Under RSM optimization, the TOFA esterification reaction achieved a conversion rate of 99.56 ± 0.23 %. After five cycles of esterification, TOFA conversion remained above 87 %. A computational fluid dynamics (CFD) model was established to predict the esterification reaction behavior in the reactor, and the TOFA conversion rate was found to be close to the experimental results through systematic simulation, by reaction kinetics equation, continuity equation, Navier-Stokes equation, and Brinkman equation. In addition, the TOFA biodiesel prepared by this study complies with EN 14214 and ASTM D6751 standards.

Intensifikasi Sintesis Diasetin dan Triasetin Melalui Esterifikasi Gliserol Dengan Katalis Berbasis Daun Bambu

The synthesis of acetins from glycerol is achieved through esterification assisted by a solid acid catalyst and microwave irradiation. Diacetin and triacetin, suitable as biofuel additives, are produced using biogenic silica from bamboo leaves, which is chemically activated with strong acid and calcined. No research has utilized silica catalysts derived from bamboo leaf ash to produce diacetin and triacetin. This study aims to employ bamboo leaf-based heterogeneous catalysts to enhance triacetin selectivity, simplify product purification and separation, and enable catalyst reuse. Furthermore, microwave application can accelerate the reaction time. The best total selectivity for diacetin and triacetin was obtained under operating conditions of 3% catalyst concentration, a 1:6 molar ratio, and 60 minutes of microwave irradiation. The yields of diacetin and triacetin under these conditions were 65.80% and 18.70%, respectively. GC-MS and FTIR analysis confirm the presence of monoacetin, diacetin, and triacetin, with a total selectivity for diacetin and triacetin of 84,50%.

Development of Solid Acid Catalysts for Synthesis of Chemicals from Sugars and Sugar Alcohols

Development of Solid Acid Catalysts for Synthesis of Chemicals from Sugars and Sugar Alcohols

Covalent organic frameworks with tunable Co–N–C for high-performance carbamate decomposition via sulfonic modification in amine-based CO2 capture

Nanowire-like COF support with sulfo group (-SO3H) decoration was designed and synthetized, to offer favourable conditions for atomically dispersing Co atoms (S–Co/NC). The ingenious coordination of sulfo group synergistically improved COF structure and Co–N–C scheme, creating high surface area and excellent catalytic activity. Lab-scale experimental evaluations confirmed that the maximum CO2 desorption rate of spent MEA-solvent increased significantly by 733 % (3.74 CO2 mmol/min) after introducing S–Co/NC catalysts, ascribed to its contribution for proton transfer and C-N break. Bench-scale experiments demonstrated that a mere 0.0125 wt% of catalyst in MEA-solvent substantially decreased the CO2 loading of lean solvent by 17.7 % at low desorption temperatures (120→110 °C), resulting in a 28.8 % reduction in energy consumption. Furthermore, the negligible degradation of catalytic performance during 100-h testing wall-validated the stability and durability of the S–Co/NC catalysts. This work provided a prominent COF-based solid acid catalysts for energy-saving solvent regeneration during amined-based CO2 capture.

Unlocking new potentials in energy-efficient carbon dioxide capture: How catalyst-phthalocyanine is leading the way

Addressing the high energy demand of amine-based carbon dioxide capture systems is crucial for achieving carbon neutrality. While enhancing energy efficiency with solid acid catalysts in amine regeneration is promising, developing more efficient catalysts remains a critical challenge. In this study, we introduce the innovative use of a robust, metal-free phthalocyanine as a catalyst to facilitate amine regeneration. Distinctively, phthalocyanine features a macrocyclic ring with an extensive π-conjugated system that functions as Lewis acid sites, diverging from conventional methods that rely on metal atoms for this role. Additionally, the nitrogen and hydrogen atoms on the macrocyclic ring act as Brönsted base sites and Brönsted acid sites, respectively. These sites collectively contribute to a significant acceleration in the CO2 desorption rate, achieving an increase of 1679% at approximately 67 ℃, which far surpasses the performance of previously investigated catalysts. Furthermore, phthalocyanine catalyzes the decomposition of carbamate and protonated monoethanolamine more efficiently than bicarbonate. This research lays the groundwork for next-generation catalysts in amine solvent regeneration of the carbon dioxide capture process.

Valorization of Bambusa striata shavings into functional superparamagnetic material and its application in biodiesel production: Response surface optimization, kinetics, thermodynamics and economic assessment

Herein, a novel highly porous biomass-based (Bambusa vulgaris striata) magnetic solid acid catalyst was developed for the first time via simultaneous activation and magnetization followed by acid functionalization. The sulfonated magnetic porous carbon was utilized as a catalyst for transesterifying Jatropha curcas oil (JCO) to biodiesel under microwave irradiation. The synthesized catalyst was extensively characterized using VSM, XRD, FTIR, SEM, EDS, TGA, XPS, Raman spectroscopy, and AFM techniques. Through Response Surface Methodology (RSM), a maximal biodiesel yield of 98.8 % was achieved over optimal optimal parametric states (catalyst loading 8 wt%, MOMR 24:1, 50 min, 80 °C). NMR confirmed JCO biodiesel formation with a FAME content of 98.04 %, and GCMS provided insight into its chemical composition. A pseudo-first-order kinetic study revealed an activation energy (Ea) of 28.734 kJ mol1. Thermodynamic analysis showed endothermic and non-spontaneous behavior with ΔH#, ΔS#, and ΔG# values of 25.928 kJ mol1, −0.193 kJ mol1 K1, and 94.251 kJ mol1, respectively. The catalyst displayed good reusability, easy recoverability, and stability, maintaining 75.4 % oil conversion even after ten consecutive cycles. Life cycle cost analysis (LCCA) estimates biodiesel production cost of $0.60 per liter, emphasizing high commercial viability.

A highly efficient Lewis acid catalyst of F-doped activated carbon for acetylene dimerization

Doping carbon-based materials with heteroatoms is considered an effective strategy to enhance their catalytic activity by altering their electronic structure and chemical properties. In this study, fluorine doped activated carbon was synthesized and used in acetylene dimerization reaction. Fluorine has the highest electronegativity (3.98) and can induce neighboring carbon atoms to possess a stronger positive charge, thereby generating Lewis acid sites between the two atoms. The resulting carbon material exhibited abundant Lewis acid sites ensuring the ample exposure and availability of catalytic sites to facilitate notable activity in acetylene dimerization. Theoretical calculations indicated that the introduction of F could help to alleviate the progression of polymers. This research provides a promising approach to the development of solid acid catalysts with excellent catalytic performance by incorporating Lewis acid sites onto carbon materials.

Agro-waste derived sulfonated biochar material as a sustainable heterogeneous catalyst for conversion of fructose to 5-hydroxymethylfurfural

BackgroundDevelopment of biomass derived solid acid catalysts has the advantage to conform the green chemistry protocol for production of 5-hydroxymethylfurfural (HMF) by dehydration of fructose. MethodWe have reported waste cashew nut shell produced char as a biochar to prepare sulfonated biochar (SBC) catalyst by incorporating –SO3H group through treatment of concentrated sulfuric acid. Significant findingsDifferent methods of characterization including XRD, FT-IR, XPS, FESEM-EDS, TEM, TPD and BET analysis, were used to study the structure, morphology, chemical compositions, acidity and porosity of the produced SBC catalysts. The mesoporous nature of the material was confirmed by the powder X-ray diffraction patterns (PXRD), type IV isotherm (BET), and flakes-like structure was observed in TEM analysis. The catalyst showed high yield of HMF (92%) under optimum conditions of 120 °C in 60 min under biphasic solvent mixture of water and toluene (1:2). High yield could be explained by high acid strength of catalyst as observed by NH3-TPD analysis. Leaching test by Sheldon's method and recyclability experiment proved the need and heterogeneity of the present catalyst.

Characteristics and catalytic properties of WO3 supported on zeolite A-derived from fly ash of sugarcane bagasse via esterification of ethanol and lactic acid

In the current trend of industrial manufacturing processes, an interest in utilization of industrial and agricultural wastes for producing green chemistry, eco-friendly product, has been increased. Therefore, this study aimed to produce ethyl lactate using solid-acid catalyst WO3/zeolite-A via esterification. Various analytical techniques, including XRF, BET, XPS, FTIR, NH3-IR, NH3-TPD, SEM-EDX, ICP-OES, XRD, TGA-DTA, and TEM, were employed to analyze the physical and chemical properties of zeolite-A and tungsten-supported on zeolite-A. The results revealed that after five reuse cycles, the lactic acid conversion rates were 20.1 % and 10.3 % for WO3/zeolite-A and Amberlyst-15, respectively. The spent WO3/zeolite-A exhibited a reduction in surface acid site, declining from 1,591.8 μmol/g in the first run to 690.1 μmol/g in the fifth run. The decline in efficiency was attributed to impurities blocking of active sites, structural alterations, and partial leaching of active species. XRD and FTIR analyses confirmed decreased crystallinity and structural changes in spent catalysts. TEM, SEM-EDS, and ICP-OES analyses showed the loss of active tungsten species and the deposition of reaction intermediates leading to a decrease in ethyl lactate yield (decreased from ca. 44 to 20 %). Despite structural changes affecting catalytic performance, WO3/zeolite-A demonstrated a good promising catalyst for ethyl lactate production over five successive cycles (with ca. 50 % decrease).

Performance assessment of novel catalytic spouted-bed vapor jet flow heat exchanger in amine-based carbon capture process

This study introduced a spouted bed and jet flow catalytic heat exchanger (SBJ-EX). This novel non-agitated technology can potentially integrate with a conventional desorption column to enhance heat transfer and CO2 desorption performance in amine-based post-combustion carbon capture systems. As its first research in the carbon capture field, this work experimentally evaluated key factors including overall heat transfer coefficient, logarithmic mean temperature difference, temperature distribution along the reactor, and cyclic loading under varied parameters such as inlet temperature of the heating oil, inlet solvent temperature, rich CO2 loadings, and mass of catalysts to simulate real-world operating conditions using benchmark MEA solvent and solid acid catalyst HZSM-5. Compared to conventional plate heat exchangers, the SBJ-EX demonstrated over a 70 % enhancement in heat transfer performance due to its effective overall heat transfer coefficient. It also exhibited impressive CO2 desorption performance even at lower temperatures with sufficient catalysts. Unlike agitated-type heat exchangers, the SBJ-EX could minimize catalyst attrition and offer more excellent stability. In contrast to fixed-bed catalyst desorbed columns, this equipment offered a more compact design for quicker and simpler catalyst replacement to reduce downtime for operators significantly. The SBJ-EX can also function as an optional backup or add-on unit to provide operators with flexibility. This work further discussed advantages and challenges of the SBJ-EX operation. This work enriched the future research outlook for this technology, and contributed a commercially viable approach to catalysts in carbon capture processes.

Low-cost and green straw derived hierarchical porous carbon as support to phosphotungstic acid for efficient and clean production of α-terpineol

This study developed a novel reciprocal template method to prepare MgO@Carbon micrometre tubes directly from straw-based biomass. Biomass carbon with a rich hierarchical porous structure (MRSC30) was obtained by acid-washing the MgO@Carbon micrometre tubes. The pore formation mechanism of MRSC30 was systematically analyzed using Density Functional Theory calculations and various characterization methods. The in situ growth of Mg(OH)Cl/MgO inside the biomass promotes the polymerized carbon precursors to be tightly affixed to the templating agent and provides exfoliation, support, and catalysis (i.e., electrostatic attraction, nucleophilic substitution, and electrophilic addition), which effectively promotes the formation of hierarchical porous carbon. The continuous release of light gases from the inside out during the prolongation of the decomposition temperature of the biomass by Mg(OH)Cl or/and MgO helps to promote the formation of stomata in the biomass carbon. The results showed that the method minimized the consumption of chemicals, energy consumption, and the time required to prepare HPC by 35.75%, 67.57%, and 52.38%, respectively. The phosphotungstic acid-loaded MRSC30 was successfully prepared as a highly amphiphilic and highly acidic solid acid catalyst and applied to the hydration of α-pinene to prepare superior performance gasoline additives (α-terpineol). Under optimal process conditions obtained in a batch reactor, the catalytic performance of the catalyst could be further improved by alternating flow using a novel semi-batch unsteady-state reactor developed in this institute, and the α-pinene conversion and the α-terpineol selectivity reached a maximum of 95.53% and 65.75%, respectively. At the same time, the reactor was able to substantially reduce the time required for hydration and the amount of moderately toxic acetone used compared to the conventional batch reactor by 20.83% and 62.50%, respectively.

Alcohol formaldehyde resin solid acid catalytic conversion of biomass into furan compounds

The conversion of waste lignocellulosic biomass into biomass platform chemicals is very promising. In this work, a novel resin-based solid acid catalyst was obtained by condensation of furfuryl alcohol with furfural, and mild calcination and sulfonation process. Then it was used to convert sugars and biomass to obtain furan compounds. Results showed that the solid acid with a furfural to furfuryl alcohol molar ratio of 3:1 is an irregular mesoporous material, with a specific surface area of 134.18 m2/g and an acid content of 2.723 mmol/g, which is extremely stable below 200 °C. 82.2 % (from fructose), 15.8 % (from glucose), 10.0 % (from cellobiose) yields of 5-HMF and 35.5 % (from xylose) yield of furfural could be obtained at 160 °C for 2 h. It can be reused more than 5 times and can restore the best catalytic effect after re-sulfonation. Notably, in the catalytic conversion of rice husk, rice straw, camphor tree branch and leaves under typical reaction conditions, 5-HMF and furfural was in yields of 9.4–24.5 % and 20.3–47.9 %, respectively. Moreover, a 10 % water dropwise to solvent can effectively promote the catalytic conversion of biomass, while there is a significant inhibitory effect after it exceeds 20 %.

Correction to: Synthesis of Porous Polymer Based Solid Acid Catalyst towards Room Temperature Thioacetal/Thioketal Formation

Correction to: Synthesis of Porous Polymer Based Solid Acid Catalyst towards Room Temperature Thioacetal/Thioketal Formation

A binary catalytic system of sulfonated metal–organic frameworks and deep eutectic solvents towards highly efficient synthesis of 5-hydroxymethylfurfural from fructose

The green synthesis of 5-hydroxymethylfurfural (HMF) from biomass feedstocks is a crucial step for the development of sustainable fuels, resins and plastics. Here, a novel binary catalytic system was developed with metal–organic frameworks (MOFs) and deep eutectic solvents (DESs), which synergically exhibited a superior fructose dehydration efficiency with a HMF yield of 98.5% within 40 min. The replacement from terephthalic acid to 2,5-furandicarboxylic acid as the organic ligand in MOFs catalysts altered the coordination microenvironment of metal nodes, resulting in remarkably enhanced fructose conversion rates. The formation of hierarchical porous structures and moderated Brønsted acid sites in sulfonated MOFs further promoted the HMF production. Notably, HMF could be readily separated from the MOFs-DESs system and the MOF catalyst maintained stable performance after six recycles. Theoretical calculations clarified a positive correlation between the hydrogen bond interaction (between fructose and DESs components) energy and reaction efficiency. This study provided a new strategy to couple hierarchical solid acid catalysts with functional solvents binary towards effective and sustainable upgrading of biomass-derived molecules.

Preparation and catalytic evaluation of phosphated zirconia nanopowder for ethanol dehydration into diethyl ether

Research on renewable energy development is intensified nowadays, including the production of diethyl ether (DEE) as a high-value alternative fuel. This study explored the catalytic conversion of ethanol into diethyl ether using a phosphated zirconia catalyst. We examined different concentrations of phosphoric acid (1, 2, 3, and 4 M) and calcination temperatures (400, 500, and 600 °C) applied to zirconia nanopowder to evaluate their influence on the acidity of the resulting phosphated zirconia. The catalysts were characterized by FTIR, XRD, SAA, SEM-EDX Mapping, and TG-DTA. Among the catalysts tested, the PZ-2-400 catalyst, prepared with a 2 M H3PO4 concentration and calcined at 400 °C, exhibited the highest acidity value of 0.56 g/mol pyridine. When operated at the optimum temperature of 225 °C, this catalyst achieved an ethanol conversion of 80.04 % and a diethyl ether yield of 1.00 %. These findings suggest that modification of ZrO2 with phosphoric acid acts as a solid acid catalyst for diethyl ether synthesis with better activity and selectivity than unmodified ZrO2.