Solid Acid Catalyst Research Articles

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.

Green and Convenient Synthesis of Pharmaceutically Active Mono and Bis-dihydroquinazolines via a One-pot Multicomponent Reaction Under Sulfamic Acid Catalysis

Introduction: Multicomponent reactions (MCRs) and green chemistry are essential criteria for the development of efficient chemical syntheses for valuable organic compounds. Method: The design, synthesis, and development of sustainable procedures for the production of novel biological and pharmaceutical molecules have gained high importance. Herein, an environmentally benign synthesis of mono- and bis-2,3-dihydroquinazolin-4(1H)-ones as pharmaceutically active compounds was carried out in good to high yields of 80-99% within 45-120 minutes. Result: The desired products were synthesized via three-component and pseudo five-component condensations of isatoic anhydride, a primary amine (aniline or ammonium acetate), and an aldehyde/dialdehyde using sulfamic acid (20%) as a solid acidic catalyst under the solvent-free condition at 100°C. Conclusion: The easy work-up procedure, metal-free and environmentally benign catalyst, green reaction conditions for performing MCRs, and high yields of pure products are some advantages of the presented protocol.

One-pot assembly of sulfated lignin/Zr coordination polymer for efficient alcoholysis of furfuryl alcohol to methyl levulinate

Biomass-derived alkyl levulinates are considered to be ideal fuel additives, and the construction of green and economic catalysts for the production of alkyl levulinates was still a challenging goal. In this work, a facile method for the synthesis of sulfated lignin/Zr coordination polymer (Zr-LSNa@SX) was developed through the coordination of sodium lignosulfonate with Zr ions by hydrothermal procedure. The catalytic performance of prepared Zr-LSNa@SX for the direct conversion of furfuryl alcohol (FA) to methyl levulinate (ML) was studied and a 73.1 % yield of ML was achieved at 180 °C in 180 min. The as-prepared sulfated lignin/Zr coordination polymer was characterized using SEM, FT-IR, and Py-FTIR techniques, and it was determined that the Brønsted acid sites of the catalyst played a crucial role in the conversion of FA to ML in methanol. This work provided a facile method for constructing the green and economical bio-based solid acid catalyst which will greatly extend the application of bio-based materials in the acid-catalyzed reaction.

Sulfonated mesoporous TUD-1: An innovative environmentally friendly solid acid catalyst for various organic transformations

TUD-1, a novel sponge-like three-dimensional mesoporous silica material, was synthesized in one-step using a hydrothermal technique and triethanolamine as a template. To enhance its acidic properties, the TUD-1 material underwent sulfonation with varying amounts of sulfonic groups (1 and 3 wt%). Structural characteristics were determined using XRD, FTIR, Raman, BET analysis, HRTEM, SEM, and XPS. Surface acidities of the catalysts were evaluated through non-aqueous potentiometric titration and FTIR analysis of chemisorbed pyridine. The performance of catalysts was assessed in various reactions, including the Pechmann reaction, Friedel-Crafts acylation reaction, and Biginelli reaction for synthesis of 7-hydroxy-4-methyl-2H-chromen-2-one, aromatic ketones and 3, 4-dihydropyrimidin-2(1H)-one. The findings confirm that the TUD-1 mesoporous structure did not undergo any significant alteration post sulfonation. The sulfonated catalysts exhibited higher surface acidities than TUD-1. A correlation between surface acidity, particularly Brönsted acid sites, and catalytic efficiency in selected reactions was evident from both catalytic testing and characterization. Under moderate conditions, TUD-1-3SO3H exhibited outstanding catalytic performance and remarkable reusability across all selected reactions.

Microwave Effect in Hydrolysis of Levoglucosan with a Solid Acid Catalyst for Pyrolysis-Based Cellulose Saccharification.

Pyrolysis-based saccharification consisting of fast pyrolysis followed by hydrolysis of the resulting anhydrosugars such as levoglucosan is a promising method for converting cellulosic biomass into glucose that can be used for producing biofuels and biochemicals. In the present study, hydrolysis of levoglucosan was evaluated in water with a polystyrene sulfonic acid resin (a solid acid catalyst) by heating under microwave irradiation or in an oil bath at 95 °C-120 °C. When the equilibrium temperature of the solution was the same, the conversion rate of levoglucosan was greater under microwave irradiation than in an oil bath. Model experiments indicate that the sulfonyl groups of the solid acid catalyst were selectively heated by microwave irradiation. The temperature of the reaction solution in the vicinity of the catalyst was locally higher than the equilibrium temperature of the solution, which enabled hydrolysis to proceed efficiently.

Pillared Bentonite Materials as Potential Solid Acid Catalyst for Diethyl Ether Synthesis: A Brief Review

Pillared Bentonite Materials as Potential Solid Acid Catalyst for Diethyl Ether Synthesis: A Brief Review

Effect of solid acid catalyst coupled decolorization process on the physicochemical properties and bioactive and volatile compounds of sesame oil

SummaryIn this study, the effects of citric acid‐loaded Hβ zeolite (F), activated clay and their modified decolorizers on the nutrients, volatile compounds and harmful substances of sesame oil in the decolorization process were evaluated. The results showed that the decolorization effect of F was second only to that of activated clay, the yield of F‐treated sesame oil sample was not significantly different from that of other decolorizers. The formation of asarinin was detected only in the sesame oil samples treated with F and H (zinc chloride‐activated clay). Compared with the activated clay‐treated sesame oil samples, the retention of tocopherols in the F‐treated sesame oil sample was significantly increased by 23.11%, and the retention of phytosterols was increased by 4.85%. The removal rate of the harmful substances Norharman and Harman in the F‐treated sesame oil sample was 96.79%, which was second only to that of the activated clay. Additionally, the removal rate of the total volatile compounds was the highest at 69.47%. The effects of different decolorizers on the sesame oil samples were closely related to the specific surface area, pore size and surface acidic sites of these decolorizers. This study could provide ideas for the industrial application of leached sesame oil, such as cosmetics and base oils.

Highly efficient hydrolysis of cellulose to sugars using supercritical CO2 as a green acid catalyst and solvent

Rapid depolymerization of cellulose into processable monomers (e.g., sugars) using solid acid catalysts is an important step for cost-effective biofuel and biochemical production, but has not yet been achieved due to the limited contact between solid cellulose and solid catalysts. Herein, the unique roles of supercritical CO2 (i.e., scCO2) as an in-situ acid catalyst and reaction solvent in achieving the ultra-fast full solid catalytic hydrolysis of cellulose are disclosed for the first time. When the ball-milling pretreated cellulose was hydrolyzed using oxidized carbon catalysts at 150 °C and 100–300 bar-CO2, the hydrolysis kinetics remarkably increased by 3× for conversion and 5× for glucose, resulting in ∼90% conversion and ∼85% total sugar selectivity at 20 min. The hydrolysis rate obtained with scCO2 here was higher than conventional ones with toxic and unrecyclable homogeneous catalysts (e.g., HCl) under harsh reaction conditions (i.e., 180–220 °C and pH of 1–2). A comprehensive reaction engineering study (e.g., temperature, CO2 pressure, stirring speed, catalyst acid properties) combined with the estimation of the solution pH by the CO2 phase equilibrium model and the in-situ and ex-situ monitoring of the phase behavior of the H2O/scCO2 solution were conducted to quantify the activity promotion by scCO2 and understand the acid-solvent roles of scCO2 toward the enhanced hydrolysis of cellulose. Specifically, the formation of the Pickering emulsions at the interface between scCO2 and water and their impact on the enhancement of the cellulose-carbon contact were proposed and verified in detail.

Sulfonic acid functionalized SBA−15 catalyst and mercaptopropionic acid promotor for the selective synthesis of p,p′−bisphenol A: Replacement to mineral acid−based process

The significance of selective catalysis in producing plastic monomers is crucial to meet sustainability and economic requirements. It is essential to develop a selective solid acid catalyst to replace irrecoverable corrosive mineral acids and thermolabile sulfonated resins for the production of p,p′−bisphenol A (BPA) isomer, a key intermediate in polycarbonate production. However, limited success has been achieved due to low activity and selectivity towards the desired p,p′−BPA isomer. Herein, a mild and selective route is presented for producing p,p′−BPA using SBA-15 functionalized sulfonic acid catalysts. Sulfonic acid-based catalysts with and without alkyl chain linkers, supported on SBA−15, were synthesized to evaluate the effect of acidity, and textual properties on the catalytic efficiency, and product selectivity. Among all the synthesized catalysts, SBA−15−Pr−SO3H exhibited the highest product selectivity. The addition of mercaptopropionic acid (as a promoter) enhanced the catalytic efficiency and afforded ∼99% acetone conversion, with 97.3% p,p′−BPA selectivity. A detailed mechanism with and without the promoter is proposed. The study also highlights the potential of mesoporous SBA−15−supported sulfonic acid catalysts as a selective and efficient catalyst for synthesizing bisphenol derivatives from the lignocellulose biomass−derived platform molecules, addressing challenges posed by fossil resources.

Lattice Boltzmann Method and Back-Propagation Artificial Neural Network-Based Coke Mapping of Solid Acid Catalyst in Fructose Conversion

Lattice Boltzmann Method and Back-Propagation Artificial Neural Network-Based Coke Mapping of Solid Acid Catalyst in Fructose Conversion

Copper Phthalocyanine Tetrasulfonic Acid, a Recyclable Solid Acid Catalyst for the Synthesis of Aryl Iodides and Azides from Aryl Amines via Diazotization

Copper Phthalocyanine Tetrasulfonic Acid, a Recyclable Solid Acid Catalyst for the Synthesis of Aryl Iodides and Azides from Aryl Amines via Diazotization

Efficient production of biodiesel from palm fatty acid distillate using a novel hydrochar-based solid acid catalyst derived from palm leaf waste

To combat fuel shortages, pollution, and the exhaustion of natural oil resources, an environmentally friendly alternative to fossil fuels, such as biodiesel, is essential for meeting global transportation demands. A novel heterogeneous acid catalyst for production of biodiesel from low-cost, high free fatty acid feedstocks was synthesized in this study by activating and impregnating hydrochar from palm leaf (PL) waste with H3PO4 and H2SO4. Subsequently, the sulfonated catalyst was utilized for the esterification of palm fatty acid distillate (PFAD). FT-IR, XRD, FESEM, EDX, BET, TGA, and surface acidity methods were employed to characterize the acid catalyst. Using the one-variable-at-a-time (OVAT) technique, the optimized reaction conditions for esterification of PFAD using the hydrochar-based catalyst were 4 wt% catalyst loading, 353.15 K reaction temperature, 4 h reaction time, and 18:1 methanol: PFAD molar ratio. At these conditions, a maximum biodiesel yield of 93.56% was achieved. The catalyst exhibited excellent reusability and stability throughout five reaction cycles, maintaining biodiesel yields above 80% after each cycle. Analysis of the fuel properties revealed that the biodiesel derived from PFAD met the physiochemical criteria outlined in ASTM D6751, the American biodiesel standard. The kinetic study revealed that the esterification reaction followed pseudo-first-order kinetics with an activation energy (Ea) of 23.70 kJ/mol. Furthermore, the thermodynamic enthalpy (∆H*) and Gibbs' free energy (∆G*) of esterification were 20.9 and 33.41 kJ/mol, respectively, indicating that the reaction was an endothermic and non-spontaneous process.

Synthesis and characterization of alumina supported molybdosilicic acid (SiMo12/Al2O3): Efficient solid acid catalyst for the synthesis of pyranopyrazole derivatives

A series of highly reusable heterogeneous catalysts (10-40 wt.% SiMo12/Al2O3), consisting of molybdosilicic acid (SiMo12) impregnated on alumina (Al2O3) support was synthesized by the wetness impregnation method. The physicochemical properties of synthesized catalyst were studied using FT-IR, XRD, SEM, EDX, TEM, BET and TG-DTA analysis techniques. The study proves that the synthesized SiMo12 catalyst efficiently incorporated on the surface of Al2O3. The catalytic activity of prepared catalyst was investigated for the synthesis of pyranopyrazole(6-amino-4-phenyl-3-methyl-2,4-dihydropyrano[2,3-c]pyrazole-5carbonitrile) via cyclocondensation reaction of aldehydes, malononitrile, hydrazine hydrate and ethyl-acetoacetate under solvent-free conditions. Among different catalysts, 30% SiMo12 supported on to Al2O3 showed the highest catalytic activity. High yield, shorter reaction time, operational simplicity, solvent-free conditions and reusability of the catalyst are the distinct features of this protocol.

Catalytic hydrothermal conversion of polypropylene

This work reports preliminary-stage studies demonstrating the highly selective conversion of polypropylene to short-chained olefins via hydrothermal catalytic processing. The production of such monomer species from waste polymers is highly desirable and has the potential to play a key role in plastics recycling and in the circular economy more broadly. Addition polymers such as polypropylene are, however, known to be particularly challenging to recycle into propene or other short-chained alkenes. Herein, we have compared and contrasted acid- and base-catalysed hydrothermal processing at a temperature of 360 °C, analysing the products of reaction by gas chromatography – mass spectrometry (GC-MS) and Fourier transform infrared (FTIR) spectroscopy. Employing the basic catalyst K2CO3, results in a 95 % yield of gas-phase products of which 52 % are propene and 9 % butenes on a mole basis. The solid acid catalyst HZSM-5 also selectively yields gaseous products, 21 % of which are propene and 22 % are butenes, the reaction proceeding via β-scission of the starting oligomers. These results represent a potential step-change in the production of monomer units from addition polymers, highlighting the potential value of catalytic hydrothermal processing in the field of polymer recycling.

Synergistic Catalysis of SO42-/TiO2-CNT for the CO2 Desorption Process with Low Energy Consumption.

To address the issue of high energy consumption associated with monoethanolamine (MEA) regeneration in the CO2 capture process, solid acid catalysts have been widely investigated due to their performance in accelerating carbamate decomposition. The recently discovered carbon nanotube (CNT) catalyst presents efficient catalytic activity for bicarbonate decomposition. In this paper, bifunctional catalysts SO42-/TiO2-CNT (STC) were prepared, which could simultaneously catalyze carbamate and bicarbonate decomposition, and outstanding catalytic performance has been exhibited. STC significantly increased the CO2 desorption amount by 82.3% and decreased the relative heat duty by 46% compared to the MEA-CO2 solution without catalysts. The excellent stability of STC was confirmed by 15 cyclic absorption-desorption experiments, showing good practical feasibility for decreasing energy consumption in an industrial CO2 capture process. Furthermore, associated with the results of experimental characterization and theoretical calculations, the synergistic catalysis of STC catalysts via proton and charge transfer was proposed. This work demonstrated the potential of STC catalysts in improving the efficiency of amine regeneration processes and reducing energy consumption, contributing to the design of more effective and economical catalysts for carbon capture.

Modeling and simulation of biodiesel synthesis in fixed bed and packed bed membrane reactors using heterogeneous catalyst: a comparative study

In this study, modeling and simulation of biodiesel synthesis through transesterification of triglyceride (TG) over a heterogeneous catalyst in a packed bed membrane reactor (PBMR) was performed using a solid catalyst and compared with a fixed bed reactor (FBR). The kinetic data for the transesterification reaction of canola oil and methanol in the presence of solid tungstophosphoric acid catalyst was extracted from the published open literature. The effect of reaction temperature, feed flow rate, disproportionation of the reactants, and reactor length on the product performance was investigated. Two-dimensional and heterogeneous modeling was applied to PBMR and the resultant equations were solved by the Matlab software. Moreover, the velocity profile in the membrane reactor was obtained. The results showed the best conditions for this reaction are 180 °C, the molar ratio of methanol to oil equal 15:1, and the input flow rate of 0.5 mL/min. In this condition, a conversion of 99.94% for the TG can be achieved in the PBMR with a length of 86 cm while a length of 2.75 m is required to achieve this conversion of the FBR. Finally, the energy consumption for the production of 8000 ton/y biodiesel in a production plant using the PBMR and the FBR was obtained as is 1313.24 and 1352.44 kW, respectively.

IADOR yields diverse shape-selective solid Lewis acid catalysts

Lewis acid catalysts convert biomass compounds to green chemicals and fuels. Among these catalysts, stannosilicate zeolites display high thermal stability and reusability. However, only a few Sn-zeolites can be prepared using conventional synthesis methods, preventing us from developing shape-selective stannosilicate catalysts. Here, we propose a synthetic approach toward shape-selective Sn-zeolite catalysts, leveraging the Assembly, Disassembly, Organization, Reassembly (ADOR) strategy. By combining isomorphous Sn incorporation (i) into germanosilicate zeolites UOV, IWW, and IWR in the A step with structural modification in the DOR steps, we targeted new Sn-zeolite structures with either parallel or intersecting 12- and 8-ring pores predominantly containing Lewis acid centers with hydrolyzed Sn-O-Si bonds. The shape-selective performance of the designed Sn-zeolite catalysts was experimentally assessed and theoretically rationalized in transformations of citronellal into citronellol by Meerwein-Ponndorf-Verley reduction and into isopulegol isomers via intramolecular cyclization. Therefore, iADOR paves the way toward new zeolite catalysts with engineered Sn active sites for green chemistry.