Acid Resin Catalyst Research Articles

Fabrication of Keggin heteropolyacid modified macroporous covalent triazine frameworks with cyano group-rich defects for high-value utilization of carbohydrates

Designing an efficient, stable and recyclable solid acid for catalytic conversion of biomass and its derived compounds to synthesize high value-added organic chemicals could effectively alleviate the environmental problems caused by the energy crisis and carbon dioxide emissions. We prepared a Keggin heteropolyacid modified macroporous covalent triazine frameworks (PW12-MCTF) catalyst using a simple template method and post-impregnation technology for efficient conversion of carbohydrates to produce 5-hydroxymethylfurfural (HMF). Abundant structural defects of MCTF can be constructed in situ through incomplete polymerization, which can firmly bind H3PW12O40 through physical confinement effect and bonding interactions. Under optimized conditions, PW12-MCTF exhibited high HMF yield (79.4 % or 44.4 %) and the highest turnover frequency (4.39 min−1 or 1.86 min−1) in microwave-assisted catalytic conversion of fructose or inulin, respectively. Its catalytic activity surpassed that of bulk PW12-CTF and commercial acid zeolite and resin catalysts, due to its appropriate acid properties, well-dispersed nature in DMSO, inter-connected pore structure and outstanding nucleophilic effect of N-rich units. Density Functional Theory (DFT) study provides a plausible mechanism in PW12-CTF-catalyzed fructose dehydration. The catalytic performance of PW12-MCTF remained unchanged after three cycles due to strong bonding interaction between the Keggin units and framework of MCTF. This study will provide a new strategy for the fabrication of heteropolyacid modified covalent organic frameworks with structural defects to achieve the high-value utilization of carbohydrates.

Continuous Synthesis of Methacrolein over Sulfonic Acid Resin Catalysts: Unraveling the Effect of Acid Strength and Solvent Permittivity

Continuous Synthesis of Methacrolein over Sulfonic Acid Resin Catalysts: Unraveling the Effect of Acid Strength and Solvent Permittivity

Heterogeneous Catalytic Conversion of Terpenes into Biofuels: An Open Pathway to Sustainable Fuels

The production and use of terpene-based fuels represents a renewable source of energy in the transportation sector, especially in the aviation sector. The literature on the conversion of terpenes into valuable compounds is not new but has been based on the production of products for cosmetics and pharmaceutics. Several established chemical routes are also a way to develop drop-in fuels. The present work explores all the main chemical processes that can transform terpenes into more valuable fuels or additives, focusing on the use of heterogeneous catalysis, catalyst type, operating conditions, and reaction performance. α-pinene is the most studied catalyst, since it is the main component of turpentine. Isomerization is the most frequently applied chemical pathway used to enhance fuel properties, and a wide group of heterogeneous catalysts have been reported, with sulphonic acid resin catalysts, transition metals, alumina, and silicates being the most used. This work also explores the current production and commercialization of terpenes, as well as the challenges for their use as fuels at a commercial scale. The future challenge is to discover new catalysts or to improve the performance of the current products and reduce production costs. The feasibility of the production and commercialization of terpene-derived fuels is also linked to oil prices.

Production of biodiesel and water conservation through conversion of free fatty acids from a domestic wastewater drain

ABSTRACT Wastewater discharge from restaurants, hotels, household kitchens, confectionaries, meat, fruits, and vegetable processing units contain free fatty acids (FFAs) from fats, oils, and greases (FOG). These FFAs are one of the major causes of sewer overflows and blockages that cause health and environmental issues. This study has investigated the use of sewer wastewater as a source of lipids for the production of alkyl esters (Biodiesel) and provides a characterization of the resulting processed water. Amberlyst A21 basic resin in a column reactor was used to recover the FFAs by adsorption from an oily layer collected from the domestic wastewater drain (Chakri drain, Rawalpindi, Pakistan) having a 33.0 ± 2.08% oily fraction with 59.7 ± 1.1% FFAs. The recovered ethanol washed FFAs from the Amberlyst A21 surface were then turned into Fatty Acid Ethyl Esters (FAEEs) in the presence of an acidic resin catalyst Amberlyst 15. The esterification reaction was studied at temperatures 50, 60, and 70°C, molar ratios of 1:2 to 1:3, acidic resin weight % of 2 to 6, and reaction time of 2 to 8 hr, respectively. A maximum FFAs conversion into esters of 91.38 ± 1.13% was noted at an esterification temperature of 70°C, molar ratio of 1:3, acidic resin weight of 6%, and a reaction time of 8 h. The fractional distillation of the esterified reaction product at 100°C improved the ester content in the reaction mixture up to 96.6 ± 0.18%, with a distilled biodiesel yield of 95.52 ± 0.21%. The collected top oily layer from sewer drain wastewater was found to have a density 947.31 kg/m3, kinematic viscosity 32.69 mm2/sec, flash point 283°C, and LHV and HHV of 26 and 28 MJ/kg, respectively, while for the produced biodiesel the density was 886 kg/m3, kinematic viscosity 4.3 mm2/sec, flash point 137°C, and LHV and HHV of 39 and 41 MJ/kg was noted, respectively. Only oily layer free wastewater after passing through PAC was found to meet Pakistan NEQS, with COD <150 mg/L, pH 6–8, Alkalinity <1000 mg/L, and Ammonia-nitrogen <40 mg/L. For every 1000 gallons of domestic sewer drain wastewater treated per 8 h work shift or 3 work shifts in a day with FFAs recovered and their conversion into biodiesel, a net profit of 54.89 and 93.32 million Pakistani rupees can be gained in the first year and then in successive years, respectively. Thus, this research provides a way to produce renewable energy fuel, biodiesel from the waste lipids (FFAs) of wastewater drains to meet the energy requirements and a solution for the conservation of water bodies.

Green Production of Phthalic Anhydride from Biobased Furan and Maleic Anhydride by an Acid Resin Catalyst

The production of chemicals such as phthalic anhydride (PA) from renewable biomass is of crucial significance for sustainable social development. Herein, we demonstrate that a 99.0 mol % yield of PA can be achieved from a Diels–Alder adduct of furan and maleic anhydride on an acid resin catalyst. The active sites on the catalyst were produced by pretreating the resin with acetic anhydride. The excellent performance of the resin catalyst is attributed to its surface enrichment effect on the reactant and good ability to suppress the side reactions. Moreover, the catalyst deactivation mechanism was clarified to be the destruction of the resin skeleton during the reaction. These results will provide a practical route for the future industrial production of PA from renewable biomass.

Efficient conversion of corn stover to 5-hydroxymethylfurfural and furfural using a novel acidic resin catalyst in water-1, 4-dioxane system

A route of corn stover conversion was developed for 5-hydroxymethylfurfural (5-HMF) and furfural production by a novel Cl-containing resin-based solid acid catalyst (Cl0.3-S-R), which was synthetized by a simple hydrothermal method through polymerization reaction of o-chlorophenol and p-hydroxybenzenesulfonic with formaldehyde. The effects of catalyst types, reaction time, substrate types, solvent types, additional water concentrations and corn stover concentrations were investigated in detail. The high 5-HMF yield of 43.8% and furfural yield of 38.1% (based on the xylose and glucose units) could be achieved from corn stover simultaneously in water/1,4-dioxane at 190 °C in 80 min, with Cl0.3-S-R as catalyst. Furthermore, the catalysts were characterized by SEM, elemental analysis, FTIR, XPS and N2 adsorption-desorption to reveal its physical and chemical properties.

Sonication pre-treatment for the intensified synthesis of tricaproin using acid-resin catalyst

In this study synthesis of triglyceride of hexanoic acid is investigated with the application of amberlyst-15 as a catalyst in a solvent free reaction mixture with pre-treatment of ultrasonic cavitation. In present research outcome of various reaction parameters like reaction temperature, loading of catalyst and molar ratio of reactant on rate of conversion of reactant is studied. Further ultrasonic pre-treatment parameters like pre-treatment time and duty cycle are studied. During study it is established that the ideal reaction conditions for the maximum conversion of reactant were molar ratio of reactant i.e., glycerol: fatty acid as 5:3, reaction temperature of 140 °C, amberlyst-15 loading of 5%. It is also established that the pre-treatment time of 25 min and 80% duty cycle gave good results. Recyclability of amberlyst-15 is established for 15 cycles of esterification reaction. The study showed that the use of ultrasonic pre-treatment and amberlyst-15 as a catalyst have beneficial effect on rate of conversion of reactant and also have an effect on reduction in reaction time to 07 h as compared to conventional synthesis of triglycerides of hexanoic acid. Maximum conversion of 96% was obtained in 07 h with ultrasonic pre-treatment and amberlyst-15.

Highly selective self-condensation of cyclohexanone: the distinct catalytic behaviour of HRF5015.

HRF5015, a perfluorosulfonic acid resin catalyst with unique pore structures, was investigated in the catalytic self-condensation of cyclohexanone under mild conditions. The morphology of HRF5015 was characterized by transmission electron microscopy (TEM) and atomic force microscope (AFM), and the reaction mechanism was studied by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The effects of reaction time and temperature on the yield of dimer were investigated under the nitrogen atmosphere. The results show that the reaction temperature is low, and especially, the selectivity of the dimer is close to 100%. The apparent activation energy for the dimer formation reaction is 54 kJ mol−1. Synergistic action of cluster structure formed by sulfonic groups and nanopores in HRF5015 may be the key factor of high-efficiency catalytic activity and high selectivity. In situ infrared spectra indicate that the intermediate is stable in the reaction process. HRF5015 is environmentally friendly and re-usable, which shows good potential in a future application.

Hydrolysis of Oligosaccharides and Polysaccharides on Sulfonated Solid Acid Catalysts: Relations between Adsorption Properties and Catalytic Activities.

Sulfonated solid acid materials, such as sulfonated carbon catalysts, are promising materials as heterogeneous catalysts for the hydrolysis of esters and polysaccharides in water solvents. The catalytic active site is a sulfonic acid functional group. Compared to conventional strong acidic ion-exchange resin catalysts, sulfonated carbon materials have less sulfonic acid functional groups but higher catalytic activity for hydrolysis of polysaccharides per catalyst weight. However, the details of catalytic properties and the substrate suitability of both catalysts are unclear. In this study, the hydrolytic activities and the adsorption properties of both catalysts were investigated for various oligosaccharides and polysaccharides with varying degrees of polymerization (DP). The catalytic activities for the hydrolysis with increase of the DP of saccharides were found to increase over the sulfonated carbon catalyst but decrease over strong acidic ion-exchange resin catalyst. The inverse catalytic properties attribute to the dependence of the amounts of adsorption and/or penetration of saccharides on the DP. Moreover, the catalytic activity per acidic sites of strong acidic ion-exchange resin is in good agreement with the value obtained by multiplying the catalytic activity of a dilute sulfuric acid by the penetration degrees.

Impacts of externally added Brønsted and Lewis acid on conversion of furfural to cyclopentanone over Ni/SiC catalyst

The conversion of furfural to cyclopentanone (CPO) involves not only hydrogenation but also acid-catalysis reactions. The step of the acid-catalysis might be catalyzed by Lewis acid or Brønsted acid or both, which was investigated in this study by employing Ni/SiC, a catalyst with “clean” surface containing negligible amounts of acidic sites. Lewis acid (nitrate salts and chloride salts) or Brønsted acid (D008, a solid acid resin catalyst) with externally added to the reaction medium. The results showed that both Lewis acid and Brønsted acid could catalyze the conversion of furfural to CPO. The further hydrogenation of furfuryl alcohol (FA) to tetrahydrofurfuryl alcohol was main side reaction, which could be suppressed more effectively with the Lewis acid like CrCl3. The yield of CPO could be up to ca. 88.1 % with the Ni/SiC-CrCl3 catalytic system. The chelation of CrCl3 with FA stabilized the CC bond in the furan ring and the hydroxyl group, preventing the side reactions while facilitating CPO formation. The synergistic effects between the cation and anion was essential for the conversion of FA to CPO as the varied nitrate salts or chloride salts chelated with furfural, FA or other reaction intermediates in distinct ways, determining distribution of the products.

Impacts of water-organic solvents on polymerization of the sugars and furans in bio-oil

Polymerization is one major issue during acid-catalyzed conversion of sugars/furans to platform chemicals. Reaction medium is one of the main factors impacting the tendencies of sugars/furans towards polymerization. In this study, conversion of sugars (fructose/glucose/xylose/xylan) and furans (hydroxymethylfurfural (HMF)/furfural/furfuryl alcohol (FA)) over a solid acidic resin catalyst in various water-organic bi-solvents (toluene, chloroform, n-butanol, tetrahydrofuran (THF), dimethyl sulfoxide (DMSO) and ethyl acetate (EA)) were investigated. The results showed toluene/chloroform as the co-solvent did not suppress the polymerization of fructose, HMF, furfural and FA while diminished the formation of LA from fructose/HMF. The organic co-solvents remarkably affected properties of the coke formed. The presence of aprotic organic solvents tended to retain the CO group in the coke formed and affected its thermal stabilities and evolution of the functionalities. Additionally, polymerization tendency of the furans with the distinct structures showed very different sensitivity with the water in reaction medium.

Excellent prospects in methyl methoxyacetate synthesis with a highly active and reusable sulfonic acid resin catalyst

A highly active and reusable sulfonic acid resin catalyst was used for DMM carbonylation to MMAc.

Second-Generation meta-Phenolsulfonic Acid-Formaldehyde Resin as a Catalyst for Continuous-Flow Esterification.

A second-generation m-phenolsulfonic acid-formaldehyde resin (PAFR II) catalyst was prepared by condensation polymerization of sodium m-phenolsulfonate and paraformaldehyde in an aqueous H2SO4 solution. This reusable, robust acid resin catalyst was improved in both catalytic activity and stability, maintaining the characteristics of the previous generation catalyst (p-phenolsulfonic acid-formaldehyde resin). PAFR II was applied in the batchwise and continuous-flow direct esterification without water removal and provided higher product yields in continuous-flow esterification than any other commercial ion-exchanged acid catalyst tested.

Conversion of Cellulose to Levulinic Acid/Ester over an Acid Catalyst: Impacts of Dispersion of Hydrogen Ions on Polymerization Reactions

Polymerization is a major challenge in the conversion of cellulose to platform chemicals, such as levulinic acid. In this study, the distinct dispersion patterns of hydrogen ions in a solid acidic resin catalyst (D008 catalyst) and H2SO4 catalyst on the polymerization reactions during conversion of cellulose to levulinic acid/ester were investigated in water and in alcohol medium. The results showed that the distinct patterns for dispersion of hydrogen ions impacted both the efficiency for conversion of cellulose and the tendency for the polymerization reactions. The hydrogen ion in D008 concentrated in pores or the local area of the catalyst, creating steric hindrance for cellulose to access the hydrogen ions but facilitated polymerization of glucose. The homogeneous dispersion of the hydrogen ion in H2SO4 facilitated conversion of cellulose and minimized the polymerization reactions, especially in alcohol medium. When alcohol is used as a reaction medium, the polymerization reaction could be effectively suppressed. Furthermore, alcoholysis was more efficient than the hydrolysis for converting cellulose to levulinic acid/ester. The reaction medium also affected properties of the coke formed. In water, the coke formed contained abundant carbonyl functionalities with a higher thermal stability. In alcohol, the coke formed had less carbonyl functionalities but the thermal stability was lower.

Nano-Silica@PVC-Bonded N-Ethyl Sulfamic Acid as a Recyclable Solid Catalyst for the Hydroxyalkylation of Phenol with Formaldehyde to Bisphenol F

Abstract Sulfamic acid functionalized PVC-coated nano-silica (NS) catalyst (NS@PVC-EDA-SO3H) was prepared via multi-step treatment processes and characterized by FT-IR, N2 adsorption-desorption, TGA/DTG, XRD, TEM, STEM-EDS, as well as acid-base back-titration. The hydroxyalkylation of phenol with formaldehyde to bisphenol F was employed to evaluate in detail its acid catalysis performances. The results indicated that the newly constructed NS@PVC-EDA-SO3H possessed richer short mesoporous to macroporous channels and highly exposed sulfamic acids and could exhibit excellent hydroxyalkylation activity and reusability owing to fast mass transfer and reaction rates for the conversion of substrates, as well as excellent structural and chemical stabilities. This new solid acid was obviously superior to the conventional homogeneous concentrated sulfuric acid and heterogeneous sulfonated resin catalysts in catalytic activity and reusability, which could achieve a remarkable formaldehyde conversion (99.9%) and selectivity of bisphenol F (94.5%) under optimal hydroxyalkylation conditions. Furthermore, it could also be recovered easily and used repeatedly at least nine times without an obvious decrease in activity.

Production of HMF from glucose using an Al3+-promoted acidic phenol-formaldehyde resin catalyst

An Al3+-modified formaldehyde-p-hydroxybenzenesulfonic acid resin catalyst (Al-SPFR) was synthesized through a hydrothermal method. N2 adsorption–desorption experiment and acid–base titration revealed that the Al-SPFR catalyst had better texture properties and higher strong acid content than the previously prepared unmodified SPFR. The effects of reaction time and temperature, catalyst loading, and water content in water/GVL mixture were investigated for glucose dehydration using Al-SPFR as the catalyst. An HMF yield of 47.4% was obtained at 170 °C for 2 h in the biphasic GVL/H2O medium. Further performing a five-cycle experiment, the HMF yield initially decreased and then remained fairly constant, and the recyclability of the Al-SPFR was reasonable.

Kinetics, mass transfer, and thermodynamic and statistical modeling study for esterification of valeric acid with n‐butanol: Homogeneous and heterogeneous catalysis

AbstractThe esterification of valeric acid with n‐butanol was studied with homogeneous and heterogeneous catalysts. The activity and performance of homogeneous p‐toluenesulfonic acid and heterogeneous cation exchange resin catalysts Amberlyst 36, Indion 190, and Amberlite IRC‐50 were evaluated. The pseudo‐homogeneous kinetic model was used to investigate the kinetic parameters of homogeneous‐ and heterogeneous‐catalyzed esterification. The UNIFAC (universal functional activity coefficient) approach was used to study the nonideality of the esterification reaction. The reaction was statistically modeled and optimized by the application of response surface methodology. The effects of independent variables such as reaction temperature, initial molar ratio, and catalyst loading on the conversion of valeric acid were investigated. The optimized conditions for the esterification reaction catalyzed by Amberlyst‐36 were found as temperature 360.4 K, initial molar ratio 3.8, and catalyst loading 6.7 wt%. The predicted conversion (89%) at these optimized conditions is in good agreement with the experimental conversion (87.3 ± 1.6%).

Experimental evaluation of a polystyrene sulphonic acid resin catalyst in the hydrolysis of low-grade lipids from the meat processing industry

In this study, a polystyrene sulphonic acid resin catalysed hydrolysis of low grade lipids from meat processing waste, via an in-situ hydrolysis pathway was evaluated for enhanced fatty acid yield. Process evaluation was achieved using a response surface methodology based on a central composite design for four process variables (temperature, catalyst load, moisture mass fraction of the meat processing waste, and reaction time). This study enabled the development of a model that was sufficient to predict fatty acid yield as a function of the four process variables investigated. The optimum values of the temperature, catalyst loading, moisture mass fraction, and reaction time for enhanced fatty acid yield were determined to be 92.5 °C, a mass ratio of 0.09 resin to wet meat processing waste, 92%, and 1 h respectively. Catalyst recovery and regeneration were also demonstrated, with up to 88% mass fraction of the catalyst recoverable, while retaining an activity of 96% relative to the fresh catalyst. The study therefore showed that it is possible to produce high yields of fatty acids under moderate temperature conditions from high moisture low grade lipid sources. It was therefore shown that a highly efficient hydrolysis process can be achieved without the energetic penalty of preliminary drying operations that are associated with lipid extractive processes characterising existing lipid hydrolysis systems.

A Synthesis, Process Optimization, and Mechanism Investigation for the Formation of Polyoxymethylene Dimethyl Ethers

Polyoxymethylene dimethyl ethers (DMMn) are promising diesel additives. The synthesis of DMMn from methylal (DMM) and paraformaldehyde over the NKC-9 acidic ion-exchange resin catalyst was investigated. Many unrecyclable by-products such as methyl formate, dimethyl ether and formic acid were produced in the reaction. To increase the selectivity of the desired products DMM3‒6 and reduce the amount of unrecyclable by-products, the effects of reaction temperature, time, pressure and the molar ratio of the raw materials were evaluated through a series of single factor experiments. Experiments revealed that trace amount of water could suppress the formation of unrecyclable by-products, and the optimum initial water content (less than 2 wt%) was investigated. In addition, the synthetic process needs to go through the polyoxymethylene hemiformals intermediate stage, and then the DMMn were obtained when polyoxymethylene hemiformals reacted with methanol. Ultimately, a possible mechanism is proposed to describe the formation of DMMn from polyoxymethylene hemiformals in detail, in which it is revealed that the formation of carbocation intermediates is important in the reaction processes.

LEWIS ACID SITES OF Mg2+-MODIFIED POLYSTYRENE SULFONIC ACID RESIN CATALYSYS FOR SYNTHESIS OF DIBUTYL SUCCINATE

The polystyrene sulfonic acid resin catalysts were fabricated, containing elements of Cl and Mg through oxidization and impregnation, and they were characterized by EDS, FT-IR spectra, Py-IR spectra, UV spectra, XPS and TGA to investigate their physiochemical properties. The catalytic performances of these catalysts were examined in the esterification reaction of succinic acid with n-butanol, and the catalytic results showed that modified resins exhibited the highest catalytic activity and achieved a high yield of dibutyl succinate (91.6%) in addition, the modified resin generated new Lewis acid sites and showed significantly higher thermal stability. The experimental results demonstrated that the Mg2+ coordinated with a sulfonic acid group to form stable active sites, which effectively decreased the deactivation caused by the thermal degradation of sulfonic acid. Moreover, the monomer structures of polystyrene sulfonic acid resin and modified polystyrene sulfonic acid resin have been modelled using B3LYP/6-311G(d,p) approximation.