Solid Acid Catalyst For Synthesis Research Articles

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

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

Synthesis of Solid Acid Catalysts of MgO–Al2O3 Mixed Oxide Containing Oxyanions by Thermal Decomposition of Anion-Exchanged Hydrotalcites

Solid acid catalysts of MgO–Al2O3 mixed oxides containing B4O72−, HPO42−, Mo7O246−, MoO42−, WO42−, and SO42− were synthesized by anion exchange with Cl− located in the space between anionic layers of hydrotalcite, followed by heat treatment at 773 K. The distance between the hydroxide layers was expanded by the intercalation of oxyanions larger than Cl−. The exchange of oxyanions in the interlayer space was confirmed by IR spectroscopy. Acid sites were generated on the obtained mixed oxides of MgO–Al2O3 by the electron withdrawing effect of the oxyanions. The acid catalyzed ethanol dehydration into ethylene and diethyl ether took place on the obtained catalysts. The effect of exchanged anions in the generation of acid sites was the largest in SO42−.

An innovative approach in the synthesis of solid acid catalyst from sugarcane bagasse for the esterification of oleic acid and methanol

Sugarcane bagasse (SCB) generated in the commercial sector would need to have means to convert the low-cost material into a high-value product(s). One possible high-value product is a solid acid catalyst (SAC) derived from SCB for possible applications in biodiesel production. In this study, a new approach and concept to simultaneously carbonize and sulfonate SCB under less severe conditions, while also recovering available sugars in SCB in the form of sugar-rich hydrolysates were explored. The approach involved a 2-h dilute acid hydrolysis (DAH) step with dilute H2SO4 (4 wt%) at 100 °C, as pre-treatment to recover about 73% of the available sugars in the hydrolysate. The post-hydrolysis SCB (PHSCB) left after the DAH along with the residual acids were then subjected to drying at 100–150 °C for 12–36 h, to induce simultaneous partial carbonization and sulfonation. The process was successfully carried out and enables the synthesis of carbonized and functionalized PHSCB. The catalyst was successfully used in the esterification of oleic acid and methanol while achieving a conversion of up to 95%. Other process parameters including the influence of solvent-to-oil ratio, catalyst loading, temperature, as well as reusability of the synthesized catalyst were also investigated.

Sulfamic acid supported on mesoporous MCM-41 as a novel, efficient and reusable heterogenous solid acid catalyst for synthesis of xanthene, dihydropyrimidinone and coumarin derivatives

Herein, the incorporation sulfamic acid (SA) into mesoporous silica (MCM-41) introduced an effective approach in numerous multicomponent reactions. SA/MCM-41 composites with different weight content of SA were successfully synthesized through easy impregnation method. The as-synthesized composites were characterized by different techniques like SEM, EDX, TEM, XRD, BET and FT-IR spectroscopy. The acidic characters of the composites have been studied using FTIR of chemisorbed pyridine and non-aqueous potentiometric titration. TEM and XRD measurements approve that MCM-41 shows an ordered mesoporous structure with hexagonal and honeycomb lattice and its mesoporous structure did not change even after modification with SA. MCM-41 shows high surface area (1287 m 2 /g), which reduced after addition of sulfamic acid until reached to 611 m 2 /g at 90 wt% SA-MCM-41. The acidic strength of the prepared composites progressively improved by raising SA contents up to 75 wt% SA/MCM-41. The as-synthesized composites were tested for multicomponent reactions such as preparation of 3,4-dihydro-pirimidin-2(1H)-ones (DHPs), 7-hydroxy-4-methylcoumarin and 14-Phenyl-14H-dibenzo [a, j] xanthene. SA/MCM-41 catalysts displayed excellent performance in 14-phenyl-14H-dibenzo [a, j] xanthene (95.8%), 3, 4-dihydropyrimidinones (94.4%) and 7-hydroxy-4-methylcoumarin (96.7%). The prepared catalysts displayed excellent reusability without significant loss in catalytic performance from the fresh run. • A highly active and stable MCM-41 supported with sulfamic acid catalysts have been successfully synthesized. • All loaded catalysts exhibited distinct catalytic activity in synthesis of xanthene, dihydropyrimidinone and coumarin. • The catalysts showed an excellent yield % up to 95% in all reactions and also show excellent recycling efficiency.

Study on Synthesis of Solid Acid Catalyst from Borassus flabellifer L. Waste with Sulfonation Method

Fiber of Borassus flabellifer L. includes agricultural wastes which containing lignocellulose components (hemicellulose and lignin) and high carbohydrate content. Siwalan coir fiber is quite potential to be used as a substrate in producing catalysts. Acid catalyst is one type of catalyst that as an important role in chemical process. This study aims to study the effect of the optimum mass ratio of carbon-KOH in the process of graphite synthesis based on siwalan charcoal so as to produce graphite with the most optimal characteristics, and optimum calcination temperature as a physical activation process in the synthesis of graphite based on siwalan coir fiber charcoal, and determine the time sulfonation which is optimum in producing acid catalysts There are 2 variables used in this study, temperature and sulfonation time. The method of making carbon is done by calcining to decompose the carbon source so that the composition is made according to what has been varied. After forming carbon-KOH composite, then sulfonation is carried out using sulfuric acid. The last step is to carry out the esterification step The process in this study discusses carboxylic acid, WCO (Cooking Oil Waste) and methanol (alcohol group).

Synthesis of Sulfonated Porous Organic Polymers with a Hydrophobic Core for Efficient Acidic Catalysis in Organic Transformations

Synthesis of sulfonated porous polymers with improved hydrophobicity and stability is of extreme importance in both academic research and industrial applications. However, there is often a trade-off between acidity and surface hydrophobicity of sulfonated polymers. In this study, we report a strategy for the synthesis of sulfonated porous organic polymers (S-PT) with improved hydrophobicity via free radical polymerization method by using a rigid and large multidentate monomer, 1,3,5-tri(4-vinylphenyl)-benzene, having a hydrophobic core. The results of vapor adsorption measurement show that S-PT has more hydrophobic properties than sulfonated poly(divinylbenzene) (S-PD), attributed to the hydrophobic core of its multidentate monomer. Furthermore, the optimization of sulfonation time established a balance between surface acidity and hydrophobicity. Under optimized conditions, S-PT afforded up to 113 mmol g-1 h-1 TOF in the esterification of oleic acid with methanol, more active than commercial Amberlyst-15 with TOF of 15 mmol g-1 h-1 and Nafion NR50 with TOF of 7 mmol g-1 h-1 . We believe that the findings of this study will provide useful insights to advance the design and synthesis of solid acid catalysts for organic transformations.

Synthesis and Initial Evaluation of Solid Acid Catalyst Derived from Spent Coffee Grounds for the Esterification of Oleic Acid and Methanol

Spent coffee grounds (SCGs) were utilized in the synthesis of a solid acid catalyst (SAC) through a carbonization–sulfonation process performed at low temperatures (350–500 °C for carbonization and 50–150 °C for sulfonation) and short processing times (1–10 h). The best SAC from the process was able to convert more than 90% of oleic acid to methyl oleate during esterification with methanol (10 mol OA/mol methanol, 80 °C, 7 h, 10%w/w catalyst loading). It was obtained by carbonizing SCG at 400 °C for 2 h and then sulfonating the biochar at 100 °C for 1 h. The reusability tests performed in 4 cycles at the same esterification conditions reveal loss of activity of about 70% of its original state, corresponding to a decrease in total acid and sulfonic acid densities from 4.22 and 3.36 mmol H+/g to 1.33 and 1.16 mmol H+/g, respectively. This process is a considerable improvement from that reported in previous works, having no activating agents in the carbonization process and with significantly shorter times for processing.

Synthesis, characterisation of nanoporous AlSiO4-5 and AlSiO4-12 catalysts, and its green catalytic application of CO2 decomposition

Global warming is a trendy term among researchers due to the increase of global temperature which causes severe environmental changes. By melting ice, causing weather extremes like flooding, water shortage and intense storm damage and disrupting the delicate balance of the oceans with increasing of CO2 level in the atmosphere. In this paper, biodegradable surfactants (SDS and SDBS) are used as a template for the synthesis of solid acid catalysts. The influence of templates in the structural changes is studied by various spectroscopic techniques. The synthesised material is packed in a new U-type catalytic reactor and used for carbon dioxide decomposition reaction. AlSiO4-5 and AlSiO4-12 decomposed the CO2 molecules into carbon monoxide, oxygen and carbon. AlSiO4-12 decomposed nearly 73% of carbon dioxide at 100°C and AlSiO4-5 decomposed 25% of CO2 at 70°C. Complete decomposition also maximum in AlSiO4-12 (31%).

The effect of polyethylene glycol addition on the synthesis of solid acid catalyst and its applications in esterification reaction

Synthesis of a catalyst by a sol-gel method is commonly conducted using a template to form pores to increase the number of active sites. In this work, mesoporous silica-carbon composites were prepared by sol-gel method using polyethylene glycol (PEG) 6000 as the template. Sodium silicate, commercially known as water glass, a cheap material, was used as the silica source. Here, PEG 6000 served as both the carbon source and the template. The silica-PEG composite was then carbonized at 550°C for 1 h to obtain silica-carbon composite. The sulfonate group was grafted into the composite by sulfonation with sulfuric acid at 100°C for 5 h. The sulfonated silica-carbon catalyst had a surface area of approximately 1490.8 m2/g. The very high surface area was able to hold a large amount of sulfonate group resulting an ion capacity of approximately 2.09. The composite was successfully be used as heterogeneous catalyst for esterification of acetic acid with ethanol with a conversion of 90.27%, higher than that of commercially Flotrol F-007.

WO3/SiO2 SOLID ACID CATALYST FOR SYNTHESIS OF GREEN SOLVENT: ETHYL LACTATE

WO3/SiO2 SOLID ACID CATALYST FOR SYNTHESIS OF GREEN SOLVENT: ETHYL LACTATE

Sulfated TiO2 nanosheets catalyzing conversion of biomass derivatives: influences of the sulfation on distribution of Brønsted and Lewis acidic sites

AbstractBACKGROUNDThe synthesis of solid acid catalysts of recoverable and environmentally friendly nature has gained increasing attention in recent years. The distribution of Brønsted and Lewis acidic sites on the surface of sulfated metal oxides determines the catalytic performance, which is affected by many key factors, such as the concentration of sulfuric acid impregnated and the morphology of the metal oxides used. In this study, TiO2 nanosheets were successfully synthesized and used as carrier for the preparation of solid acid catalysts.RESULTSThe concentration of sulfuric acid for the impregnation resulted in various distributions of Brønsted and Lewis acidic sites on the surface of sulfated TiO2. With a medium concentration of sulfuric acid (1 mol L−1) for the impregnation, the highest ratio of Brønsted to Lewis acidic sites can be achieved, and the catalyst showed superior catalytic activity for the conversion of furfuryl alcohol (FA) to ethyl levulinate (EL) in ethanol and the conversion of fructose to 5‐hydroxymethylfurfural (HMF) in dimethyl sulfoxide (DMSO).CONCLUSIONThe sulfation of TiO2 nanosheets induced the formation of both Brønsted and Lewis acidic sites. The Brønsted acidic sites were more effective for catalyzing the conversion of FA or fructose. The poor recyclability of the 1.0‐SO42−/TiO2 catalyst in the conversion of FA to EL in ethanol, a protic solvent, was due to the leaching of sulfur species. The deactivation of the catalyst in DMSO was due to coking, which could be resolved via calcination of the coke species in air. © 2019 Society of Chemical Industry

Synthesis of Solid Acid Catalyst from Fly Ash for Eugenol Esterification

A series of fly ash-based heterogeneous acid catalysts were prepared by chemical and thermal treatment. Fly ash was chemically activated using sulfuric acid and followed by thermal activation. Characterization methods of XRD, BET, SEM-EDX, and the performance in esterification of eugenyl acetate production was carried out to reveal the physical and chemical characteristics of prepared catalysts. Activated catalyst showed high silica content (96.5%) and high BET surface area of 70 m2.g-1. The catalyst was proven to be highly active solid acid catalyst for liquid phase esterification of eugenol with acetic acid yielding eugenyl acetate. A yield of 43-48% was obtained with activated fly ash catalysts for 90 minutes reaction. These catalysts may replace beneficially the conventional homogenous liquid acid to the eco-friendly heterogeneous one.

Catalyst Activity of Solid Acid Catalyst Derived From Agricultural Biomass for Biodiesel Production From Waste Cooking Oil

Homogeneous alkali catalyst produces soap as a by-product and generates a large amount of wastewater. This study investigates the potential of three types of biomass namely oil palm frond, coconut shell and groundnut shell to be developed as a solid acid catalyst for transesterification of waste cooking oil into biodiesel. The synthesis of solid acid catalyst is conducted by incomplete carbonization of biomass followed by sulfonation using concentrated sulfuric acid to incorporate the sulfonic group in the carbon body. The porosity of prepared catalyst was characterized by adsorption/desorption technique and surface acidity was evaluated by means of back titration method. Coconut shell showed the highest acid density of 0.51 mmol/g followed by groundnut shell and oil palm frond with 0.16 mmol/g and 0.12 mmol/g respectively. The biodiesel production was carried out at reaction conditions of methanol-to-oil ratio 20:1, reaction temperature 60 ºC, reaction time 6 h and catalyst loading 6 wt%. The highest biodiesel conversion was achieved using a coconut shell as a catalyst with 86.5%, followed by groundnut shell and oil palm frond. The use of solid acid catalyst derived from biomass could explores new market value for waste material while minimizing the solid waste production and further reduces cost and energy consumption in biodiesel production.

Strongly proton exchanged montmorillonite K10 (H+-Mont) as a solid acid catalyst for highly efficient and environmental benign synthesis of biscoumarins via tandem Knoevenagel–Michael reaction

In this study, synthesis of micro/meso porous acid-activated montmorillonite K10 (H+-Mont) was carried out by the activation of Na+-montmorillonite with HCl (4 M) at the controlled conditions. The prepared H+-Mont clay was then characterized using FT-IR, SEM, EDX, XRD and BET analyses. SEM and BET surface analyses represented that by the acid-activation, adjacent layers of montmorillonite K10 (Mont K10) were exfoliated to tiny segments leading to raise of surface area and total pore volume in H+-Mont system rather than the alone Mont K10. Catalytic activity of the prepared H+-Mont clay was further studied as a potent solid acid catalyst for synthesis of biscoumarin materials via tandem Knoevenagel–Michael reaction of 4-hydroxycoumarin with aromatic aldehydes. All reactions were carried out in a mixture of H2O-EtOH (1:1) at room temperature to afford the products in high to excellent yields within 25–50 min.

A Highly Efficient and Recyclable Solid Acid Catalyst for Synthesis of Spiro-oxindole Dihydroquinazolinones Under Ultrasound Irradiation

A simple, efficient and green procedure for the synthesis of spiro-oxindole dihyfroquinazolinones was developed by multi-component condensation of isatoic anhydride, aniline and isatin in the presence of a novel solid acid catalyst under ultrasound irradiation. The present environmentally benign protocol offers several advantages, such as shorter reaction time, a wide range of functional group tolerance, the use of an inexpensive heterogeneous catalyst, and a high yield of products via a simple experimental and work-up procedure. The mesoporous solid acid catalyst was directly prepared from phytic acid by microwave-sulfonation method without template. The phytic acid based solid acid was fully characterized by means of Fourier transform infrared spectroscopy(FTIR), Raman spectroscopy, X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS), and transmission electron microscopy(TEM). The catalyst can be recovered and reused for at least five runs without significant impact on the product yields.

Synthesis of solid acid catalysts for esterification with the assistance of elevated pressure

Abstract Acidic catalysts dedicated for esterification processes were prepared by immobilization of (3-mercaptopropyl)trimethoxysilane (MPTMS) on mesoporous silica and niobiosilicate material using a new methodology, i.e. solvothermal technique with increased pressure. The structure and surface properties of the samples obtained were examined using N2 adsorption/desorption, XRD, TEM, XPS and elemental analysis. The impact of modification technique as well as the presence of niobium in the sample on the acidity of final materials was investigated. It was found that the application of external pressure during the solvothermal modification of mesoporous silica with MPTMS allows obtaining materials with a greater number of acidic sites. These samples showed a high activity and stability in esterification of acetic and propionic acid with n-butanol and n-hexanol.

Titanate nanotubes-bonded organosulfonic acid as solid acid catalyst for synthesis of butyl levulinate.

In this study, titanate nanotubes-bonded organosulfonic acid (TNTs–SO3H) was prepared and employed as an efficient heterogeneous catalyst for esterification of levulinic acid with n-butanol. Two reaction products pseudo n-butyl levulinate (pseudo-BL) and n-butyl levulinate (BL) were detected by GC-MS. The catalyst showed 86.8% conversion of levulinic acid with 99.7% selectivity towards n-butyl levulinate. TNTs–SO3H exhibited strong acidic sites and high stability even after seven cycles of usage and would be well expected to be a potential candidate for alkyl levulinate production.

Effects of Ultrasound Irradiation on Synthesis of Solid Acid Catalysts

The studies based on morphological characterization to assess the effects of ultrasound irradiation on synthesis of solid acid catalysts. Three sets of catalyst formulation were synthesized by both wet impregnation method and ultrasound assisted methods with different wt. % of Ni loading on γ-Al2O3. The XRD, BET, TEM and FESEM techniques were used to characterize the nano-particles. Physicochemical characterization revealed that the synthesized catalysts particles using ultrasound irradiation were in nano size range (1-24.5 nm) with equal dispersion of metal oxide, high surface area with increase of metal loading and high phase purity than the catalysts synthesized conventional method. These catalysts were also found in various crystal structures like cubic, monoclinic and tetrahedral. The use of ultrasound irradiation has great significance over the wet impregnation method in relation to the rate of synthesis of nanocatalysts. The high surface area, high thermal stability and small particle size (up to 1 nm) are the basic elements for high activity of solid acid catalysts in hydrocracking and hydrodeoxygenation of various feedstock in petroleum industries.

Novel porous and hydrophobic POSS-ionic liquid polymeric hybrid as highly efficient solid acid catalyst for synthesis of oleate

A novel porous and hydrophobic Brønsted acidic solid catalyst (POSS-[VMPS][H2SO4]) was successfully synthesized by copolymerization of polyhedral oligomeric vinylsilsesquioxanes (POSSs) and sulfonic acid-functionalized imidazole ionic liquids. Catalytic tests for the esterification of oleic acid with methanol have shown that this newly obtained polymeric hybrid exhibits very high catalytic activity and selectivity, which was more active or comparable to those of the common solid acid Amberlite-732 and liquid acid H2SO4. Moreover, the catalyst has a good recyclability without significant loss in the activity.

ChemInform Abstract: Cellulose Sulfuric Acid as a Bio‐Supported and Efficient Solid Acid Catalyst for Synthesis of Pyrazoles in Aqueous Medium.

AbstractCellulose sulfuric acid efficiently catalyzes the coupling reaction of 1,3‐dicarbonyl compounds with hydrazine and hydrazide derivatives furnishing pyrazole derivatives in good to excellent yields.