Heterogeneous Solid Acid Catalyst Research Articles

Metal-free approach towards efficient synthesis of FDCA using a p-toluene sulfonic acid (p-TSA)-derived heterogeneous solid acid catalyst and oxone over two steps from HMF, fructose and glucose

In this work, a metal-free approach towards synthesis of 2,5-furandicarboxylic acid (FDCA) from HMF, fructose and glucose is reported over two steps using p-TSA–POM solid acid catalyst in the first step and oxone as an oxidant in the second step.

Оценка бренстедовской кислотности протонных цеолитов с помощью VTIR-спектроскопии --- обзор текущих исследований

Many industrial applications of protonic zeolites as solid-acid heterogeneous catalysts rely on the strength or their Brønsted acidity, which (together with zeolite topology) affects both, catalytic activity and selectivity. Therefore, the convenience to have an accurate (and simple) experimental technique for measuring Brønsted acid strength. The enthalpy change, ΔH0, corresponding to the hydrogen bonding interaction of a weak base (such as CO or dinitrogen) with their Brønsted acid [Si(OH)Al] hydroxyl groups should directly correlate with the zeolite acid strength. Nevertheless, because of simplicity, the bathochromic shift of the O–H stretching frequency, Δν(OH), is usually measured by IR spectroscopy at a low temperature, and correlated with acid strength, for ranking zeolite acidity. Herein the use of variable-temperature IR (VTIR) spectroscopy to determine simultaneously ΔH0 and Δν(OH) is demonstrated; followed by an abridged overview showing that direct correlation between Δν(OH) and Brønsted acid strength can be misleading when ranking zeolite acidity.

Ranking the Bronsted Acid Strength of Protonic Zeolites with VTIR Spectroscopy --- An Overview of Current Research

Many industrial applications of protonic zeolites as solid-acid heterogeneous catalysts rely on the strength or their Br nsted acidity, which (together with zeolite topology) affects both, catalytic activity and selectivity. Therefore, the convenience to have an accurate (and simple) experimental technique for measuring Br nsted acid strength. The enthalpy change, Delta H0, corresponding to the hydrogen bonding interaction of a weak base (such as CO or dinitrogen) with their Br nsted acid [Si(OH)Al] hydroxyl groups should directly correlate with the zeolite acid strength. Nevertheless, because of simplicity, the bathochromic shift of the O-H stretching frequency, Deltaν(OH), is usually measured by IR spectroscopy at a low temperature, and correlated with acid strength, for ranking zeolite acidity. Herein the use of variable-temperature IR (VTIR) spectroscopy to determine simultaneously Delta H0 and Deltaν(OH) is demonstrated; followed by an abridged overview showing that direct correlation between Deltaν(OH) and Br.nsted acid strength can be misleading when ranking zeolite acidity. Keywords: VTIR spectroscopy, br nsted acidity, H-zeolites

Optimization of Trans-esterification Process and Characterization of Biodiesel from Soapstock Using Silica Sulfuric Acid as a Heterogeneous Solid Acid Catalyst

The main objective of this study was production, optimization, and fuel quality characterization of biodiesel from equal weight ratio blended acid oil of cottonseed and sunflower soapstock using silica sulfuric acid as a solid acid catalyst in laboratory scale. The physicochemical properties of soap stock samples and extracted acid oil from each soap stock were determined. The experiment was designed by design expert (version 11) software. The 5-level 4-factors (methanol to acid oil molar ratio, catalyst weight, stirring rate, and reaction time) were designed using the central composite design method. From the experimental results, the maximum biodiesel yield of 90.68% was obtained using methanol to acid oil molar ratio of 7:1 using catalyst 5.5(%wt/wt) with a stirring rate of 300rpm at 3hr reaction time. The average value of triplicate experiment of biodiesel yield from the experimentation at optimized condition was 92.62%. The analysis of variance results indicated that satisfactory results were achieved. The carried out physiochemical properties of produced biodiesel were within a range and some were closest to American and European biodiesel standards.

Brønsted acidic cellulose-PO3H: An efficient catalyst for the chemoselective synthesis of fructones and trans-esterification via condensation of acetoacetic esters with alcohols and diols

Cellulose is the most abundant organic source and has expedient a great deal of interest as renewable and emerged as sustainable feedstock. The functionalization of cellulose as designed catalytic system intriguing furnished to the production of fine chemicals. Herein, we synthesized an environmental friendly solid acid catalyst by functionalizing cellulose with phosphoric acid (PO3H). The successful functionalization of cellulose with PO3H was confirmed by 31P NMR, ICP-OES, FE-SEM, and XPS analysis. ICP-OES revealed the presence of phosphorus content of ∼1.0 wt. % on the catalyst's surface while elemental mapping by FESEM and XPS shows a uniform distribution of phosphorus over the material. The synthesized solid acid catalyst was utilized for condensation of diols with acetoacetic esters in solvent-free conditions to synthesize fine chemicals. The present approach not only circumvented the one-step protection and other products but more fascinatingly provided trans-esterification of acetoacetic esters with diols and n-alcohols. The catalyst was successfully used for chemoselective protection on ethyl acetoacetate with 1, 2 diols to essential fructone molecule with ∼100% conversion and 99% selectivity. The results suggested that the catalyst has the advantage over commercial solid acid heterogeneous and homogeneous catalysts.

Synthesis and Characterization of Heterogeneous Solid Acid Catalyst from Alstonia scolaris Stalks for Biodiesel Production using Waste Cooking Oil

Background: Waste biomass derived reusable heterogeneous acid based catalysts are more suitable to overcome the problems associated with homogeneous catalysts. The use of agricultural biomass as catalyst for transesterification process is more economical and it reduces the overall production cost of biodiesel. The identification of an appropriate suitable catalyst for effective transesterification will be a landmark in biofuel sector Objective: In the present investigation, waste wood biomass was used to prepare a low cost sulfonated solid acid catalyst for the production of biodiesel using waste cooking oil. Methods: The pretreated wood biomass was first calcined then sulfonated with H2SO4. The catalyst was characterized by various analyses such as, Fourier-transform infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS) and X-ray diffraction (XRD). The central composite design (CCD) based response surface methodology (RSM) was applied to study the influence of individual process variables such as temperature, catalyst load, methanol to oil molar ration and reaction time on biodiesel yield. Results: The obtained optimized conditions are as follows: temperature (165 ˚C), catalyst loading (1.625 wt%), methanol to oil molar ratio (15:1) and reaction time (143 min) with a maximum biodiesel yield of 95 %. The Gas chromatographymass spectrometry (GC-MS) analysis of biodiesel produced from waste cooking oil was showed that it has a mixture of both monounsaturated and saturated methyl esters. Conclusion: Thus the waste wood biomass derived heterogeneous catalyst for the transesterification process of waste cooking oil can be applied for sustainable biodiesel production by adding an additional value for the waste materials and also eliminating the disposable problem of waste oils.

Synthesis of dihydropyrimidinones via multicomponent reaction route over acid functionalized Metal-Organic framework catalysts

Multi component reactions over heterogeneous solid acid catalysts are extremely important owing to easy separation, amenable recycling, and prospective scaling up of the process. Here, we are reporting the synthesis of biologically important dihydropyrimidinones over postsynthetic modified Cr-based metal–organic framework materials as heterogeneous catalysts containing the bifunctional Lewis and Brønsted acid sites. Cr-based metal–organic frameworks contained coordinatively unsaturated metal sites as inherent Lewis acid sites, whereas postsynthetic modifications introduced the Brønsted acid sites in the framework. A direct one pot synthesis route was employed to produce the pristine MOF in pure aqueous medium without using any additives. The bulk structure, morphology, surface and bonding properties of the synthesized materials were thoroughly characterized with powder XRD, FTIR, XPS, FE-SEM, TGA, and N2 sorption isotherms. A qualitative evolution of acid strength was carried out over the functionalized MOFs. Among the post synthetic functionalized materials, carboxylic acid functionalized framework exhibited a very high yield of dihydropyrimidinones under solvent less moderate reaction conditions. The catalyst also demonstrated a robust recyclability and wide substrate scope. Comparative study showed a very high catalytic activity of the postsynthetic modified MOFs in comparison to the reported literature. The reaction condition was optimized by varying parameters like solvent, temperature, reaction duration and catalyst loadings. The mechanistic studies indicated the involvement of both the Lewis and Brønsted sites acid sites of the catalysts in the multicomponent reaction.

Cross‐linked poly(N‐vinylpyrrolidone)‐titanium tetrachloride complex: A novel stable solid TiCl4 equivalent as a recyclable polymeric Lewis acid catalyst for regioselective ring‐opening alcoholysis of epoxides

AbstractCross‐linked poly(N‐vinylpyrrolidone) resin beads were prepared as macromolecular ligand precursors by suspension copolymerization of N‐vinyl‐2‐pyrrolidone and N,N′‐methylenebisacrylamide (MBA) as a crosslinking agent in water. Subsequently, the resulting polymer carrier precursor was readily combined with titanium tetrachloride to form a stable polymeric coordination complex (PNVP/TiCl4), and this novel stable TiCl4 equivalent evaluated as a heterogeneous and reusable solid Lewis acid catalyst for the regio‐and stereoselective nucleophilic ring opening of various epoxides with various alcohols to prepare β‐alkoxy alcohols in excellent yields without generating any waste. The MBA‐cross‐linked PNVP and resultant catalyst were characterized by Fourier transform infrared spectroscopy (FT–IR), field‐emission scanning electron microscope (FE–SEM), energy dispersive X‐ray (EDX), inductively coupled plasma (ICP), and thermogravimetric analysis (TGA) techniques. Moreover, the catalyst is very stable, easily separated, and reused at least five times without significant loss of activity. In terms of scope, yields, the amount of catalyst used, and reaction time, the PNVP‐TiCl4 complex catalyst is an improvement over previously reported heterogeneous catalysts for ring opening of epoxides methods. Further, the experimental outcome revealed that using the copolymer beads as carriers with a high percentage of crosslinking and the high mesh size leads had an adverse effect on the reaction rate.

5-HMF production from industrial grade sugar syrups derived from corn and wood using niobium phosphate catalyst in a biphasic continuous-flow tubular reactor

This work demonstrated the promise of using industrial-grade sugar syrups derived from corn and wood, i.e., high fructose corn syrup (HFCS), glucose corn syrup (GCS) and wood-based sugar (TMP-Bio Sugar), as cheaper and competitive feedstocks for 5-HMF production using niobium phosphate as a heterogeneous solid acid catalyst in a biphasic continuous-flow tubular reactor. 5-HMF yield as high as 53.1% with 100% sugar (glucose and fructose) conversion was obtained from catalytic dehydration of HFCS-90 (containing 90 wt% fructose) at 150 °C, with feed concentration of 200 mg/ml (glucose and fructose) and aqueous to organic phase ratio of 1:5 (v/v). Catalyst stability with time was tested over 20 h of continuous-time on stream, and the reusability of the catalyst was studied after in-situ regeneration of the used catalyst by calcination in the air for removing the deposited humins and coke on the surface of the catalyst particles. The regenerated catalyst showed good activity with almost constant selectivity, although at lower glucose conversion and reduced 5-HMF yield compared to the fresh catalyst, indicating that the in-situ regeneration process could recover a part of the acid sites on the catalyst surface. The produced humins during the reaction were characterized by Fourier transform infrared spectrometry (FT-IR), thermogravimetric analysis (TGA) and elemental analysis (CHNS). The results showed high aromaticity and the presence of a high degree of unsaturated compounds in the structure of humins.

Catalytic dehydration of glucose to 5-HMF using heterogeneous solid catalysts in a biphasic continuous-flow tubular reactor

This work aimed to produce 5-hydroxymethylfurfural (5-HMF) from glucose in a biphasic continuous-flow tubular reactor with various heterogeneous solid acid catalysts or combined solid acid-base catalysts. Among the catalysts tested, niobium phosphate (NbP) was found to be the most active catalyst for glucose dehydration with a maximum 5-HMF yield of 45% at 150 °C. The higher activity of NbP was attributed to its higher total number of acid sites and BET surface area, as well as the presence of both Lewis acid and Brønsted acid sites. The effects of different operating conditions such as aqueous to organic (A/O) phase ratio, reaction temperature and feeding flow rate on the activity of some selected catalysts were studied. Reducing A/O ratio by increasing the extracting organic phase flow rate and increasing the reaction temperature (up to 150 °C) were found to positively affect 5-HMF production from glucose in the presence of NbP. Kinetics study demonstrated that the overall reaction of glucose dehydration to 5-HMF over the NbP catalyst is a first-order reaction with the reaction rate constants (k) determined as 0.06, 0.21 and 0.6 min−1 at 110, 130 and 150 °C, respectively, and the apparent activation energy (Ea) calculated to be 77 kJ/mol.

Development of heterogeneous catalysts and solid acid catalysts based on metal-organic framework (MOF) or porous coordination polymer (PCP)

Development of heterogeneous catalysts and solid acid catalysts based on metal-organic framework (MOF) or porous coordination polymer (PCP)

Biodiesel (Methyl Esters)

Biodiesel, an environmentally friendly biomass-based fuel, is gaining popularity globally as a cost-effective way to meet rising fuel demand. However, the high cost of raw materials and catalysts continues to drive up biodiesel production. An alternative feedstock with a heterogeneously catalyzed reaction could be the most cost-effective way to stabilize industrial biodiesel growth. Understanding these issues led to the idea of using waste palm oil as a feedstock for biodiesel production. While using waste materials as feedstock for biodiesel is an elegant solution, converting high free fatty acids (FFA) directly into methyl esters has some drawbacks. High FFA processes (acid esterification, then base transesterification) are costly. The commercial processes currently use a homogeneous system with sulfuric acid to catalyze both esterification and transesterification. However, heterogeneous solid acid catalysts are preferred over hazardous mineral acids for high FFA esterification because they are less corrosive, produce less waste, and are easier to separate from reactants and products by filtration, recovery, and reusability. Heterogeneous acid catalysts can also simultaneously catalyze transesterification and esterification reactions. Thus, new waste-based support for heterogeneous catalysts (solid acid catalysts) is required to convert waste oils into biodiesel.

A Two-Step SO3H/ICG Catalyst Synthesis for Biodiesel Production: Optimization of Sulfonation Step via Microwave Irradiation

Conventional heating, a common method used for heterogeneous solid acid catalyst synthesis unknowingly consumes massive time and energy. In this study, acid catalyst was prepared through sulfonation process of incomplete carbonized glucose (ICG) via microwave-assisted technique to shorten the heating time and energy consumption. Optimization of the sulfonation process of ICG via microwave-assisted was carried out. Four-factor-three-level central composite design (CCD) was used to develop the design of experiments (DOE). Interaction between two factors was evaluated to determine the optimum process conditions. A quadratic model was proposed for prediction of biodiesel yield (Y) from palm fatty acid distillate (PFAD) and its conversion (C). The application of DOE successfully optimized the operating conditions for the two-step SO3H/ICG catalyst synthesis to be used for the esterification process. The optimized conditions of the best performing SO3H/ICG with maximum Y and C were at 7.5 minutes of reaction time, 159.5 mL of H2SO4 used, 671 rpm of stirring rate as well as 413.64 watt of power level. At these optimum conditions the predicted yield percentage and conversion percentage were 94.01% and 91.89%, respectively, which experimentally verified the accuracy of the model. The utilization of sulfonated glucose solid acid catalyst via microwave-assisted in biodiesel production has great potential towards sustainable and green method of synthesizing catalyst for biodiesel. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Recent Advances on Cellulose Sulfuric Acid as Sustainable and Environmentally Benign Organocatalyst for Organic Transformations

Cellulose sulfuric acid has proved its competence as a potential bio-compatible, non-toxic, and inexpensive heterogeneous solid acid catalyst in synthetic organic chemistry. Owing to its remarkable properties, such as non-hygroscopic nature, recyclability, superior catalytic activity and high stability, it has been actively explored as an efficient and biodegradable organocatalyst in diverse chemical transformations of synthetic relevance. This review attempts to summarize a significant advancement and catalytic applications of cellulose sulfuric acid for the synthesis of a plethora of biologically relevant organic molecules.

Green sonosynthesis of phenazinpyrimidines using Co3O4/ZnO@N‐GQDs@SO3H nanocomposite as a robust heterogeneous catalyst

AbstractSO3H functionalized Co3O4/ZnO@N‐GQDs nanocomposite as a green heterogeneous solid acid catalyst has been utilized for the synthesis of phenazinpyrimidines by the four‐component reaction of 2‐hydroxy‐1,4‐naphthaquinone, o‐phenylenediamine, aldehydes, and 6‐amino‐1,3‐dimethyluracil under ultrasonic irradiations. The catalyst has been characterized by Fourier‐transform infrared spectroscopy, scanning electron microscope, X‐ray powder diffraction, energy‐dispersive X‐ray spectroscopy, thermogravimetric analysis, Brunauer–Emmett–Teller, and vibrating‐sample magnetometer). This method provides several benefits, including excellent yields in short reaction times, wide range of products, and applying the sonochemical methodology as efficient method.

Development of lignin based heterogeneous solid acid catalyst derived from sugarcane bagasse for microwave assisted-transesterification of waste cooking oil

The production of biodiesel by using homogeneous or heterogeneous catalysts is not favourable due to difficult catalyst recovery, purification of the product in case of homogeneous catalysts and longer reaction time, severe reaction conditions and high production cost are the drawbacks of heterogeneous catalysts. Different sulfonated catalysts were synthesized to overcome these problems and their feasibility on industrial scale. Therefore, the focus of this study was to synthesize a sulfonated catalyst using activated carbon produced from the lignin extracted from sugarcane bagasse and used in the transesterification of waste cooking oil with methanol using microwave as heating source. The catalyst was prepared by varying the sulfonation temperature (140–220 °C) for 120 min and characterized by using thermogravimetric analysis (TGA), scanning electron microscope (SEM), fourier transform infrared spectroscopy (FT-IR), surface area (BET) and elemental analysis by CHNS analyzer. The catalyst prepared at 180 °C for 2 h showed excellent characteristics in terms of surface area i.e., 30.31 m2. g−1, acidic density 4.74 mmol. g−1, pore volume 0.03 cm3 g−1, pore size of 9.44 nm, functional groups attachments, surface morphology and crystallographic structure. The process of transesterification was optimized by varying reaction time (5–25 min), methanol to oil molar ratio (6:1–24:1), catalyst loading (5–20 wt% to oil) and temperature (40–70 °C). The maximum yield (89.19%) of biodiesel was achieved after 15 min with a methanol to oil molar ratio of 18:1 at 60 °C and 15 wt% of catalyst. The reusability and stability of the prepared catalyst up to six cycles with minor loss in its activity i.e., 8% for low-grade feedstocks having higher value of free fatty acid content (FFA) was studied.

Synthesis of Pyrano [2,3-c] Pyrazole Derivatives Using a Novel Ionic-Liquid Based Nano-Magnetic Catalyst (Fe3O4@SiO2@(CH2)3NH@CC@Imidazole@SO3H+Cl−)

The current study is a molecular engineering approach designed for synthesize an ionic-liquid-based nano-magnetic solid acid heterogeneous catalyst, namely Fe3O4@SiO2@(CH2)3NH@CC@Imidazole@SO3H. Following the synthesis of the mentioned catalyst, various techniques were used to characterize, including Infrared (IR), Field Emission Scanning Electron Microscopy (FESEM) and Transmission Electron Microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDX), EDX elemental mapping, Thermal gravimetric analysis (TGA) and Differential thermal analysis (DTA), and Vibrating Sample Magnetometer (VSM). The activity of the as-synthesized catalyst was evaluated in the synthesis of pyrano [2,3-c] pyrazole derivatives. It can easily be recovered using an external magnet and used repeatedly. The FTIR proved the stability of the as-synthesized catalyst even after five recovery steps. The most exciting finding was that pyrano [2,3-c] pyrazole derivatives could be produced in a short time and high yield (56–98%). The systematic design of experiment (DOE), finally, was applied to optimize the reaction condition.

Development of a continuous-flow tubular reactor for synthesis of 5-hydroxymethylfurfural from fructose using heterogeneous solid acid catalysts in biphasic reaction medium

5-Hydroxymethylfurfural (5-HMF) is an important biomass-derived platform chemical used to produce polymers, biofuels, and other valuable industrial chemicals.

Defective acidic 2D COF-based catalysts for boosting the performance of polyoxymethylene diethyl ether synthesis under mild conditions.

Polyoxymethylene diethyl ethers (PODEEn) are oxygenated fuel additives with high performance due to their advantageous fuel properties. PODEEn can alleviate carbon debt as the production can utilize bioethanol and biomass syngas. Heterogeneous solid acid catalysts are desirable for an efficient PODEEn synthesis. In this study, well-defined sulfonated phthalocyanine-containing polymers were prepared, and the physicochemical properties were analyzed, exhibiting a 2D π-π stacking structure with crystalline-amorphous mixed phases. Owing to the tuning defects of the COF framework by mixing polymerization, the accessibility of the network and the capacity of strong acid were improved for the polymeric catalyst, showing an excellent activity with trioxane (TOX) conversion of 89% and PODEE2-8 selectivity of 87% at 80 °C under atmospheric pressure.

Silica–sulfuric acid and alumina–sulfuric acid: versatile supported Brønsted acid catalysts

–SO3H functionalized silica and alumina have emerged as efficient and eco-compatible heterogeneous solid acid catalysts for the construction of various important molecular skeletons.