Acetalization Of Glycerol Research Articles

Easy and Fast Production of Solketal from Glycerol Acetalization via Heteropolyacids.

This work presents an effective and fast procedure to valorize the main waste produced from the biodiesel industry, i.e., the glycerol. The acetalization of glycerol with acetone represents an effective strategy to produce the valuable solketal, a fuel additive component. In this work, the catalytic efficiency of different commercial heteropolyacids (HPAas) was compared under a solvent-free system. The HPAs used were H3[PW12O40] (PW12), H3[PMo12O40] (PMo12) and H4[SiW12O40] (SiW12). The influence of reactional parameters such as reactants stoichiometry, catalyst concentration and reaction temperature were investigated in order to optimize experimental conditions to increase cost-efficiency and sustainability. HPAs demonstrated to be highly efficient for this type of reaction, presenting a high and fast glycerol conversion, with high selectivity to solketal under sustainable conditions (solvent-free system and room temperature medium). The activity of HPAs using 3% to glycerol weight and a glycerol/acetone ratio of 1:15 followed the order: PW12 (99.2%) > PMo12 (91.4%) > SiW12 (90.7%) as a result of the strong acidic sites after 5 min. In fact, only 5 min of reaction were needed to achieve 97% of solketal product in the presence of the PW12 as a catalyst. This last system presents an effective, selective and sustainable catalytic system to valorize glycerol.

Mixotrophic cultivation enhances lipid productivity and fatty acid profile towards efficient production of microalgae-based biofuel from Desmodesmus sp. DLK

The selection of an appropriate strain is important for the sustainability of algae-based oil industries. In the current study, a novel omega-3 fatty acid-rich microalgal strain was isolated and identified as Desmodesmus sp. Dal Lake Kashmir (DLK) based on its morphology and molecular characterization. Its potential as biofuel feedstock was established based on its appropriate fatty acid profile and enhanced lipid productivity. The growth of Desmodesmus sp. DLK was evaluated using varying concentrations of three exogenous carbon sources (glucose, glycerol and sodium acetate) to examine the potential of the freshwater microalga to ameliorate biomass and lipid production for proficient biofuel production. A phenomenal enhancement in biomass productivity (12.8-fold) and lipid productivity (22-fold) was detected with 1% glucose in comparison to control. Supplementation with glycerol boosted the productivity of biomass and lipid maximum by 11.4-fold (5 g.L−1 gly) and 26.8-fold (10 g.L−1 gly), respectively. Analyses of fatty acid methyl esters from mixotrophically grown culture, via gas chromatography and mass spectrometry, exhibited a prevalence of palmitic acid (C16:0; 37%) and oleic acid (C18:1; 53%) demonstrating desirable properties for biofuel quality. This study highlights that the mixotrophic cultivation of Desmodesmus sp. DLK redirects algal metabolite fluxes towards the production of improved lipids, suitable for biofuel production.

Sustainable microwave-assisted solketal synthesis over sulfonic silica-based catalysts

Sulfonic and propylsulfonic silica-based catalysts were synthesized, characterized and tested in the acetalization of glycerol (G) by a sustainable, solvent-free and fast procedure, under microwave irradiation, to produce solketal (S). The catalysts were prepared by different grafting procedures and their surface and structural properties were investigated by means of N2 adsorption isotherms, Thermogravimetric Analysis (TGA), X-ray Photoelectron Spectroscopy (XPS) and X-Ray Fluorescence Spectroscopy (XRF). Under the optimized reaction conditions (Temperature 40 °C, microwave power ˂100 W, time 2 min and 1:12 glycerol/acetone molar ratio) the sulfonic materials, produced by the hydrothermal grafting, showed excellent performance in terms of activity, selectivity and stability, with no leaching of sulfonic groups after several cycles. By the correlation of the structure properties of the materials and their activity, the performance of the catalysts was shown strictly correlated both to the acidity and the surface density of the active sites.

Fe3+ and chlorotrimethylsilane modified NaY catalysts display enhanced activity and durability for acetalization of glycerol to solketal

Solketal is known as a promising non-BPA plasticizer. However, fast and robust synthesis of solketal from bio-oxygenates remains a grand challenge, as strong surface polarization often deactivates acidic catalysts. We proposed and validated a dual designing strategy, involving (1) Fe3+ modified Bronsted acidity and (2) chlorotrimethylsilane (CTS) altered hydrophilicity for enhanced activity and stability of NaY catalysts. As one of the key findings, Fe3+ exchanged NaYs display an unusual shortened Si-OH bond and electronically reconfigured Fe3+ sites for a 4-fold activity enhancement. Furthermore, CTS modified FeY materials further alleviate surface passivation of glycerol and water, leading to an 18-fold activity improvement and better durability for acetalization of glycerol. CTS modified FeY catalysts display remarkable stability against varies impurity molecules. The dual modification methodology provides useful information on rational design of durable catalysts for synthesis of various other non-BPA derivatives.

Sulphonated biomass-based catalyst for solketal synthesis by acetalization of glycerol – A byproduct of biodiesel production

Research on biomass-based catalyst is beneficial for the sustainability of biodiesel industry owing to its wide availability of feedstock, non-toxicity and biodegradability. Cellulose based heterogeneous solid carbon catalyst was prepared from cellulose by treating cellulose with concentrated sulphuric acid in innocuous hydrothermal conditions. It shows promising potential as a suitable catalyst for the synthesis of solketal (a biofuel additive) by acetalization of glycerol, the waste product of biodiesel production. 97.1 ± 0.4% of solketal was produced under the optimum conditions of 1:5 M ratio of glycerol and acetone, catalyst loading of 7 wt% at 70 °C in 10 min. 90% of catalytic activity was retained even after five catalytic cycles making the catalyst highly efficient. With further investments; this method may be used for the preparation of biofuel additive in an industrial level.

Kinetics of Aldehyde Flavorant-Acetal Formation in E-Liquids with Different E-Cigarette Solvents and Common Additives Studied by 1H NMR Spectroscopy.

Flavorants, nicotine, and organic acids are common additives found in the e-liquid carrier solvent, propylene glycol (PG) and/or glycerol (GL), at various concentrations. Some of the most concentrated and prevalent flavorants in e-liquids include trans-cinnamaldehyde, vanillin, and benzaldehyde. Aldehyde flavorants have been shown to react with PG and GL to form flavorant-PG and -GL acetals that have unique toxicity properties in e-liquids before aerosolization. However, there is still much that remains unknown about the effects of different e-cigarette solvents, water, nicotine, and organic acids on the rate of acetalization in e-liquids. We used 1H NMR spectroscopy to determine the first-order initial rate constant, half-life, and % acetal formed at equilibrium for flavorant-acetal formation in simulated e-liquids. Herein, we report that acetalization generally occurs at a faster rate and produces greater yields in e-liquids with higher ratios of GL (relative to PG). trans-Cinnamaldehyde acetals formed the fastest in 100% PG-simulated e-liquids, followed by benzaldehyde and vanillin based on their half-lives and rate constants. The acetal yield was greatest for benzaldehyde in PG e-liquids, followed by trans-cinnamaldehyde and vanillin. Acetalization in PG e-liquids containing aldehyde flavorants was inhibited by water and nicotine but catalyzed by benzoic acid. Flavorant-PG acetal formation was generally delayed in the presence of nicotine, even if benzoic acid was present at 2-, 4-, or 10-fold the nicotine concentration, as compared to the PG e-liquids with 2.5 mg/mL flavorant. Thus, commercial e-liquids with aldehyde flavorants containing a higher GL ratio (relative to PG), little water, no nicotine, nicotine with excess organic acids, or organic acids without nicotine would undergo acetalization the fastest and with the highest yield. Many commercial e-liquids must therefore contain significant amounts of flavorant acetals.

Evaluation of production processes of glycerol acetals using process intensification by flow chemistry

Currently, glycerol has been receiving great attention worldwide for being an important by-product formed during the production of biodiesel in high quantities, being considered, therefore, a very promising raw material for obtaining products with greater added value. Particularly, glycerol acetylation stands out for the glycerol acetals synthesis, which have application as fuel additives. However, in conventional processes, such reaction requires long times and significant acid excess in relation to glycerol. Based on that, the present work aims to apply process intensification, through millichannel reactor, for the acetylation reaction. The results obtained showed that the expressive area/volume ratio of the microreactors added to the high mixing efficiency allowed obtaining, in a few minutes (< 5 min), high glycerol conversions and high selectivities to diacetin. In general, the results showed that the acetals selectivities were directly influenced by the residence time and inversely influenced by the molar ratio of acetic acid/glycerol.

Highly active and scalable SO3H functionalized carbon catalyst synthesized from bagasse for transformation of bio-based platform chemicals into fuel precursors and its in-depth characterization studies

Scalable synthesis of SO3H functionalized carbon from sugar industry waste (bagasse) and detailed structural characterization and activity were reported. The incorporation of SO3H functionality groups on the carbon surface and the growth of the aromatic carbon framework was supported by FT-IR and 13C CP-MAS NMR analysis. The hydrothermally synthesized carbon exhibited total acidity of 5 mmol/g and uniform distribution of sulphur on the surface of carbon. The synthesized catalyst was found to be efficient for the acetalization, alkylation and alcoholysis reactions and exhibits excellent stability during the reactions. Various bio-derived carbonyl compounds were demonstrated by the solvent-free acetalization of bio-derived glycerol gives 50–100% conversion and 52–98% selectivity towards solketal derivatives at room temperature. The synthesized catalyst's reactivity was better than the commercially used Brønsted/Lewis acids. Furthermore, the SO3H functionalized carbon was also used for alcoholysis followed by ring-opening of furfuryl alcohol, giving 67–98% selectivity towards alkyl levulinates with complete conversion of furfuryl alcohol. The mechanistic pathway suggests that the alcoholysis reaction goes through three different intermediates (2-alkoxymethylfuran, 4,5,5-trialkoxypentan-2-one, and 5-hydroxy-4,5-dialkoxypentan-2-one) to produce the alkyl levulinates. Additionally, the catalyst was tested for solvent-free condensation of 2-methylfuran with various carbonyl compounds to selectively produce an excellent yield of fuel precursors (for C12-C15 hydrocarbons) at 60 °C. The catalyst was reused up to four cycles with 14% loss in the conversion of furfural for acetalization of glycerol, and negligible losses in the alkylation of 2-methylfuran were observed.

Microwave synthesis of fuel additive over modified amorphous aluminophosphate: Kinetics

The afford work is deliberated to scrutinize a simple solid acid catalytic system for the synthesis of solketal used as a fuel additive under microwave irradiation. The solid acids such as amorphous aluminophosphate (AlPOS) and metal‐aluminophosphates (m-AlPOS) were prepared and characterized by PXRD, FT-IR, BET, SEM, TEM, EDAX, NH 3 -TPD/n-butylamine back titration and ICP-OES techniques. FeAlPOS solid acid showed highest glycerol conversion in a shorter time with comparable catalytic activity of p-TSA Bronsted acid. The impact of reaction parameters like temperature, time, amount of catalyst, molar ratio, speed of agitation and reusability are discussed. The particle size of the m-AlPO samples were reckoned by deploying Debye-Scherrer equation. Reactant pre-adsorption experiments and kinetic study were also taken up. FeAlPOS catalyst is an efficient solid acid catalyst for acetalization of glycerol with acetone and its catalytic activity comparable with p-TSA (homogeneous acid catalyst) under microwave irradiation. .

Improved Natural Mordenite as Low-Cost Catalyst for Glycerol Acetalization into Solketal – An Effective Fuel Additive

The increase in biodiesel production results in an excessive amount of crude glycerol by-product. Therefore, production of solketal –an effective additive of gasoline fuel-from glycerol and acetone via catalytic acetalization could improve the added value of glycerol. This study investigates enhancement of natural mordenite catalytic properties through the hydrothermal recrystallization method for glycerol acetalization. The hydrothermal temperature was varied at 150, 170 and 190 oC to form ZT 150, ZT 170 and ZT 190, respectively. The samples were characterized using the x-ray diffraction and the scanning electron microscope-Energy dispersive X-Ray. They were later used as catalysts for glycerol acetalization with acetone. The best obtained catalyst was further studied to explore the effect of acetone on glycerol ration. The glycerol conversion was deter-mined using the ASTM D7637-10 titration method. Solketal product was identified by using the Fourier transform infrared spectroscopy. The results show that the recrystallization temperature affects the intensity of the mordenite phase and quartz impurity phase in the modified zeolites. A high recrystallization temperature led to a higher phase of mordenite, peaking at 170oC, beyond which the quartz impurity phase increased. Glycerol acetalization conversions over zeolite parent, ZT 150, ZT 170 and ZT190 with acetone to glycerol ratio of 3 were 16.1%, 30.4%, 33.9% and 32.5%, respectively. When the ratio of acetone to glycerol was increased to 12, the glycerol conversion over ZT 170 catalyst reached 59%, a good starting point for further modifications. Overall finding demonstrated a straight-forward fabrication of catalyst from natural resource to enhance glycerol as the biodiesel production by-product into a higher value end-product of solketal.

Acetalization of glycerol over sulfated UiO-66 under mild condition

Sulfated metal–organic framework has attracted much attention as a versatile heterogeneous acid for its strong acid strength, large surface area and regular pore channels. In this work, sulfated UiO-66 (UiO-SO3H-x) was prepared via the direct oxidation of 2-mercaptobenzoic acid substituted UiO-66. The structure and property of the synthesized UiO-SO3H-x were characterized via XRD, FTIR, static water contact angles, XPS, TG-DTA, N2 adsorption–desorption, SEM and TEM in detail. It was found that sulfonic acid groups dispersed homogenously in the framework of UiO-SO3H-x. And UiO-SO3H-0.2 exhibited excellent performance and stability for the synthesis of solketal from surplus glycerol among the tested solid acids (H3PW12O40, Amberlyst-45, HY, HBEA, HZSM-5 and ZrHP). The detected conversion of glycerol reached 70.3% with a 99.8% selectivity toward solketal at 60 °C, and it could maintain its initial activity in five recycles. The highest TOF of each acid site in UiO-SO3H-0.2 reached 676.0 h−1. Moreover, it was versatile for the acetalization of glycerol with other ketones/aldehydes.

Ordered WOx/mesoporous SnO2 catalysts with excellent acetalization performance for producing bio-additives from glycerol

• Highly ordered mesoporous WOx/SnO2 catalysts have been applied to the glycerol acetalization reaction. • Mesoporous WOx/SnO2 catalysts exhibited excellent catalytic performance in batch-type and continuous flow-type processes for catalytic synthesis of solketal from glycerol. • In a batch type process, 100% glycerol conversion and a solketal yield of 97.4% were achieved. Highly ordered WO x /mesoporous SnO 2 (WO x /meso‑SnO 2 ) catalysts with varying WO x loadings of (5 ∼ 20) wt% displaying excellent catalytic performance were demonstrated in the acetalization of glycerol with acetone. The synthesized catalysts were analyzed using various techniques including X-ray diffraction, N 2 -isotherm, electron microscopy, H 2 temperature programmed reduction, raman spectroscopy, and thermogravimetric analysis. For the acetalization of glycerol with acetone, the most active catalyst was found to be WO x /meso‑SnO 2 with 20 wt% WO x , and the maximum conversion of glycerol (100%) was obtained after 2 h at 20 °C, providing 97.4% selectivity (97.4% yield) for the five-membered product (solketal), due to the presence of a large number of acidic sites on the surface of the catalyst. The catalytic activity of 20 wt% WO x /meso‑SnO 2 was also studied in a flow reactor. Tests were carried out at 30 °C, acetone/glycerol=30, WHSV=(4 or 8) h − 1 , and atmospheric pressure for 24 h. The catalytic results showed that, when the WHSV was 4 h − 1 , after 24 h of time-on-stream, both the glycerol conversion of (100 to 97.9)% and solketal yield of (97.5 to 93.6)% slightly decreased. This result suggests the potential of the 20 wt% WO x /meso‑SnO 2 catalyst for the industrial acetalization of glycerol.

Heteropolyacid supported on the composite of bentonite and ionic liquid containing acidic polymer: A highly selective catalyst for glycerol acetalization to solketal

Acetalization of glycerol that is the by-product of biodiesel to fuel additives has received considerable attention. However, formation of a mixture of products in this acid-catalysed process is a challenging issue. In this research, a highly selective catalyst is devised that can selectively acetalize glycerol to solketal. To prepare the catalyst, bentonite clay was first decorated with an acidic polymer containing sulfonic acid and carboxylic acid functional groups. Then, the carboxylic acid groups of the polymer were changed to ionic liquids through reaction with triethanolamine. Finally, phosphotungstic acid was immobilized on the bentonite-polymer composite and the resultant catalyst was characterized. To achieve the highest catalytic activity, the catalyst amount and phosphotungstic acid loading have been optimized. It was found that 10 wt.% catalyst with 20 wt.% phosphotungstic acid loading led to 100% conversion and 99% yield to solketal under solvent-free condition at 55 °C. Moreover, the catalyst could be recycled up to four reaction runs without significant loss of its activity. Comparative studies with ionic liquid-free control catalyst approved that the presence of ionic liquid in the structure of the catalyst played an important role in the selectivity of the catalyst and ionic liquid-free counterpart led to less selectivity and formation of 2,2-dimethyl-1,3-dioxane-5-ol as by-product.

Sustainable Upgrade of Bioderived Glycerol to Solketal through Acetalization over Metal-Free Mordenite Catalysts

In the current work, acetalization of crude glycerol to produce valuable solketal, a renewable fuel additive, is studied over metal-free mordenite-based catalysts. The perfect combination of the appropriate acidity and suitable porosity is required to achieve optimum solketal yield from glycerol. The property–activity correlation was established through various physicochemical characterizations, and reaction parameters were optimized to maximize the solketal yield. The modified mordenite catalyst showed exceptionally high catalytic activity toward the acetalization of crude glycerol and as high as 99% yield of solketal was achieved under mild reaction conditions, i.e., a reaction temperature of 60 °C, a time of 4 h, and atmospheric pressure. The catalyst showed tolerance for water and other impurities present in crude glycerol in addition to excellent recyclability up to three cycles without any regeneration treatment. The economical, easy-to-prepare, recyclable, metal-free, moisture-tolerant nature of the catalyst makes it a promising catalyst candidate to be used at a larger scale. The catalytic process has the potential to utilize crude glycerol obtained from biodiesel plants for the synthesis of biofuel additives solketal. This highlights the industrial and environmental significance of this work.

Acetalization of Glycerol with Citral over Heteropolyacids Immobilized on KIT-6

Glycerol acetalization with citral was studied using a heteropolyacid (tungstophosphoric acid) supported on KIT-6, as a catalyst, at 100 °C. Different catalysts were synthesized. Catalysts were characterized by scanning electron microscopy (SEM), inductively coupled plasma (ICP), X-ray diffraction (XRD), attenuated total refletion-Fourier transform infrared spectroscopy (ATR-FTIR), and potentiometric titrations. At a fixed time, the glycerol conversion increased with the H3PW12O40 (PW) on KIT-6. PW4-KIT-6 material had a higher conversion than other catalysts. The optimization of glycerol’s acetalization with citral was studied under the PW4-KIT-6 catalyst. After 5 h, it was found that, at T = 100 °C, with m = 0.3 g of solid, molar glycerol:citral = 1:2.25, the conversion of glycerol was 89%. Moreover, the PW4-KTI-6 catalyst showed good catalytic stability.

Sulphonated Carbon Catalyst for Microwave-Assisted Synthesis of Solketal by Acetalization of Glycerol

Sulphonated Carbon Catalyst for Microwave-Assisted Synthesis of Solketal by Acetalization of Glycerol

Modified boehmite: a choice of catalyst for the selective conversion of glycerol to five-membered dioxolane

The catalytic activity of WO3@boehmite for the acetalization of glycerol with aromatic aldehydes is described in this article. The catalyst is selective towards dioxolane (up to 96%) with excellent conversion (up to 100%) in selective substrates.

Catalytic acetalization of glycerol waste over alkali-treated natural clinoptilolite

One of the most potential byproducts of transesterification that has been produced in a large amount is glycerol. Converting glycerol into Solketal via catalytic acetalization using natural zeolites is an interesting route to improve its economic value. Natural zeolites are abundant and inexpensive catalysts with low crystallinity and surface area. Thus, modification of its properties is required to improve material characteristics and alter the transesterification reaction. Investigation of the effect of NaOH concentration treatment on the Bayah natural zeolite was performed from 0.1 to 0.4 M NaOH at 65 °C and 30 min of mixing. Physical characteristic analysis, such as X-ray diffraction, proves that natural zeolite from Bayah was identified predominantly as clinoptilolite. The crystallinity significantly improved after NaOH treatment and could reach a high crystallinity material at 0.4 M NaOH. The textural properties using nitrogen physisorption are also shown by a high surface area of 164 m2/g (from parent Z-0.4; 19 m2/g). In addition, the mesopore volume also improved after alkali treatment, increasing the mass transfer of molecules. The application of modified natural zeolite for glycerol acetalization was tested in a glass tube reactor at a temperature of 50 °C for 90 min showing a significant alteration in conversion from 3.5 % (parent zeolite) to 90.4 % (modified zeolite).

Glycerol acetalization over highly ordered mesoporous molybdenum dioxide: Excellent catalytic performance, recyclability and water-tolerance

Highly ordered mesoporous molybdenum dioxide (meso-MoO2) was successfully synthesized by a nano-replication method using a mesoporous silica template with 3D cubic Ia3d mesostructure. Structural analyses using X-ray diffraction, N2 sorption, and electron microscopy indicated that the meso-MoO2 material exhibited high surface area (106 m2/g), large pore volume (0.66 cm3/g), and well-defined mesopores. Under the optimized reaction conditions, the meso-MoO2 catalyst showed excellent catalytic performances for the acetalization of glycerol with acetone (95.8% of glycerol conversion, and 97.8% of solketal selectivity) at 20 °C, due to its high surface area with large number of acid sites. During recycling, the meso-MoO2 catalyst exhibited a slight decrease in activity; and after a simple regeneration at 350 °C, the catalytic performances could be completely recovered. More importantly, a partial hydrophobic treatment of the meso-MoO2 catalyst dramatically enhanced the water-tolerance during the catalytic reaction.

Nanocasted perovskites as potential catalysts for acetalization of glycerol

Herein, we report on the catalytic activity of ABO3 perovskites (A = La, Sr or Sn, B = Co, Mn, Sn, Fe, or Al) synthesized by nanocasting using silica-based KIT-6 and SBA-15 as hard templates. The search for less expensive and easy to synthesize active catalysts is gaining momentum due to global financial markets that escalate the prices of precious metals. Interestingly, alternatives that utilize affordable commodities than precious metals have attracted interest. The biodiesel industry is playing a more central part in fuel economy in many developing economies. This work focuses on circumventing the drawbacks of the bio-fuel industry by valorising glycerol, a by-product of biodiesel production into value-added chemicals through the acetalization reaction. The as-synthesized perovskites, with surface areas ranging from 19 to 99 m2/g, showed up to 100% glycerol conversion and selectivity towards 2-methylol-1,4-dioxaspirol [4,5] decane. Perovskites containing tin (Sn) showed better catalytic activity than the rest of the catalysts. The NH3-TPD results suggest that the greater catalytic activity observed in tin-based perovskites is mainly due to their high acidity content. Furthermore, we showed that the catalyst reusability can be studied in-depth using kinetics and our catalyst showed good stability in the first two cycles.