Acetalization Of Glycerol Research Articles

Bioprospecting of Metschnikowia pulcherrima Strains, Isolated from a Vineyard Ecosystem, as Novel Starter Cultures for Craft Beer Production

Several studies in recent years have shown that the use of non-Saccharomyces yeasts, used both in single and in mixed fermentations with Saccharomyces cerevisiae, can help produce craft beers with distinctive compositional characteristics. The aim of this study was to evaluate the suitability of three Metschnikowia pulcherrima strains, isolated from Albanian vineyards, for use as starters in the brewing process. Because of its specific enzymatic activities (protease, β-glucosidase, and β-lyase) and its low production of hydrogen sulfide, M. pulcherrima 62 was selected as a starter culture for the production of craft beer. Specifically, the suitability of this yeast for use in sequential inoculation with S. cerevisiae S0-4 for the production of an American IPA-style beer and the main volatile compounds produced during fermentation were evaluated. The results show significant differences in the glycerol, isoamyl alcohol, and isoamyl acetate contents in beer obtained by sequential inoculum of M. pulcherrima 62 with S. cerevisiae S0-4 compared to beer obtained using S. cerevisiae S0-4 as a single starter. Therefore, these preliminary data support the candidacy of M. pulcherrima 62 as a new starter in the brewing process.

Selective synthesis of oxygenated fuel derivative from microwave assisted acetalization of glycerol: Optimization and mechanistic investigations

Glycerol contains 52 wt% oxygen content, therefore unable to be directly used as fuel due to its poor combustion ability. Thus, the catalytic conversion of glycerol into various oxygen-containing fuel additives is grabbing more attention nowadays. This work provides a novel, sustainable, and eco-friendly method for synthesizing heterogeneous acid carbon catalysts from pearl millet cob (PMC) waste. The hydrothermal carbonization process was carried out at different temperatures to fabricate the series of sulfonated pearl millet cob (SPMC) catalysts. XRD, FT-IR, SEM-EDS, XPS, BET, TGA, and CHNSO analyses were performed to characterize fabricated catalysts. The synthesized catalyst, SPMC-70 (catalyst synthesized at 70 °C temperature), possesses OH, COOH, and SO3H functional groups and a significant total acid density (2.03 mmol/g) with 37 m2/g surface area. The SPMC catalysts were employed for the microwave-assisted acetalization reaction of glycerol with acetone for solketal production. The optimization process was carried out using various reaction parameters, including catalyst dosage (2–6 wt.%), reaction temperature (30–60 °C), glycerol to acetone (GL to AC) molar ratio (1:3–1:9), and reaction time (4–13 min). The SPMC-70 catalyst showed the highest catalytic activity among all the synthesized catalysts and provided 99.11 ± 0.3 % GL conversion with 100 % selectivity of solketal under optimal reaction conditions. Additionally, the recyclability test was performed, and it found that the best catalyst was reusable for up to five reaction cycles. These results showed the effectiveness of carbon-based heterogeneous acid catalysts in deriving a fuel additive, solketal.

Biochar carbon nanodots for catalytic acetalization of biodiesel by-product crude glycerol to solketal: process optimization by RSM and life cycle cost analysis

Carbon-based nanodots have garnered recent interest for their simple synthesis and versatile utility, ranging from biomedical to (opto) electronic applications, evolving into a tunable and biocompatible material. Here, for the first time, a biochar (lotus leaf) derived carbon nanodots was synthesized through hydrothermal carbonization. The synthesized hollow spherical biochar was engineered via functionalization by grafting –SO3H active sites. The attained catalyst was broadly analyzed by XRD, FTIR, TGA, BET, SEM–EDX, TEM, and XPS analysis after which it was applied for the acetalization reaction of crude glycerol (a biodiesel by-product) to form solketal, a potential fuel additive to valorize the large waste stream generated from biodiesel industry. Employing the RSM-CCD methodology, the experimental matrix was executed, and subsequent data were scrutinized through multiple regressions to model a quadratic equation. Under specific reaction parameters—a reaction duration of 14 min, a molar ratio of 7.5:1, and a catalyst loading of 5.7 wt.%, maximum solketal yield (95.7%) was attained through the ultrasonication method. Finally, to conclude, life cycle cost analysis (LCCA) for solketal production was studied here which determined the overall cost of solketal production per kilogram to be 0.719 USD ($), indicating high commercial applicability.

Synthesis of Solketal Catalyzed by Acid-Modified Pyrolytic Carbon Black from Waste Tires.

Solketal, a widely used glycerol-derived solvent, can be efficiently synthesized through heterogeneous catalysis, thus avoiding the significant product losses typically encountered with aqueous work-up in homogeneous catalysis. This study explores the catalytic synthesis of solketal using solid acid catalysts derived from recovered carbon blacks (rCBs), which are obtained through the pyrolysis of end-of-life tires. This was further converted into solid acid catalysts through the introduction of acidic functional groups using concentrated H2SO4 or 4-benzenediazonium sulfonate (BDS) as sulfonating agents. Additionally, post-pyrolytic rCB treated with glucose and subsequently sulfonated with sulfuric acid was also prepared. Comprehensive characterization of the initial and modified rCBs was performed using techniques such as elemental analysis, powder X-ray diffraction, thermogravimetric analysis, a back titration method, and both scanning and transmission electron microscopy, along with X-ray photoelectron spectroscopy. The catalytic performance of these samples was evaluated through the batch mode glycerol acetalization to produce solketal. The modified rCBs exhibited substantial catalytic activity, achieving high glycerol conversions (approximately 90%) and high solketal selectivity (around 95%) within 30 min at 40 °C. This notable activity was attributed to the presence of -SO3H groups on the surface of the functionalized rCBs. Reusability tests indicated that only rCBs modified with glucose demonstrated acceptable catalytic stability in subsequent acetalization cycles. The findings underscore the potential of utilizing end-of-life tires to produce effective acid catalysts for glycerol valorization processes.

Sulfonated Graphene‐Based Materials as Heterogeneous Acid Catalysts for Solketal Synthesis by Acetalization of Glycerol

AbstractAcid catalysis plays a pivotal role in the industrial landscape due to its multifaceted contributions to various chemical processes in numerous sectors, including petrochemicals, polymers, food processing, and biodiesel production, among others. Sulfonated graphenes hold notable relevance as heterogeneous acid catalysts due to their unique combination of graphene's structural properties and the introduction of sulfonic groups as catalytic acid sites. Herein, we report the preparation of three sulfonated graphene‐based materials – sulfonated reduced graphene oxide (rGO‐SO3H), chlorosulfonated reduced graphene oxide (rGO‐HSO3Cl) and sulfonated graphene oxide (GO‐SO3H) – by different synthetic approaches. Physicochemical, textural, morphological, and acidic properties of all materials were characterized in detail by different instrumental techniques. Innovatively, these materials have been evaluated as heterogeneous acid catalysts in the solketal synthesis by acetalization of glycerol, which is considered an interesting building block to produce added‐value products. The density of acidic active sites and hydrophobicity were found to be conditioning parameters of the resulting catalytic activity in terms of conversion and selectivity. The best catalytic performance was obtained by rGO‐SO3H, reaching the maximum conversion towards solketal in 15 minutes under mild reaction conditions. The reusability and stability of all materials were also examined after three consecutive acetalization reactions with only a slight loss of catalytic activity.

Co-upcycling of Plastic Waste and Biowaste via Tandem Transesterification Reactions.

Polyethylene terephthalate (PET) and glycerol are prevalent forms of plastic and biowaste, necessitating facile and effective strategies for their upcycling treatment. Herein, we present an innovative one-pot reaction system for the concurrent depolymerization of PET plastics and the transesterification of glycerol into dimethyl terephthalate (DMT), a valuable feedstock in polymer manufacturing. This process occurs in the presence of methyl acetate (MA), a byproduct of the industrial production of acetic acid. The upcycling of biowaste glycerol into glycerol acetates renders them valuable additives for application in both the biofuel and chemical industries. This integrated reaction system enhances the conversion of glycerol to acetins compared with the singular transesterification of glycerol. In this approach, cost-effective catalysts, based on perovskite-structured CaMnO3, were employed. The catalyst undergoes in situ reconstruction in the tandem PET/glycerol/MA system due to glycerolation between the metal oxides and glycerol/acetins. This process results in the formation of small metal oxide nanoparticles confined in amorphous metal glycerolates, thereby enhancing the PET depolymerization efficiency. The optimized coupled reaction system can achieve a product yield exceeding 70% for glycerol acetates and 68% for PET monomers. This research introduces a tandem pathway for the simultaneous upcycling of PET plastic waste and biowaste glycerol with minimal feedstock input and maximal reactant utilization efficiency, promising both economic advantages and positive environmental impacts.

Metal‐ and Acid‐Free Photocatalytic Approach Using Quinone‐Based Hyper‐Crosslinked Porous Catalysts for the Valorization of Glycerol into Solketal

Two metal‐ and acid‐free anthracene (AN) and anthraquinone (AQ)‐based photocatalysts (HCP‐AQ‐2Ph and HCP‐AN‐2Ph) are synthesized and used for the effective acetalization of glycerol to obtain selectively solketal, an added‐value compound with several industrial applications and high demand as an oxygenated additive of fuels. HCP‐AQ‐2Ph and HCP‐AN‐2Ph are prepared by a Friedel–Crafts coupling reaction between the AQ or AN and biphenyl (2Ph) as comonomer which leads to the formation of high thermally stable hyper‐crosslinked porous networks with specific surface areas of 295 and 596 m2 g−1, respectively. Initial tests suggest that HCP‐AN‐2Ph is a less efficient catalyst compared to HCP‐AQ‐2Ph. However, subsequent runs indicate that during the first trial, the AN units are oxidized, resulting in a catalyst (HCP‐AN(OX)‐2Ph) just as effective as the AQ‐based one. The quantitative and selective conversion of glycerol into solketal is achieved in just 3 h using a 4 wt% catalyst and maintaining this catalytic performance for at least 5 cycles. In addition, the process can be scaled allowing the obtaining of solketal with high purity on a gram scale. These results place these catalysts among the most effective for the selective production of solketal from glycerol compared to previously reported metal‐ or acid‐catalyzed reaction.

The Role of the Heterogeneous Catalyst to Produce Solketal from Biodiesel Waste: The Key to Achieve Efficiency.

The valorization of the large amount of crude glycerol formed from the biodiesel industry is of primordial necessity. One possible direction with high interest to the biorefinery sector is the production of fuel additives such as solketal, through the acetalization of glycerol with acetone. This is a chemical process that conciliates high sustainability and economic interest, since solketal contributes to the fulfillment of a Circular Economy Model through its use in biodiesel blends. The key to guarantee high efficiency and high sustainability for solketal production is the use of recovery and recyclable heterogeneous catalysts. Reported works indicate that high yields are attributed to catalyst acidity, mainly the ones containing Brönsted acidic sites. On the other hand, the catalyst stability and its recycling capacity are completely dependent of the support material and the acidic sites incorporation methodology. This review intends to conciliate the information spread on this topic and indicate the most assertive strategies to achieve high solketal production in short reaction time during various reaction cycles.

Facile synthesis of mordenite zeolites from bamboo leaves ash for acetalization of benzaldehye and glycerol using non-microwave instant heating

BackgroundsBamboo leaves ash (BLA) is a cheap and sustainable silica source but under-utilized. In this work, mordenite zeolites with various morphologies synthesized from BLA are reported. MethodologyOur strategy involves merely mixing of silicate and aluminate solutions where parametric crystallization study successfully captured three mordenite synthesis recipes. The prepared solids are then characterized with XRD, SEM, XRF, FTIR, TGA/DTG, N2 sorption and TPD-NH3 before their catalytic behavior is tested in acetalization . Significant findingsMordenites with three distinct shapes (nanostick, intergrown bulky ball, nanorod) are successfully synthesized via parametric crystallization study. Some mordenite zeolites contain hierarchical micro/mesoporosity which is beneficial in acetalization of benzaldehye and glycerol. The nanorod-like mordenite is the best catalyst (80.2 ± 2.4 % conversion, 54.4 ± 0.3 % selective towards 2-benzyl-4-hydroxymethyl-1,3-dioxolane) and its catalytic performance is better than those of classical homogeneous and zeolite catalysts with high recyclability.

Deep eutectic solvents based on glycerol as selective extractants for the recovery of aromatic hydrocarbons and petroleum acids from model fuel

The study set out to extract various types of hydrocarbons from model fuels using deep eutectic solvents based on glycerol. These solvents were synthesised by mixing glycerol as acting as a hydrogen bond donor with ammonium chloride or triethylammonium acetate [tea] [AcO]- acting as a hydrogen bond acceptor at room temperature in a volume ratio of 1:6. A mixture of n-decane and n-hexadecane was selected as components of the model fuel. For the extraction of mixtures of benzene, ethylbenzene (5%), p-, m-, o-cresol, fluorenone (3.5%) and petroleum acids (25%), these deep eutectic solvents were used at room temperature, as well as at a temperature of 60°C, and at atmospheric pressure. Extraction efficiency was evaluated by [1]NMR spectroscopy. The results demonstrated the complete single-stage extraction of p-, m- and o-cresols from the model fuel using the studied deep eutectic solvents. A deep eutectic solvent based on glycerol and triethylammonium acetate was found to have the highest extraction efficiency. The recovery rates for benzene, ethylbenzene, and fluorenone at room temperature are achieved in 3 hours of stirring (75, 25, and 53%, respectively). M- and o-cresols were fully recovered in 1 hour in a single step using a deep eutectic solvent based on triethylammonium acetate, while complete extraction of aromatic acids from a mixture of petroleum acids in model fuel was achieved using a deep eutectic solvent obtained by mixing ammonium chloride and glycerol.

Preparation of millimeter-sized spherical SiO2–Al2O3 with various acid catalysts for the acetalization of glycerol with acetone

Preparation of millimeter-sized spherical SiO2–Al2O3 with various acid catalysts for the acetalization of glycerol with acetone

Solvent-Resistant Adhesive Gel with Thermal Post-Tunability.

Adhesives have received extensive attention in flexible bioelectronics, wearable electronic medical devices, and biofuel cells. However, it is a challenge to achieve late regulation of performance once polymer-based gels are formed. Here, a double-network organogel composed of a hydrophilic and hydrophobic polymer network and a polyamide acid network was successfully prepared. In diverse liquid environments (including isopropyl alcohol, glycerol, epichlorohydrin, n-propanol, dichloromethane, triethanolamine, ethanol absolute, hydrogen peroxide, and ethyl acetate), the organogel adhesive demonstrated remarkable properties. It exhibits a strong tensile strength of 200 kPa, a high fracture strain reaching 560%, and an impressive adhesion strength of 38 kPa. In addition, the organogel demonstrates exceptional adhesive properties toward polytetrafluoroethylene, plastics, metals, rubber, and glass. Note that the organogel could also regulate adhesive and tough performance by thermally triggering a cyclization reaction even after the organogel has been formed. The strategy provides a new idea for designing soft materials with post-tunability.

Enhancing the catalytic properties of silicalite-1 through ammonium fluoride modification for waste glycerol acetalization.

Silicalite-1 is a silica with a zeolitic MFI (Mobil Five) structure devoid of noticeable catalytically active (e.g., acid) sites. In this study, we present its modification with NH4F solutions of varying concentrations (0.5-3 M), which generates efficient and selective acid sites for the acetalization of glycerol with acetone towards solketal (2,2-dimethyl-1,3-dioxolane-4-methanol). The creation of acid sites is attributed to the partial elimination of external silanol groups in silicalite-1 and the generation of some framework defects, resulting also in increased porosity. The characterization of the modified materials was performed using various techniques, i.e. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), temperature-programmed desorption of ammonia (TPD-NH3), and Fourier-transform infrared spectroscopy (FTIR). The results demonstrate that the newly created acidic sites of Brønsted and Lewis nature exhibit significantly higher acidic strength and enhanced accessibility for reagents compared to the pristine one, resulting in exceptional glycerol conversion in the acetalization of glycerol with acetone and notable selectivity towards solketal. Glycerol conversion over modified silicalite-1 reached nearly 70%, with the selectivity to solketal exceeding 98% at 70° C after 1 hour of reaction time, using a mixture of glycerol and acetone in a 1 : 1 ratio. The proposed reaction mechanism takes into account a combination of Brønsted and Lewis acid sites. The obtained results indicated that Brønsted acid sites, especially those of higher strength, are the most beneficial in this process. The remarkable catalytic performance and stability of modified silicalite-1 make it a promising candidate for potential industrial applications in the utilization of waste glycerol formed in the biofuel industry.

Effect of temperature on the dynamic wettability of Chinese fir wood: integrative consideration of surface spreading, penetration and evaporation

Abstract Wood wettability, the process of liquid interaction with wood surfaces, is influenced by wood surface chemistry, structure, ambient conditions, and temperature. Understanding how temperature impacts wood wettability is crucial for high-temperature manufacturing processes. In this study, the sessile drop method was employed to explore the dynamic wettability of Chinese fir wood using three different liquids (water, glycerol and polyvinyl acetate (PVAc)) across a range of temperatures (25, 40, 60 and 80 °C). By considering spreading, penetration and evaporation, we revealed that the dynamic wettability of Chinese fir was strongly dependent on temperature and the type of liquid. Temperature elevation enhances wettability, leading to reduced contact angles and increased penetration ratios. Water exhibited the highest wettability, followed by glycerol, with PVAc being the least wetting agent. Notably, after 180 s of wetting at 80 °C, the measured contact angles were 0° for water, 45° for glycerol, and 120° for PVAc. When accounting for evaporation, the penetration of water decreased from 57 % to 47 % (25 °C) and 100 % to 62 % (80 °C). The activation energies for the penetration of water and PVAc into Chinese fir exhibited variations, with values of 35.3 and 158.3 kJ/mol, respectively. These comprehensive wetting results, covering spreading, penetration and evaporation, provide valuable insights into wood–water and wood–adhesive interactions, particularly when exposed to high-temperature conditions.

Kinetic & thermodynamic studies of green fuel additive solketal from crude glycerol over metakaolin clay catalyst

Biodiesel synthesis produces about 10 % glycerol as a byproduct, prompting environmental concerns. The utilization of crude glycerol into valuable products requires an Eco-friendly technique. This study depicts glycerol acetalization using acetone and novel catalyst acid-treated metakaolin clay. Raw kaolin clay was calcined at 600 °C and treated with acid at 102 °C for 3 h. Afterward, acid activated clay was filtrate and dried in oven to remove moisture content. The catalyst prepared with a 5 M solution of sulfuric acid exhibited the highest surface area of 82.33 m2. g−1 and gave the highest yield (80 %) of Solketal with 73 % of glycerol conversion under optimum conditions. The ketalization reaction of Solketal synthesis was studied in terms of thermodynamics and kinetics. A Langmuir-Hinshelwood rate expression based on two-parameter kinetic law was used in this study. From the kinetic studies, activation energies (EA) of forward and backward reactions were found to be K1 = 39.23 kJ. mol−1 and K2 = 35.70 kJ. mol−1 respectively. Furthermore, reaction was exothermic having an enthalpy of ΔHo = −18.86 kJ. mol−1 and the entropy ΔSo = −0.1 kJ. mol−1 calculated from this process. Solketal derived from sustainable sources such as bio-glycerol and biomass-based acetone, has a wide range of uses as fuel additives and medicines industry. This research marks a significant advancement in the development of a continuous synthesis technique for Solketal and its recovery from glycerol-acetone mixtures.

Valorizing biomass waste glycerol to fuel additive at room temperature using a nanostructured WO3/Nb2O5 catalyst

We developed a nanostructured catalyst consisting of WO3 nanoparticles and Nb2O5 nanorods for efficient glycerol acetalization to produce a fuel additive (solketal) at room temperature. Particularly, the WO3/Nb2O5 nanocatalyst calcined at 400 °C (WO3/Nb2O5–4) contains W5+ species and optimum acid sites, which enhanced glycerol conversion (92.3%) with 95.6% of solketal selectivity at room temperature. The structure stability of the WO3/Nb2O5–4 catalyst during the reaction is showcased by hot-filtration study and XRD/XPS characterization. However, the inadequate regeneration of the Brønsted acid sites led to a gradual decrease in the recyclable activity of the WO3/Nb2O5–4 catalyst.

One-pot synthesis of MoO3-ZrO2 solid acid catalyst for solvent-free solketal production from glycerol

Glycerol acetalization to solketal is a promising method of increasing the additional value of glycerol, which is a by-product in biodiesel industry. In this work, a series of mesoporous x-MoO3-ZrO2 (x = Mo/Zr) solid acid catalysts with controllable Mo contents were designed and synthesized for the acetalization of glycerol. As important influence factors of solid acid catalysts, the mesoporous structure and existential state of Mo species were systematically investigated. Results show that Mo species were introduced as planned and existed in a homogeneously dispersed state in MoO3-ZrO2 materials. The acidic properties of MoO3-ZrO2 were explored through NH3-TPD and pyridine-chemisorbed FT-IR spectroscopy, and the formation of Brønsted and Lewis acid sites was confirmed by density functional theory calculations. Given their excellent acidity, MoO3-ZrO2 catalysts were employed for the acetal reaction of glycerol. Among the tested catalysts, the 20 %-MoO3-ZrO2 catalyst exhibited the optimal catalytic performance and reusability, achieving a conversion of 89 % for glycerol and a selectivity of 97 % for solketal. Consequently, MoO3-ZrO2 is a green solid acid catalyst with promising applications in solvent-free solketal production from glycerol.

MOF-808 as an Efficient Catalyst for Valorization of Biodiesel Waste Production: Glycerol Acetalization.

Glycerol is the main residue in the biodiesel production industry; therefore, their valorization is crucial. The acetalization of glycerol toward fuel additives such as solketal (2,2-dimethyl-1,3-dioxolan-4-methanol) is of high interest, promoting circular economy since it can be added to biodiesel or even fossil diesel to improve their quality and efficiency. Straightforward-prepared metal-organic framework (MOF) materials of the MOF-808 family were applied to the valorization of glycerol for the first time. In particular, MOF-808(Hf) was revealed to be an effective heterogeneous catalyst to produce solketal under moderate conditions: a small amount of the MOF material (only 4 wt% of glycerol), a 1:6 ratio of glycerol/acetone, and a temperature of 333 K. The high efficiency of MOF-808(Hf) was associated with the high amount of acid centers present in its structure. Furthermore, its structural characteristics, such as window opening cavity size and pore diameters, were shown to be ideal for reusing this material for at least ten consecutive reaction cycles without losing activity (conversion > 90% and selectivity > 98%). Remarkably, it was not necessary to wash or activate the MOF-808(Hf) catalyst between cycles (no pore blockage occurred), and it maintained structural integrity after ten cycles, confirming its ability to be a sustainable heterogeneous catalyst for glycerol valorization.

Synthesis and Characterization of Isopropylidene Glycerol Acetate and Isopropylidene Glycerol Propanoate Compounds

Isopropylidene Glycerol Acetate (IGA) and Isopropylidene Glycerol Propanoate (IGP) as ester compounds using acetic and propanoic acids have been synthesized, characterized, and studied for their antibacterial properties. The IGA was synthesized from ethyl acetate (EtOAc) and 1,2-O-isopropyliden glycerol (IPG) with a mole ratio of 1:8 through a transesterification reaction. Meanwhile, the IGP was synthesized using ethyl propanoate (EP) with the same ratio and method as IGA. All materials in this study were identified using FT-IR, GC-MS, 1H-NMR, and 13C-NMR. The characterization results indicated that the compounds of EP, IPG, IGA, and IGP had been successfully formed and identified. It was also revealed that the compounds of EP, IPG, IGA, and IGP were successfully synthesized with yields of 37.72, 27.78, 70.11, and 63.83%, respectively. The antibacterial activity test revealed that neither IGA nor IGP inhibited the growth of Staphylococcus aureus or Escherichia coli at concentrations of 62.5; 125; 250; 500; and 1000 ppm. Therefore, it was asserted that ester compounds synthesized with short-chain carboxylic acids, such as propanoic and acetic acids, lacked antibacterial properties.

Wet-impregnated niobosilicate catalysts for glycerol conversion into solketal

Novel mesoporous niobosilicate materials with a homogeneous dispersion of niobium species were synthesized via impregnation of (NH4)3[Nb(O2)2(edtaO2)]·H2O·H2O2 on different hydrophilic surfaces of porous siliceous supports: extra small silica nanoparticles (XS-SiO2) and silica nanotubes (NTs-SiO2) bearing three different Si/Nb molar ratios of 74, 37 and 18. The Nb-silica catalysts obtained were calcined at 600 °C and then fully characterized by different physico-chemical techniques. The niobium precursor was found to be successfully loaded on the two silica support surfaces without noticeable modification of the silicate structural integrity. The Nb-containing catalysts were applied as active and selective heterogeneous catalysts for acid-catalyzed condensation of glycerol with acetone yielding solketal (2,2-dimethyl-1,3-dioxolane-4-methanol). The catalytic performance of these materials is ascribed to the enhanced accessibility of their active sites given by their morphology and to the suitable combination of acid sites. Moreover, no leaching of active sites was evidenced and the catalyst reusability studies indicated that the Nb-XS-74 and Nb-NTs-74 catalysts were successfully recyclable and highly stable in the acetalization of glycerol. The robustness and stability of the mesoporous Nb-silicate materials were also supported via characterization of the spent catalysts after the fifth recycling.