Glycerol Conversion Research Articles

Quasi-homogeneous photoelectrochemical organic transformations for tunable products and 100% conversion ratio

Photoelectrochemical (PEC) organic transformation at the anode coupled with cathodic H2 generation is a potentially rewarding strategy for efficient solar energy utilization. Nevertheless, achieving the full conversion of organic substrates with exceptional product selectivity remains a formidable hurdle in the context of heterogeneous catalysis at the solid/liquid interface. Here, we put forward a quasi-homogeneous catalysis concept by using the reactive oxygen species (ROS), such as ·OH, H2O2 and SO4•−, as a charge transfer mediator instead of direct heterogeneous catalysis at the solid/liquid interface. In the context of glycerol oxidation, all ROS exhibited a preference for first-order reaction kinetics. These ROS, however, showcased distinct oxidation mechanisms, offering a range of advantages such as ∼ 100 % conversion ratios and the flexibility to tune the resulting products. Glycerol oxidative formic acid with Faradaic efficiency (FE) of 81.2 % was realized by the H2O2 and ·OH, while SO4•− was preferably for glycerol conversion to C3 products like glyceraldehyde and dihydroxyacetone with a total FE of about 80 %. Strikingly, the oxidative coupling of methane to ethanol was successfully achieved in our quasi-homogeneous system, yielding a remarkable production rate of 12.27 μmol h−1 and an impressive selectivity of 92.7 %. This study is anticipated to pave the way for novel approaches in steering solar-driven organic conversions by manipulating ROS to attain desired products and conversion ratios.

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.

Roles of Ce1−xZrxO2/SBA-15 in Selective Catalytic Glycerol Conversion to Lactic Acid Process: Process Behaviors and Kinetic Analyses

Roles of Ce1−xZrxO2/SBA-15 in Selective Catalytic Glycerol Conversion to Lactic Acid Process: Process Behaviors and Kinetic Analyses

Ir-Fe bimetallic catalysts for selective glycerol hydrogenolysis

This work studied the effect of adding Fe to an Ir/γ-Al2O3 catalyst in different Fe/Ir molar ratios (0.5, 1.0, and 2.0) on the conversion and selectivity of the glycerol hydrogenolysis reaction. Additionally, the effect of the calcination of the solids was evaluated. The catalysts were prepared by incipient wetness impregnation of the Ir and Fe salts on the support and were characterized by textural analysis, XRD, TPR, XPS, and TEM-EDS techniques. The interaction between Ir and Fe was evidenced in the characterization of the catalysts. The addition of Fe to the Ir catalyst led to an increase in activity; however, this effect was better observed for the non-calcined catalyst series. The calcined catalyst series did not present a significant increase in glycerol conversion and selectivity to 1,2-PDO, probably due to the sintering of Ir occasioned by the catalyst's calcination, as observed in the characterization. For non-calcined bimetallic catalysts, the conversion increased from 7 % to 21.5 % for IrFe2.0/γ-Al2O3 catalyst, probably due to the synergic effect between both metals and the formation of Ir-Fe bimetallic particles, as evidenced in EDS mapping and XPS analysis. In the presence of this catalyst, selectivity to 1,2-PDO remained high (90.1 %).

Understanding the reaction dynamics of glycerol conversion into glycerol carbonate by transesterification of carbonic acid esters over CaO

The conversion of glycerol into value-added products is crucial for reducing waste generation in the biodiesel industry. In this context, glycerol carbonate has emerged as a promising molecule, capable of being produced through various processes, with glycerol transesterification being considered the most environmentally friendly method. In order to investigate the transesterification process comprehensively, this work focused on reactions between glycerol and different carbonic acid esters (dimethyl carbonate, diethyl carbonate, ethylene carbonate, and propylene carbonate), utilizing calcium oxide (CaO) as a basic catalyst. The catalyst was obtained commercially and characterized by X-ray diffraction (XRD), infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The catalyst characterizations showed that it consisted of nano and micrometric particles with high purity, making it suitable for use without prior pretreatment. The reactions were conducted in a batch reactor using dimethylformamide as a solvent, and the products were analyzed by gas chromatography (GC-FID and GC-MS). Experiments were performed to investigate the effects of different reaction parameters on the formation process of glycerol carbonate and potential co-products. CaO showed moderate catalytic activity in glycerol conversion, which occurred in three steps, forming glycerol carbonate with high selectivity, along with small amounts of co-products, glycidol and glycerol tricarbonate. Thus, considering the results obtained in this and other studies, it was possible to identify that moderately strong basic catalysts favor simple reaction mechanisms, predominantly yielding glycerol carbonate. Conversely, highly basic catalysts induce more complex reaction mechanisms, resulting in significant formation of co-products.

Start-up of glycerol-driven denitrifying phosphorus removal from wastewater: The effects of the microaerobic environment

Glycerol, an abundant by-product of biodiesel production, represented a promising carbon source for enhancing nutrient removal from low C/N ratio wastewater. This study discovered a novel approach to initiate glycerol-driven denitrifying phosphorus removal (DPR) in situ by creating a short-term microaerobic environment within the aerobic zone. This approach facilitated the in-situ conversion of glycerol, which was subsequently utilized by denitrifying phosphate accumulating organisms (DPAOs) for DPR. The feasibility and stability of glycerol-driven DPR were validated in a continuous-flow pilot-scale reactor. Anaerobic phosphorus release increased from 1.0 mg/L/h to 2.5 mg/L/h, with fermentation bacteria and related functional genes showing significant increases. The stable stage exhibited 92.8% phosphorus removal efficiency and 55.5% DPR percentage. The microaerobic environment enhanced fermentation bacteria enrichment, crucial for glycerol-driven DPR stability. The collaborative interaction between fermentation bacteria and phosphate accumulating organisms (PAOs) played a key role in sustaining glycerol-driven DPR stability. These findings provide a robust theoretical foundation for applying glycerol-driven DPR in established wastewater treatment plants.

Metabolic versatility of anaerobic sludge towards platform chemical production from waste glycerol

Waste glycerol is produced in excess by several industries, such as during biodiesel production. In this work, the metabolic versatility of anaerobic sludge was explored towards waste glycerol valorization. By applying different environmental (methanogenic and sulfate-reducing) conditions, three distinct microbial cultures were obtained from the same inoculum (anaerobic granular sludge), with high microbial specialization, within three different phyla (Thermodesulfobacteriota, Euryarchaeota and Pseudomonadota). The cultures are capable of glycerol conversion through different pathways: (i) glycerol conversion to methane by a bacterium closely related to Solidesulfovibrio alcoholivorans (99.8% 16S rRNA gene identity), in syntrophic relationship with Methanofollis liminatans (98.8% identity), (ii) fermentation to propionate by Propionivibrio pelophilus strain asp66 (98.6% identity), with a propionate yield of 0.88 mmol mmol−1 (0.71 mg mg−1) and a propionate purity of 80–97% and (iii) acetate production coupled to sulfate reduction by Desulfolutivibrio sulfoxidireducens (98.3% identity). In conclusion, starting from the same inoculum, we could drive the metabolic and functional potential of the microbiota towards the formation of several valuable products that can be used in industrial applications or as energy carriers.Key pointsVersatility of anaerobic cultures was explored for waste glycerol valorizationDifferent environmental conditions lead to metabolic specializationBiocommodities such as propionate, acetate and methane were produced

Engineering Lewis-Acid Defects on ZnO Quantum Dots by Trace Transition-Metal Single Atoms for High Glycerol-to-Glycerol Carbonate Conversion.

Efficient conversion of biomass wastes into valuable chemicals has been regarded as a sustainable approach for green and circular economy. Herein, a highly efficient catalytic conversion of glycerol (Gly) into glycerol carbonate (GlyC) by carbonylation with the commercially available urea is presented using low-cost transition metal single atoms supported on zinc oxide quantum dots (M1-ZnO QDs) as a catalyst without using any solvent. A facile one-step wet chemical synthesis allows various types of metal single atoms to simultaneously dope and introduce Lewis-acid defects in the ZnO QD structure. It is found that doping with a trace amount of isolated metal atoms greatly boosts the catalytic activity with Gly conversion of 90.7%, GlyC selectivity of 100.0%, and GlyC yield of 90.6%. Congruential results from both Density Functional Theory (DFT)and in situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (in situ DRIFTS) studies reveal that the superior catalytic performance can be attributed to the enriched Lewis acid sites that endow optimal adsorption, formation of the intermediate for coupling between urea and Gly, and desorption of GlyC. Moreover, the tiny size of ZnO QDs efficiently promotes the accessibility of these active sites to the reactants.

Elucidation of synergism in Ce-Zr/SBA-15 mesoporous catalysts and the effects on the activity in selective glycerol to lactic acid reaction

The continued conversion of glycerol to value-added chemicals is essential in ensuring the sustainable development of the biodiesel industry. Selective catalytic oxidation of glycerol to lactic acid provides an alternative approach to valorizing glycerol. A mesoporous SBA-15 supported mixed-metallic oxide catalyst is deemed essential to selectively produce lactic acid in this mixed parallel and multi-step reaction. SBA-15-supported bimetallic Ce and Zr oxides were proved to be highly efficient catalysts for the selective glycerol oxidation into lactic acid in base-free media. The synergism between Ce and Zr in the bimetallic oxide compounds could enhance the creation of oxygen vacancies in the catalyst via the reduction of Ce4+ to Ce3+. The 2:1CeZr/SBA-15 catalyst exhibited prominent catalytic activity in selectively oxidizing glycerol to lactic acid, with a glycerol conversion of 91.8% and a lactic acid yield of 35.1%. This work achieved superior catalytic performance compared to previously conducted studies, primarily due to the significantly higher initial glycerol concentration employed in this study. To ascertain the intrinsic active sites of the catalyst, the physicochemical properties of the catalyst were thoroughly examined using BET, FTIR, XRD, FESEM, TEM, CO2-TPD, O2-TPD, and H2-TPR analysis. This work concluded that the synergistic interaction of the active sites, which led to the formation of active oxygen species, facilitated primary dehydrogenation of the terminal -OH bond in glycerol. Hence, in this work, a plausible glycerol conversion mechanism over the 2:1CeZr/SBA-15 catalyst was also proposed.

Galvanostatic Electroshock Synthesis of Low Loading Au-Pt Nanoalloys onto Gas Diffusion Electrodes as Multifunctional Electrocatalysts for a Glycerol-Fed Electrolyzer.

Water electrolysis is increasingly considered a viable solution for meeting the world's growing energy demands and mitigating environmental issues. An inventive strategy to mitigate the energy requirements involves substituting the energy-intensive oxygen evolution reaction (OER) with biomass-derived glycerol electrooxidation. Nonetheless, the synthesis of electrocatalysts for controlling the selectivity towards added-value chemicals at the anode and efficient H2 generation at the cathode remains a critical bottleneck. Herein, we implemented a galvanostatic electroshock synthesis approach to control the reduction kinetics of Au(III) and Pt(IV) to grow ultra-low amount of gold-platinum alloys on a gas diffusion electrode (12-26 µgmetal cm‒2) for glycerol-fed hydroxide anion exchange membrane based electrolyzer. The symmetric GDE-Au100-xPtx||GDE-Au100-xPtx systems showed a notable improvement in electrolyzer performance (GDE-Au64Pt36 = 201 mA cm-2) as compared to monometallic versions (GDE-Au100Pt0 = 18 mA cm-2, GDE-Au0Pt100 = 81 mA cm-2). Chromatography (HPLC) analysis underscores the critical importance of bulk electrolysis methodology (galvanostatic vs potentiostatic) for the efficient conversion of glycerol into high-value-added products. Regarding the electrical energy required to produce 1 kg of H2 for such an electrolyzer fed at the anode with glycerol, our results confirm a drastic decrease by a factor of at least two compared with conventional water electrolysis.

Unveiling the catalytic potential of K2ZnF6 fluoroperovskite for glycerol oligomerization

AbstractThis study systematically evaluates fluorine‐containing materials with varying compositions of K, Al, Co, Cu, Mg, and Zn as catalysts for glycerol oligomerization. Comprehensive analyses were conducted for all of the catalysts, considering their structural, compositional, morphological characteristics, and basicity, to understand them in greater depth. Among these analyses, gas chromatography was employed to examine the composition of the reaction products. The investigation extended to a recycling study under optimized conditions. Thermogravimetric analysis and X‐ray photoelectron spectroscopy were used to characterize the spent catalysts. Catalytic activity was found to be influenced strongly by the fluorine content, demonstrating remarkable performance for the materials containing fluoroperovskites such as KMgF3 in the catalyst KMgAFC, and K2ZnF6 in KZAFC. Remarkably, KZAFC with 20% fluorine exhibited superior glycerol conversion (68%) and selectivity for diglycerol (27%). Comparative analysis with ZnAl‐layered double hydroxide highlighted the positive impact of fluorine on catalytic activity. Introducing a calcination step in the catalyst recovery process also demonstrated improved activity during recycling. Interestingly, KZAFC exhibited stability over four reaction cycles, presenting an economic advantage over homogeneous catalysts. The study also shed light on the potential fluorine loss at the surface and potassium leaching into reaction products, correlating these phenomena with the observed decline in activity. These comprehensive findings contribute significantly to advancing sustainable glycerol valorization through heterogeneous catalysis.

Selective Conversion of Glycerol to Lactic Acid in Water via Acceptorless Dehydrogenation Catalyzed by a Water-Soluble Metal-Ligand Bifunctional Iridium Catalyst.

An efficient method for the selective conversion of glycerol, the major byproduct of the biodiesel manufacturing process, to lactic acid in water via acceptorless dehydrogenation has been developed. In the presence of a water-soluble [Cp*Ir(6,6'-(OH)2-2,2'-bpy)(H2O)][OTf]2 (0.1 mol %) and KOH (1.1 equiv), the reaction proceeded at 120 °C for 24 h to afford the desired product in >99% yield with >99% selectivity. It was confirmed that OH functional groups in the ligand were crucial for the activity of the iridium complex. Furthermore, density functional theory calculations and mechanistic experiments were also undertaken.

Solar-driven highly selective conversion of glycerol to dihydroxyacetone using surface atom engineered BiVO4 photoanodes

Dihydroxyacetone is the most desired product in glycerol oxidation reaction because of its highest added value and large market demand among all possible oxidation products. However, selectively oxidative secondary hydroxyl groups of glycerol for highly efficient dihydroxyacetone production still poses a challenge. In this study, we engineer the surface of BiVO4 by introducing bismuth-rich domains and oxygen vacancies (Bi-rich BiVO4-x) to systematically modulate the surface adsorption of secondary hydroxyl groups and enhance photo-induced charge separation for photoelectrochemical glycerol oxidation into dihydroxyacetone conversion. As a result, the Bi-rich BiVO4-x increases the glycerol oxidation photocurrent density of BiVO4 from 1.42 to 4.26 mA cm−2 at 1.23 V vs. reversible hydrogen electrode under AM 1.5 G illumination, as well as the dihydroxyacetone selectivity from 54.0% to 80.3%, finally achieving a dihydroxyacetone production rate of 361.9 mmol m−2 h−1 that outperforms all reported values. The surface atom customization opens a way to regulate the solar-driven organic transformation pathway toward a carbon chain-balanced product.

Application of Stemphylium lycopersici Extracts Immobilized on MCM-48type Mesoporous Materials as Biocatalysts for Monoacylglycerol Production.

Monoacylglycerols are eco-friendly and inexpensive emulsifiers with a range of applications. The traditional synthetic route is not eco-friendly, while enzymatic catalysis offers milder reaction conditions and higher selectivity. However, its application still is limited due to the costs. In this context, endophytic fungi can be source to new biocatalysts with enhanced catalytic activity. Based on this perspective, the aim of this study was perform the synthesis of MAG's through transesterification reactions of solketal and different vinyl esters, using crude and immobilized lipolytic extracts from the endophytic fungi Stemphylium lycopersici, isolated from Humiria balsamifera. The reactions were conducted using 100 mg of biocatalyst, 1 mmol of substrates, 9 : 1 n-heptane/acetone, at 40 °C, 200 rpm for 96 h. In the reactions using the ILE and stearate, laureate and decanoate vinyl esters it was possible to obtain the correspondent products with conversion rates of 52-75 %. Also, according to the structure drivers used in MCM-48 synthesis, different morphologies and conversions rates were observed. Employing [C16MI] Cl, [C14MI] Cl and [C4MI] Cl, the 1-lauroyl- glycerol conversion was 36 %, 79 % and 44 %, respectively. This is the first work involving the immobilization of an endophytic fungi and its utilization as a biocatalyst in the production of MAG's.

Efficient Photoelectrocatalytic glycerol to dihydroxyacetone synergistic hydrogen production on Co-LDH nanowires modified TiO2 nanorod arrays

The highly selective conversion of glycerol into high value-added products, accompanied by hydrogen generation, through photoelectrocatalytic technology represents an upcycling process that enhances resource utilization and sustainability. In this study, we designed a composite photoanode with a Type II heterojunction structure, Co-LDH(6 h)/TiO2, achieving a high glycerol conversion rate (1083.22 mmol·m−2·h−1) and hydrogen production rate (20.35 mmol·m−2·h−1) while maintaining a high level of DHA selectivity (48 %). Characterization revealed that the engineered Type II heterojunction significantly enhanced visible light absorption and charge separation, thereby reducing electron-hole recombination and improving the efficiency of glycerol conversion and hydrogen production. Furthermore, it was confirmed by in-situ Fourier transform infrared that the Co-LDH(6 h)/TiO2 composites exhibited significant affinity for adsorption intermediate hydroxyl group in glycerol and rapid desorption of DHA, which is a critical factor in achieving high selectivity for the oxidation pathway to DHA. Mechanistic analyses and isotopic labelling indicate that the photogenerated holes in the Co-LDH(6 h)/TiO2 photoanode are the primary active species responsible for the oxidation of glycerol, yielding a spectrum of valuable products. This research provides a novel strategy and in-depth understanding for developing efficient photoanodes for selective oxidation in organic reactions.

Iron-modified Cu/γ-alumina catalyst for the selective hydrogenolysis of glycerol

This study introduces a novel Cu-based catalyst for the selective hydrogenolysis of glycerol to 1,2-propanediol, synthesized by impregnating mesoporous γ-alumina with Cu and Fe. Characterization was performed using various analytical methods, and tests were conducted in a tubular continuous reactor under specific conditions. Iron was found to have multiple modifying effects, influencing the modification of Cu clusters on the catalyst surface and the radial Cu concentration profile inside the particles. A low Fe/Cu ratio resulted in an almost egg-shell Cu profile, whereas higher Fe levels produced a more uniform distribution. Interestingly, minor Fe additions led to larger Cu clusters, while higher amounts resulted in smaller clusters and decreased glycerol conversion. The effect of Fe on Cu clusters size, acid sites concentration, and Cu radial profile, as well as the influence of these parameters on the glycerol conversion and selectivity towards 1,2-PD are discussed in this study.

Selective formation of glycolic acid by photocatalytic conversion of glycerol under sunlight with SnO2-based heterojunctions

Glycerol is a byproduct of biodiesel synthesis and is one of the most readily available platform molecules originating from biomass. Heterogeneous photocatalysis is a strategic approach, and reactions run under ambient conditions convert glycerol into industrially relevant molecules such as glycolic acid. The p-n type heterojunctions are useful photocatalysts because they can decrease the bandgaps and facilitate electron promotion between the bands of materials, thereby optimizing the formation of reactive oxygen species (ROS) and increasing reaction efficiencies. In this study, photocatalysts were synthesized via coprecipitation with a 5 % w/w mixture of Cu2+ and Ni2+ precursors, which produced the p-n heterojunctions SnO2/CuO-5 % and SnO2/NiO-5 %, respectively. Was observed an increase in the surface areas of the materials, which were ∼19 and 62 m2/g for SnO2/CuO-5 % and SnO2/NiO-5 %, respectively. The addition of metals to the heterojunctions enabled the use of solar light, due to the decrease of the bandgaps of the materials to 1.9 and 2.0 eV for SnO2/CuO-5 % and SnO2/NiO-5 %, respectively; these were lower than of SnO2 (2.54 eV). The photocatalytic activities of the heterojunctions were tested via glycerol oxidation, and after 4 h, the SnO2/CuO-5 % heterojunction exhibited the highest reaction efficiency (19 %), followed by 13 % and 11 % for SnO2/NiO-5 % and SnO2, respectively. The selectivities indicated the reaction pathway, in which glyceraldehyde and tartaric acid were intermediates for glycolic acid production; glycolic acid is the precursor to polyglycolic acid (PGA), for which production levels are increasing. The results of this study point to new technological pathways enabling responsible use of the resources present in nature and reuse of their byproducts, as with the conversion of glycerol to economically attractive molecules and contribute to a sustainable economy.

SiO2-coated HZSM-5 catalysts for dehydration of bio-based glycerol to acrolein

As biodiesel production from triglyceride transesterification increases, by-product glycerol is accumulated, motivating the development of novel mechanism for converting glycerol into valuable chemicals. In the present work, for the selective production of acrolein from glycerol, SiO2-coated HZSM-5 molecular sieve with preciously controlled surface was designed. As characterized by NH3-TPD and pyridine adsorption IR, the total acid and the Lewis acid amounts of SiO2-coated HZSM-5 were decreased whereas the Brønsted acid amount remained almost unchanged. SiO2-coated HZSM-5 catalyst exhibited selectivity to acrolein of 64%, in glycerol conversion of 100% under reaction temperature of 300°C, much higher than HZSM-5 catalyst with acrolein selectivity of 52%. The catalytic activity durability was also improved by the modification of the surface properties because SiO2 coating reduced the surface acid amount and the micropore volume of HZSM-5, suppressing side reactions and inhibiting carbon deposition efficaciously.

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.

Impacts of ball-milling on ZSM-5 zeolite properties and its catalytic activity in the two-phase glycerol ketalization with acetone

A series of acidic ZSM-5 zeolites were mechanically ball-milled for different periods and further applied as catalysts in the liquid-phase glycerol ketalization with acetone. Structural and textural characterizations showed that the samples had considerable crystallinity and micropore volume loss due to amorphization. On the other hand, due to a comminution effect, the external surface area increased and particle size reduced. TPD and FTIR analyses with probe molecules with different sizes, such as ammonia, pyridine (Py), and 2,6-di-tert-butylpyridine (DTBPy) chemisorbed on the catalyst acid sites, aided in quantifying the various levels of accessibility of chemicals. The treated materials lost acidity due to amorphization or blockage of pores, but the milling enabled higher accessibility of bulkier chemicals to acid sites, as revealed by the chemisorption of Py and DTBPy. A crucial balance of acidity, accessibility, and hydrophobicity was tailored by milling time. The one-hour grounded zeolite had a glycerol conversion 35 % greater than the pristine sample and 67 % greater than the eight-hour milled sample. The results showed that ball milling is a tool to improve the catalytic activity of zeolites with bulky chemicals by fine-tuning the milling time.