The growing demand for sustainable aviation fuels (SAFs) has driven interest in biomass-derived fuel precursors. This study investigates the aldol condensation of furfural and cyclopentanone (CP) over a series of Ce-modified zeolites and mesoporous catalysts to produce 2-(2-furylmethylidene) CP (FC) and its dimer 2,5-bis(2-furylmethylidene) CP (F2C), both relevant as SAF intermediates. A range of Ce-based materials, including Ce-H-Y-80, Ce-MCM-41, Ce-SBA-15, and Ce-H-Beta with varying Si/Al ratios, were synthesized and tested under specific reaction conditions. Catalyst characterization revealed distinct differences in surface area, acidity, basicity, and pore architecture, all contributing to the performance. Ce-MCM-41 exhibited the highest selectivity to FC (57%) at 65% conversion, linked to its mesoporosity and balanced acid-base properties. To further assess this catalyst's performance, additional kinetic studies and reaction modeling were conducted, along with extended characterization of the spent and regenerated catalyst to evaluate stability and reusability. Zeolitic Ce-H-Beta catalysts demonstrated strong Br & oslash;nsted acidity and delivered high conversion with moderate selectivity. A mechanistic correlation between acidity/basicity and activity was supported by the literature data. These findings highlight the potential of Ce-based heterogeneous catalysts in upgrading biomass-derived compounds into SAF precursors and support further development of regenerable, multifunctional catalytic materials.

The production of aromatics, specifically benzene, toluene and xylenes (BTX), from bio-derived feedstock such as ethanol and furfural can be achieved by zeolite catalysts. However, the formation of coke strongly limits this reaction leading to catalyst deactivation. In-depth understanding of the relationship between the catalyst characteristics and the mechanism of carbon deposit is needed to improve potential applicability of this novel approach for BTX production. Evaluation of the catalytic activity of beta and ZSM-5 zeolites in the aromatization of ethanol and furfural, coupled with the characterization of the spent catalysts, gave important insights on the structure and features that are required to increase the aromatics formation. With these investigations it was possible to determine the location of the catalytic sites that are active in the aromatization reaction, defining at the same time the mechanism of deactivation by coke formation. These findings give important advances for the future design of efficient catalysts for the aromatics production.

The direct oxidation of methane to methanol (DOMTM) in the liquid phase was investigated using a copper alpha-3,5-(di-tert-butyl)phenyl phthalocyanine (CuPc) supported on hierarchical ZSM-5 zeolites prepared by alkaline desilication, with H2O2 as an oxidant (50 degrees C, 30 bar CH4, 0.5 M H2O2). Catalysts with varying Cu loadings (0.5-1.0 wt%), framework compositions (SiO2/Al2O3 = 23 and 30), and thermal treatment (intact CuPc vs. calcined) were evaluated. Qualitative kinetic analysis was performed through the quantification of the products over time (0-4 h) by HPLC, 1H NMR, and potentiometric titration. X-ray absorption spectroscopy (XAS) established that the CuPc macrocycle remains structurally intact after incorporation into the zeolite (Cu-N distance 1.94 & Aring;, coordination number similar to 4.4), while calcination leads to complete macrocycle decomposition and formation of isolated Cu2+-2Z framework species, as confirmed by XANES, UV-Vis-diffuse reflectance spectroscopy, and H2-TPR. Elemental mapping by HAADF-STEM demonstrated that copper is homogeneously dispersed throughout the zeolite. Calcination significantly improved catalytic performance. The catalyst 1CuPc-ZSM-5-30-DS-Calc (Cu/Al molar ratio = 0.17) achieved a CH3OH productivity of 553 mu mol gcat-1 h-1 and 47% selectivity at isoconversion (0.1%), corresponding to a methanol yield of 4.3 molCH3OH molCu-1 h-1, surpassing many recent reported phthalocyanine-based systems for DOMTM. An even higher methanol yield of 8.0 molCH3OH molCu-1 h-1 was obtained over 0.5CuPc-ZSM-5-30-DS-Calc (Cu/Al molar ratio = 0.09). The Br & oslash;nsted to Lewis acid site (BAS/ LAS) ratio and Br & oslash;nsted acid site density were identified as key descriptors of CH3OH selectivity and productivity. These findings establish that CuPc functions primarily as a precursor to well-dispersed Cu2+ active sites, and that copper speciation, zeolite acidity, and mesoporosity jointly govern methanol selectivity in this reaction system.

The direct oxidation of methane to methanol (DOMTM) remains challenging due to the low reactivity of methane and difficulties in achieving high activity and selectivity under mild conditions. In this work, Cu-ZSM-5 catalysts were systematically investigated using H2O2 as oxidant in water at 50 degrees C to establish quantitative structure-activity relationships. Comprehensive characterization of copper speciation, dispersion, acidity, and framework aluminum coordination was performed. Preservation of the MFI structure was confirmed by X-ray diffraction, while Br & oslash;nsted and Lewis acid sites were quantified using pyridine adsorption, and framework and extra-framework aluminum coordination was determined by 27Al solid-state NMR. Copper dispersion, quantified by N2O oxidation-H2 reduction (TPR), along with UV-Vis diffuse reflectance spectroscopy and H2-TPR, indicated the presence of isolated Cu2+ species. Turnover frequency exhibited non-monotonic dependencies on Br & oslash;nsted acid site density and BAS/LAS ratio. Methanol formation was maximized (productivity of 750 mu mol g-1 h-1 with a selectivity of 49% to methanol) within Br & oslash;nsted acid site densities of 0.58-0.96 mu mol m-2 and BAS/LAS ratios of 1.0-1.7, highlighting the synergistic effect of BAS-LAS pairs. These results demonstrate that high methanol productivity arises from a cooperative interplay between copper dispersion, acid site density, and BAS-LAS synergy. Rigorous quantification of all oxidation products (CH3OOH, CH3OH, HCHO, HCOOH, CO2) enabled accurate evaluation of catalytic performance under low-conversion conditions.

Unlike temperature-programmed desorption (TPD) of ammonia (NH 3 -TPD) and Fourier-transform infrared spectroscopy of adsorbed pyridine (pyridine-FTIR), where ammonia and pyridine adsorb and desorb without reaction, TPD of isopropylamine (IPAm-TPD) relies on a Brønsted-acid-catalyzed decomposition of isopropylamine to propylene and ammonia to selectively probe Brønsted acidity. Prior studies have reported altered IPAm-TPD responses for metals-modified zeolites relative to pristine zeolites, yet hypotheses on the cause have diverged. This work examined the acidity characterization results of pristine and zinc-modified H-ZSM-5 zeolites from IPAm-TPD against those from NH 3 -TPD, and pyridine-FTIR. For pristine zeolites, the IPAm-TPD data exhibited the expected Brønsted-site-related propylene desorption feature, with propylene amounts proportional to framework aluminium, strongly adsorbed ammonia in NH 3 -TPD, and Brønsted-associated pyridine in pyridine-FTIR. However, the IPAm-TPD data of the zinc-modified zeolites was more complex, with multiple desorption features. The mass spectrometry data and comparison of the quantitative IPAm-TPD results to those of NH 3 -TPD and pyridine-FTIR suggested contributions from a Brønsted-site-related propylene release, an additional, likely Lewis-site-related propylene release, and unidentified side products overlapping with typical propylene responses, possibly from dehydrogenation and aromatization reactions. When the Brønsted-site-related propylene response was quantified and compared to quantitative pyridine-FTIR results, the results seemed representative of Brønsted acidity despite the side reactions.

Removal of pharmaceuticals from wastewater remains a major environmental challenge, requiring efficient and selective Advanced Oxidation Processes (AOPs). Catalytic and non-catalytic ozonation was investigated in a laboratory-scale reactor under optimized flow conditions (500-750 mL min-1, 98 % O2 feed). Ozonation kinetics of active pharmaceutical ingredient mixtures (APIs) consisting of ibuprofen (IBU), diclofenac (DCF), carbamazepine (CBZ), sulfadiazine (SDZ), and sulfamethoxazole (SFX) (40 mg L-1 each) - was investigated using iron-modified zeolite catalysts, Fe-H-Y and Fe-H-Beta, under semi-batch operations (0.5 g catalyst, 20 degrees C) in order to correlate degradation and mineralization efficiency with catalyst structure, acidity, and stability. Both catalysts significantly improved the ozone utilization compared to non-catalytic ozonation. Interestingly, Fe-H-Y accelerated initial degradation rate, while the use of Fe-H-Beta resulted in the highest level of mineralization. Adsorption-desorption analysis revealed that the molecular size and polarity controlled the interactions between the pharmaceutical and the catalyst: smaller polar compounds (SDZ, SFX) exhibited stronger adsorption on the catalyst, while bulkier molecules (DCF, IBU) were restricted to external surfaces. Post-reaction characterization confirmed that the Fe-H-Y retained more surface area and exhibited lower Fe leaching, while Fe-H-Beta showed significantly higher carbon deposition. Overall, Fe-H-Y combined rapid kinetics and structural stability, while Fe-H-Beta provided higher mineralization, at the expense of more extensive fouling. The study demonstrated that optimized ozonation conditions, coupled with tailored zeolite catalysts, markedly improve the oxidation efficiency and long-term performance in the oxidation of pharmaceuticals.

A new PVC based membrane sensor was constructed for determination of Cu2+ in various samples. The sensor exhibits a super-Nernstian slope of 29.1mV per decade over a wide concentration range (1×10-7 × 1x10-1 Mol L -1). It has a response time of about 15 s and can be used for at least 8 weeks without any divergence in potentials. The proposed sensor revealed very good selectivities for Cu2+ over a wide variety of other cations over a pH range 3–7. It was applied to the direct determination of copper in tap water samples and, as an indicator electrode, in potentiometric titrations of Cu2+ ion. The electrode was also successfully applied to the speciation of Copper in aqueous solutions.

Glucose transformation to methyl lactate was investigated over microporous Sn-H-Y- zeolite with SiO2/Al2O3 ratio of 30 as well as alkali metal modified mesoporous dealuminated Sn-H-Y-zeolites in the temperature range of 150-180oC. The catalysts were synthesized either by evaporation-impregnation or ion-exchange methods using a two-step procedure for Sn-and K-modification. The catalysts were characterized by several physico-chemical methods including SEM, TEM, pyridine adsorption-desorption FTIR, UV-VIS spectroscopy, solid state NMR-spectroscopy, nitrogen adsorption, TGA and CHNS for spent catalysts. The highest yield of methyl lactate of 72

Zeolite 13X and 5A were modified with nickel using three different methods: evaporation impregnation, deposition precipitation, and ion-exchange for comparison in CO2 methanation. The catalysts were tested in a lab scale fixed bed reactor and their physico-chemical properties were characterized by XRD, SEM-EDX, TEM, STEMEDX, nitrogen physisorption, H2-TPR and NH3-TPD. The physico-chemical characterization results of Ni modified 13X and 5A zeolite catalysts showed that the zeolite structure did not change after the Ni modification by different catalyst synthesis methods, although the surface area and micro-pore volume decreased. The average diameter of NiO and the NiO cluster size range of Ni zeolite catalyst synthesized with ion exchange are smaller than the catalysts prepared by the evaporation impregnation and deposition preparation. Ni dispersed well through 13X, while a lot of Ni appeared on the crystal outer surface of 5A zeolite. Evaporation impregnation and deposition precipitation prepared Ni13X catalysts exhibited a higher activity than ion-exchange prepared samples on CO2 methanation. The catalyst performance of Ni5A-IE and Ni13X-IE zeolite catalysts, which were synthesized using the ion-exchange method for CO2 methanation was limited by the actual loading of Ni. The Ni 13X catalysts have less CH4 selectivity which could be attributed to their lower acidity. Ni13X-EIM catalyst showed good catalytic stability at 360 degrees C, with no catalyst deactivation during a 200 h catalyst stability test.

Transformation of methyl lactate to acrylic acid was investigated over Ca3(PO4)2, Ca2(P2O7) and their mixture in the temperature range of 250-425 degrees C. The initial concentration of methyl lactate in water was varied from 2 wt% to neat methyl lactate. The results showed that these phosphate catalysts did not contain any measurable amounts of either acid sites or basic sites. The best catalyst was Ca3(PO4)2 giving 62% selectivity to acrylic acid at 75% conversion at 400 degrees C using GHSV of 95280 h-1 and 2 wt% methyl lactate in the initial feed. This catalyst exhibited larger surface area in comparison to Ca2(P2O7). Elemental analysis revealed that some Ca leaching occurred during reaction, while in case of Ca2(P2O7) the calcium leaching was 3.4 fold higher than observed for Ca3(PO4)2. Long-term results over Ca3(PO4)2 showed that extensive catalyst deactivation occurred during the first 11 h time-on-stream, after which the activity dropped only slightly. In addition to kinetic studies with different parameters, also, kinetic modeling was performed and the activation energies for formation of different products were determined over different catalysts.

Parent, hierarchical, and metal-modified hierarchical zeolite Y were investigated as heterogeneous catalysts in the R-(+)-limonene epoxidation, a catalytic route for synthesizing precursors of bio-polycarbonates, an alternative to isocyanate polyurethanes. The fresh catalysts underwent detailed characterization using XRD, N 2 physisorption, TEM, SEM-EDX, pyridine-FTIR, NH 3 -TPD, CO 2 -TPD, UV - Vis-DRS, and solid-state NMR. Spent materials were investigated by TPO-MS and TGA, confirming low coke formation on the catalytic surface. The most active material was K - Sn-modified dealuminated zeolite Y, reflected in a high turnover frequency (TOF) of 96 h -1 . This material exhibited the lowest Br & oslash; nsted to Lewis acidity ratio (0.1), the highest mesoporosity fraction (43%), and the lowest total surface area (465 m 2 g -1 ). Aprotic polar solvents with high polarity and medium donor capacity appeared suitable for limonene epoxidation. Limonene conversion of ca. 97% was reached at 70 degrees C, H 2 O 2 : limonene molar ratio = 7, and acetonitrile as a solvent, while selectivity to total monoepoxides exhibited values up to 96% under different reaction conditions. Hydration of internal epoxides to limonene diol was favored at high temperatures and high H 2 O 2 /limonene molar ratios. The efficiency of H 2 O 2 reached maximum values of about 85% at low H 2 O 2 amounts, while no significant influence was observed for temperature, catalyst amount, and the initial concentration of limonene. A plausible reaction mechanism was proposed for the R-(+)-limonene epoxidation with H 2 O 2 based on the experimental findings.

Fine chemicals are produced in small annual volume batch processes (often <10,000 tonnes per year), with a high associated price (usually >USD 10/kg). As a result of their usage in the production of speciality chemicals, in areas including agrochemicals, fragrances, and pharmaceuticals, the need for them will remain high for the foreseeable future. This review article assesses current methods used to produce fine chemicals with heterogeneous catalysts, including both well-established and newer experimental methods. A wide range of methods, utilising microporous and mesoporous catalysts, has been explored, including their preparation and modification before use in industry. Their potential drawbacks and benefits have been analysed, with their feasibility compared to newer, recently emerging catalysts. The field of heterogeneous catalysis for fine chemical production is a dynamic and ever-changing area of research. This deeper insight into catalytic behaviour and material properties will produce more efficient, selective, and sustainable processes in the fine chemical industry. The findings from this article will provide an excellent foundation for further exploration and a critical review in the field of fine chemical production using micro- and mesoporous heterogeneous catalysts.

Several parents and Sn-modified microporous and mesoporous catalysts were investigated in Prins cyclization of isoprenol with isovaleraldehyde for the production of the desired cis isomer of pyranol, Florol ® using dimethylcarbonate as a solvent in the temperature range of 30-60oC. The highest selectivity to pyranols, 70% was obtained over microporous Sn-Y-80 (number denotes SiO2/Al2O3 ratio) at 40oC, while 64% selectivity to pyranols was obtained at 99% conversion over dealuminated H-Y-80 exhibiting mesoporosity and low Brønsted to Lewis acid ratio of 0.16. For microporous catalysts even higher BA/LA ratio and large amounts of Lewis acid sites were beneficial, as was the case for H-Y-30 modified with SnCl2, because the reaction occurred mainly on the outer surface of the catalyst.

Fine chemicals are produced in small annual volume batch processes (often <10,000 tonnes per year), with a high associated price (usually > $10/kg). As a result of their usage in the production of speciality chemicals, in areas including agrochemicals, fragrances and pharmaceuticals, their necessity will remain high for the foreseeable future. This review article assesses current methods used to produce fine chemicals with heterogeneous catalysts, including both well-established methods as well as newer experimental methods. A wide range of methods utilising microporous and mesoporous catalysts has been explored, including their preparation and modification before use in industry. Their potential drawbacks, as well as benefits, have been analysed, with their feasibility compared to newer, recently emerging catalysts. The field of heterogeneous catalysis for fine chemical production is a dynamic and ever-changing area of research. This deeper insight into catalytic behaviour and material properties will produce more efficient, selective, and sustainable processes in the fine chemical industry. The findings from this article will provide an excellent foundation for further exploration and a critical review in this field of fine chemical production using micro- and mesoporous heterogeneous catalysts.

Furfural is a very interesting bio-based platform molecule that can be derived from the pentoses found in hemicelluloses, such as xylose and arabinose. Furfural displays significant potential as a source for the production of various chemicals. By oxidizing furfural with hydrogen peroxide, a range of products can be obtained, including diacids such as succinic and maleic acids, as well as lactones such as 2(5H)-furanone. In this study, the oxidation of furfural was conducted using niobia as a heterogeneous catalyst, which displayed an interesting behavior, giving 2,3-dihydroxybutanedioic acid (tartaric acid) as the main oxidation product. Other typical oxidation products, namely succinic acid and 2(5H)-furanone were also obtained in moderate concentrations. Tartaric acid and the rest of the oxidation products were identified by GS-MS, 1H NMR and 13C NMR. A wide range of conditions were screened to reveal the catalytic behavior of the system, enabling furfural consumption and formation of tartaric acid. Additionally, a plausible reaction network was established based on a previously proposed mechanism and experimental observations that accounted for the production of tartaric acid. Oxidation of furfural was conducted using niobia as a heterogeneous catalyst, which displayed an unconventional behavior, giving 2,3-dihydroxybutanedioic acid (tartaric acid) as the main oxidation product.

The electrocatalytic oxidation (ECO) of glucose on gold requires alkaline conditions and relatively high potentials (>0.3 V-RHE). Although the adsorption of hydroxide ions (OHads) is also known to occur under these conditions, the generally accepted proton-coupled electron transfer mechanism for sugar ECO does not explicitly state the role of OHads in the sugar adsorption or oxidation steps. To investigate this, we carried out a combined experimental and density functional theory (DFT) study on the ECO of glucose and xylose over a nanogold catalyst under temperature and pH control. Grand canonical DFT (GC-DFT) was used to identify the preferred reaction mechanism in which OHads facilitates the thermodynamically feasible formation of gluconic and xylonic acid. Calculated results also showed that OHads plays a role in improving the acid selectivity. Constant-potential electrolyses in sugar solutions were performed using mesoporous (Sibunit) carbon-supported Au nanoparticles (AuNPs) with an average cluster size of 4.7 nm. Experimental results showed that the highest conversions for glucose (57.7%) and xylose (49.4%) were obtained at 25 degrees C and pH 12.5, with gluconic and xylonic acid selectivity of 81.5 and 87.8%, respectively. The catalytic activities were high considering the low Au loading (similar to 0.1% wt). Higher pH led to a decrease in the ECO rate possibly due to excess hydroxide ions blocking active sites for sugar adsorption. Our results highlight the importance of computational studies in elucidating reaction mechanisms for sugar ECO where sugar acids are the main oxidation products. This is crucial in designing reaction systems for the viable production of these value-added chemicals from biomass.

The Special Issue “Microporous and Mesoporous Materials for Catalytic Applications has twelve peer-reviewed articles (Contributions 1–12), out of which there are eight research papers (Contributions 1–8) and four review papers (Contributions 9–12) [...]

Iron inclusion in the composition of the zeolite crystal structure endows it with new and useful properties. However, direct synthesis involving Fe, frequently creates unfavorable conditions that hinder the crystallization process and generate impurity phases. For this reason, novel methods, which include iron within the zeolitic matrix, are being sought out. This article presents a one-pot synthesis of iron-modified zeolite X. The resulting materials were characterized, and their textural, electrical, and magnetic properties were studied.

Co-processing of n-hexadecane with lignin derived isoeugenol as a model compound was investigated in this work using low-cost mono-and bimetallic iron and nickel supported on H-Y-5.1 zeolite. Different Fe-Ni metal ratios in the catalyst led to different reaction rates of processes and product distribution. The presence of just 0.26 wt% isoeugenol in the mixture with n-hexadecane made hydroisomerization-hydro cracking of the latter two-fold less active. Catalysts with smaller metal particle sizes, lower than 6 nm were more efficient pointing out on structure sensitivity. Extremely high activity in co-processing was obtained over 2 wt% Fe - 8 wt% Ni/H-Y-5.1 catalysts with the median metal particle size of 4.6 nm and metals-to-acid site ratio of 8.6. Fe catalyst were much less active in isoeugenol hydrodeoxygenation, while high cracking activity of hexadecane was observed in the presence of Ni. Alkylation of n-hexadecane was a feature of 8 wt% Fe - 2 wt% Ni/H-Y-5.1, whereas, over the 5 wt% Fe - 5 wt% Ni/H-Y-5.1 bifunctional catalyst no undesired oxygen-containing cyclic products were detected. This catalyst exhibited the highest hydrogen consumption according to temperature programmed desorption, which can serve as a marker for efficient hydrodeoxygenation. The spent catalysts contained ca 40 wt% of coke with predominantly aliphatic species. (c) 2023 The Author(s). Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).