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Zirconium oxide-based catalysts for the oxygen reduction reaction (ORR) in polymer electrolyte fuel cells were synthesized via heat treatment of zirconium polyacrylate in an NH3 atmosphere. The effects of gas atmosphere and heat treatment temperature on the material structure were systematically examined. The formation of zirconium oxide nanoparticles and carbon residues, which act as electron conduction paths, was observed in all samples. The structure of the material varied significantly depending on the heat treatment conditions. The samples heat-treated in the NH3 atmosphere showed greater exposure to zirconium oxide nanoparticles and an increase in the specific surface area of the carbon residue caused by NH3-induced etching. In addition, the conductivity of the carbon residue increased, and its quantity decreased with increasing heat treatment temperature. This trade-off was optimally controlled at 800 °C, which resulted in a high rest potential and a large ORR current density. This study demonstrates that the heat treatment of organometallic complexes in an NH3 atmosphere is highly effective for exposing metal oxide nanoparticles and increasing the specific surface area of the carbon residue, providing valuable insights into the design of electron conduction paths for metal oxide-based catalysts. [ABSTRACT FROM AUTHOR]

Two kinds of oxide-zeolite composite support, Ce-beta and Zr-beta were prepared by a simple wet impregnation method and adopted for the preparation of palladium-based catalysts for catalytic oxidation of methane. The Pd/6.8Zr-beta catalyst showed superior methane oxidation performance, achieving T 50 and T 90 of 417 °C and 451 °C, respectively, together with robust hydrothermal stability. Kinetic analysis has shown that incorporating Zr into the catalyst significantly enhanced its efficiency, nearly tripling the turnover frequency (TOF) for methane combustion compared to the Pd/beta catalyst. This enhanced performance was attributed to the dispersion of Zr on the zeolite surface, which not only promoted the formation of active PdO sites but also helped maintain the high Pd2+ content via facilitating the oxygen migration during the reaction, thus improving both the catalyst's activity and stability. In the Pd/8.6Ce-beta catalyst, doped CeO 2 tended to aggregate in the zeolite's pores, adversely affecting the catalyst's efficiency. This aggregation promoted the formation of inactive Pd4+ species, a result of the enhanced metal-support interaction. This finding is critical for understanding the implications of dopant selection in the design of high-activity methane oxidation catalysts. [ABSTRACT FROM AUTHOR]

Electrochemical carbon dioxide reduction to n‐propanol, a high‐energy‐density C3 chemical, presents a promising method for the long‐term storage of renewable electricity. However, the C1‐C2 coupling step, crucial for C3 conversion, suffers from low selectivity and sluggish conversion rate. In this study, a strategy is proposed to regulate the adsorption of C2 active species on Cu by introducing an atomically dispersed Zr, which can effectively enhance the electroreduction of CO2 to n‐propanol. In situ infrared spectroscopy and theoretical studies unveil that the introduce of atomically dispersed Zr modulates the adsorption configuration of *C2 intermediates and strengtnens the binding with *C2 intermediates, thus lowing the energy barrier of the C1–C2 coupling process and accelerating the conversion efficiency. This novel catalyst achieves a n‐propanol Faradaic efficiency of 14.4 ± 0.3% and a high production rate of 70.0 ± 1.0 mA cm−2, comparable to the best reported values of the CO2‐to‐propanol electroconversion. This study highlights the effectiveness of designing synergistic electrocatalysts to boost the production of high‐value energy products, providing a promising path toward achieving carbon neutrality. [ABSTRACT FROM AUTHOR]

A heterogeneous zirconium catalyst was grafted on a ceria‐coated silica support, denoted as Zr(OEt)x/CeO2/SiO2. It exhibited higher catalytic activity compared to its homogeneous counterpart, Zr(OEt)4, in the conversion of carbon dioxide to diethyl carbonate using tetraethyl orthosilicate as a regenerable agent in the absence of any dehydrating agents under non‐protic conditions. We found that the ceria‐coated silica (CeO2/SiO2) support not only improved the catalytic activity of Zr(OEt)4 but also inhibited catalyst deactivation during catalyst recycling tests. Furthermore, we analyzed the surface of the Zr(OEt)x/CeO2/SiO2 catalysts by FE‐SEM and EDX. [ABSTRACT FROM AUTHOR]

A zirconocene dichloride‐catalyzed alkene hydrosilylation is reported that can be applied to non‐activated and conjugated terminal and internal alkenes. It involves a catalytic Zr‐walk process and leads to a selective conversion to the linear product. Lithium methoxide serves as mild catalyst activating agent, which significantly increases the applicability and operational simplicity in comparison to earlier zirconium(II)‐based protocols. Supported by additional experiments and calculations, a mechanism via zirconium(IV) intermediates is proposed. Due to the benign nature and ready‐availability of the zirconium catalyst, the reaction is an attractive alternative to established alkene hydrosilylation methods. [ABSTRACT FROM AUTHOR]

This study investigated the development and optimization of sol–gel synthesized Ni/ZrO2-Al2O3 catalysts, aiming to enhance the decomposition efficiency of CF4, a potent greenhouse gas. The research focused on improving catalytic performance at temperatures below 700 °C by incorporating zirconium and tungsten as co-catalysts. Comprehensive characterization techniques including XRD, BET, FTIR, and XPS were employed to elucidate the structural and chemical properties contributing to the catalyst's activity and durability. Various synthesis ratios, heat treatment temperatures, and co-catalyst addition positions were explored to identify the optimal conditions for CF4 decomposition. The catalyst composition with 7.5 wt% ZrO2 and 3 wt% WO3 on Al2O3 (3W-S3) achieved over 99% CF4 decomposition efficiency at 550 °C. The study revealed that the appropriate incorporation of ZrO2 enhanced the specific surface area and prevented sintering, while the addition of tungsten further improved the distribution of active sites. These findings offer valuable insights into the design of more efficient catalysts for environmental applications, particularly in mitigating emissions from semiconductor manufacturing processes. [ABSTRACT FROM AUTHOR]

Traditional polyurethane (PU) catalysts, especially dibutyl tin dilaurate, face scrutiny over toxicity concerns, leading to interest in safer alternatives. In an unexpected turn of events, research into a commercially available antibacterial agent revealed that it drastically reduced the pot life of PU coatings. Experiments show that when PU coatings were formulated with the antibacterial agent as catalyst, drying time and solvent resistance were improved as compared to traditional tin and zirconium catalysts. Further analysis showed that this was the result of copper compounds and it could be shown that a similar catalytic effect was achieved through Cu(II)-sulfate and Cu(II)-acetate. Such copper salts are not yet commonly known as replacements for tin catalysts. Possible mechanisms such as heterogenous catalysis or in-situ formation of the active compound were discussed. [ABSTRACT FROM AUTHOR]

Carbonyl compounds serve as essential raw materials in the production of fine chemicals and pharmaceuticals. An economical and environmentally-friendly route to generating carbonyl compounds involves the catalytic oxidation of alcohols and hydrocarbons using heterogeneous catalysts. In this work, we synthesize a series of vanadium-doped ordered mesoporous zirconium oxophosphate (V/M-ZrPO) nanocomposites via a modified one-pot evaporation-induced self-assembly approach. Characterization results confirm the successful embedding of vanadium species into the framework of the M-ZrPO support. Dispersion of vanadium sites generates catalysts exhibiting enhanced performance for the selective oxidation of alcohols and hydrocarbons to carbonyl compounds. In particular, the 20 V/M-ZrPO catalyst demonstrates excellent reusability and broad substrate compatibility. Relative to established catalytic materials, the 20 V/M-ZrPO catalyst demonstrated superior performance across key metrics including product yield, reaction time, and recyclability. These findings highlight the promise of V/M-ZrPO nanocomposites as efficient and durable catalysts for sustainable carbonyl compound production. [ABSTRACT FROM AUTHOR]

A series of ethylene/1-octene copolymers synthesized with diamine-bis(phenolate) complexes activated with Al(iBu)3/[Ph3C][B(C6F5)4] were subjected to preparative temperature rising elution fractionation (TREF). The complexes used differed in the type of metallic center (Zr or Ti) or the amine donor in the pendant arm of the ligand (NMe2 or NiPr2). The obtained fractions were then characterized via FTIR, DSC and GPC methods. It was found that all the copolymers had very broad chemical composition distributions, and the most heterogeneous was the copolymer produced by the titanium complex bearing a ligand with the NiPr2 donor group. The difference in the comonomer incorporation into the macromolecules of the fractions was as high as 8.3 mol%. The melting temperature and molecular weight of the fractions changed nearly linearly with the increased elution temperature. Copolymers produced by zirconium catalysts were also fractionated by molecular weight using the solvent/non-solvent technique with subsequent analysis of the fractions. It was shown that the fractions have a similar composition, low molecular weight distribution and very broad comonomer distribution. Therefore, the comonomer content in the fractions was not a function of the molecular weight as was observed for the copolymers synthesized with the Ziegler–Natta catalysts. [ABSTRACT FROM AUTHOR]

In this study, a mono-functional ZrO2 nanomaterial was treated with sulfur and loaded with two different percentages of platinum metals (i.e., 0.5 and 1 wt%) to generate an acidic bi-functional Pt/SZrO2 nanocatalyst for the purpose of increasing the catalytic activity and selectivity together. This work aims to determine the least amount of the costly platinum metal that can be added to the catalyst to achieve the appropriate balance between the acidic and metallic sites. Both rapid deactivation of the super-acid nanaocatalyst and fast cleavage of the zero-octane n-heptane chain can consequently be prevented throughout the reaction. This can be achieved by accelerating the hydroisomerization reactions at a pressure of 5 bar to reach the highest selectivity towards producing the desired multi-branched compound in fuel. Several characterization techniques, including XRD, SEM, EDX, BET, and FTIR, have been used to evaluate the physical properties of the catalysts. The best reaction product was obtained at 230 °C compared to the other tested temperatures. The conversion, selectivity, and yield of reaction products over the surfaces of the prepared catalysts followed this order: 0.5 wt% Pt/SZrO2 > 1 wt% Pt/SZrO2 > 0.5 wt% Pt/ZrO2 > 1 wt% Pt/ZrO2 > SZrO2 > ZrO2. The highest conversion, selectivity, and yield values were obtained on the surface of the 0.5 wt% Pt/SZrO2 catalyst, which are 69.64, 81.4 and 56.68 wt%, respectively, while the lowest values were obtained on the surface of the parent ZrO2 catalyst, which are 43.9, 61.1 and 26.82, respectively. The kinetic model and apparent activation energies were also implemented for each of the hydroisomerization, hydrogenation/dehydrogenation, and hydrocracking reactions, which track the following order: hydroisomerization < hydrogenation/dehydrogenation < hydrocracking. The lowest apparent activation energy value of 123.39 kJ/mol was found on the surface of the most active and selective 0.5% Pt/SZrO2 nanocatalyst. [ABSTRACT FROM AUTHOR]

This work constitutes a new trial to enhance the properties of palladium supported on alumina modified with zirconium used as catalysts for methane combustion. The effect of the support drying mode is studied. For this aim, Al2O3-ZrO2 binary oxides with zirconium loading of 2 and 5% in weight were prepared using sol–gel process then dried under ordinary or supercritical conditions. Palladium with a loading of 0.5% was deposited on the support by wet impregnation. Several techniques have been used to investigate differences between the two types of the derived catalysts. [ABSTRACT FROM AUTHOR]

Dry reforming of methane (DRM) bears great hope for the catalytic community as well as environmentalists for its potential to convert two greenhouse gases, CH4 and CO2, together into synthetic feedstock "syngas". The stable tetragonal zirconium yttrium oxide phase over the "Yttria‐zirconia supported Ni" catalyst (Ni/YZr) brings >70% CH4 conversion against 50% CH4 conversion over zirconia supported Ni catalyst) in 7 h time‐on‐stream (TOS). The use of the second metal oxide (MOx; M = Ho, Ga, Gd, Ba, Cs) in a small amount (4 wt%) over Ni/YZ catalyst is found to promote the catalytic activity further. Herein, we have prepared such metal‐promoted yttria‐zirconia supported Ni catalyst, employed them for DRM and characterized them with surface area porosity, X‐ray diffraction, spectroscopic techniques, temperature programmed techniques and transmission electron microscopy. A fine correlation of characterization results with catalytic activity brings out various useful information that would be useful for establishing yttria‐zirconia supported Ni catalyst for DRM. Ni stabilized over cubic zirconium holmium oxide phase in 5Ni4Ho/YZr catalyst, cubic zirconium gadolinium oxide phase in 5Ni4Gd/YZr catalyst and cubic zirconium barium oxide phase in 5Ni4Ba/YZr catalyst perform excellent toward DRM. Catalytically, 5Ni4Ho/YZr catalyst achieves CH4 conversion as high as ~85% whereas 5Ni4Ba/YZr and 5Ni4Gd/YZr show CH4 conversions of about ~80%. Even in 30 h TOS study, 5Ni4Ho/YZr catalyst showed >81% CH4 conversion with retaining highest H2/CO (0.97). [ABSTRACT FROM AUTHOR]

We report here the preparation and investigation of isolated Zr centers supported on a high surface area silica for the conversion of carboxylic acids to internal ketones by ketonic decarboxylation (ketonization) and the aldol condensation of ketones to dimeric enones. Catalysts were synthesized by the grafting of Cp2ZrCl2 on the surface of amorphous silica. The connectivity of Zr was characterized by XRD, UV-vis, and Raman spectroscopy. For the lowest Zr loading, Zr is present predominantly as isolated monomeric species. As the Zr loading is increased, a progressively larger fraction of Zr forms oligomeric species and ZrO2 nanoparticles. Measurements of catalytic activity show that the turnover frequency for carboxylic acid ketonic decarboxylation reaction and aldol condensation of ketones decreases monotonically with increasing Zr loading. An H/D kinetic isotope effect was not observed over isolated Zr catalysts, suggesting that α-H abstraction is not the rate-determining step, rather C-C bond forming may be rate limiting for both reactions. This conclusion is supported by computational modeling of the reaction mechanism. The proposed catalytic cycle for ketonization proceeds via a β-keto acid intermediate on isolated Zr sites that are always coordinatively saturated with C-C bond formation as the rate-limiting step. C-C bond formation is also rate-determining for aldol condensation, with an apparent activation energy that is in good agreement with the experiment if the resting state is a saturated ZrOH site with two adsorbed ketone molecules.

Methyl benzoate (MB) compounds are prepared by reacting various benzoic acids with methanol using an acidic catalyst. In this study, the solid acids of zirconium metal solids fixed with various substances were studied. We determined that zirconium metal catalysts with fixed Ti had the best activity. The catalytic synthesis of a series of MB compounds using titanium zirconium solid acids was studied. The direct condensation of benzoic acid and methanol using a metallic Lewis acid without other auxiliary Bronsted acids is reported for the first time. [ABSTRACT FROM AUTHOR]

In the realm of innovative materials for sustainable energy applications, the synergistic integration of metal oxides has the potential to revolutionize catalytic processes. In the pursuit of effective energy conversion, this study meticulously fabricated and evaluated binary ZrO2–Co3O4 oxides in different ratios (Zry:Co1−y where y = 0.1, 0.3, 0.7, 0.9) for electrocatalytic water oxidation. Through comprehensive characterization and electrochemical studies, the excellent activity of the optimized Zr0.1:Co0.9 oxide catalyst was uncovered. Our findings revealed that this composite exhibited a high current density of 658 mA cm−2 at a potential of 1.76 V vs. RHE. This robust catalyst demonstrated an overpotential of 260 mV to achieve a current density of 10 mA cm−2. Moreover high stability of catalyst was evident even after 48 h. The optimized catalysts with low zirconium content provided better active sites for enhanced efficiency. This research highlighted the synergistic effect of these metal oxides, offered significant potential for developing high-performance catalysts for water oxidation.Graphical abstract: In the realm of innovative materials for sustainable energy applications, the synergistic integration of metal oxides has the potential to revolutionize catalytic processes. In the pursuit of effective energy conversion, this study meticulously fabricated and evaluated binary ZrO2–Co3O4 oxides in different ratios (Zry:Co1−y where y = 0.1, 0.3, 0.7, 0.9) for electrocatalytic water oxidation. Through comprehensive characterization and electrochemical studies, the excellent activity of the optimized Zr0.1:Co0.9 oxide catalyst was uncovered. Our findings revealed that this composite exhibited a high current density of 658 mA cm−2 at a potential of 1.76 V vs. RHE. This robust catalyst demonstrated an overpotential of 260 mV to achieve a current density of 10 mA cm−2. Moreover high stability of catalyst was evident even after 48 h. The optimized catalysts with low zirconium content provided better active sites for enhanced efficiency. This research highlighted the synergistic effect of these metal oxides, offered significant potential for developing high-performance catalysts for water oxidation. [ABSTRACT FROM AUTHOR]

In this work the mechanism of L‐lactide polymerization promoted by NSSN zirconium complexes was investigated through DFT methods with the aim to understand as the electronic and steric features of the ligand affect the energy reaction. It was observed that the rate determining step of the process is the opening of the L‐lactide ring and that by increasing the steric hindrance, evaluated by changing geometric parameters and topographic steric maps, or the electron‐withdrawing properties of the ligand, the corresponding energy barrier increases. On the other hand, calculations foresee that a small and electron‐releasing substituent on the nitrogen atom of the ligand, such as the methyl group, is desirable in order to obtain NSSN zirconium based catalysts with improved activity in the ROP of the L‐lactide. [ABSTRACT FROM AUTHOR]

Tuning the coordination environments of metal single atoms (M1) in single‐atom catalysts has shown large impacts on catalytic activity and stability but often barely on selectivity in thermocatalysis. Here, we report that simultaneously regulating both Rh1 atoms and ZrO2 support with alkali ions (e.g. Na) enables efficient switching of the reaction products from nearly 100 % CH4 to above 99 % CO in CO2 hydrogenation in a wide temperature range (240–440 °C) along with a record high activity of 9.4 molCO gRh−1 h−1 at 300 °C and long‐term stability. In situ spectroscopic characterization and theoretical calculations unveil that alkali ions on ZrO2 change the surface intermediate from formate to carboxy species during CO2 activation, thus leading to exclusive CO formation. Meanwhile, alkali ions also reinforce the electronic Rh1‐support interactions, endowing the Rh1 atoms more electron deficient, which improves the stability against sintering and inhibits deep hydrogenation of CO to CH4. [ABSTRACT FROM AUTHOR]

Our work is around the heterogeneous catalysts based on phosphate. This is all the more important as Morocco has a significant wealth of world reserves of this mineral. This application of natural phosphate alone or modified, has been successfully generalized to many reactions (Claisen Schmidt condensation, selective hydration of nitriles...). And more precisely is around the zirconium phosphate catalyst, and its catalytic application in the synthesis of 2-arylquinazolin-4(3H)-ones through the study of physicochemical parameters in order to opt for the one that offers the most economic, ecological and technical advantages. [ABSTRACT FROM AUTHOR]

γ‐Valerolactone (GVL) is a renowned starting material in production of bio‐fuels, valuable chemicals and polymers. The one‐pot tandem synthesis of GVL from furfural without a cumbersome intermediate separation/purification process is highly desired, yet the transformation remains challenging owing to the complicated reaction routes. Zirconium phosphate (ZrPO), a cheap and easily prepared solid catalyst with Lewis–Brønsted dual acidity, is herein discovered to enable one‐pot tandem transformation of furfural into GVL with using 2‐propanol as H‐donor/solvent to proceed smoothly. In addition, ZrPO prepared by hydrothermal method exhibits superior catalytic performance in comparison with the counterpart prepared by co‐precipitation method, giving a 42.7% yield of GVL at 180 °C. The difference in catalytic activity between ZrPO materials prepared by hydrothermal method and co‐precipitation method is linked with their morphology and acid sites density. Furthermore, the as‐prepared ZrPO catalyst works in a heterogeneous manner and can be reused for multiple times without significant deactivation. © 2022 Society of Chemical Industry and John Wiley & Sons, Ltd [ABSTRACT FROM AUTHOR]

MnOx-CeO2, MnOx-ZrO2, MnOx-ZrO2-CeO2 oxides with the Mn/(Zr + Ce + Mn) molar ratio of 0.3 were synthesized by coprecipitation method followed by calcination in the temperature range of 400–800 °C and characterized by XRD, N2 adsorption, TPR, TEM, and EPR. The catalytic activity was tested in the CO oxidation reaction. It was found that MnOx-CeO2, MnOx-ZrO2-CeO2, MnOx-ZrO2 catalysts, calcined at 400–500 °C, 650–700 °C and 500–650 °C, respectively, show the highest catalytic activity in the reaction of CO oxidation. According to XRD and TEM results, thermal stability of catalysts is determined by the temperature of decomposition of the solid solution Mnx(Ce,Zr)1−xO2. The TPR-H2 and EPR methods showed that the high activity in CO oxidation correlates with the content of easily reduced fine MnOx particles in the samples and the presence of paramagnetic defects in the form of oxygen vacancies. The maximum activity for each series of catalysts is associated with the start of solid solution decomposition. Formation of active phase shifts to the high-temperature region with the addition of zirconium to the MnOx-CeO2 catalyst. [ABSTRACT FROM AUTHOR]

• Development of a green catalyst using abundant and low-cost materials. • Demonstrated 40.85 % increase in CO 2 desorption and 37.86 % reduction in energy consumption. • Showcasing remarkable stability over 50 absorption/desorption cycles. • Offering insights into sustainable clay-based catalysts for energy-saving carbon capture. The prevalent amine-based carbon capture technology faces scalability hurdles due to its considerable energy consumption during the regeneration process. To address this, an innovative, cost-effective catalyst using zirconium oxyhydroxide (ZrO(OH) 2) modified diatomite was developed in this work. The catalyst was tested in a 30 wt% monoethanolamine (MEA) solution at 87 °C, demonstrating a remarkable enhancement in CO 2 desorption efficiency. Specifically, the 1/4 Zr/D catalyst increased CO 2 desorption by 40.85 %, reduced desorption time by 25.25 %, and lowered energy consumption by 37.86 % compared to the non-catalyzed process. After 50 cycles of absorption and desorption, the catalyst demonstrated remarkable stability, rendering it a highly promising candidate for industrial-scale carbon capture applications. Characterizations of XRD, BET, FT-IR, NH 3 -TPD, and Py-IR revealed the catalyst's physicochemical properties and suggested a mechanism for its catalytic action. A possible catalytic mechanism is proposed as well. This study offers significant insights into the advancement of sustainable clay-based catalysts for efficient and energy-saving carbon capture processes. [ABSTRACT FROM AUTHOR]

• Nanostructures of ZrO x can be prepared by oxidizing Zr/Au(111) with O2 or CO2. • At < 0.05 ML, strong oxide-metal interactions prevent the growth of ZrO x islands. • ZrOx nanostructures react much better with CO2 and H2 than bulk zirconia. • Under mixtures of CO2/H2 formation of HCOO, CO3 and CH3O was detected on ZrO2/Au(111). In this study, the growth of ZrO x on Au (111) was investigated using scanning tunneling microscopy (STM) and synchrotron-based ambient pressure X-ray photoelectron spectroscopy (AP-XPS). Nanostructures of ZrO x (x = 1,2) at the sub-monolayer (≤ 0.3 ML) level were prepared by vapor depositing Zr metal onto Au (111) followed by oxidation with O 2 or CO 2. At low coverages of the admetal (< 0.05 ML), the formed ZrO x nanostructures were dispersed randomly on the terraces and steps of the Au(111) substrate. Strong oxide-metal interactions prevented the formation of islands of zirconia. The ZrO x nanostructures displayed a reactivity towards CO 2 and H 2 not seen for bulk zirconia. C 1 s AP-XPS results indicated that CO 2 molecules adsorbed on Zr/ZrO x /Au(111) surfaces could undergo partial decomposition on Zr (CO 2, gas → CO gas + O ads), or react with oxygen sites from ZrO x to yield carbonates (Zr-CO 3, ads). After exposing ZrO 2 /Au (111) surfaces to 1:3 mixtures of CO 2 :H 2 , the formation of HCOO, CO 3 , and CH 3 O was detected in AP-XP spectra. These chemical species decomposed at temperatures in the range of 400‒600 K, making them possible reaction intermediates for methanol synthesis. [Display omitted] [ABSTRACT FROM AUTHOR]

Organoboron compounds have extreme potential for organic synthesis. Ready functionalization of organoboron intrigued people to develop various protocols for their synthesis. Over the last several decades, there has been a substantial development in synthesizing new organoboron compounds using transition metals. Among various transition metals, zirconium has also been found to catalyze diverse reactions of organoboron. The zirconium chemistry has become more popular with the development of zirconium metallocenes, particularly bis(cyclopentadienyl)zirconocene chloride hydride, the well‐known Schwartz reagent. These zirconium metallocenes possess a significant role in hydrozirconation, hydroboration, hydrogenation, carbozirconation, and a promising tri‐n‐butyl tin hydride alternative. This minireview focuses on the various transformations of organoboron employing zirconium catalysts that have been developed so far. [ABSTRACT FROM AUTHOR]

Alkyl levulinates (AL), which are important biomass derivatives, have the potential of conversion into different valuable compounds. This study addressed the production of alkyl levulinate from xylose by applying mesoporous zirconium phosphates (AL-MZP-Pr-SO3H, MZP-Pr-SO3H), which served as good heterogeneous catalysts. The characterization of these catalysts was done using FT-IR spectroscopy, low and wide-angle XRD, N2 adsorption–desorption, ICP, TEM, and SEM. Then the impact of a large number of parameters, like the temperature of reaction, the time of reaction, the catalyst amount, and xylose initial amount was probed. The findings revealed that the maximum n-butyl levulinate yield was 82% at the temperature of 170 °C, after 6 h; meanwhile, the maximum ethyl levulinate yield was 49% at 150 °C, after 6 h. The catalysts can be easily separated from the reaction mixture and regenerated by a simple activation step, with the possibility of reusing at least four times without significant reduction in the catalytic activity. [ABSTRACT FROM AUTHOR]

The preparation conditions of silica‐supported metallocene catalysts impact the catalytic performance and consistency in ethylene polymerization. In a commonly used catalyst impregnation technique, the concentrations of catalyst solutions and the contact time between silica microparticles and catalyst solutions are used to ensure uniform and stable immobilization of coactivator methyl aluminoxane (MAO) and metallocenes. The overall catalytic activities for olefin polymerization, catalyst particle fragmentation, and the resulting polymer particle morphology depend upon the distribution of active catalyst sites within the silica catalyst particle. This work presents both experimental and theoretical modeling studies on the intraparticle spatial distribution of MAO and metallocene in highly porous silica microparticles for ethylene polymerization in a liquid‐slurry phase. The silica‐catalyst solution contact times and the catalyst solution concentrations are used as two major variables to vary the intraparticle catalyst site distributions. The overall aluminum and zirconium contents in the catalyst and their radial distributions are observed to be strongly affected by the impregnation conditions. A mathematical model is also derived for the catalyst impregnation process and it provides adequate predictions of the impregnation process characteristics. [ABSTRACT FROM AUTHOR]

In order to promote development of linear/branched block polyethylenes based on new catalytic systems, we synthesized a novel α-diimine nickel(II) complex with isopropyl substituents on ortho-N-aryl and hydroxymethyl phenyl substituents on para-N-aryl structures. The activity of α-diimine nickel(II) catalyst was 3.02×106 g·molNi−1·h−1 at 70 °C, and resultant polyethylene possessed 135/1000C branches. The linear/branched block polyethylenes were synthesized from ethylene polymerization catalyzed by the α-diimine nickel(II) complex/bis(phenoxyimine) zirconium in the presence of diethyl zinc. With the addition of ZnEt2 (from 0 to 400), the melting peak of resultant polyethylene changed from a single melting peak to bimodal melting peaks. The molecular weights of resultant polyethylene ranging from 26.8 kg/mol to 17.1 kg/mol and PDI values varying gradually from 24.4 to 15.2 were obtained via adjusting ZnEt2 equiv. and molar ratio of two catalysts. In addition, the branching degree of the polyethylene increased from 13/1000C to 56/1000C with the increase of the proportion of α-diimine nickel(II) catalyst. Using this binary catalyst system, the reaction temperature of chain shuttling polymerization can be carried out at 70 °C, which is more conducive to industrial application. [ABSTRACT FROM AUTHOR]

• A series of excellent properties NH 3 -SCR catalysts. • The introduction of Ce and Zr can increase SCR activity and anti-thermal aging in NOx abatement. • 6%Ce-2%Zr/Cu-ZSM-5 catalyst has an excellent SCR activity than Cu-ZSM-5 catalyst in the presence of water vapor. The effects of cerium and cerium + zirconium supported over Cu-ZSM-5 on SCR activity and anti-thermal aging performance in NOx abatement have been studied. X-ray diffraction, scanning electron microscopy, UV–vis diffuse reflectance, temperature-programmed technologies, Fourier transform infrared spectroscopy, and in-situ diffuse reflectance infrared Fourier transform spectroscopy were used to characterize the surface properties and transition-state species of the catalysts. The 6 %Ce-2 %Zr/Cu-ZSM-5 catalyst exhibits excellent NOx purification activity under dry and water vapor conditions and the best thermal aging resistance. Copper and zirconium species formed are in the nanometer size range and are well dispersed on the ZSM-5 surface, and cerium was formed with the low crystallinity of CeO 2 as an increase of cerium content. Cerium and zirconium addition improve copper dispersion and the cooperative effect between copper and cerium/zirconium. Zirconium can promote the presence of copper in the form of ionic state rather than oxides, improve copper species dispersion, assist to stabilize the framework of ZSM-5, and prevent copper cations precipitation sintering. There were no obvious correlations between acid site strength and the SCR catalytic activity. The NH 3 -SCR reaction over 6 %Ce-2 %Zr/Cu-ZSM-5 catalyst co-follows the Eley-Rideal and Langmuir-Hinshelwood mechanism. [ABSTRACT FROM AUTHOR]

Tin zirconium oxide catalysts (Sn-based TMO s) were successfully prepared with three different methods, ultrasonic-assisted hydrothermal, sol-gel, and traditional precipitation method, and applied for biodiesel production. The physicochemical and the catalytic efficiency by the esterification of stearic acid of the as-synthesized catalysts were investigated by different techniques. The production of biodiesel (as methyl stearate) has emerged as a greener and renewable substitute for petro based diesel fuel. The optimization of the esterification conditions for maximum yield of biodiesel was performed by studying different factors as the catalyst preparation method, reaction time, molar ratio of alcohol to stearic acid, reaction temperature, and the catalyst concentration. The preferred catalyst (SnZr h) was optimized as the reaction temperature of 120 °C, 150 M ratio of methanol to stearic acid, 0.2 g catalyst amount and reaction time of 60 min. The SnZr h catalyst exhibited 74% yield of methyl stearate. Also, the kinetic and thermodynamic studies of stearic acid esterification reaction were inspected. The reusability of the optimized tin zirconium oxide catalyst for seventh runs was professionally studied. The computational chemistry study showed that the interaction mechanism between the optimized catalyst and stearic acid was preferable between SnO 2 active sites and carbonic group of stearic acid. • (Sn-based TMOs) catalysts were prepared with three different methods and their physicochemical properties were studied.. • Their catalytic efficiency for biodiesel production was investigated. • Optimization of the esterification conditions, Kinetic, and thermodynamic studies were inspected.. • The reusability of the optimized catalyst for seventh runs was studied. • The mechanism was proposed and emphasized by computational chemistry study. [ABSTRACT FROM AUTHOR]

The present article reports the synthesis of a new magnetic mesoporous nanocomposite with core–shell structure, formulated as Fe3O4@MCM‐41@ZrCl2. The prepared reagent was successfully characterized using different types of methods. The combination of unique properties of MCM‐41 as an inimitable mesoporous compound, satisfying magnetic nature of the Fe3O4 magnetic nanoparticles and substantial catalytical applications of zirconium, caused the favorable efficiency of the intended nanocomposite in the synthesis of 1‐(benzothiazolylamino)phenylmethyl‐2‐naphthols via a multicomponent condensation reaction of 2‐aminobenzothiazole, 2‐naphthol, and aromatic aldehydes in absence of solvent in good to high yields (70–90%). Green conditions of the reactions, easy separation, practicability, product purity, reusability of the catalyst, affordability, and environmentally profits are the considerable advantages of this protocol. [ABSTRACT FROM AUTHOR]

In the recent years, considerable interest in the development of clean and renewable alternative energy resources has been observed to overcome the problems of dwindling fossil reserves, environmental pollution and increasing energy demand for a sustainable future. In this respect, hydrogen is considered a sustainable, clean, and energy-rich fuel. Photoelectrochemical (PEC) water-splitting is deemed to be a very promising technology hydrogen production. A number of research endeavors have been dedicated to develop efficient catalysts for this process. An optimum photoelectrocatalyst drives down the energy needed for the disassociation of water by lowering the overpotential of the process and make it competent for commercial applications. Recently, a lot of Zirconium (Zr) and Carbon (C) based compounds have been analyzed for PEC water-splitting. This review article intends to offer insight and timely reference for the progress on Zr and C based catalyst for practical PEC water-splitting in a comprehensive and concise manner. With emphasis on the photoelectrochemical performance, relative design strategies and different approaches to improve or optimize the photoelectrocatalyst materials with Zr and C are discussed. Research approach and recommendations for future PEC water-splitting are also proposed. [Display omitted] • Critical review related to sustainable production of hydrogen from abundantly available feedstock (water). • Recent research on emergent catalyst based on Zirconium (Zr) and Carbon (C) are summarized for water-splitting application. • Presents comprehensive progress on Zr and C-based catalyst and their characteristic vis-a-vis efficiency for water splitting. [ABSTRACT FROM AUTHOR]

A hollow core–shell magnetic zirconium hydroxide catalyst was synthesized and employed for the catalytic transfer hydrogenation (CTH) ofnumerous biomass-derived platform molecules (furfural and other carbonyl compounds). 93.9% conversion of furfural and 97.3% selectivity of furfuryl alcohol was achieved under mild reaction conditions (160 °C, 4 h, 0.1 g catalyst) with 2-propanol as the H-donor. After 7 times of reaction cycles, the catalyst retained excellent conversion (91.1%) and selectivity (97.8%) and no structural damage was found. Furthermore, a scale-up experiment was carried out, and the results proved that the catalyst has a prospect for industrial applications in the CTH reaction. [ABSTRACT FROM AUTHOR]

This paper reported thermal properties of ethylene copolymers with di- and tri-alkenylsilsesquioxanes (POSS) synthesized by bis(phenoxy-imine) Ti, Zr, V, and V salen-type complexes. Ethylene copolymers with multi-alkenyl POSS obtained by such complexes contain multi-alkenyl POSS incorporated into the polymer chain as a side group. They were characterized by different thermal behavior depending on the kind of multi-alkenyl POSS comonomer, and type of the catalyst used, as well as polymerization conditions and thus the structure of the copolymer chain. Ethylene/POSS copolymers differed in incorporation of POSS into the polymer chain, content of specific unsaturation groups, and molecular weight, as well as heterogeneity of polymer chain compositions. The incorporation of multi-alkenyl POSS into the polymer chain affected melting and crystallization processes of copolymers in different ways. The POSS units could act as a nucleating agent of macromolecules. The increasing POSS content in E/POSS copolymers resulted in increasing thermal stability of obtained products, regardless of the kind of multi-alkenylsilsesquioxanes used. Thermal stability of such copolymers increased with decreasing content of trisubstituted vinylene groups (internal saturations) as well. The highest improvement of thermal stability over 85 °C in comparison with PE was observed in case of E/POSS copolymers synthesized by bis(phenoxy-imine) zirconium catalyst. The composition heterogeneity of E/POSS copolymers was found to affect markedly thermal stability of E/POSS copolymers. [ABSTRACT FROM AUTHOR]

Stereoblock polypropylenes bearing isotactic, atactic, and syndiotactic polypropylene segments were successfully prepared by dry methyl aluminoxane activated binary catalysts system, Ph2CFluCpZrCl2 and {Me2Si(2,5-Me2-3-(2-MePh)-cyclopento[2,3-b]thiophen-6-yl)2}ZrCl2, in the presence of iBu3Al as a chain shuttling agent. By studying the catalyst activity, chain transfer efficiency, and reversibility of chain transfer reaction of each catalyst system, as well as the molecular weight and polydispersity of the resulting polymers, the alkyl exchange reactions between the zirconium catalyst and different main-group metal alky were estimated, respectively. Based on the optimized react condition, the chain shuttling polymerization was conducted by binary catalyst system in the presence of iBu3Al under both atmospheric and high pressure. Resultant polymers were identified as stereoblock polypropylenes according to microstructure and physical properties analyses by 13C{1H}-NMR, DSC, and GPC. [ABSTRACT FROM AUTHOR]

• KITZx catalysts were synthesized with different Si/Zr molar ratio. • These catalysts were characterized by various methods and used in the production of butyl levulinate from xylose. • The good yield of butyl levulinate reached 87.7% over KITZ20 under optimal conditions. • The selected catalyst was recycled and reused for several times. Organic intermediates, like n-butyl levulinate, have a widespread application, especially in organic synthesis. Thus, direct synthesis of n-butyl levulinate from xylose was investigated over the mesoporous zirconium silicate catalysts (KITZx (X = 20,10)). The catalysts were identified through various methods like FESEM, EDS, XRD, FT-IR, nitrogen adsorption-desorption, ICP-AES, and NH 3 -TPD). An integrated catalytic protocol includes dehydration, and alcoholysis led to the selective formation of n-butyl levulinate and gave a yield of 87.7% over KITZ20 under optimal conditions. Various reaction parameters, for example, the effect of temperature, reaction time, the influence of the catalyst, and the amount of xylose were investigated. The spent catalyst can be effectively recovered after the thermal regeneration of KITZ20 and has good reusability. [ABSTRACT FROM AUTHOR]

• Effects of V content on properties of V-doped ZrO 2 (VZrO- x) were investigated. • Incorporation of V dopant in Zr lattice generated more Zr cus 4+ cations. • VZrO- x showed superior PDH activity and recyclability than pure ZrO 2. • Deactivation of VZrO- x was suppressed by co-feeding hydrogen. Bulk ZrO 2 is a highly active and selective catalyst for dehydrogenation of propane (PDH), in which coordinatively unsaturated Zr cations (Zr cus 4+) serve as active sites. Substitution of dopant ions into Zr lattice can improve its catalytic activity by generating more Zr cus 4+ sites. In this work, a series of vanadium-doped ZrO 2 metal oxides (VZrO- x) have been prepared and the influences of vanadium content on their properties have been systematically investigated. Various characterization techniques showed that an appropriate amount of vanadium dopant helps more Zr cus 4+ sites to be created by a structural transformation and H 2 pretreatment. However, excess vanadium dopant led to a negative effect on the catalytic activity owing to the formation of bulk-like V 2 O 5 crystallites. The catalytic activity of VZrO- x is well correlated with the amount of Lewis acid sites because Zr cus 4+ cations correspond to Lewis acid sites. The VZrO-8 catalyst exhibited two times higher activity than pure ZrO 2. Moreover, for repeated cycles the activity was totally recovered by oxidative regeneration followed by reductive pretreatment. Finally, the performance test results showed that H 2 co-feeding can further enhance the activity by suppressing coke deposition during PDH. [ABSTRACT FROM AUTHOR]

Stearic acid (SA) and urea (U) are very potential for use in stearamide production through the amidification process. Using metal catalyst zirconium tetrachloride and 2-propanol with n-hexane as a mixed solvent, parameters such as substrate molar ratio, catalyst concentration, and solvent ratio have been varied to maximize the yield of stearamide. Response Surface Methodology (RSM) is supported by Central Composite Design (CCD) was applied to determine the optimum parameter value that produces the maximum conversion of stearic acid. Results showed that the regression model can be used and shows a very strong relationship between parameters which is characterized by the value of R² (0.9207) was high and the p-value of the interaction of variance was <0.05. According to this model, increasing of the substrate molar ratio and catalyst concentration leads to increasing the conversion of stearic acid, and the highest yield of stearamide concentration was obtained at substrate molar ratio of 8/1 (U/SA), catalyst concentration of 4% (w/wSA) and the solvent ratio of 1/1 (v/wSA). The highest conversion of stearic acid was found to be 90%. [ABSTRACT FROM AUTHOR]

• α-Olefins are important bulk and fine chemicals employed for the synthesis of plastics, detergent alcohols and lubricants for instance. The synthesis of α-olefins from ethylene, an abundantly available and inexpensive feedstock, is highly attractive, is carried out in megaton scale annually and is a key application of homogenous catalysis. Unfortunately, the synthesis of branched olefins is challenging especially in direct or so call on-purpose synthesis. We recently reported a molecular Ti catalyst (Science 2022) permitting the selective reaction between an α-olefin and two ethylene molecules to overcome this problem. Unfortunately, the synthesis of the Ti pre-catalyst(s) is very challenging preventing easy derivative modifications to fully exploiting the potential of the novel reaction. • We report on an easily accessible zirconium catalyst that permits the co-oligomerization of 1-hexene and ethylene. • We report synthesis and structure of six novel Zr precatalysts. • Some of the Zr catalyst systems introduced here show an extremely high activity in ethylene homo-oligomerization. Selective co-oligomerizations between α-olefins and ethylene are of high interest since they allow to extend the α-olefin scope employing inexpensive and abundantly available ethylene. Here we report on an easily accessible zirconium catalyst that permits the co-oligomerization of 1-hexene and ethylene with an activity of 2200 kg/mol h bar and a co-oligomer selectivity of 65 mol%. In more detail, we report synthesis and structure of six novel Zr precatalysts, their ethylene homo-oligomerization behavior and the co-oligomerization of the most promising of the six precatalysts. Criteria were activity and selectivity (α-value). Some of the Zr catalyst systems introduced here show an extremely high activity in ethylene homo-oligomerization up to 96,600 kg/mol h bar. [ABSTRACT FROM AUTHOR]

Oxidative desulfurization (ODS) emerges as a critical player in enhancing efficient fuel desulfurization and promoting sustainable clean energy. Metal-organic frameworks (MOFs) show great potential as ODS catalysts because of their exceptional porosity and versatility. This study explores the use of amorphous metal-organic frameworks (aMOFs), which combine MOFs' structural advantages with unique properties of amorphous materials, to enhance catalytic efficiency in ODS. Traditional methods for synthesizing MOFs rely on solvent-thermal or solvent-free methods, each with limitations in environmental impact or scalability. To address this, we introduce a novel strategy utilizing a small quantity of benzoic acid (BA) modifier to facilitate the solvent-free, one-pot, mechanical synthesis of amorphous zirconium terephthalate (GU-2BA-3h). The resulting GU-2BA-3h demonstrates exceptional ODS performance, efficiently removing 1000 ppm of dibenzothiophene (DBT) in just 6 min at 60 °C. Amorphous GU-2BA-3h features an expanded external surface area, increased acidic sites, and exceptional stability, resulting in a high turnover frequency (19.6 h−1) and outstanding catalytic activity (53.2 mmol g−1 h−1), establishing it as a highly efficient ODS catalyst. This remarkable performance arises from the formation of dangling carboxyl groups and active metal sites due to the competitive coordination of benzoic acid with the linker. Experimental evidence confirms that these carboxyl groups and exposed Zr-OH sites interact with oxidants, generating hydroxyl radicals that effectively eliminate sulfur-containing compounds. Furthermore, the methodology exhibits universality in constructing amorphous Zr-based MOFs, and provides an eco-friendly, cost-effective route for efficient ODS catalyst production. [Display omitted] • Solvent-free, modulator-assisted, one-pot mechanochemical synthesis for defect-rich amorphous zirconium terephthalate materials. • Superior activity for ODS (1000 ppm DBT complete desulfurization at room temperature within 30 min). • Excellent stability, high external surface area, large average pore size and abundant Lewis acid sites. • Suspended carboxyl groups and defective metal sites enhancing the decomposition of H 2 O 2 , generating hydroxyl radicals. [ABSTRACT FROM AUTHOR]

• CH 3 OH selectivity of 71.8% and TOF CO2 = 13.4 s−1 are achieved over CuO/Ce 0.4 Zr 0.6 O 2. • Surface metallic Cu is active to improve H 2 adsorption. • Cu-Ce-Zr solid solution is benefit to enhance CO 2 adsorption. • Both m-HCOO* and bi-HCOO* are active intermediate species for CO 2 hydrogenation to CH 3 OH. • The accumulation of m-HCOO* is a slow and key step for CO 2 hydrogenation to CH 3 OH. A series of ternary copper-cerium-zirconium catalysts containing two kinds of copper species, surface CuO and Cu-Ce-Zr solid solution, are prepared and studied for catalytic properties of CO 2 hydrogenation to methanol. The copper-cerium- zirconium catalyst calcined at 450 °C (CCZ-450) is much more favorable for improving the nature of surface CuO species and forming Cu-Ce-Zr solid solution than others. The best catalytic behavior in terms of methanol selectivity (T = 280 °C, S CH3OH = 71.8%), turnover frequency (TOF CO2 = 13.4 × 10−2 s−1) and activation energy (E a = 28.5 kJ/mol) are achieved using CCZ-450. The excellent catalytic performance of CCZ-450 is attributed to the stronger H 2 adsorption ability arising from highly dispersed surface CuO specie with higher copper surface area and higher concentration of active bi/m-HCOO* intermediate caused by the formation of Cu-Ce-Zr solid solution. Both the dispersion and surface area of active sites and the activation abilities of CO 2 are critical for catalyst activity and product selectivity. In situ diffuse reflectance infrared fourier transform spectroscopy (DRIFTS) experiments at 3 MPa confirm that both bi-HCOO* and m-HCOO* are the active intermediates for CO 2 hydrogenation to methanol. The accumulation of m-HCOO* on the catalyst surface is the crucial step of CO 2 hydrogenation to methanol. [ABSTRACT FROM AUTHOR]

The first example of an efficient and direct dehydrogenative boration of alkenes for vinyl boronate ester synthesis was achieved using a zirconium catalyst. Our methodology avoids using precious transition metals, additional hydrogen acceptors, high temperatures, and long reaction times, which were required to overcome the reducing ability of borane, to give alkyl boronate esters. Detailed mechanistic studies revealed a reversible reaction pathway and further suggested applying the zirconium complex as a "shuttle catalyst" for transfer boration, which thus sidesteps the use of relatively sensitive borane. [ABSTRACT FROM AUTHOR]

Ni based phosphate zirconium catalysts were prepared by impregnation technique and used under CH 4 dry reforming conditions. Catalysts (x%Ni/8%PO 4 –Zr, where x = 5, 10, 15 or 20) were characterized by nitrogen physical adsorption-desorption, X-ray diffraction, temperature programmed reduction, CO 2 and NH 3 temperature programmed desorption, thermal gravimetric analysis and transmission electron microscopy (TEM-EDAX). Catalysts displayed a typical mesoporous structure and different reducibility grade as a function of Ni loading, diagnostic of a different extent of metal-support interaction. Activity and stability strongly depend upon Ni loading while the best performance was observed for catalyst characterized by a Ni loading of 10 wt%. The CO 2 -TPD profiles of spent catalysts indicated that such catalyst had more tendency to gasify coke formed over the catalyst surface. TGA analysis of used catalysts quantitatively showed that catalysts at higher Ni loading deactivated as result of huge graphitic carbon formation on catalyst surface. On the contrary, system 10%Ni8%PO 4 /ZrO 2 turns out to be an excellent candidate to conduct the methane reforming reaction with CO 2 without coke formation at high CH 4 and CO 2 conversions. Phosphate play a fundamental role in promoting Ni–ZrO 2 interaction which reflects in the stabilization of catalytic system against metal sintering and coke formation. • Ni supported on phosphate-zirconia with loading (5-20 wt%) were synthesized. • The effect of phosphate modified zirconia was investigated. • The catalyst with 10 wt% Ni loading exhibited the best performance. • Phosphate modification enhanced Ni–Zr interaction and thus improved coke resistance. [ABSTRACT FROM AUTHOR]

Catalytic transfer hydrogenation (CTH) of the C=O bond has been considered to be one of the most important processes for the synthesis of fuels and chemicals. In this study, zirconium hydroxyphosphonoacetate (Zr‐HPAA) was synthesized by solvent‐thermal method for the transfer hydrogenation of furfural (FF) to furfuryl alcohol. As expected, the Zr‐HPAA, which comprises P−O‐Zr and C−O‐Zr linkages, shows high activity for catalytic transfer hydrogenation of FF to FA. Besides, the effects of time, temperature, catalyst dosage and solvent on the reaction were investigated in detail, with FF conversion (98%) and FA yield (96%) at 150 °C in 1.5 h. The activation energy (Ea) of the reaction was calculated as 47.04 kJ/mol and the lower activation energy was associated to the high catalytic activity of Zr‐HPAA. It is easy to separate catalyst after the reaction and the catalyst exhibits high activity for at least five reaction cycles. [ABSTRACT FROM AUTHOR]

In principal, the direct copolymerization of ethylene with polar comonomers should be the most efficient means to introduce functional groups into conventional polyolefins but remains a formidable challenge. Despite the tremendous advances in group 4‐centered catalysis for olefin polymerization, successful examples of ethylene + polar monomer copolymerization are rare, especially without Lewis acidic masking reagents. Here we report that certain group 4 catalysts are very effective for ethylene + CH2=CH(CH2)nNR2 copolymerizations with activities up to 3400 Kg copolymer mol−1‐Zr h‐1 atm‐1, and with comonomer enchainment up to 5.5 mol % in the absence of masking reagents. Group 4 catalyst‐amino‐olefin structure–activity‐selectivity relationships reflect the preference of olefin activation over free amine coordination, which is supported by mechanistic experiments and DFT analysis. These results illuminate poorly understood facets of d0 metal‐catalyzed polar olefin monomer copolymerization processes. [ABSTRACT FROM AUTHOR]

Abstract Nickel on zirconium oxide catalyst showed a high activity for the transfer hydrogenation of methyl levulinate and levulinic acid to γ-valerolactone (GVL) using 2-propanol as a hydrogen donor. The GVL yield of 94% at 373 K and 92% even at 363 K were attained for the hydrogenation of methyl levulinate. For the hydrogenation of levulinic acid, the GVL yield of 86% was attained at 393 K. The studies of the reactions on each component, i.e., nickel or ZrO 2 showed that nickel in the Ni/ZrO 2 catalyst largely contributed to the hydrogenation of the substrate and ZrO 2 had a high activity for the lactonization of the hydrogenated product. Graphical abstract Unlabelled Image Highlights • Transfer hydrogenation of methyl levulinate and levulinic acid to γ-valerolactone • The yield of 92% even at 363 K were attained for the hydrogenation of methyl levulinate. • Ni mainly contributed to the hydrogenation and ZrO 2 contributed to the lactonization. [ABSTRACT FROM AUTHOR]

Mixed oxide catalysts yMn-Zr-Ti (y/10/10 with y = 1, 3, 5, 7 and 9) for the selective catalytic reduction (SCR) of NOx with NH3 in the presence of oxygen were synthesized by co-precipitation. The catalyst 5Mn-Zr-Ti exhibited a catalytic activity higher than 87% above 160 °C and N2 selectivity above 92% at 100-300 °C. The SCR performance was quite stable at 180 and 200 °C for 15 h. Mn species are shown to improve the catalytic activity by providing more surface labile oxygen, while a synergistic effect among Mn, Zr and Ti species suppressed the generation of N2O. According to in situ DRIFT analysis, NOx was primarily reduced by the reaction of bidentate nitrate and monodentate nitrito species with adsorbed NH3. Subsequently, a comprehensive reaction mechanism was proposed. Accordingly, the formation of NH species was inhibited, and hence, the N2O formation by the reaction of NH and bidentate nitrate was suppressed. Furthermore, the investigation of the deactivation mechanism by SO2 indicated that both the deposition of ammonium sulfates and the sulfation of Mn active sites resulted in the deactivation of the catalyst 5Mn-Zr-Ti. The deposition of ammonium sulfates at 180 °C was more pronounced than that at 220 °C. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract A series of ZrO 2 supports were treated by ammonia solution with different reflux digestion time, and loaded 25 wt% MoO 3 for sulfur-resistant CO methanation reaction by incipient-wetness impregnation method. The MoO 3 /ZrO 2 catalysts were also characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), infrared spectra of adsorbed pyridine (Py-IR). Compared to the undigested ZrO 2 , ZrO 2 with reflux digestion in ammonia solution could achieve more oxygen vacancies, less Lewis acidic sites, smaller crystalline MoO 3 and more amount of active sites. Generally, when the support reflux digested in ammonia solution exceed 12 h, the CO conversion of digested catalysts Mo/A-ZrO 2 - x h reached 60%, while the CO conversion of undigested catalysts was just 36% at the same reaction condition. [ABSTRACT FROM AUTHOR]

• Zr-BEA zeolite has good acetaldehyde aldol condensation selectivity to crotonaldehyde (over 85%). • Zr site coverage and pore blocking are the dominant reasons for the deactivation mechanism. • Carbonaceous deposits are mainly unsaturated aldehydes, unsaturated ketones, and aromatic species. Zr-BEA zeolite was introduced to the aldol condensation of acetaldehyde and showed high crotonaldehyde selectivity (over 85%), but it suffered from rapid deactivation, where the conversion of acetaldehyde decreased from 16.4% at 1 h to 6.5% at 8 h. The spent Zr-BEA zeolites at different time-on-stream (TOS = 1, 2, 4, 6, and 8 h) were characterized by SEM, XRD, XPS, FT-IR, TGA, N 2 physical adsorption, and GC–MS to understand the deactivation mechanism. Pore blocking and Zr active site coverage caused by carbonaceous deposits were both responsible for the deactivation. Furthermore, the main carbonaceous species were unsaturated aldehydes, unsaturated ketones, and aromatic compounds. [Display omitted] [ABSTRACT FROM AUTHOR]

Molybdenum carbide catalysts supported on monoclinic and tetragonal zirconium oxide were studied for hydrogen production through aqueous phase reforming of ethanol. Catalysts were characterized by N 2 physisorption, XRD, TPR and XPS. Results showed that 10%Mo 2 C/m-ZrO 2 was less carburized and had a lower surface area than 10%Mo 2 C/t-ZrO 2 and 10%MoC/t-ZrO 2. Mo oxide was identified on the surface as well as two types of Mo oxycarbide and Mo oxynitride. The α crystalline phase of the carbide was more active than β phase and was ascribed to its higher relative superficial distribution. However, the α phase generated less H 2 probably because there was less oxycarbide presence. 10%Mo 2 C/m-ZrO 2 produced significantly more H 2 and was stable for five consecutive reactions. This catalyst showed higher carburization degree after the reaction, which greatly enhanced the generation of H 2 , suggesting that carbides species improved H 2 production compared to oxycarbides. [Display omitted] • Mo carbides and oxycarbides favor H 2 production through aqueous phase reforming. • β carbide phase showed higher H 2 selectivity but less activity than α phase. • Zirconium oxide has oxygen vacancies that might have enhanced Mo 2 C H 2 selectivity. [ABSTRACT FROM AUTHOR]

This study explores the novel production of high-performance glass ceramics (GCs) by harnessing readily available and cost-effective raw materials schist, dolomite, and magnesite for the first time. The nominal composition for the base glass, G (30) , was designed based on the eutectic composition of the diopside-anorthite ratio with 30% enstatite content within the quaternary CaO-MgO-Al 2 O 3 -SiO 2 system. To enhance nucleation, chromium (Cr 2 O 3) and zirconium (ZrO 2) oxide were separately introduced into the base glass batch in two ratios (0.5% and 1%), producing four additional batches-Cr (0.5) , Cr (1) , Zr (0.5) , and Zr (1) , orderly. All these batches were melted at temperatures ranging from 1450 °C to 1550 °C then cast into glass discs and rods. Double-stage heat treatment schedule, 750 °C /2 h followed by 950 °C and 1050 °C/1 h separately, was employed to induce the transformation of prepared glass into GCs. X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) techniques were applied to orderly investigate the developed crystalline phases and the prevailing micro-structures of the prepared GCs. The glass ceramic with the highest Cr 2 O 3 ratio, Cy (1) which was treated at 1050 °C/1 h, displayed the most adequate microstructure and minimal pore formation in comparison with other GCs. As well, the favorable physicochemical properties, Vickers microhardness (6.43 GPa), low thermal expansion coefficient (0.171 ×10 −6 °C−1) at 29–100 °C, and the exceptional resistance for acid and alkali corrosion (95%), nominate such GS sample, Cy (1) , for several architectural applications. • Mica schist was used as novel material to prepare glass ceramics materials. • Glass compositions were prepared within the (CaO-MgO-Al 2 O 3 -SiO 2) system. • The MgO-rich phase was crystallized into forsterite upon heat treatment. • Cr 2 O 3 nucleation catalyst promote volume crystallization of glasses. • ZrO 2 has a general detrimental effect on the glass ceramic microstructure. [ABSTRACT FROM AUTHOR]