One-pot fabrication of vanadium-doped ordered mesoporous zirconium oxophosphate catalyst for the synthesis of carbonyl compounds

Abstract

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.

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1. Introduction

Carbonyl compounds serve as indispensable precursors for the synthesis of various fine chemicals and pharmaceuticals.^1–3 A widespread and effective route for carbonyl production involves selective oxidation of alcohols and hydrocarbons.^4–7 Although homogeneous catalysts enable such oxidations with high activity and selectivity, challenges related to catalyst separation and reactor engineering have motivated the pursuit of heterogeneous catalytic systems.^8–10 In particular, transition metal catalysts have emerged as an economical and environmentally-friendly alternative to homogeneous counterparts.^11–13 Among prospective metals, vanadium exhibits favorable redox properties^14–16 and coordination chemistry for oxidation reactions. For example, Rezaei et al. demonstrated the efficacy of vanadium phosphate species supported on rosebud-shaped silica for the oxidation of toluene to benzaldehyde.¹⁷ Additionally, Li et al. utilized zirconium phosphate-supported vanadium catalysts to selectively oxidize glycerol under aerobic conditions.¹⁸ Nevertheless, high loadings are generally required to achieve adequate catalytic activity, and few studies have explored the incorporation of vanadium species into ordered mesoporous supports.^19,20

Beyond the nature of active sites, the number of accessible sites also critically impacts catalytic performance.^21–23 Structured mesoporous materials possess regular pore patterns, consistent pore widths, and large exposed surfaces - features that have generated significant interest for catalytic applications. The extensive porous network enables homogeneous dispersion of active components throughout the support framework, providing abundant active sites for reactant adsorption and conversion. Consequently, the rational design of vanadium-doped mesoporous architectures could yield optimized heterogeneous catalysts.

Herein, we synthesized a series of vanadium-doped ordered mesoporous zirconium phosphate (V/M-ZrPO) nanocomposites using an altered single-step self-assembly approach. The influence of precise vanadium loadings on the textural, chemical, and catalytic properties is investigated systematically. Our findings confirm the successful incorporation of highly dispersed vanadium species into the parent M-ZrPO material. Introduction of accessible and uniform vanadium sites significantly enhances the catalytic performance for selective alcohol and hydrocarbon oxidations to generate carbonyl compounds. Notably, the 20 V/M-ZrPO catalyst demonstrates remarkable reusability alongside broad substrate compatibility. These results signify V/M-ZrPO composites as promising heterogeneous catalysts for sustainable carbonyl production.

2. Experiment

2.1 Materials

Zirconyl chloride octahydrate (ZrOCl₂·8H₂O, Aladdin Chemistry Co. Ltd), C₂H₅OH (Sinopharm Chemical Reagent Co. Ltd), ammonium metavanadate (NH₄VO₃, Aladdin Chemistry Co. Ltd), trimethyl phosphate (PO(OCH₃)₃, Aladdin Chemistry Co. Ltd), Pluronic P123 (M_av = 5800, Sigma Aldrich), and ultrapure water (18.2 MΩ) were used in this study. Alcohol substrates including 1-phenylethanol, 4-methoxybenzyl alcohol, benzyl alcohol, cyclohexanol, cyclohexanemethanol, cyclopentanol, diphenylmethanol, and hydrocarbon substrates such as 1,4-diethylbenzene, ethylbenzene and diphenylmethane were purchased from Aladdin Chemistry Co. Ltd.

2.2 Fabrication of V/M-ZrPO materials

The V/M-ZrPO nanocomposites were fabricated through a modified one-pot evaporation-induced self-assembly approach. Specifically, Pluronic P123 was utilized as the structure-directing agent, while ZrOCl₂·8H₂O, NH₄VO₃, and PO(OCH₃)₃ served as the respective precursors for Zr, V, and P. The detailed protocol for the preparation of V/M-ZrPO was presented here: first, about 1.18g P123 was dissolved in 15 mL pure ethanol under 1 hour stirring to achieve a transparent solution. Subsequently, defined amounts of ZrOCl₂·8H₂O and NH₄VO₃ (totally as 5 mmol), along with 3.75 mmol of trimethyl phosphate, were sequentially added to the mixture. With stirring for 6 hours, the reaction solution was moved to a Petri dish and subjected to evaporation-induced self-assembly at 65°C for 2 days, followed by 100°C for 1 day. The obtained xerogel was then heated at 500°C for 5 hours, with a increasing rate of 1 °C min⁻¹. The final V/M-ZrPO materials were denoted as XV/M-ZrPO, where X refers to the molar percentage of vanadium.

2.3 Characterization

Powder X-ray diffraction (XRD) patterns were collected using a Bruker D8 Advance diffractometer equipped with a Cu Kα radiation source (40 kV, 40 mA, λ = 0.15406 nm). Small-angle XRD was performed at 2θ angles from 0.6° to 5.0°, while wide-angle XRD scanned 2θ angles from 10.0° to 80.0°.

Nitrogen physisorption experiments were carried out at −196 °C using a Micromeritics 3Flex surface characterization analyzer. Prior to measurements, samples were degassed at 300 °C for 2 hours under vacuum.

(High-resolution) Transmission electron microscopy ((HR)TEM), energy dispersive X-ray spectroscopy (EDS), as well as elemental mapping were performed on a FEI TECNAI G2 F20 instrument working at 200 kV.

Raman spectra were obtained using a LabRam HR instrument that has a charge-coupled device (CCD) detector under 532 nm laser over the spectral from 100 to 1500 cm⁻¹ at room temperature.

UV-visible (UV-vis) spectra were recorded from 200 to 800 nm using a PE Lambda 650S spectrophotometer at ambient conditions.

Temperature-programmed reduction (TPR) experiments were performed using a Chembet PULSAR TPR/TPD analyzer (Quantachrome Instruments). Typically, 0.1 g Samples were heated from 40–950 °C at a ramp rate of 20 °C min⁻¹ with a flow of 40 mL min⁻¹ 5% H₂/Ar.

X-ray photoelectron spectroscopy (XPS) was carried out using a Thermo Scientific ESCALAB 250Xi instrument. The obtained P, Zr, V, and O spectra were calibrated according to the C 1s peak (284.8 eV).

Gas chromatography–mass spectroscopy (GC-MS) instrument (Agilent-7890B-7000D) was employed to identify the reaction products.

Inductively coupled plasma (ICP) was conducted on a Thermo Fisher iCAP PRO(OES).

2.4 Electrochemical characterization of V-M-ZrPO in oxidizing reaction

Catalytic oxidation reactions were examined in a 50 mL round-bottom flask loaded with V/M-ZrPO catalyst, acetonitrile solvent, and 1-phenylethanol substrate successively. The oxidant tert-butyl hydroperoxide (TBHP) was subsequently introduced, marking the start of the reaction. Reaction progress was monitored by analyzing substrate conversion and product selectivity using a Shimadzu GC-2010Plus gas chromatography instrument, which is equipped with a flame ionization detector (FID) as well as a Rtx Wax column (50 m × 0.32 mm × 0.25 μm). For recycling studies, the spent catalyst was recovered via centrifugation after each run and calcined at 500°C in air for 3 hours prior to the next use.

3. Results and discussion

3.1 Ordered mesoporous structure

The structure of the V-M-ZrPO materials was investigated using small-angle X-ray diffraction (SAXD), N₂ physisorption, and pore-size distribution (PSD) analysis. As depicted in Fig. 1a, a distinct diffraction peak at around 1° corresponds to the (100) reflection of a two-dimensional hexagonal mesostructure with p6mm symmetry.^24,25 The presence of this peak in all samples indicates a well-defined long-range ordering of the mesopore lattice. Introduction of V species, however, resulted in a shift of the (100) peak to lower angles and peak broadening, signifying unit cell expansion and reduced crystallite size. The d₁₀₀-spacings calculated using Bragg's Law are tabulated in Table 1.

Fig. 1 (a) Low-angle X-ray diffraction, (b) N₂-physisorption, and (c) pore size distribution of V/M-ZrPO series.

Table 1 Textural properties and content of different elements

Samples	SAXD	N2-physisorption			Contents obtained from XPS (at%)
	d 100 (nm)	Specific surface area^b (m^2 g^−1)	Pore size^c (nm)	Pore volume^d (cm^3 g^−1)	V	Zr	P	O
a Acquired from XRD patterns using Bragg's law. b The specific surface area was calculated via the Brunauer–Emmett–Teller (BET) method with the relative pressure ranging from 0.05 to 0.30. c The pore size was obtained from the adsorption branch of isotherms by using Barrett–Joyner–Halenda (BJH) method. d The pore volume was determined from the amount of nitrogen adsorbed at a relative pressure of 0.990.
0 V/M-ZrPO	8.83	163	5.63	0.22	0.0	16.2	14.6	69.2
5 V/M-ZrPO	9.29	190	6.64	0.26	1.6	15.1	14.0	69.3
10 V/M-ZrPO	9.49	179	6.57	0.30	2.0	15.9	13.6	68.5
15 V/M-ZrPO	9.70	205	6.57	0.28	2.8	14.7	13.6	68.9
20 V/M-ZrPO	9.70	175	6.55	0.29	3.4	14.7	12.1	69.8

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The N₂ sorption isotherms shown in Fig. 1b present a type IV behavior with hysteresis loops of H1-type^26,27 within 0.4–0.7 P/P₀, consistent with capillary condensation in uniform mesopores. The ordered mesochannels are also evidenced in TEM images (Fig. 2) along both parallel and perpendicular directions. Addition of V led to an upward shift of the adsorption branch and hysteresis loop, reflecting an increase in pore size. PSD data in Fig. 1c further verifies a narrow distribution of 2–9 nm sized pores, with the average pore diameter becoming larger at higher V content. Table 1 compiled textural parameters of all samples. Upon V-doping, the specific surface area first increased from 163 m² g⁻¹ (V/M-ZrPO) to 205 m² g⁻¹ (15 V/M-ZrPO), before decreasing to 175 m² g⁻¹ for 20 V/M-ZrPO. A similar trend was observed for pore size and volume. The pore size improves from 5.63 nm to 6.64 nm and gradually decreases to 6.55 nm after 5 V/M-ZrPO, and an increase of pore volume was observed for V doped samples by 18–36%. XPS and EDS analyses also confirmed successful V incorporation, though the surface actual content was lower than nominal values, especially at higher loadings.

Fig. 2 TEM of (a) 0 V/M-ZrPO, (b) 5 V/M-ZrPO, (c) 10 V/M-ZrPO, (d) 15 V/M-ZrPO, (e) 20 V/M-ZrPO, (f) SAED of 20 V/M-ZrPO, and elemental mapping of (g) 20 V/M-ZrPO, (h) O, (i) P, (j) Zr and (k) V.

TEM was utilized to visually inspect the mesoporous morphology of the V/M-ZrPO materials, as depicted in Fig. 2. Regular striped frameworks representing the characteristic parallel-aligned mesochannels were clearly observed along the [110] orientation in Fig. 2a–e. Additionally, cylindrically-shaped pores aligned perpendicular to the [001] direction were distinctly visible in Fig. 2d, confirming the existence of long-range order in the materials. This periodic mesostructure corroborates the N₂ sorption results indicating cylindrical pores. From the micrographs, pore diameters of approximately 6 nm were estimated, consistent with pore size distribution data. Importantly, no detectable V aggregations were found, implying that vanadium species are homogeneously dispersed among mesoporous skeletons. The selected area electron diffraction (SAED) was performed to further investigate the crystallographic characteristic of V/M-ZrPO. The results in Fig. 2f exhibits broad diffraction rings, indicative of the low crystallinity of these mesoporous samples. This finding is aligned with XRD data. Elemental mapping of 20 V/M-ZrPO (Fig. 2g–k) further illustrates the uniform spatial distribution of O, P, Zr, and V, substantiating highly dispersed V species throughout the mesostructure achieved via the one-pot EISA synthesis.

3.2 Chemical bonds

The crystalline nature of the V/M-ZrPO samples was examined by XRD. As shown in Fig. 3a, all materials displayed similar diffractograms consisting of only two broad, weak peaks in the 20–40° and 40–70° ranges. These peaks can be indexed to the (100) and (110) reflections associated with the short-range wall periodicity of a 2D hexagonal mesoporous lattice in ZrPO frameworks, even at varying V loadings. In conjunction with the relatively sharp low-angle peak from SAXD, the presence of broad higher-angle peaks is characteristic of ordered mesoporous structures containing both long-range pore ordering and short-range wall crystallinity. The absence of distinct V-associated diffraction features indicates highly dispersed V species incorporated within the mesoporous skeletons via the one-pot synthesis. This can be attributed to isolation of V atoms by the surrounding Zr and P framework atoms, yielding homogeneous dispersion without segregated V-oxide phases. Such isolated and evenly distributed V sites may account for the observed improvements in textural properties and provide abundant accessible active sites for reactant adsorption and conversion.

Fig. 3 (a) WXRD, (b) Raman, (c) UV-vis, and (d) H₂-TPR characterizations of V/M-ZrPO samples.

Raman spectroscopy was employed to investigate the bonding characteristics within the V/M-ZrPO materials. As shown in Fig. 3b, samples with low V content (below 5%) displayed no distinctive peaks. However, new peaks emerged at 890 cm⁻¹ and 1030 cm⁻¹ for V loadings of 10% and above, with increasing intensity at higher V concentrations. The peak at 890 cm⁻¹ can be attributed to symmetric V–O–V bridging vibrations²⁸ associated with vanadyl (VO²⁺) moieties incorporated into the phosphate framework. Meanwhile, the 1030 cm⁻¹ peak likely contains overlapping signal from asymmetric V=O terminal stretches²⁹ in vanadyl groups.

UV-vis spectroscopy was utilized to probe the oxidation states and coordination environments of V species within the V/M-ZrPO samples. As shown in Fig. 3c, the undoped 0 V/M-ZrPO material displayed a characteristic absorption around 230 nm from Zr–O–P bonds.³⁰ Upon incorporating V, a broad peak emerged at 250–550 nm, whose intensities increased progressively with higher V content. The peak can be ascribed to ligand-to-metal charge transfer transitions of tetrahedrally coordinated V⁵⁺ centers in VO₄³⁻ units and d–d transitions associated with octahedral V⁴⁺ sites in VO²⁺ moieties. The presence of this broad peak confirms the integration of V⁵⁺ and V⁴⁺ species into Zr⁴⁺ phosphate sites during synthesis.

The redox behaviors of V species within the samples were investigated via H₂ temperature-programmed reduction experiments, with profiles shown in Fig. 3d. The undoped material displayed no reduction peaks, while introduction of V led to emerging signals and increased with higher V content, attributed to the greater number of reducible V centers. Additionally, the reduction peak shifted to lower temperatures from 610 °C down to 583 °C, suggesting decreased V-framework interactions and increased reducibility of V sites.

X-ray photoelectron spectroscopy (XPS) was utilized to characterize the chemical states, compositions, and V⁴⁺/V⁵⁺ ratios of surface V species. The V 2p spectra in Fig. 4c exhibit peaks around 525.2 eV and 517.7 eV whose intensities strengthen with increasing V content. The 525.2 eV peak corresponds to V⁵⁺ centers present as tetrahedral VO₄³⁻ units, while the 517.7 eV peak originates from octahedral V⁴⁺ sites in VO²⁺ moieties. With the increased doping of V, the V⁴⁺/V⁵⁺ ratios gradually rose from 4.0 to 4.6 calculated from peak areas, probably due to an increased number of V atoms competing for a limited amount of lattice oxygen.

Fig. 4 XPS narrow spectra of the (a) Zr 3d, (b) P 2p, (c) V 2p, and (d) O 1s orbitals, respectively.

The O 1s XPS data in Fig. 4d shows two peaks at 532.8 eV and 531.9 eV for 0 V/M-ZrPO from coordinated oxygen ligands attached to Zr metal centers and phosphate oxygen species, respectively. After V addition, the 532.8 eV peak disappeared, reflecting the replacement of Zr–O bonds with new V–O and P–O linkages. Meanwhile, the phosphate O peak gradually shifted to lower binding energies down to 531.5 eV for 20 V/M-ZrPO, indicating electron enrichment of the phosphates due to coordination with lower charge V⁴⁺ centers instead of V⁵⁺.

3.3 Catalytic performance

Given the excellent redox properties, the V/M-ZrPO samples were evaluated for liquid-phase electro oxidization of 1-phenylethanol - an important model reaction producing acetophenone, which serves as a versatile precursor in fine chemical industries.

The findings of the catalytic performance of V/M-ZrPO in the oxidation of this substrate are displayed in Fig. 5. All components are confirmed by GC-MS. Without introducing vanadium species, the 0 V/M-ZrPO sample could achieve a yield of acetophenone of 21.2%, similar to the uncatalyzed reaction. Nevertheless, when adding vanadium elements, the yield of acetophenone dramatically increased by almost 2-fold and achieved 59.4% for 5 V/M-ZrPO, indicating the prime output was attributed to the introduced vanadium species in the mesoporous structure of V/M-ZrPO. Also, by elevating vanadium contents progressively, the electrochemical catalytic capability gradually enhanced and attained 94.5% yield for 20 V/M-ZrPO. Furthermore, the yield of acetophenone depending on 20 V/M-ZrPO catalyst load was investigated. The results showed an initial increase in yield with increasing amount, plateauing at ∼94% at 100 mg. However, the yield decreased slightly if the catalyst load increase continues. This might be because of over-adsorption of 1-phenylethanol on the catalyst surface that blocks active sites and inhibit electron transfer for the oxidation reaction.

Fig. 5 Yield of acetophenone catalyzed by (a) varying the V content in 0.1 g V/M-ZrPO and (b) different catalyst loads for 20 V/M-ZrPO. The reactions were conducted in 15 mL CH₃CN with 0.01 mol 1-phenylethanol and 0.03 mol TBHP at 80 °C for 6 h.

To further investigate reaction parameters on catalytic performance, oxidant concentration and reaction temperature effect were considered for 1-phenylethanol electro-oxidation by 20 V/M-ZrPO in Fig. 6. Fig. 6a showed that the increasing oxidant level has a positive effect on product yield, but the effect was not that pronounced after the TBHP level reached 3 mmol. Fig. 6b indicated that the yield increased to 92.8% when the reaction temperature increased to 80 °C, after which the value almost stalled.

Fig. 6 Effect of (a) TBHP oxidant concentration and (b) reaction temperature on 1-phenylethanol electro-oxidation by 20 V/M-ZrPO.

To optimize the reaction time of the catalyst for the liquid-phase electro oxidation of 1-phenylethanol, 20 V/M-ZrPO was tested for 10 h. As displayed in Fig. 7a, kinetic experiments identified 6 hours as the ideal reaction time for 20 V/M-ZrPO. Hot filtration was performed following 1 h of reaction time. The drastically reduced rate of acetophenone yield after removing the catalyst indicates the heterogeneity of 20 V/M-ZrPO catalyst. Also, to find out the stability of the catalyst, five successive runs were conducted, and excellent reusability was demonstrated over these catalytic cycles with only 4% deactivation.

Fig. 7 (a) Reaction time optimization with hot filtration results after 1 h reaction (b) reusability test of 20 V/M-ZrPO.

To validate the resilience of the 20 V/M-ZrPO catalyst, N₂ adsorption, UV spectroscopy, XPS, TEM with elemental mapping and ICP are performed subsequent to the reaction. In Fig. 8a and b, a sustained specific surface area of 136 m² g⁻¹ and a reduced primary pore diameter to 4.79 nm are observed, suggesting the preserved microstructure. In Fig. 8c, a conspicuous absorption band near 300 nm in the UV-visible spectra implies the incorporated vanadium into the phosphate position as detected in pristine samples. Further substantiation is derived from XPS data, which unambiguously demonstrates the consistent valence states of Zr, P, and V, attesting to structural integrity. Complementary TEM imagery (Fig. 8g) reveals that the mesochannels remain parallel and undisturbed, affirming the retention of an ordered mesoporous architecture post-catalytic process. Furthermore, elemental mapping conclusively verifies the homogeneous dispersion of V alongside O, P, and Zr following the catalytic reaction. Lastly, ICP analysis of the post-reaction solution discloses a minimal vanadium concentration of merely 15.3 mg L⁻¹, testifying to insignificant leaching of vanadium during the catalytic event. Collectively, these exhaustive analyses serve as compelling evidence supporting the remarkable robustness of the 20 V/M-ZrPO catalyst material.

Fig. 8 Post-reaction analysis of 20 V/M-ZrPO via (a) N₂-physisorption, (b) pore size distribution, (c) UV-vis spectra, XPS of (d) Zr 3d, (e) P 2p, (f) V 2p, (g) & (h) TEM and elemental mapping of (i) O, (j) P, (k) Zr and (l) V.

The catalytic performance of 20 V/M-ZrPO for the oxidation of 1-phenylethanol was compared to other catalysts reported in the literature, as summarized in Table 2. These benchmark catalysts consist of those based on transition metals as well as noble metals. The results indicate that even with microwave irradiation, some of the transition metal-based catalysts were unable to achieve higher acetophenone yields than 20 V/M-ZrPO. Furthermore, these catalysts usually exhibited poor recyclability. Comparable yields were obtained using other transition metal catalysts, but required reaction times twice as long. The noble metal-based catalysts generally gave higher yields but had limitations such as prolonged reaction times or inadequate reusability. Taken together, these findings suggest 20 V/M-ZrPO is an effective catalyst for the catalytic oxidation of 1-phenylethanol, without apparent drawbacks in terms of yield, reaction time, or recyclability.

Table 2 Catalytic oxidation performance comparison of 1-phenylethanol to acetophenone by different catalysts

Catalyst	Oxidant	Reaction time (h)	Temperature (°C)	Yield (%)	Recyclability^a	Ref.
a Recyclability refers to cycles when the yield loss is within 5%. b Microwave irradiation. c Reaction pressure is at 10 Atm.
20 V/M-ZrPO	TBHP	6	80	92.8	>5	This work
FeO(OH), Fe^3+O(OH), Fe3O4	t-BuOOH	3^MW^b	80	82	2	31
Cu(II)@10% CatMP-1	TBHP	12	70	94	>10	32
[Cu(H2R)(HL)]·H2O	TEMPO	0.25^MW^b	80	85	/	33
CoCl2 −5% CNTs	t-BuOOH	1^MW^b	80	85	1	34
1.0 wt% Pd/60 wt% PK–SiO2	O2^c	12	100	100	/	35
1 wt% Au/carbon xerogel	TBHP	2^MW^b	150	90	1	36
MnO2 commercial	TBHP	7	RT	84	1	37

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Expanding the substrate scope revealed 20 V/M-ZrPO could efficiently oxidize a range of alcohols (benzyl alcohol, 4-methoxybenzyl alcohol, diphenylmethanol, cyclohexanol, cyclopentanol, cyclohexanemethanol) along with hydrocarbons (ethylbenzene, 1,4-diethylbenzene, diphenylmethane) with high yields of desired carbonyl products, as listed in Table 3. This broad applicability highlights 20 V/M-ZrPO as a promising heterogeneous catalyst in selective oxidation reactions, enabled by highly dispersed V active sites incorporated within the stable mesoporous backbone structure.

Table 3 Catalytic performance of 20 V/M-ZrPO in liquid phase oxidation of different substrates

Entry	Substrates	Con. (%)	Major products	Sel.(%)
a CH3CN 15 mL, substrates 0.01 mol, TBHP 0.03 mol, catalyst mass 0.1 g, 80 °C, 4 h. b CH3CN 15 mL, substrates 0.01 mol, TBHP 0.03 mol, catalyst mass 0.1 g, 80 °C, 12 h. c CH3CN 15 mL, substrates 0.01 mol, TBHP 0.03 mol, catalyst mass 0.1 g, 80 °C, 6 h.
1^a		57		66 : 34
2^b		96		11 : 89
3^c		98		18 : 82
4^c		92		100
5^b		94		100
6^b		74		100
7^b		65		30 : 70
8^b		95		75
9^b		86		44 : 56
10^b		79		100

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4. Conclusion

In summary, we have successfully synthesized vanadium-doped ordered mesoporous zirconium phosphate (V/M-ZrPO) nanocomposites through a facile one-pot self-assembly approach and confirmed isolated vanadium species were homogenously incorporated into the parent ZrPO framework in mixed V⁴⁺/V⁵⁺ oxidation states. The highly dispersed and accessible vanadium active sites led to significantly enhanced catalytic performance in liquid phase oxidations of 1-phenylethanol and various alcohols/hydrocarbons to selectively produce carbonyl compounds. In particular, 20 V/M-ZrPO demonstrated excellent activity, broad substrate scope, and favorable reusability. These combined advantages highlight vanadium-doped mesoporous ZrPO as a promising sustainable catalyst platform.

Conflicts of interest

There are no conflicts to declare.

Acknowledgements

The authors sincerely acknowledge the financial support from the National Natural Science Foundation of China (No. 21606098); Qinglan Project of Jiangsu Province of China; Natural Science Key Project of the Jiangsu Higher Education Institutions (20KJA530002); Jiangsu Provincial Engineering Research Center for Biomedical Materials and Advanced Medical Devices (CEMD-2001); the Foundation of Key Laboratory for Palygorskite Science and Applied Technology of Jiangsu Province (HPZ202001); Natural Science Key Project of Huaiyin Institute of Technology (23HGZ006); Natural Science Research Program of Huai’an (HAB202364).

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