Key Takeaways & Executive Findings
- •• • Achieved 99.2% conversion of benzyl alcohol and 94.1% yield of benzaldehyde under mild conditions (100 °C, 0.5 MPa O2, 1 h), demonstrating high efficiency for selective oxidation. • • The H-Cu/C catalyst, derived from HKUST-1, features Cu(0) nanoparticles dispersed in a carbon matrix with island-like Cu2O active sites, ensuring stability and activity. • • The catalytic system shows broad substrate scope: over 99% conversion and above 95% aldehyde yield for various substituted aromatic alcohols, including electron-donating and electron-withdrawing groups. • • Catalyst regeneration via H2 reduction allows reuse without significant activity loss, enhancing economic viability for industrial application.
Abstract
A Cu-based carbon catalyst (H-Cu/C) with octahedral morphology was synthesized by pyrolyzing the metal-organic framework (MOF) precursor HKUST-1 under inert N2 atmosphere. Characterization via XPS, XRD, SEM, and HRTEM revealed that Cu(0) nanoparticles were uniformly dispersed in a carbon matrix, with island-like Cu2O structures serving as active sites. The carbon matrix effectively stabilized the metal nanoparticles, suppressing migration and sintering during reaction. Combined with TEMPO and using molecular oxygen as a green oxidant, the H-Cu/C catalyst exhibited high efficiency in the selective oxidation of aromatic alcohols to corresponding aldehydes under alkali-free conditions. Using benzyl alcohol as a model substrate, an alcohol conversion of 99.2% and a benzaldehyde yield of 94.1% were achieved under mild conditions (100 °C, 0.5 MPa O2, 1 h). The catalytic system demonstrated excellent universality for various mono- and ortho/para-disubstituted aromatic alcohols, affording conversions over 99% and aldehyde yields above 95%. The catalyst could be regenerated via H2 reduction and reused without significant loss of activity. This work provides a new strategy for designing green and efficient non-noble metal catalytic systems for oxidation reactions.
1. Introduction
Conventional oxidation of alcohols to aldehydes relies on stoichiometric heavy metal salts or strong acids, leading to poor atom economy and severe environmental pollution. These methods conflict with green chemistry principles, necessitating the development of catalytic systems that use molecular oxygen as a benign oxidant. The challenge lies in achieving high selectivity and activity under mild, base-free conditions while maintaining catalyst stability.
This study addresses the bottleneck by employing a metal-organic framework (MOF)-derived copper-based carbon catalyst (H-Cu/C) combined with TEMPO. The catalyst's unique structure, with Cu nanoparticles stabilized by a carbon matrix and Cu2O active sites, enables efficient activation of molecular oxygen. The system achieves near-quantitative conversions and high yields for aromatic alcohols, offering a green, efficient, and reusable alternative to conventional methods.
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LUO Yang, ZHANG Shujing, MA Hong, WANG Chenguang (2026). Selective Oxidation of Aromatic Alcohols to Aldehydes Catalyzed by HKUST-1-Derived Cu-Based Carbon Material and TEMPO. Journal of Fuel Chemistry and Technology. https://doi.org/10.1016/S1872-5813(26)60635-4
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Frequently Asked Questions
What is the role of the carbon matrix in the H-Cu/C catalyst and how does it affect catalytic performance?
The carbon matrix stabilizes Cu nanoparticles, preventing migration and sintering during reaction. This maintains high dispersion of active sites, contributing to the catalyst's high activity and stability, as evidenced by consistent performance over multiple cycles.
How does the catalyst perform under industrial-scale conditions, particularly regarding oxygen pressure and temperature?
The catalyst operates effectively under mild conditions (100 °C, 0.5 MPa O2), achieving 99.2% conversion and 94.1% yield for benzyl alcohol. These conditions are industrially feasible, reducing energy costs and safety concerns compared to harsher requirements.
What is the substrate scope and limitation of this catalytic system?
The system shows excellent universality for various aromatic alcohols, including those with electron-donating groups (e.g., -CH3, -OCH3) and electron-withdrawing groups (e.g., -Cl), achieving >99% conversion and >95% yield. However, aliphatic alcohols were not tested, and steric hindrance may affect reactivity for bulky substrates.
How does the catalyst compare to noble metal catalysts in terms of cost and performance?
The H-Cu/C catalyst uses non-noble copper, significantly reducing material costs. Performance metrics (99.2% conversion, 94.1% yield) are comparable to noble metal systems, and the catalyst can be regenerated via H2 reduction, enhancing economic viability.
What are the key factors for catalyst deactivation and how is regeneration achieved?
Potential deactivation may arise from Cu oxidation or sintering. The carbon matrix mitigates sintering, and regeneration via H2 reduction restores activity, as demonstrated by reuse without significant loss. Long-term stability under continuous operation remains to be evaluated.
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