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Three morphologies of ZnO [spherical (S), rod (R) and disk (D)] were synthesized and tested as supports for Au nanoparticles for the selective oxidation of glycerol, 1,2-propanediol, 1,2-butanediol, and isopropanol at their secondary hydroxyl group to produce the corresponding ketones. The Au-ZnO(0 0 1) interface exhibits a strong electron sink effect and abundant oxygen vacancies, greatly promoting the adsorption of O 2 and the adsorption and conversion of polyols at their secondary hydroxyl moiety. Moreover, the as-formed Auδ+-OH* site resulting from O 2 activation can efficiently extract the hydrogen of the C-H bond of the key RCHO*CH 2 OH intermediate on the Zn-O v site of ZnO(0 0 1) surfaces. Therefore, the Au/ZnO-D exhibits superior catalytic activity (turnover frequency >500h−1) and ketone selectivity (>80 %) than other catalysts with different ZnO facets exposed. [Display omitted] • Three morphologies of ZnO [spherical (S), rod (R) and disk (D)] were synthesized to support Au nanoparticles. • Au/ZnO-D exhibits superior catalytic activity and ketone selectivity. • Au-ZnO(0 0 1) interface exhibits a strong electron sink effect and abundant oxygen vacancies. • Auδ+-OH* site can efficiently extract the hydrogen of the C-H bond of the key RCHO*CH 2 OH intermediate. In-depth understanding and precise tuning of the crystal facet-dependent catalytic properties of supported catalysts are critical for polyol oxidation. Herein, we report a crystal-facet-dependent study of Au-ZnO interfaces for the selective promotion of the oxidation of various polyols and alcohols (glycerol, 1,2-propanediol, 1,2-butanediol, and isopropanol) at the secondary hydroxyl position to produce the corresponding ketones. Three facets of the zinc oxide support, ZnO(1 0 1), ZnO(1 0 0) and ZnO(0 0 1), associated with nanoparticles of various morphologies (spherical (S), rod (R) and disk (D), respectively), were found to induce different electronic local environments and surface oxygen vacancy contents at the Au-ZnO interface. In particular, the ZnO(0 0 1) facet dominating in the Au/ZnO-D nanoparticles can store more electrons from Au, and such electron sink effect, together with the generation of oxygen vacancies (Zn-O v), synergistically enhances the adsorption of O 2 and polyols at the secondary hydroxyl position. Moreover, it was determined that the as-formed Auδ+-OH* site resulting from O 2 activation can efficiently extract the hydrogen of the C-H bond of the key RCHO*CH 2 OH intermediate on the Zn-O v site of ZnO(0 0 1) surfaces. Consequently, the Au/ZnO-D catalyst exhibits unprecedented catalytic activity (turnover frequency >500 h−1) and ketone selectivity (>80 %) for glycerol oxidation. [ABSTRACT FROM AUTHOR]

A Ni 1 Co 1 O x catalyst with lattice distortions was prepared by a modified hard template method. Elemental analysis shows that Ni tends predominantly to disperse on the surfaces of the nanoparticles. Under the optimum reaction conditions (80 °C, 20 h, and 1.5 g NaOH), Ni 1 Co 1 O x catalyst could exhibit optimum catalytic performance (78.5% conversion, 66.5% GLYA selectivity, and recycling for four times). • A lattice-distorted Ni 1 Co 1 O x catalyst was synthesized by a modified hard template method. • High selectivity toward glyceric acid was obtained on the Ni 1 Co 1 O x catalyst. • Electron transfer from Ni cations to Co cations results in the generation of surface oxygen vacancies. • The oxygen vacancies of Co and Ni species promote the oxidation of glycerol to glyceric acid. Developing cheap and highly efficient catalysts for the selective oxidation of glycerol to value-added carboxylic acids still remains a challenge. Here, non-noble-metal Ni–Co oxide catalysts with lattice distortions are reported for the first time as highly efficient and stable catalysts for the oxidation of glycerol to glyceric acid. The Ni 1 Co 1 O x catalyst, prepared by a modified hard template method, exhibits superior activity (1.5 × 10−3 s−1), excellent glyceric acid selectivity (66.5%), and good stability under mild conditions (80 °C, 1 MPa O 2). Multiple characterizations demonstrated that the nanosized Ni 1 Co 1 O x catalyst (2.3 nm) contains lattice distortion Ni–Co structures with nickel-rich surfaces. This morphology induces electron transfer from Co cations (mainly Co3+) to Ni cations (mainly Ni3+), resulting in the generation of surface oxygen vacancies. Density functional theory calculations and catalytic kinetics demonstrated that oxygen vacancies on Co species could improve glyceric acid selectivity by preventing the cleavage of C C bond, and oxygen vacancies on the Ni species could promote the activation of C H bonds, which results in the exceptional catalytic performance of Ni 1 Co 1 O x. The novel Ni–Co oxide catalyst with lattice distortions synthesized here may provide some guidance for the rational design of inexpensive and highly efficient catalysts for the catalytic oxidation of biopolyols. [ABSTRACT FROM AUTHOR]

Graphical abstract In-situ coating of SBA-15 with MgO was synthesized in one-step procedure to form the mesoporous solid bases. Then, the Pt nanoparticles were loaded by NaBH 4 reduction method. Subsequently, the Pt/MgO-SBA-15 catalyst was applied to the selective oxidation of glycerol to obtain C 3 products. Highlights • Novel hybrid Pt/MgO/SBA-15 catalysts were prepared. • The Pt nanoparticles was restricted in the channel of MgO/SBA-15. • The synergistic effect between Pt and MgO enhanced glycerol oxidation activity. • Oxygen active sites of MgO promoted the dehydrogenation reaction. Abstract Enhanced metal-support interaction is the key for selective oxidation of glycerol to value-added carboxylic acids. However, the rational control of interfacial properties still remains a significant challenge. In this work, we prepared hybrid Pt/MgO/SBA-15 catalysts for the facile oxidation of glycerol to glyceric acid in the absence of liquid alkalis. It was found that the confinement effect of SBA-15 leads to restricted Pt nanoparticles in the MgO/SBA-15 channel with a unique "strip" shape. Such a morphology and the strong electron coupling effect between Pt and MgO species synergistically enhanced glycerol oxidation over Pt-MgO sites. A volcanic-shaped relationship between Mg/Si ratio and catalytic performance was established experimentally, and the Pt/MgO/SBA-15 (0.1) catalyst showed excellent combined selectivity for C 3 products (glyceric acid, glyceraldehyde and dihydroxyacetone) with a remarkable turn over frequency (TOF) of 1671.2 h−1 higher than the reported catalysts under base-free conditions. Furthermore, density functional theory (DFT) calculations confirmed that the oxidation reaction could be promoted by oxygen defects of MgO sites, resulting in a reduction of the energy barriers for C H and O H activation. These insights may provide a new way to the supported solid base catalyst design and mechanistic study. [ABSTRACT FROM AUTHOR]

Moderate WO x surface density of Ni/WO x -ZrO 2 with higher Brønsted/Lewis acid sites ratio enhances LDPE hydrocracking and obtains the maximum liquid yield. [Display omitted] • The non-noble Ni catalysts achieves the LDPE hydrocracking process under a mild condition. • The Ni/WO x -Zr catalysts achieves 100 % LDPE conversion with 76.9 % liquid yield. • The WO x surface density shows a volcanic-shape relationship with the B/L ratio of catalyst. • The LDPE hydrocracking performance has a linear relationship with the B/L ratio of catalyst. Chemical upcycling through catalytic hydrocracking to fuels has potential to mitigate the serious environmental issues caused by plastic waste. Herein, non-noble tungstate-zirconia supported nickel catalyst (Ni/WO x -ZrO 2) with tunable Brønsted/Lewis (B/L) ratio was firstly proposed for the hydrocracking of low-density polyethylene (LDPE), which achieves hydrogenation/dehydrogenation on Ni sites and cracking/isomerization on WO x -ZrO 2 , respectively. Excellent 100 % LDPE conversion with 76.9 % liquid yield was achieved, which is comparable to noble Ru-based and Pt-based catalysts. Quantitative linear relationship between B/L ratio and hydrocracking performance was established, and the key to boost performance was keenly controlling the volcanic-shape relationship between surface WO x density and B/L ratio of catalyst. Moderate WO x surface density with higher B/L ratio enhances LDPE hydrocracking, and inhibits the hydrogenation of the primary products. However, excessive WO x polymerized and formed WO 3 crystals, compensating acid sites and inhibiting LDPE hydrocracking. This work is of prime scientific and industrial significance to the rational design of catalysts for industrial plastic hydrocracking. [ABSTRACT FROM AUTHOR]

We construct defective Auδ−-O v interfacial structures by tuning the calcination temperature of ZrO 2 support to boost the oxidation of amino alcohols to amino acids. Finally, the Au/ZrO 2 -600 catalyst with rich defective Auδ−-O v interfacial sites exhibits 98.8% product yield for the oxidation of diethanolamine to iminodiacetic acid at only 30 °C. The catalyst system is further extended to the oxidation of other amino alcohols, involving monoethanolamine and triethanolamine, to their corresponding amino acids with excellent catalytic performance. [Display omitted] • Defective Au-ZrO 2 interfacial structure was constructed by tuning the calcination temperature of ZrO 2 support. • The Auδ−-O v interfacial site displays the unique synergistic adsorption effect and electron transfer ability. • O v site prioritizes the adsorption of amino groups in amino alcohols, avoiding the occupation of Auδ− main sites. • Electron-rich Auδ− nearby O v site adsorbs the hydroxyl groups and activates the C-H bond activation of NH 2 CH 2 CH 2 O* intermediates. Designing efficient active sites to facilitate the oxidation of hydroxyl group to carboxylic acid under the influence of nitrogen-containing functional groups is worth exploring, but it is rarely investigated. Herein, we construct defective Au-ZrO 2 interfacial structures by tuning the calcination temperature of ZrO 2 support to boost the oxidation of amino alcohols to amino acids. Interestingly, the modification of calcination temperature induces the escape of saturated coordination oxygen atoms in ZrO 2 support, leaving behind abundant surface oxygen vacancy (O v). The as-formed Auδ−-O v interfacial site displays the unique synergistic adsorption effect and electron transfer ability. Specifically, the O v site voluntarily adsorbs the –NH 2 group of amino alcohol, thus ensuring that the electron-rich Auδ− nearby O v site adsorbs the hydroxyl groups and activates the C-H bond activation of NH 2 CH 2 CH 2 O* intermediates. Consequently, Au/ZrO 2 -600 catalyst with more defective Auδ−-O v interfacial sites exhibits 98.8 % product yield for the oxidation of diethanolamine to iminodiacetic acid at only 30 °C. The catalyst system is further extended to the oxidation of other amino alcohols, involving monoethanolamine and triethanolamine, to their corresponding amino acids with excellent catalytic performance. [ABSTRACT FROM AUTHOR]