WO x has good performance in olefin epoxidation, however, the presence of a large amount of Brönsted acid on WO x affects the selectivity of epoxy products. In this paper, broken carbon spheres ( b-C spheres) treated with nitric acid were used as support to anchor WO x in dynamic solvothermal process. Based on GC–MS and GC-IR detection, the obtained WO x /C greatly increased selectivity of 1,2-epoxyhexane from 16.0% ( pure WO x ) to 92.1% in epoxidation of 1-hexene. The improvement of WO x performance is attributed to the reduction of Brönsted acid sites and electron cloud density after loading, which may all result from interaction between WO x and oxygen-containing functional groups of b-C spheres. Above changes not only effectively inhibit the hydrolysis of 1,2-epoxyhexane, but also are conducive to nucleophilic reaction of H 2 O 2 to WO x, which is beneficial to the activation of H 2 O 2 . Finally, an epoxidation mechanism with oxygen vacancies as the main route under WO x /C catalysis is reasonably proposed. Graphical Abstract
Keto-alcohols, which are traditionally produced from fossil resources with multisteps, are considered as important intermediates for diversified high-value-added fine chemical synthesis due to their involved carbonyl and hydroxyl groups. Herein, direct cellulose hydrogenolysis to C3-C4 keto-alcohol products (hydroxyacetone and 1(3)-hydroxy-2-butanone) was achieved over Ni-WOx/C catalysts with an W/Ni atom ratio of 1.0–5.0. The keto-alcohol yield was proposed to strongly depend on the W/Ni ratio and the catalyst annealing temperature. The highest keto-alcohol yield of 63% was obtained at the optimal balance of basic/acidic WOx species and metallic Ni. The introduction of Ni facilitated the formation of the basic W5+ sites, which enhanced the formation of basic sites at the Ni-WOx interface. The synergistic effect between the basic W5+ and acidic oxygen vacancy (Vö) could activate the target C–O/C═O bonds, promoting the isomerization of glucose and C3-C4 aldehyde intermediates with the assistance of the interfacial Ni. The cooperative adsorption of the −OH and −C═O groups at the Ni-O-W-Vö interface stabilized the adjacent ketone and hydroxyl groups and kept the other hydroxyl groups for hydrogenolysis, obtaining the final C3-C4 keto-alcohols. This work expanded the application of cellulosic biomass, enabling the green and sustainable synthesis of the high-value C3-C4 keto-alcohol products using lignocellulosic biomass as a raw material.
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