Highly Dispersed Copper Nanoparticles Supported on Activated Carbon as an Efficient Catalyst for Selective Reduction of Vanillin

Abstract

Highly dispersed copper nanoparticles (Cu NPs) supported on activated carbon (AC) are effectively synthesized by one-pot carbothermal method at temperature range of 400-700 °C. The X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller analysis reveal that Cu NPs with diameters of 20-30 nm are evenly anchored in carbon matrix. The 15 wt%-Cu/AC-600 catalyst (derived at 600 °C) exhibits best bifunctional catalysis of aqueous-phase hydrodeoxygenation (HDO) and organic-phase transfer-hydrogenation reaction (THR) to selectively transform vanillin to 2-methoxy-4-methylphenol (MMP). In HDO of vanillin, the as-prepared catalyst achieves a 99.9% vanillin conversion and 93.2% MMP selectivity under 120 °C, 2.0 MPa H within 5 h. Meanwhile, near-quantitative vanillin conversion and 99.1% MMP selectivity are also obtained under 180 °C within 5 h in THR of vanillin by using 2-propanol as hydrogen donor. The transforming pathways of vanillin are also proposed: vanillin is transformed into MMP via intermediate of 4-hydroxymethyl-2-methoxyphenol in HDO case and by direct hydrogenolysis of vanillin in THR course. More importantly, the activity and the selectivity do not change after 5 cycles, indicating the catalyst has excellent stability. The Cu-based catalyst is relatively cheap and preparation method is facile, green, and easy scale-up, thus achieving a low-cost transformation of biomass to bio-oils and chemicals.

Glycerol: An Optimal Hydrogen Source for Microwave-Promoted Cu-Catalyzed Transfer Hydrogenation of Nitrobenzene to Aniline

“…Cu(0)NPs have been efficiently prepared in glycerol (Dang-Bao et al, 2017), and some polyolstabilized CuNPs have been used in the reduction of nitrobenzene (Saha and Ranu, 2008;Duan et al, 2012;Santhanalakshmi and Parimala, 2012). Although several applications for copper catalysis in transfer hydrogenation have already been reported in the literature (Štefane and Požgan, 2014;Fan et al, 2018;Zhang and Li, 2019), the use of CuNPs for nitrobenzene reduction via transfer hydrogenation has not received much attention, to the best of our knowledge (Feng et al, 2014). In fact, the common approach to nitro benzene reduction by Cu catalysis is performed in the presence of NaBH 4 , which is used as a hydride donor (Wu et al, 2013;Aditya et al, 2017;de Souza et al, 2017).…”

Mechanochemical Preparation of Magnetically Separable Fe and Cu-Based Bimetallic Nanocatalysts for Vanillin Production

“…Such signals were found in all prepared materials, as shown in Figure 1. A broad band around 20.0 • , which was observed for samples treated at 100 • C and 200 • C, could be attributed to the presence of amorphous carbon [7,19,21]. In turn, the aforementioned signal clearly decreased at higher temperature due to the partial elimination of the carbonaceous matrix.…”

“…In this regard, Cu based nanoparticles (NPs) have been widely investigated due to their chemical and physical properties, besides the earth-abundant and inexpensive characteristics of this metal [6]. Moreover, Cu nanoparticles supported on carbon have demonstrated to be a promising option, favoring the formation of highly dispersed NPs and resulting in synergistic interactions which could further boost the catalytic response [7]. In addition, the design of bimetallic nanocatalysts, by adding a second metal, could lead to tunable electronic and/or structural properties, hence modifying the catalytic performance, in terms of activity, selectivity, and stability [8].…”

In situ hydrodeoxygenation of vanillin over Ni–Co–P/HAP with formic acid as a hydrogen source

“…6(a), under the reaction conditions of 2 mmol vanillin, 0.05 g catalyst, 20 mL isopropanol, 190 C and 3 h. It can be seen from Fig. 6(a) that in the initial stage of the reaction, due to the small amount of formic acid in the system, the decomposition of formic acid cannot provide sufficient hydrogen, and HMP cannot be hydrogenated in time to generate MMP, resulting in the side reaction of aldol condensation, 32,33 and the selectivity of the product MMP was 49.55%. As the amount of formic acid increases, the hydrogen source in the reaction system increased, the selectivity of MMP was increased signicantly.…”