Nano-Magnetic NiFe2O4 and Its Photocatalytic Oxidation of Vanillyl Alcohol—Synthesis, Characterization, and Application in the Valorization of Lignin

Abstract

Here, we report on a phyto-mediated bimetallic (NiFe2O4) preparation using a Boswellia carterii extract, which was characterized by XRD, FT-IR, TGA, electron microscopy, magnetic spectroscopy, and Mössbauer spectroscopy measurements. The prepared nano-catalysts were tested for oxidation of lignin monomer molecules—vanillyl alcohol and cinnamyl alcohol. In comparison with previously reported methods, the nano NiFe2O4 catalysts showed high photocatalytic activity and selectivity, under visible light irradiation with a nitroxy radical initiator (2,2,6,6-tetramethylpiperidinyloxy or 2,2,6,6-tetramethylpiperidine 1-oxyl; TEMPO) at room temperature and aerobic conditions. The multifold advantages of the catalyst both in terms of reduced catalyst loading and ambient temperature conditions were manifested by higher conversion of the starting material.

Nitrogen‐doped Titanium Dioxide for Enhanced Photocatalytic Oxidation of Vanillyl Alcohol into Vanillin

“…Photocatalysis is able to effectively transforming various biomass derived molecules in effective, energy‐saving, and inexpensive processes [13] . In particular, the selective photocatalytic oxidation of bio‐alcohols to their corresponding carbonyls under mild conditions are suggested as widespread and fundamental reactions, which have been extend to the oxidation of lignin and its model compounds without the assistant of stoichiometric poisonous oxidants [14] .…”

“…For the vanillin production by visible light irradiation, typically, an external oxidant and an alkaline environment were required. For instance, the selectivity of vanillin could be up to over 90 % under visible light irradiation when using ZnFe 2 O 4 and NiFe 2 O 4 as photocatalysis [6,13] . However, the external TEMPO, H 2 O 2 and alkali increased the costs and complexity of the reaction system [19] …”

“…For instance, the selectivity of vanillin could be up to over 90 % under visible light irradiation when using ZnFe 2 O 4 and NiFe 2 O 4 as photocatalysis. [6,13] However, the external TEMPO, H 2 O 2 and alkali increased the costs and complexity of the reaction system. [19] Therefore, the continuous improvement of the selective oxidation performances of the vanillyl alcohol into the vanillin production is recommended.…”

“…Photocatalysis is able to effectively transforming various biomass derived molecules in effective, energy-saving, and inexpensive processes. [13] In particular, the selective photocatalytic oxidation of bio-alcohols to their corresponding carbonyls under mild conditions are suggested as widespread and fundamental reactions, which have been extend to the oxidation of lignin and its model compounds without the assistant of stoichiometric poisonous oxidants. [14] In previous literatures, several photocatalysts have been fabricated and applied to produce vanillin from different lignin degradation products, such as ferulic acid, (isoÀ )eugenol, and vanillyl alcohol, through simple oxidation routes.…”

Rose-like Bi2WO6 Nanostructure for Visible-Light-Assisted Oxidation of Lignocellulose-Derived 5-Hydroxymethylfurfural and Vanillyl Alcohol

“…Several semiconductor heterojunction photocatalysts have been fabricated to achieve an excellent activity in catalysis and dye degradation, − but only a few photocatalysts have been documented for the photocatalytic conversion of VOL to VAL, which are associated with low VOL conversion and selectivity of VAL. Various heterogeneous photocatalytic materials based on TiO 2 , NiFe 2 O 4 , ZnFe 2 O 4 , CeO 2 , and ZrO 2 and catalysts involving noble metals have been reported for VOL to VAL transformation, − but there is still a need for methods associated with effective oxidation of HMF and VOL, with high product selectivity under mild photocatalytic reaction conditions, using a simple photocatalyst.…”