Oxidation of limonene over molybdenum dioxide-containing nanoporous carbon catalysts as a simple effective method for the utilization of waste orange peels

Abstract

A new method of the oxidation of natural limonene, obtained from waste orange peels, using relatively inexpensive MoO 2 -containing activated carbon catalysts is presented. The contents of molybdenum in the catalysts were equal to 0.68, 1.32, and 2.64 wt%, and these new materials were investigated using various instrumental methods (ICP-AES, XRD, SEM, and GC), as well as liquid nitrogen sorption. The oxidation of limonene was performed separately with H 2 O 2 and t-butyl hydroperoxide (TBHP) as the oxidants under the following conditions: temperature of 70°C, molar ratio of limonene/oxidant = 1:2, methanol concentration 95 wt%, catalyst content 2.45 wt%, and reaction times of 0.5-72 h. All catalysts were active in the oxidation of limonene. With H 2 O 2 as the oxidant, carveol (selectivity of 42-65 mol%) and perillyl alcohol (selectivity of 10-30 mol%) were the main products of the limonene oxidation, and carvone and 1,2-epoxylimonene diol were by-products. For the oxidations with TBHP, the conversion of limonene was lower than with hydrogen peroxide. This new environmentally friendly method allows for the transformation of organic waste material into industrially important value-added products.

Photoinduced Oxygen Atom Transfer to α‐Pinene and R‐Carvone using a Dioxo‐Molybdenum (VI) Complex Incorporated within a Modified UiO‐67 (Zr/Ti) MOF

“…The typical symmetric (670 cm À 1 ), asymmetric (687 cm À 1 ), and bending (459 cm À 1 ) interactions of the ZrÀ O bonds of the MOF lattice were also exhibited. [17] The obtained ligand ratios were determined by 1 H NMR, as shown in Table 1. The BET surface area values (A BET ) of the MOFs were determined by N 2 adsorption/desorption.…”

“…The transformation of monoterpenes into high‐value products is essential for the valorization of essential oils and their derivatives, [1] including some residues from paper and pulp industries. Key reactions in the conversion of essential oils include oxidation, hydrogenation, isomerization, hydration, hydroformylation, and condensation.…”

DFT Studies of the Activity and Reactivity of Limonene in Comparison with Selected Monoterpenes

“…Compared to products obtained using dioxygen as an oxidant, diepoxide (DLO), 8,9-LO, or polymer were additionally formed. For HOOH, the following complexes were used: cobalt sandwich-type polyoxometalates [39], tungstophosphates [2], polyoxotungstates [11], Schiff base complexes with Co(II) and Cu(II) and the same compounds but immobilized in zeolite-Y [40], manganese(II) acetylacetonate on MCM41 [41], Al 2 O 3 [42], the ions of non-transition metal [1], methyltrioxorhenium with different ligands [43], activated carbon where the active phase was the magnetite Fe 3 O 4 [44] or MoO 2 [45], complexes of VO and copper(II) with Schiff base ligands entrapped in the supercages of zeolite-Y [46], homogeneous and heterogeneous VO and iron(II) with Schiff base ligands [47], γ-Fe 2 O 3 /SiO 2 -NHFeP prepared from nanospheres and 5,10,15,20-tetrakis (pentafluorphenylporphyrin) iron(III) [48], heterogeneous Mn(III), Fe(III), and Co(III) porphyrin-based complexes immobilized on zeolite [49] or others complexes based on zeolite-Y [50][51][52] in which enclosing the catalyst in the porous structure of the support prevents the dimerization of the complexes, ensuring their catalytic activity. Catalysts used with t-butyl hydroperoxide as the oxidant are also zeolites, e.g., zeolite-Y with entrapped VO with Schiff base ligands [50], organic hybrid materials [26,53], Ti-MCM-41, and Ti-MWW compounds [54], iron(II) [55], molybdenum(II) complexes [56], salen-like Jacobsen's catalysts with manganese(III) [57] or carbon-based complexes with cobalt(II) acetylacetonate [58].…”