The Studies on α-Pinene Oxidation over the TS-1. The Influence of the Temperature, Reaction Time, Titanium and Catalyst Content

Abstract

The work presents the results of studies on α-pinene oxidation over the TS-1 catalysts with different Ti content (in wt%): TS-1_1 (9.92), TS-1_2 (5.42), TS-1_3 (3.39) and TS-1_4 (3.08). No solvent was used in the oxidation studies, and molecular oxygen was used as the oxidizing agent. The effect of titanium content in the TS-1 catalyst, temperature, reaction time and amount of the catalyst in the reaction mixture on the conversion of α-pinene and the selectivities of appropriate products was investigated. It was found that it is most advantageous to carry out the process of α-pinene oxidation in the presence of the TS-1 catalyst with the titanium content of 5.42 wt% (TS-1_2), at the temperature of 85 °C, for 6 h and with the catalyst TS-1 content in the reaction mixture of 1 wt%. Under these conditions the conversion of α-pinene amounted to 34 mol%, and the selectivities of main products of α-pinene oxidation process were: α-pinene oxide (29 mol%), verbenol (15 mol%) and verbenone (12 mol%). In smaller quantities also campholenic aldehyde, trans-pinocarveol, myrtenal, myrtenol, L-carveol, carvone and 1,2-pinanediol were also formed. These products are of great practical importance in food, cosmetics, perfumery and medicine industries. Kinetic studies were also performed for the studied process.

Recent Advances and Challenges in the Valorization of α‐Pinene toward Value‐Added Chemicals

“…The authors claimed that the catalytic system works without the requirement of additives or ligand. [19] Agnieszka Wróblewska et al reported titanium-silicalite (TS-1) catalysts for the oxidation of 𝛼-pinene [20,21] In one of the study, this research group revealed the autooxidation of 𝛼-pinene catalyzed by TS-1 with different titanium contents and achieved a conversion of 41.81 mol.% with a selectivity of 30.25 mol.% at 80 °C in 24 h under air atmosphere without the use of any organic solvents. The catalyst TS-1 exhibited autooxidation, isomerization and hydration of 𝛼-pinene and resulted in the respective products such as 𝛼-pinene oxide, campholenic aldehyde/carveol and 1,2-pinane diol.…”

“…Using this heterogeneous catalyst (0.5 wt.%), 40 mol.% conversion of 𝛼-pinene was achieved with 35 mol.% selectivity of 𝛼-pinene oxide at 100 °C in 2 h. The reported catalytic system is low-cost heterogeneous catalyst derived from the effective management of waste biomass. [20] Recently, in 2023, the same group reported porous ZSM-5 zeolites with different aluminium content as an active catalyst with oxygen. The catalytic efficiency was tested for the epoxidation of 𝛼 -pinene and observed 49 mol.% conversion with 28 mol.% selectivity of 𝛼-pinene oxide at 95 °C in 6 h. The catalytic system has the advantage of simple post-work process due to the avoidance of liquid oxidant such as hydrogen peroxide.…”

“…Using this heterogeneous catalyst (0.5 wt.%), 40 mol.% conversion of α‐pinene was achieved with 35 mol.% selectivity of α‐pinene oxide at 100 °C in 2 h. The reported catalytic system is low‐cost heterogeneous catalyst derived from the effective management of waste biomass. [ 20 ]…”

The Application of Clinoptilolite as the Green Catalyst in the Solvent-Free Oxidation of α-Pinene with Oxygen

“…These compounds are readily used in the cosmetic and food industries, as well as in medicine as raw materials for obtaining perfumes, flavors, pharmaceuticals, and vitamins [38][39][40]. α-Pinene derivatives include such compounds as α-pinene oxide, campholenic aldehyde, L-carveol, verbenol, verbenone, trans-pinocarveol, myrtenal, myrtenol, carvone, and 1,2-pinanediol [41,42]. α-Pinene oxide is used in organic syntheses as the raw material for obtaining valuable compounds such as campholenic aldehyde, isopinocamphone, p-cymene, trans-sobrerol, and trans-carveol [43].…”

“…Various catalysts were used for the oxidation of α-pinene, including titanium-silicate catalysts such as Ti-MCM-41 [53,54], TS-1 [42], and Ti-MMM-2 [55], and transition metal salts such as CuI, CuCl, CuCl 2 , PdCl 2 , and PdBr 2 [56]. Carbonaceous materials obtained from pine cones were also described as catalysts for the oxidation of α-pinene [41].…”