Carbon catalysts from pine cones – Synthesis and testing of their activities

Abstract

The work presents research on the synthesis of carbon catalysts from pine cones and their application in the oxidation of α-pinene. The preparation of carbon catalysts involved chemical activation with an aqueous potassium hydroxide solution and carbonization of the obtained precursor. The pine cones carbonization was performed for 1 h at the temperatures range from 700° to 1000°C in an inert gas atmosphere (N2). Characterizations of the activated carbons were performed with the following instrumental analyses: XRD, SEM, and XPS. No solvent was used in the oxidation studies, and molecular oxygen was the oxidizing agent. The effects of three parameters – temperature, amount of the carbon catalyst, and reaction time – on the values of conversion of α-pinene, as well as the product selectivities, were investigated. It was shown that it is most advantageous to perform the oxidation of α-pinene at 100 °C for 1 h with the PC_850 catalyst (so-named for the temperature of its carbonization process, 850 °C), whose content in the reaction mixture is 0.5 wt%. Under these conditions, the conversion of α-pinene amounted to 41 mol%. Moreover, the selectivities of the three main products were: α-pinene oxide (28 mol%), verbenol (16 mol%), and verbenone (13 mol%). In addition to these products, other valuable compounds, such as campholenic aldehyde, pinocarveol, myrtenal, myrtenol, carveol, carvone, and pinanediol were also produced.