Abstract

Bark of Pinus Radiata is a low-value product of the cellulose industry despite its high content of polyphenols as condensed tannins. The main product of the thermal decomposition of condensed tannins present in radiata pine bark are catechols. These compounds are high-value chemicals due to their antibacterial and membrane anchor properties. On this context, the fast pyrolysis of radiata pine bark and its tannins, obtained by methanol-water extraction of bark, were performed using a fluidized bed bench-scale system. The effect of temperature on the yield of pyrolysis products (biochar and pyrolysis-oil) and concentration of the main monophenols present in pyrolysis-oil was studied. The pyrolysis-oils were characterized by GCMS analysis and the monophenols were quantified by GCMS-FID analysis. Besides, SEM images of the obtained biochar were made. The biochar obtained from bark pyrolysis has the typical structure of lignocellulosic biochar, while the one obtained from water-insoluble tannins shows a microsphere-type structure. Yields of pyrolysis products presented the conventional trends. The yield of pyrolysis-oils present a parabolic shape with a maximum at 500 ºC and 550 ºC, for the pyrolysis of bark and its water-insoluble tannins, respectively. The effect of temperature on the concentration of catechols is noticeable for pyrolysis of bark, while for pyrolysis of water-insoluble tannins the effect is slight. The concentration of catechols is higher in the pyrolysis-oil obtained from water-insoluble tannins than from bark. However, the production of catechols from pine bark pyrolysis seems to be more convenient given the low yield of water-insoluble tannins reached in the extraction stage.