CHANGES IN PORE SIZE DISTRIBUTION WITH PYROLYSIS TEMPERATURE, PARTICLE ASPECT RATIO AND PRETREATMENT BY LEACHING OF LARGE BEECH WOOD PARTICLES

摘要

When assessing the usefulness of pyrolysis chars as porous materials for the application as adsorbents, catalysts or catalyst supports, one of the most important parameters of the assessment, besides the specific surface area, is their pore size distribution. The aforementioned processes are highly pore size selective, hence inappropriate pores sizes of the applied material can lead to the material's uselessness for a given application. In terms of the application of pyrolysis char as a soil amendment (i.e., biochar), pore size also plays a major role. For example, in case of a too large share of micropores, even though the water capacity is relatively high, water is only partially available for plants due to strong capillary forces in the micropores pores . Besides their beneficial environmental applications, porous materials of biomass origin, like pyrolysis chars, are characterized by the possibility to change their porous structure with production parameters. Therefore, the possibility exists to set production process parameters in a way that allows obtaining a material with a desired pore size distribution. It makes pyro-chars more advantageous materials in comparison to its current, strongest market rival - silica-alumina materials. Even if the desired structure of the carbonaceous porous material is not obtained in the primary production process (pyrolysis), it is possible that specifically pre-processed materials will behave better in upgrading/activation processes (e.g., steam activation) and in the end, a tailor-made material, with tailor-made pore size distribution will be obtained.