Pyrolýza syrových vedlejších živočišných produktů

Abstract

This bachelor thesis deals with the thermochemical processing of raw animal by-products, specifically of raw beef bones by using pyrolysis. The thesis focuses on the study of microwave and conventional pyrolysis of raw beef bones and on assessing the influence of process conditions (microwave pyrolysis time and microwave power, use of chemical activation, conventional pyrolysis temperature) on the yields of the resulting pyrolysis products and the properties of the solid product. The thesis, therefore, also includes the physicochemical characterization of the solid pyrolysis product using selected analytical methods such as the thermogravimetric analysis (TGA), organic elementary analysis (OEA), X-ray fluorescence spectroscopy (XRF), nitrogen physisorption at 77 K and Raman spectroscopy. It was found that both the heating method (microwave vs. convection) and the pyrolysis process significantly influence the yields of individual pyrolysis products. Microwave pyrolysis yielded a higher solid fraction (up to 61 wt.%), particularly when chemical activators were used, while conventional pyrolysis resulted in a higher liquid fraction yield (up to 50 wt.%). Organic elementary analysis of the solid pyrolysis products revealed a carbon content ranging from 6.8–21.1 wt.%, with the highest carbon contents achieved when chemical activation was used. Chemical analysis of the solid pyrolysis products using X-ray fluorescence spectroscopy confirmed a high content of mineral elements, particularly calcium and phosphorus. Chemical analyses suggest that the solid pyrolysis products are composite materials consisting of a minor carbonaceous fraction and a major inorganic fraction. Physisorption analyses confirmed the predominantly mesoporous-macroporous nature of the prepared solid products, with the formation of micropores in the solid product structure occurring only when chemical activation was used. Raman spectroscopy revealed differences in the order of the carbon structure of the prepared solid products depending on the preparation conditions. While the higher temperature of conventional pyrolysis contributes to the graphitization of the carbon structure, chemical activation and microwave pyrolysis contribute to a higher degree of disorder in the carbon structure. Based on the results obtained, it can be concluded that by selecting appropriate pyrolysis process parameters for raw beef bones pyrolysis, it is possible to specifically influence the yield of pyrolysis products and the properties of the resulting composite solid product. Thanks to the high content of Ca, P, and N, the acceptably low content of volatile combustible matter, and the microporous-mesoporous structure, the prepared solid products have potential for further applications, such as sorbents or soil remediants.