Evaluation of Biochar Production Through Slow Pyrolysis of Corn Agroindustry Residues in the Department of Córdoba, Colombia

Biomass emerges as a promising source for bioenergy generation and valuable by-products, offering a sustainable alternative for utilizing agro-industrial waste. Among thermochemical conversion techniques, pyrolysis stands out for its capacity to transform biomass into three main products: Syngas, Bio-oil, and Biochar. Biochar, the result of biomass conversion, can represent between 4% and 40% of the original mass, depending on the conditions of the pyrolysis process. This solid material is of particular interest due to its multiple potential applications, which are regulated by international standards such as the International Carbon Standard and European EBC certification. In this study, a predictive model was developed to characterize the properties of corn cob biochar produced at different pyrolysis temperatures. The model is based on experimental thermogravimetric analysis and elemental analysis of the biomass, using empirical correlations to predict H/C ratios, OC content, inorganic content, heating value, and formation enthalpy. The results show that the pyrolysis temperature significantly affects the characteristics of biochar. It was observed that the thermochemical transformation of biomass reaches a maximum in gross calorific value at temperatures of 500°C, with an H/C ratio of 0.3 and an O/C ratio of 0.1. The formation enthalpies of biochar increase with the pyrolysis temperature, associated with the increase in organic carbon concentration. Furthermore, it is estimated that biochar begins to form at temperatures above 380°C, achieving a minimum H/C ratio of less than 0.7.