Improving Nitrogen Retention in Algal Biochar Pyrolysis by Co‐Pyrolysis with Glucose

Abstract Algal biomass is a promising pyrolysis feedstock, however, large amounts of nitrogen‐containing compounds (NH 3 , HCN,…) are emitted during its conversion. These emissions can be decreased by incorporating nitrogen in the biochar's carbon matrix via co‐pyrolysis. This study investigates whether adding glucose (GL) to the microalgae, Arthrospira sp . (SP), increases the nitrogen fixation in the solid biochar. Moreover, scalable (co‐) pyrolysis experiments are linked with micro‐scale pyrolysis. Using hyphenated pyrolysis (Py–GC–MS, TG‐IR) and characterization (CHNS, XPS, and Raman) techniques the phenomena associated with the incorporation of nitrogen in the biochars are unraveled. Co‐pyrolyzing SP and GL increased biochar yields and nitrogen retention, which is attributed to Maillard reactions occurring in the initial pyrolysis stages. In conclusion, this study provides evidence that co‐pyrolysis of microalgae and reducing sugars is a more sustainable strategy to produce algae‐based biochar.