The Impact of Lignin Content on the Pyrolysis Time-Temperature Curves during Biochar Production from Household Biowaste

Biochar can be used as a carbon sequestration method or for other value-added applications in industries like agriculture or environmental control. Organic wastes can be converted to biochar by heating in an inert environment in a process known as pyrolysis. This process can be carbon negative as in pyrogenic carbon capture and storage (PyCCS). We studied the influence of feedstock lignin content on the pyrolysis process using ten different feedstocks, including walnut shells, banana peels, and sunflower seed shells. Pyrolysis was conducted at 500°C in a tube furnace with two thermocouple probes monitoring the temperature of the upper and lower regions of the tube. We have found that different feedstocks have different trends in their pyrolysis time-temperature curves, and there can be both exothermic and endothermic regions in the curves. The data indicates that the maximum change in temperature decreases linearly as the lignin content increases, and reaction time increases as lignin percentage increases. In an additional study, pyrolysis was conducted at various temperatures on three different feedstocks: walnut shells, cardboard, and sawdust. We have found expected trends within feedstock types, such as the solid yield increasing as the pyrolysis temperature decreases. We will present the endothermicity of pyrolysis as both a function of feedstock and temperature.