Investigation of the properties and reactivity of biocarbons at high temperature in mixture of CO/CO2

Abstract

The CO2 gasification reactivity of biocarbons produced from birch wood chips under different atmospheric and pressurised conditions was investigated in this work. The reactivity tests were conducted by using a Macro-TGA at 1100°C in a gas mixture of 50% CO2 and 50% CO to simulate the conditions in an industrial ferromagnese furnace. The results showed that biocarbons produced under different conditions have different CO2 gasification reactivities. The biocarbon produced in an atmospheric fixed bed reactor has the highest reactivity. This biocarbon has a high surface area and content of catalytic inorganic elements, which favour the Boudouard reaction and consumes fixed carbon. Scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS) showed that migration and transformation behaviours of inorganic elements in the studied biocarbons are different at the same gasification condition. Together with inductively coupled plasma atomic emission spectroscopy (ICP-OES) analysis, SEM-EDS analysis revealed that the most intensive transformation of inorganic elements occurred during gasification of the biocarbon sample produced at atmospheric conditions with slow heating rate and purging of N2. Such pyrolysis condition promotes presence of catalytic inorganic elements on the biocarbon surface, which promotes the Boudouard reaction.