Thermochemical Conversion Behavior of Turkish Lignite/Poppy Capsule Pulp Blends in N2 and CO2 Atmospheres

Abstract

In this study, Thermogravimetric Analyzer coupled with Fourier Transform Infrared Spectroscopy (TGA-FTIR) was used for the determination of the thermochemical conversion reactivity of two different types of Turkish lignite coal (Tunçbilek and Orhaneli-Gümüşpınar) and poppy capsule pulp (PCP) mixtures under pyrolysis conditions at nitrogen (N2) and carbon dioxide (CO2) atmospheres. Activation energies (Ea) and pre-exponential factors (A) were determined according to Coats-Redfern method and first-order reaction model. In CO2 atmosphere, all samples exhibited an extra weight loss around 800 - 850 ° C, different from the N2 atmosphere, due to the reactive nature of CO2 during thermal decomposition. FTIR analysis confirmed this finding, at high temperatures CO formation were observed in the CO2 atmosphere. In all mixtures, the third zone experimental decomposition temperature is lower than that obtained theoretically in N2 atmosphere, showing that there might a synergistic interaction between the PCP and the lignite samples. The Ea of PCP/Tunçbilek lignite mixtures are smaller than the Ea of their parent components indicating synergy in N2 and CO2 atmospheres. However, initial and maximum decomposition temperatures for the parent components remain unchanged for these mixtures. Moreover, especially at temperatures higher than 600 °C, the Ea for biomass/lignite mixtures found lower than the theoretical values, due to the possible synergistic interactions between PCP and coal samples. According to FTIR analysis, CO, CH4, CHn and ether/amine components were detected. Gaseous pyrolysis product compositions were highly dependent on temperature, and gas species formation was consistent with the weight loss of samples.