Pyrolysis solid product as a sorbent for flue gases mercury capture - Part I: Sorbent formation and characteristics

Abstract

This study investigates the pyrolysis of various materials (solid recovered fuel, digestate, hay pellets, straw, polyethylene, and tires) at temperatures ranging from 350 to 650 degrees C, with retention times between 90 and 190 minutes and a heating rate of 10 degrees C center dot min-1. Its focus is on utilizing pyrolysis residue-char as a sorbent for mercury capture from flue gas during conventional fuel combustion. Physical and chemical activation techniques employing NaOH as an oxidizing agent are used to enhance surface area and pore volume. Characterization techniques, including thermogravimetric analysis, Fourier transform infrared spectroscopy, scanning electron microscopy and various analyses, are employed. Results indicate solid fraction recoveries of 77%wt. for solid recovered fuel, 58%wt. for tires, and 48%wt. for straw, with average recoveries of 47%wt. solid, 18.7%wt. gaseous, and 34.3%wt. liquid fractions. After applying the activation processes, the results reveal that the most suitable sorbent is the straw sample, where the specific surface area and pore volume are 148.95 m2 center dot g-1 and 0.0569 cm3 center dot g-1 after physical activation and 640.98 m2 center dot g-1 and 0.2867 cm3 center dot g-1 after chemical activation, respectively. These findings suggest promising applications for pyrolysis char as sorbents, with significant improvements achieved through activation methods. The application of the developed sorbents for mercury capture in a real flue gas environment is closely investigated in Part II of this study.