Journal Article

Catalytic Decomposition of Toluene over Fe.sub.2O.sub.3 Nanocluster During Chemical Looping Gasification

Zhao, Shanhui, Zhang, Siwen, Gu, Haiming

2024

Overview

Chemical looping gasification (CLG) is an effective technology for efficient utilization of coal, biomass and other fuels. In this work, the detailed mechanism of catalytic decomposition during CLG for toluene, a tar model compound, was studied by using reactive force field molecular dynamics (ReaxFF MD) method. Results show that toluene hardly decomposes at temperature lower than 2000 K. Improving temperature could significantly improve decomposition efficiency but also enhances the polymerization to produce PAHs and soot precursor, with largest molecule weight of 2175 (C.sub.177H.sub.51, 3000 K, 400 ps). Fe.sub.2O.sub.3 nanocluster, as oxygen carrier, could improve the decomposition efficiency of toluene and reduce the decomposition temperature. At 2000 K and 200 ps, the catalytic conversion of toluene reaches 60%. A large amount of H.sub.2, CO, C.sub.2H.sub.2 and other small molecular gases are generated during the catalytic decomposition of toluene. At 3000 K, the yield of H.sub.2, CO and C.sub.2H.sub.2 reached 132 %mole, 117 %mole and 40 %mole of toluene, respectively. Meanwhile, polymerization reactions are largely inhibited by Fe.sub.2O.sub.3 nanocluster and the largest molecule is C.sub.20H.sub.9O, the weight of which is much lower than soot precursor in thermal decomposition. Kinetic results show that the activated energy of catalytic decomposition is about 74 kJ/mole, which is much lower than thermal decomposition (382 kJ/mole). Detailed reaction mechanism reveals that lattice oxygen on Fe.sub.2O.sub.3 nanocluster act as the active sites, which enhance the decomposition of toluene.

• Publisher: Springer
• Subject: Molecular dynamics / Polymerization / Toluene