Gas generation characteristics and kinetics during catalytic pyrolysis of distiller's grains by coal slag for...

In this research, catalytic and non-catalytic pyrolysis of distillers' grains (DG) were conducted on a micro fluidized bed reaction analyzer (MFBRA) to assess Fe-rich coal slag's reaction activity and then support DG's staged gasification utilization. The research focused on the online generation characteristics of gas components (H₂, CO, CO₂, CH₄, C₂H₄, etc.) and the corresponding reaction kinetics in pyrolysis with and without coal slag. Meanwhile, the evolution of char structure and coal slag's physicochemical features were also analyzed. The results show that both catalytic and non-catalytic pyrolysis can be finished within about 5.5 s, including an initial rapid release (S1) and the following slow release stage (S2). More than 70 % gas products were produced in S1. Coal slag had weak effect on pyrolysis time in S1 and S2, but strongly promoted the generation of H₂, CO, CO₂, C₂H₄, and total gas products and suppressed that of CH₄. Meanwhile, the generation rate of H₂ and CO₂ became much higher. For the calculated activated energies (Ea), in S1, Ea for CO, CO₂, C₂H₄, and total gas products were significantly higher than those in S2, except H₂. Compared to non-catalytic pyrolysis, Ea for H₂, CO, CO₂, C₂H₄, and total gas products were much lower in both S1 and S2. However, Ea for CH₄ was much lower in S1 and higher in S2. Meanwhile, char from catalytic pyrolysis had a more developed porous structure and higher intensity of aromatic C-H and alkyl ethers on its surface. After catalytic pyrolysis, the intensity of Fe₃O₄ decreased, while that of FeO increased significantly, leading to a decrease of coal slag's catalytic activity. The research is beneficial to coordinated utilization of DG and coal slag by gasification process, well promoting the clean production and environment management of Chinese Baijiu industry.