Catalytic Effect of Metal Chlorides on Coal Pyrolysis Using TG & PY-GC/MS

ABSTRACT

In this study, thermogravimetric analysis (TGA) with a final temperature of 1000°C at a heating rate of 10°C/min and rapid pyrolysis are used to analyze the catalytic pyrolysis effect of CaCl₂ and NiCl₂ on lignite samples, mainly including pyrolysis reaction analysis and tar product distribution. To avoid the influence of minerals on the pyrolysis reaction, acid-washed coal is selected and mixed with metal cations for further analysis. The TGA results show that when mixed with 6 wt. % Ca or Ni, the weight loss rate of acid-washed lignite increases from 46.46% to 59.76% and 54.66%, respectively. At pyrolysis temperatures above 600°C, the performance on coal pyrolysis transformation of Ca is significantly better than that of Ni. The effect of the catalyst on coal pyrolysis could be divided into three stages. Due to catalysis, the pyrolysis of the most unstable structure of coal is advanced to the first stage, which makes the second stage show a certain catalytic inhibition. Kinetic analysis reveals that the activation energy of pyrolysis is obviously reduced by catalysts, and comparatively, the most energy is needed at the second stage. The tar mainly contains substances with 5 to 16 carbon atoms, and aromatic hydrocarbons, as the main components, account for more than 90% of the tar composition. The yield of light aromatic compounds increases with the catalysts Ca and Ni, while the yield of polycyclic aromatics decreases.

KEYWORDS:

• Pyrolysis
• metal cations
• thermogravimetric
• kinetics
• tar distribution

Additional information

Funding

This research is funded by the Research Program Foundation of Nanjing Institute of Technology [YKJ 201998] and the Research Program Foundation of Nanjing Institute of Technology [YKJ 201733].