The effect of CaO on coal gasification reaction with high-temperature copper slag as catalyst

ABSTRACT

In order to improve the calorific value and reducibility of the syngas produced by traditional coal gasification technology, and to solve the problem of high cost of heat source in coal gasification, this paper proposes to use high-temperature copper slag as the heat carriers and catalyst for coal gasification, and CaO as the CO₂ adsorbent during the coal gasification reaction. In this way, the proportion of H₂ in the syngas gas can be increased, and the coal gasification reaction can be improved. In the experiment, the samples with different ratios were fully mixed, and then thermogravimetric experiment and gasification experiment were carried out. Through research, the following rules were found. The use of high-temperature copper slag as the heat source and catalyst in coal gasification can lead to a 20% increase in the final weight loss rate. Additionally, when CaO is used as the CO₂ adsorbent during the coal gasification reaction, a noticeable secondary weight loss occurs at around 600°C and can reach a maximum speed of 0.19%/min. The use of the C/S/CaO = 1/1/2 ratio can result in a maximum weight loss rate of 23%. Meanwhile, the C/S/CaO = 1/2/1 group has been shown to achieve a maximum weight loss speed of 0.5%/min, and the C/S/CaO = 1/1/1 group exhibits a maximum secondary weight loss speed of 0.32%/min. The samples after gasification experiment were analyzed by SEM, CaO produced clustered iron-based and porous structure on the surface of copper slag in gasification reaction. Based on the Coats-Redfern method, kinetics of gasification reaction is obtained, and the optimum fitting function is C2, mechanism functions didn’t change with the variation of C/S/CaO. The research results suggest that CaO and copper slag can both enhance the coal gasification reaction. In addition, CaO is proven to be a more affordable and accessible CO2 adsorbent compared to other alternatives.

KEYWORDS:

• copper slag
• coal gasification
• CaO
• catalysis
• kinetic analysis

Highlights

• The waste heat from copper slag is being used to gasify low-calorific-value lignite coal.

• CaO is used as a CO₂absorbent in syngas.

• The Coats-Redfern method is used to investigate the kinetics of coal gasification reaction.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The work was supported by the 2022 Science and Technology Think Tank Youth Talent Plan [20220615ZZ07110238]; Open Project of State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization [CNMRCUKF2207]; Natural Science Foundation of China [52104397]; Open Fund Project Regulations of State Key Laboratory of Clean Energy Utilization [ZJUCEU2021020].