The temperature effect and system equilibrium of preparing powdered activated coke sorbent in a rapid carbonization-activation two-step process

ABSTRACT

In this study, a rapid carbonization-activation two-step process for preparing powdered activated coke (PAC) sorbent is proposed. Shengli lignite is utilized as the feedstock to prepare PACs through this process, employing various combinations of carbonization and activation temperatures. The pore structure, surface functional groups, yield and SO₂ adsorption properties of the PACs are comprehensively analyzed. Additionally, Aspen Plus software is employed to calculate the system equilibrium of this process. Results demonstrate that the performance of the prepared PAC is predominantly influenced by the activation temperature. Despite variations in carbonization temperature, consistent performance and yield are achieved as long as the activation temperature remains constant. Through the experimental design, the optimum combination of carbonization temperature and activation temperature of the two-step process is optimized, that is, the carbonization temperature is 750°C, and the activation temperature is 950°C. The S_BET of the PAC prepared under optimal condition is 550 m²/g, and its SO₂ adsorption capacity is 116.58 mg/g, which are both higher than that of the other ACs. The system equilibrium indicates that the optimal parameters for PAC preparation can be achieved by employing a water and air spray technique between the combustion zone and activation zone, with a water spray rate of 1.70 (kg/kg coal for combustion) and an air spray rate of 2.75 (kg/kg coal for combustion). In addition, the maintenance of system equilibrium necessitates the combustion of a certain amount of gas to elevate the temperature through the injection of a specific quantity of air into the carbonization step, with an air spray rate set at 11.00 (kg/kg coal for combustion).

KEYWORDS:

• Rapid carbonization-activation
• two-step process
• temperature effect
• system equilibrium
• SO₂ sorbent

Acknowledgements

This project is funded by the Qingdao Postdoctoral Program Funding (QDBSH20220202045), National Natural Science Foundation of China (22078176), Shandong provincial Natural Science Foundation (ZR2022ME176, ZR2021ME049), and Taishan Industrial Experts Program (TSCX202306135).

Disclosure statement

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

Additional information

Funding

The work was supported by the National Natural Science Foundation of China [22078176]; Natural Science Foundation of Shandong Province [ZR2022ME176]; Shandong provincial Natural Science Foundation [ZR2022ME176, ZR2021ME049]; Qingdao Postdoctoral Program Funding [QDBSH20220202045]. Taishan Industrial Experts Program [TSCX202306135].