Preparation of Porous Coke by Microwave Pyrolysis of Oily Sludge: Optimization Through Response Surface Methodology and TG-FTIR Analysis

Oily sludge (OS) is a kind of solid waste with precious oil resources in the petroleum industry. Because OS poses a severe threat to the environment, the treatment of OS has been widely studied. In this work, OS was used to prepare porous sludge coke a through microwave pyrolysis and one-step ZnCl2 activation technique. The response surface methodology was designed to optimize the parameters of the preparation process of porous sludge coke, and the interaction between the parameters was further analyzed. The experimental result showed that the model could fit the experimental results well. The optimal iodine adsorption value of porous sludge coke, 785.23 mg/g, was obtained by using the response surface methodology when the microwave power was 797 W, the ZnCl2 addition ratio was 0.5, and the pyrolysis time was 25 min. The experimental result showed that the model could fit the experimental results well. The influence of ZnCl2 on the pyrolysis of OS was investigated through TG-FTIR. The results showed that the presence of ZnCl2 could prevent the fracture of C-H bond, reduce the rate of carbon source loss caused by the fracture of long-chain hydrocarbons to produce short-chain hydrocarbons in OS, and enrich the carbon source of sludge coke. On the other hand, the molten ZnCl2 occupied the tiny pores when the oil components in the OS volatilized, which can enrich the pore volume of the sludge coke.