Characteristics and kinetic analysis of the catalytic pyrolysis of oily sludge under new nickel-ore–based catalysts

Thermal analysis of oily sludge (OS) from steel mills was conducted to understand its added value. The effect of additional catalysts (calcined olivine (C-OL), iddingsite (C-ID), xiuyan jade (C-XY), and their nickel carrier on OS pyrolysis performance was also investigated. The physical properties of OS showed a large number of resins and irons. It was found that OS pyrolysis involves water evaporation, light hydrocarbon escape, the crack of resins, asphaltene decomposition, and inorganic mineral decomposition. TG results demonstrated that the prepared catalyst can effectively improve the weight loss, in which the C-OL (Ni) increased by 11.58 wt.%. The kinetic behavior of the three main weight loss zones in the catalytic pyrolysis of OS was subsequently analyzed. The apparent activation energies of the main stages of OS pyrolysis were 61.03, 18.07, and 62.92 kJ/mol, respectively. The addition of C-OL significantly reduced the apparent activation energies by 31.34, 5.74, and 44.46 kJ/mol. The evaluation of the pre-exponential factor revealed that all stages of OS pyrolysis followed a diffusion model, and the reaction path was not changed by the ore catalysts.