The rate-limiting step in the integrated coal tar decomposition and upgrading- iron ore reduction reaction determined by kinetic analysis

Abstract

Simultaneously achieving high-quality catalytic cracking of light tar, maintaining a large target product yield and improving the reductivity of iron ore, is major step towards enhancing the energy conversion efficiency of the coal chemical industry and ironmaking applications. To achieve the aforementioned goals, an experiment involving regulation under coal pyrolysis, with iron ore as a catalytic bed, optimization of carbon deposition in spent samples and integration of multiple similar reaction factors between the pyrolysis of experimental samples and volatile decomposition-carbon deposition was designed. The mass fraction and yield of the light tar produced when the pyrolysis tar is passed through a goethite bed are 75.1 % and 5.34 % at the upper reactor temperature of 550 °C, respectively, which are higher than those of the other two iron ore. Additionally, because the iron ore contains carbon deposits at the nanometre scale, compared with the original iron ore, the spent sample exhibits a peculiar phenomenon in which the reactivity increases. The reduction degree, metallization ratio of the iron ore and kinetic characteristics are compared and analysed, confirming a response mechanism to enhance the reduction degree on various fluctuating factors at temperatures exceeding 800 °C, and revealing that the reduction reaction occurs consecutively in four consecutive according to the efficiency of the conversion. In absence of sufficient CO2 in the reaction and according to the calculated activation energy, the carbon gasification reaction was identified as a rate-limiting step in the reduction reaction. The activation energy and rate-limiting step provide a pathway featuring pollution reduction, clean energy and energy conservation aimed towards the deployment of integrated technology for tar upgrading and iron ore reduction.