Study on surface characteristics of oil shale during fluidized combustion

Combustion experiments of oil shale were conducted in bench-scale CFB reactor. Samples of oil shale char were obtained under different bed temperature and different resident time. Adsorption isotherms were determined by Micromeritics Gemini 2380 specific area analyzer under nitrogen atmosphere. The specific surface areas and pore size distribution of samples were determined based on BET model and BJH theory, respectively. While surface fractal dimensions were calculated with FHH model. The results showed that all the samples consist of continuous and complete system of pores. Specific area and pore size distribution of different samples present relatively similar tendency; most pore sizes were at maximum around 3 nm. Specific surface area and volume of pores increased rapidly with the increasing of resident time in the reactor, and then decreased gradually. But compared to specific area, there is some delay of which burned at 750°C are about 1.5 times more than the samples prepared at 850°C. In the early stage of combustion, the fractal dimensiuon of char samples increase sharply, and then decrease slightly. At the same time, the fractal dimension of char samples was significantly higher than that of original samples.