Influence of the Demineralization of Naturally Oxidized Coal on Sorbent Texture

The influence of preliminary demineralization of coal by aqueous solutions of hydrochloric and hydrofluoric acid on the texture of sorbents produced by thermolysis in the presence of potassium hydroxide is investigated (when the mass ratio of the KOH and the coal is 2.0). The results show that successive treatment of coal with 10% hydrochloric and 10% hydrofluoric acid decreases the coal’s ash content to a residual value of about 0.6%. In thermolysis, a sorbent with an ash content of 1.5% is obtained on thermolysis. In comparison with sorbent from untreated coal, the sorbent from the demineralized coal is characterized by higher specific surface and total pore volume. In the treated coal, more than 70% of the pore space consists of micropores.