Home – Home – Jornals – Chemistry for Sustainable Development 2017 number 3

The article summarizes the results of the studies performed at the Institute of Chemistry and Chemical Technology SB RAS from 1998 to 2014 in the area of thermocatalytic transformations of brown and sapropelite coal into gaseous and liquid fuels, binding and carbon materials. The fundamentals were developed for the autothermal process of brown coal carbonisation in a fluidized bed of catalyst with obtaining semi-coke and carbon sorbents. Additionally, the simultaneous preparation of fuel gas and syngas based on parallel operation of two fluidized bed reactors that are pyrolyser and gasifier was studied. Due to the use of a fluidized bed of catalyst particles during oxidative carbonization of brown coal, we managed to combine in one apparatus the processes of combustion and thermal treatment of coal. Metallurgical slags capable of oxidizing volatile substances released from coal were used as catalysts at elevated temperatures. The developed method allowed regulating the degree of coal carbonisation and, respectively, the properties of the resulting carbon products by changing the consumption coefficients of powdery coal and air fed to the reactor. Herewith, the depth of thermal treatment of coal and such characteristics of the resulting carbon product, as the heat of combustion, a content of volatile substances, its chemical composition and porosity were changed. Only the most reactive part of fuels was gasified in a catalytic boiling layer in a mode of partial gasification of coal and the porous carbon product was formed, the latter could be used as a sorbent. It was proposed to produce syngas by using a pyrolyser-gasifier. Semi-coke formed during brown coal carbonisation in a pyrolyser was raw materials for steam gasification. Since the major part of volatile substances was already removed from semi-coke, the release of resinous products did not accompany its gasification. Therefore, the product gas did not require expensive purification from impurities before its use in synthesis processes. New methods for the preparation of liquid fuels and road binders were proposed. They were based on the process of hydrogenation of brown coal and its mixtures with oil residues and synthetic polymers in the presence of mechanically activated iron-ore catalysts in the environment of hydrogen donor solvents. Products of joint refining of brown coal, oil residues and synthetic polymers wastes were used to obtain road binders, and it was proposed to obtain modifiers for paving asphalt based on oil-resistant rubbers and liquid coal products. The optimum conditions for thermal refining of sapropelite coal in a reactor with a fluidized bed were selected. They provided the increased yield of liquid products in comparison with the known processes of semicoking of coal. The composition of the products allowed their refining by standard oil refining technologies.