Transformation of industrial steel slag with different structure-modifying agents for synthesis of catalysts

Abstract

Abstract Industrial slag containing Si, Al, Ca, Fe, Mg and Ti was used as source for synthesis of novel catalytic materials upon variation of the treating agents (sodium hydroxide, ethylenediaminetetraacetic acid disodium salt dihydrate - sodium hydroxide and tetraethylammonium hydroxide - sodium hydroxide mixtures) and synthesis parameters (solution concentration, synthesis temperature and time). Physico-chemical properties of the raw slag and the catalysts were evaluated by nitrogen physisorption, scanning electron microscopy, energy dispersive X-ray analysis, temperature programmed desorption of CO2 and NH3, transmission electron microscopy, and X-ray powder diffraction. Catalytic activity of the most promising slag-based material was investigated in analytical pyrolysis of wood biomass. Synthesized materials exhibited highly crystalline phases of CaCO3, Ca(OH)2, Ca2SiO4, SiO2, Al2O3, Fe2O3,and TiO2 and showed high basicity due to the presence of large amounts of basic components. Treatment with surfactants had a significant influence on formation of acid sites. Modification of slag textural properties and internal porous structure by such treatment resulted in formation of pores and channels depending on the leaching agent. Upon variation of a leaching agent the specific surface area of the raw slag could be changed from 19 m2/g up to 80 m2/g, what turned out to be important in creation of an effective catalyst for biomass pyrolysis. Slag treatment improved its catalytic activity, which was evidenced by variations of the liquid yield and composition of pinewood derived compounds in non-catalytic and catalytic pyrolysis using original slag and the catalysis synthesized on its basis.