Research on Thermal Stability of Sorbents on the Basis of Microspheres Modified With Ferrocyanides of Transient and Heavy Metals

The mass-spectrometer method was used to investigate the compositions of gas phases formed at thermal decomposition of inorganic sorbents on the basis of alumosilicate microspheres modified with ferrocyanides of copper, iron, cobalt, tungsten and vanadium. The research was carried out in a static mode in vacuum in the temperature range of 180–500°C. The chemical composition of modifiers corresponded to formulas: K₂Cu[Fe(CN)₆]; K₂Cu₃[Fe(CN)₆]₂; Fe₄[Fe(CN)₆]₃; KFe[Fe(CN)₆]; Co₂[Fe(CN)₆]; xH₄Fe(N)₆·yWO₃·zH₂O; xH₄Fe(CN)₆·yV₂O₅·zH₂O. The basic components of gas phases after thermal effect on these structures are hydrogen, water, carbon dioxide and monoxide, nitrogen, and cyanic hydrogen. With the temperature growth the intensity of gas evolution increases, the ratio between the components vary, paraffin hydrocarbons and unsaturated hydrocarbons appear (ethane, acetylene, propene). The content of methane varies within ∼0.2–2 % vol. weakly correlating with experimental conditions. The composition of the gas phases produced during thermal effect on the modified microspheres is most probably a superposition of physical and chemical processes connected with the influence of the matrix itself, with individual heat resistance of the modifiers and products of their decomposition, as well as with that circumstance, that products of reactions can interact with each other. In general the character of the processes during thermal decomposition of mixed ferrocyanides of M_xE_y[Fe(CN)₆]z type (where M is an alkali metal, and E is some “heavy metal”) applied onto cenocpheres is determined mostly by the polarization effect of the “heavy” metal on anion [Fe(CN)₆]⁻⁴.