Kinetic and thermodynamic studies of the non-isothermal decompositions of nickel malonate dihydrate and nickel hydrogen malonate dihydrate

Non-isothermal decompositions (including TG, DTG, DTA and DSC) of nickel ma lonate dihydrate and of nickel hydrogen malonate dihydrate were studied in different dynamic atmospheres of N-2, H-2 or air. The reaction of the hydro gen malonate salt commences at a lower temperature than the corresponding n ickel malonate salt. IR spectroscopy showed that nickel acetate was formed as a reaction interme diate during the decompositions of both reactants. X-ray diffraction showed that nickel metal was the predominant product from reactions in N-2 or H-2 atmospheres while nickel oxide, together with some nickel metal, was forme d during reaction in air. Gas chromatography identified CO2, CO, acetic aci d ethyl alcohol together with appreciable amounts of methyl formate and eth yl formate as the volatile decomposition products. Kinetic and thermodynamic parameters of the decomposition of the two reacta nt salts were calculated. (C) 1998 Elsevier Science B.V. All rights reserve d.