Thermogravimetric evolved gas analysis of urea and urea solutions with nickel-alumina catalyst

Thermal decomposition of urea, and aqueous urea solutions, in the presence of 18 wt % nickel on alumina was studied by thermogravimetric analysis. A range of evolved gas species (a wider range than reported previously) were monitored by mass spectroscopy, with the evolved gases also analysed using FTIR. Results supported previous evidence of major urea decomposition starting ca. 133 °C, though a previously unreported two stage evolution was detected by MS in the first episode. For aqueous urea solutions, at temperatures from 80 °C, evolution of nitrogen was observed, along with a simultaneous release of some NH3 and what was considered to be H2 (by the detection of a m/z = 2 ion). Activity of nickel alumina catalyst for H2 steam reforming could not be discerned by this method, though its influence was apparent by differing evolution profiles of HCN, and NH3 in comparison to uncatalysed samples.