Studies of hydrogen spillover. Part 1.—Study of the rate, extent and products of hydrogen spillover from platinum to the trioxides of tungsten and molybdenum

Abstract

The rates and extents of hydrogen sorption by platinised tungsten trioxide and molybdenum trioxide have been measured between 273 and 363 K and between 3 and 101 kN m^–2. Maximum diffusion coefficients for hydrogen spilling-over from platinum to the trioxide supports have been estimated. X-Ray diffraction, differential thermal analysis and thermogravimetric analysis, e.s.r. and i.r. spectroscopy indicate that the products of this spillover are hydrogen bronzes of tungsten and molybdenum. These may be represented as H_xWO₃, where x has a maximum value of 0.46, and H_xMoO₃, where x has a maximum value of 1.63. The latter violates the ranges of composition previously accepted for bronzes. The chemical and thermal stability of these bronzes is discussed in terms of their structures.