Gold on titanium dioxide—the hydrogen-oxygen reaction

4 Gold on titanium dioxide—the hydrogen-oxygen reaction 

Zeolites are well known for their ability to absorb molecules selectively and as acid-base catalysts for, e.g. cracking, isomerisation and alkylation of hydrocarbons. They are aluminosilicates (Si,Al) c02j with an 

The INS spectra of zeolites have been calculated by force-field methods [106,107]. Note that the hydrogen atoms follow the displacements of the framework atoms due to the lattice modes (480-970 cm ). The lattice modes (Al-0 and Si-O stretching and bending modes) are therefore observed in the INS spectra—another example of hydrogen riding modes. 

Type Y zeolite is a synthetic analogue of the mineral faujasite the Site-A1 ratio is between 1.5 and 3. The structure consists of a three-dimensional array of spherical supercages 13 A in diameter. These spheres are connected by 7.4 A windows. The sodalite cages are truncated octahedra of diameter 7.6 A. The INS spectra of NaY and H-NaY, which are typical zeolite spectra, are shown in Fig. 7.26 and the peaks are listed and assigned in Table 7.16 [108,109]. 

The sodium ions of Na zeolite Y may be substituted by ammonium ions [110]. The degree of hydration of the NH4Y depends on the thermal treatment water is retained up to 373 K and lost at 473 K. The sodium ions may be replaced partly by ammonium ions and partly by caesium ions. Ammonium ions may also be introduced by treatment of the acidic zeolite with ammonia gas. The caesium ions occupy the supercages and the ammonium ions are restricted to the sodalite cages. 

---