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Ni-Pt/H-Y zeolite catalysts with different Ni contents were prepared and applied to the disproportionation of toluene and 1,2,4-trimethylbenzene in the temperature range 250-400°C. The line broadening XRD analysis indicates that the increasing Ni addition decreases the crystallinity of zeolites. ESCA studies show the complete reduction of Ni species up to 0.3 wt.% Ni addition over 0.1 wt.% Pt/H-Y and further addition leads to the occurrence of unreduced nickel species as NiAl 2 O 4 . A TEM study shows the formation of bimetallic (Ni-Pt) particles of nanoscale size and the average particle size is found to increase with increasing Ni loading. Acidity measurements by NH 3 -TPD and pyridine-adsorbed FT-IR spectroscopy show the increasing occupation of acid sites by increasing nickel loading. The catalytic activity of Ni-Pt/H-Y zeolite and Pt/H-Y catalysts was compared and it was found that addition of Ni up to 0.3 wt.% increases conversion of toluene and 1,2,4-trimethylbenzene, disproportionation selectivity and sustainability of the catalysts. Further addition of Ni leads to a decrease in conversion and disproportionation selectivity and increasing dealkylated products, which may be due to the presence of unreduced Ni species and pore blockage by large-sized bimetallic particles formed.

The dielectric constant of sodium chlorate has been analyzed on the basis of a Mason-Debye-type relaxation formula. A consistent description of the temperature dependence of the phonon structure and the dielectric-constant behavior as a function of frequency and temperature is obtained for this nonferroelectric order-disorder crystal. The fluctuation meccan»nm responsible for the dielectric relaxation behavior is identified as that of the apex reversal of the chlorate ion as one approaches the transition temperature.

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