Masao Nakano

Catalyst for purifying exhaust gas

A catalyst for purifying an exhaust gas comprising a zeolite catalyst ion-exchanged with a transition metal, which is heat-treated in a gas stream containing a sulfur oxide, optionally followed by washing with a glycol.

Nitrogen adsorption properties of cubic and orthorhombic Li-exchanged low silica X

Abstract The adsorption capacity of nitrogen on Li-exchanged low silica X zeolite (LiLSX) was measured at various temperatures. The isosteres for 100% Li-exchanged LSX (Li100%LSX), where the logarithm of pressure is plotted against the inverse of absolute temperature, are divided into two straight lines. The discontinuous temperature range of the isosteres corresponded to that of the cubic–orthorhombic symmetry change for Li100%LSX. The unexpected increase in nitrogen adsorption on Li100%LSX at low temperature is due to the increase in the number of main adsorption sites (Li ions at site III(′)) caused by the cubic–orthorhombic symmetry change induced by temperature. The isosteric heat of adsorption on the orthorhombic phase agrees with that on the cubic phase.

Para-Selective Chlorination of Chlorobenzene on Modified Y-Type Zeolites

Para-selective liquid-phase chlorination of chlorobenzene was investigated on modified Y-type zeolites. It was indicated that chlorination occurred in the pore of zeolites. Less acidic Na-Y revealed to present higher para-dichlorobenzene selectivity than H-Y. In order to modify catalyst properties of Na-Y, Na-Y was impregnated with sodium chloride solution. Thus obtained NaCl-impregnated Na-Y showed about 5-6% higher para-selectivity than the original Na-Y. This improvement was explained by salt-bearing effect and salt-modification effect. ESCA showed electron transfer from chloride anion to aluminum and 27 Al MAS NMR indicated that sodium at S II moved to the direction of the center of sodalite cage. Thus, it was strongly suggested that acid strength of active site was weakened by salt-bearing and as a result para-selectivity increased. Although salt-modification effect is not clear yet, it was considered that NaCl blocked less selective active site on the outer surface or that NaCl influenced the active site on the surface somehow. When salt-bearing Y-type zeolites of various silica to alumina ratios(3.6-5.5) were studied, higher para-selectivity was obtained for each of the catalysts than their originals. The zeolite of silica/alumina ratio 4.6 gave the highest para-selectivity. Dependence of para-selectivity on silica/alumina ratio was explained by acid strength and the number of active site.

90 Catalytic combustion of 1,2-dichloroethane with hybrid catalysts composed of zeolite and Pt/Al2O3

Abstract Various Pt-loaded catalysts were evaluated for combustion of 1,2-dichloroethane (EDC). The Pt/Na-zeolite showed high catalytic activity, but the decrease of activity was observed with reaction time. On the other hand, Pt/Al 2 O 3 catalyst showed a low and stable activity. The activity of EDC conversion depended on adsorbed amount of EDC on the support, Pt dispersions, and these stability. The hybrid catalysts composed of zeolite and Pt/Al 2 O 3 showed high and stable activity. It was suggested that zeolite worked as adsorption site EDC, and the adsorbed species were decomposed on the surface of Pt/Al 2 O 3 .