EFFECT OF PT PARTICLE-SIZE ON H D EXCHANGE OF METHANE EVER ALUMINA-SUPPORTED AND ZEOLITE-SUPPORTED CATALYSTS/

Deuterium exchange in methane was studied over a series of Pt/Al2O3 an d Pt/mazzite catalysts. The reaction proceeds by a simple stepwise mec hanism with CH3D being the primary product. Large and small metal part icles located in zeolite and alumina catalysts have different catalyti c activity with respect to deuterium exchange in methane. The rate of reaction per Pt atom was the same on the catalysts investigated for pa rticles > 15-20 Angstrom and considerably lower than the rate of react ion on samples with smaller Pt clusters. The activity of small cluster s of Pt (diameter < 15-20 Angstrom) depended on the nature of the supp ort.