INCORPORATION OF CARBON INTO PALLADIUM DURING LOW-TEMPERATURE DISPROPORTIONATION OF CO OVER PD ZRO2 PREPARED FROM GLASSY PD-ZR ALLOYS/

Pd/ZrO2 prepared from oxidation of glassy Pd-Zr alloys was found to di sproportionate carbon monoxide already at about 370 K. The studies whi ch involved thermal analysis (DTA, TG) combined with mass spectroscopy and X-ray diffraction showed that interaction of CO with Pd/ZrO2 lead s to its disproportionation followed by incorporation of carbon into t he palladium lattice. The interstitial solid solution of carbon in pal ladium with a maximal carbon content of 15 atom % begins to form at ab out 450 K. This solution is stable under a CO atmosphere up to about 6 70 K; at higher temperatures it decomposes to elemental Pd and carbon. The carbon placed in the interstitial positions of the palladium latt ice is very reactive and is oxidized with oxygen to CO2 at temperature s as low as 350 K. The interstitial carbon reacts with hydrogen to for m methane at about 400 K.