The Influence of Plasma Chemical Treatment of a Platinum Catalyston Its Activity in the Dehydrogenation of Cyclohexane

摘要

The influence of plasma chemical treatments on the catalytic activity of 0.64 wt % Pt/Si0_2and1.0 wt % Pt/Si0_2platinum catalysts in the dehydrogenation of cyclohexane was studied. The state of the sur-face of the catalysts was examined using X-ray photoelectron spectroscopy. Temperature hysteresis caused bythe formation of active carbon was observed in flow experiments. It was shown that the reaction on the initialcatalysts occurred on neutral and positively charged Pt particles, and that the active centers contained carbon.After catalyst treatment with a high-frequency plasma in H_2,its activity increased by many times because ofthe formation of a large number of low-activity centers on positively charged platinum particles also contain-ing carbon. Glow discharge plasma in Ar sharply decreased catalytic activity, and the reaction then predom-inantly occurred on centers localized on neutral Pt particles, whereas centers on positive Pt particles wereblocked. The state of the substrate (silica gel) did not change under the action of plasmas of both kinds.