CO在F-T合成用铁催化剂上吸附和解离的研究

INVESTIGATION OF ADSORPTION AND DISSOCIATION OF CO ON THE SURFACE OF CATALYSTS

早在40—50年代,人们对CO+H2反应机理曾提出了各种不同的机理和假设。目前主要有争论的问题是CO以分子态吸附在催化剂表面上直接与吸附氢反应,还是解离成表面炭进行反应,或者是解离和非解离的CO在催化剂表面上同时发生竞争反应。

Adsorption, dissociation and disproportionation of CO on fused and precipitated iron catalysts were studied by pulse and thermogravimetric techniques. Four kinds of adsorption state were found on the surface of catalysts. Over the temperature range of 0-78℃, physical adsorption of CO prevailed on the fused iron catalyst. In the range of 0-200℃ CO was chemically adsorbed on the surface of the catalyst in a molecular state. In 200-280℃ both the adsorption species of molecular state(CO_((?)d)) and surface carbon species of CO dissociation(C_((?)d)) appeared on the surface of the catalyst. Dissociated adsorption was essential above 280℃. Similar adsorption states also exited on the surface of the precipitated iron catalyst. But its adsorption amount is higher than that of the fused iron catalyst at the same temperature and the disproportionation of CO commenced at lower temperature.