Influence of pulse discharge plasma on composition of La2O3 catalyst

The catalytic activity of La2O3 catalyst influenced by plasma- temperature and temperature alone was studied. The reduction of SO2 by CO over La2O3 catalyst was carried out in a stainless-steel needle-gauze reactor. The changing rules of the catalyst components and their phase contents with the increase of temperature and discharge voltage, and the difference while the catalyst working under plasma- temperature and temperature alone were studied, respectively. Before the reaction, the La2O3 catalyst was treated by hydrolysis. After the catalyst was subjected to plasma-temperature or temperature alone for 2 h, its XRD pattern was immediately measured for determining the catalyst composition and calculating their contents. The results showed that when the temperature was lower, the influence of pulse discharge plasma on the phase contents of the catalyst was notable. In the range from room temperature to 300 degreesC, there was a new phase (LaO)(2)(SO4) appearing in plasma-temperature manner, however, in the range from 400 to 500 degreesC, the catalyst composition had no difference in the two manners but the phase contents had different changing trends, compared with that in lower- temperature range. The emergence of the new phase (LaO)(2)(SO4) was due to plasma heating and plasma oxidation. The formation of LaOOH, which was greatly influenced by temperature, was the key process for active component of La2O3 catalyst. There was a most suitable discharge voltage for the reaction.