DEACTIVATION OF SCR DENOX CATALYSTS BY FUEL-PHOSPHATE

摘要

An increased deactivation of DeNO_x catalysts installed in coal fired power plants by phosphorus was experienced in German coal-fired utilities during co-combustion of secondary fuels. Although the increase of the phosphate concentration in the fuel mix was below 1 wt-%, the contribution to the deactivation was significant. The volatility of phosphorus fuel compounds was considered as a reason. Similar to the German coal-secondary fuel mixes are some sub-bituminous coals such as PRB which also were reported to increase deactivation due to an increased phosphorus content. For a clarification of prevailing mechanisms, lab-scale tests were carried out to confirm a potential deactivation by volatile phosphates. The data was supplemented by bench scale combustion tests as well as by full scale measurements of deactivated catalyst samples. With this data, a deactivation mechanism was suggested. A summary of the results is given in this paper.