不同的WO3掺杂量对CeO_(2)的NH_(3)-SCR催化性能影响研究

Effects of WO_(3) doping amounts of CeO_(2) on NH_(3)-SCR catalytic performance

针对二氧化铈(CeO_(2))活性低、活性温度范围窄的问题,提出了利用浸渍法合成不同三氧化钨(WO_(3))掺杂量的CeO_(2)催化剂的方法,发现4%WO_(3)/CeO_(2)(催化剂中W物质的量为Ce物质的量的4%)为最佳WO_(3)掺杂量的铈基催化剂。结果表明,该催化剂在150~425℃的宽温度区间表现出了90%以上的NO_(x)转化率和N_(2)选择性,同时也具有较好的抗SO_(2)和H_(2)O中毒性能。X射线光电子能谱(XPS)结果表明,4%WO_(3)掺杂能增加CeO_(2)表面化学活性氧物种,从而大幅提高中、低温催化活性。氨气程序升温脱附(NH_(3)-TPD)结果表明,4%WO_(3)掺杂能丰富CeO_(2)的表面酸性位、提高其酸性位强度,有利于反应物种的吸附和活化。因此,适量WO_(3)掺杂改性能够有效增强CeO_(2)的SCR催化性能。

Synthesize of cerium dioxide(CeO_(2))catalysts with different WO_(3) doping amounts by impregnation was proposed to solve the problem of low activity and narrow reaction temperature window of CeO_(2).The results show that 4%WO_(3)/CeO_(2)(molar ratio)is the best cerium-based catalyst.The catalyst shows a NO_(x) conversion rate and N_(2) selectivity over 90%in a wide temperature range of 150-425℃,and also has excellent resistance to SO_(2) and H_(2)O poisoning.X-ray photoelectron spectroscopy(XPS)results show that 4%WO_(3) doping can increase CeO_(2) surface chemically active oxygen species,which greatly improves the catalytic activity at low and medium temperatures.Ammonia programmed temperature desorption(NH_(3)-TPD)results show that 4%WO_(3) doping can enrich CeO_(2) surface acid sites and acid site strength,which is more conducive to the adsorption and activation of reactive species.Therefore,proper doping of WO_(3) can effectively enhance SCR catalytic performance of CeO_(2).