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Extraordinary Deactivation Offset Effect of Arsenic and Calcium on CeO2–WO3 SCR Catalysts
Environmental Science & Technology ( IF 10.8 ) Pub Date : 2018-07-10 , DOI: 10.1021/acs.est.8b00746 Xiang Li 1 , Xiansheng Li 2 , Tianle Zhu 1 , Yue Peng 2 , Junhua Li 2 , Jiming Hao 2
Environmental Science & Technology ( IF 10.8 ) Pub Date : 2018-07-10 , DOI: 10.1021/acs.est.8b00746 Xiang Li 1 , Xiansheng Li 2 , Tianle Zhu 1 , Yue Peng 2 , Junhua Li 2 , Jiming Hao 2
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An extraordinary deactivation offset effect of calcium and arsenic on CeO2–WO3 catalyst had been found for selective catalytic reduction of NO with NH3 (NH3–SCR). It was discovered that the maximum NOx conversion of As–Ca poisoned catalyst reached up to 89% at 350 °C with the gaseous hourly space velocity of 120 000 mL·(g·h)−1. The offset effect mechanisms were explored with respect to the changes of catalyst structure, surface acidity, redox property and reaction route by XRD, XPS, H2-TPR, O2-TPD, NH3-TPD and in situ Raman, in situ TG, and DRIFTS. The results manifested that Lewis acid sites and reducibility originating from CeO2 were obviously recovered, because the strong interaction between cerium and arsenic was weakened when Ca and As coexisted. Meanwhile, the CaWO4 phase generated on Ca poisoned catalyst almost disappeared after As doping together, which made for Brønsted acid sites reformation on catalyst surface. Furthermore, surface Ce4+ proportion and oxygen defect sites amount were also restored for two-component poisoned catalyst, which favored NH3 activation and further reaction. Finally, the reasons for the gap of catalytic performance between fresh and As–Ca poisoned catalyst were also proposed as follows: (1) surface area decrease; (2) crystalline WO3 particles generation; and (3) oxygen defect sites irreversible loss.
中文翻译：
砷和钙对CeO 2 –WO 3 SCR催化剂的非活性失活抵消效应
已经发现钙和砷对CeO 2 -WO 3催化剂具有非凡的失活补偿效应，可用于用NH 3（NH 3 -SCR）选择性催化还原NO 。它被发现的最大NO X作为钙的转化中毒的催化剂，在350与120 000毫升的气时空速·（克·h）的最多时达到89％℃，-1。探讨了XRD，XPS，H 2 -TPR，O 2 -TPD，NH 3改变催化剂结构，表面酸度，氧化还原性能和反应路线的抵消效应机理。-TPD和原位拉曼，原位TG和DRIFTS。结果表明，当铈和砷共存时，铈与砷之间的强相互作用被削弱了，CeO 2产生的路易斯酸位和还原性得到了明显的恢复。同时，砷中毒后，Ca中毒催化剂上生成的CaWO 4相几乎消失，从而使布朗斯台德酸位在催化剂表面重整。此外，两组分中毒催化剂的表面Ce 4+比例和氧缺陷位点数量也得到恢复，有利于NH 3。活化和进一步的反应。最后，提出了新鲜的和As-Ca中毒催化剂之间催化性能差距的原因，其原因如下：（1）表面积减少；（2）结晶WO 3颗粒的产生；（3）缺氧部位不可逆的损失。
更新日期：2018-07-12
中文翻译：
砷和钙对CeO 2 –WO 3 SCR催化剂的非活性失活抵消效应
已经发现钙和砷对CeO 2 -WO 3催化剂具有非凡的失活补偿效应，可用于用NH 3（NH 3 -SCR）选择性催化还原NO 。它被发现的最大NO X作为钙的转化中毒的催化剂，在350与120 000毫升的气时空速·（克·h）的最多时达到89％℃，-1。探讨了XRD，XPS，H 2 -TPR，O 2 -TPD，NH 3改变催化剂结构，表面酸度，氧化还原性能和反应路线的抵消效应机理。-TPD和原位拉曼，原位TG和DRIFTS。结果表明，当铈和砷共存时，铈与砷之间的强相互作用被削弱了，CeO 2产生的路易斯酸位和还原性得到了明显的恢复。同时，砷中毒后，Ca中毒催化剂上生成的CaWO 4相几乎消失，从而使布朗斯台德酸位在催化剂表面重整。此外，两组分中毒催化剂的表面Ce 4+比例和氧缺陷位点数量也得到恢复，有利于NH 3。活化和进一步的反应。最后，提出了新鲜的和As-Ca中毒催化剂之间催化性能差距的原因，其原因如下：（1）表面积减少；（2）结晶WO 3颗粒的产生；（3）缺氧部位不可逆的损失。
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