CAJ | 학술논문

采用分步浸渍法分别制备了LaCeZr和YCeZr组合助剂改性的介孔Al_2O_3负载的Mn基系列氧化物催化剂,用X射线衍射、氮气吸附-脱附、X射线吸收精细结构、X射线光电子能谱和程序升温还原等方法对催化剂进行了表征,探讨了催化剂中Mn物种的存在形式及其还原性能,并与样品催化CO和C_3H_8的氧化活性相关联.结果表明,样品中Mn物种主要以Mn_3O_4形式存在,该物种在不同样品中与载体的作用强弱不同,从而表现出不同的还原性能和催化活性.助剂改性有效抑制了Mn-Al之间的相互作用,提高了Mn-O键的活动度,从而提高了催化剂的氧化活性.相比于YCeZr助剂,LaCeZr助剂改性更大程度上提高了Mn物种的还原性,因而大大提高了催化剂的氧化性能.650℃焙烧的LaCeZr组合助剂改性的介孔Al_2O_3负载的Mn氧化物催化剂,在0.035%SO_2存在的条件下对CO的氧化活性并未下降,对C_3H_8的氧化活性下降幅度也较小,表现出优越的抗硫性能和氧化性能.
채용분보침지법분별제비료LaCeZr화YCeZr조합조제개성적개공Al_2O_3부재적Mn기계렬양화물최화제,용X사선연사、담기흡부-탈부、X사선흡수정세결구、X사선광전자능보화정서승온환원등방법대최화제진행료표정,탐토료최화제중Mn물충적존재형식급기환원성능,병여양품최화CO화C_3H_8적양화활성상관련.결과표명,양품중Mn물충주요이Mn_3O_4형식존재,해물충재불동양품중여재체적작용강약불동,종이표현출불동적환원성능화최화활성.조제개성유효억제료Mn-Al지간적상호작용,제고료Mn-O건적활동도,종이제고료최화제적양화활성.상비우YCeZr조제,LaCeZr조제개성경대정도상제고료Mn물충적환원성,인이대대제고료최화제적양화성능.650℃배소적LaCeZr조합조제개성적개공Al_2O_3부재적Mn양화물최화제,재0.035%SO_2존재적조건하대CO적양화활성병미하강,대C_3H_8적양화활성하강폭도야교소,표현출우월적항류성능화양화성능.
The manganese oxide catalysts supported on mesoporous Al_2O_3 modified by LaCeZr or YCeZr were prepared by successive im-pregnation. The structure of the catalysts was characterized by X-ray diffraction, N2 adsorption-desorption, X-ray absorption fine structure, X-ray photoelectron spectroscopy, and temperature-programmed reduction by H_2. The state of manganese species and their reducibility were investigated and correlated with the CO and C_3H_5 oxidation performance of the catalysts. The results demonstrate that the manganese species mainly exist as Mn_3O_4 crystallites, which interact with the support Al_2O_3. The different interaction strength determines the reducibility and catalytic properties of the catalysts. The promoters LaCeZr or YCeZr effectively inhibit the interaction between Mn and Al oxides, increasing the mobility of Mn-O bond and the catalytic activity of the corresponding catalysts. Compared with YCeZr, the promoter LaCeZr improves the reducibility of MnO_x to a larger extent, enhancing the activity more obviously. The catalysts modified by LaCeZr calcined at 650 ℃ ex-hibits high oxidation performance and sulfur resistance. In the presence of 0.035% SO_2 in the feed, the CO oxidation activity of the catalyst can be well maintained, and the C_3H_8 oxidation activity decreases only a little.