Self-sustained combustion of carbon monoxide over CuCe0.75Zr0.25O delta catalyst: Stability operation and reaction mechanism
Self-sustained combustion of carbon monoxide over CuCe0.75Zr0.25O delta catalyst: Stability operation and reaction mechanism
复制标题
CuCe0.75Zr0.25O δ催化剂上一氧化碳的自持续燃烧：稳定运行和反应机理
DOI：
10.1016/j.proci.2018.05.114
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发表时间：
2019
影响因子：
3.4
通讯作者：
Dou Baojuan
中科院分区：
文献类型：
--
作者：
Bin Feng;Kang Running;Wei Xiaolin;Hao Qinglan;Dou Baojuan
采用溶胶-凝胶法研究了CuCe_（0.75）Zr_（0.25）O_（0.25）δ催化剂的CO自持燃烧性能，并与CuCe_（0.75）Zr_（0.25）O_（0.25）δ（H）和CuCe_（0.75）Zr_（0.25）O_（0.25）δ催化剂进行了对比，考察了分散CuO、Cu-Ce和Ce-Zr固溶体等不同活性位的敏感性。CuCe_（0.75）Zr_（0.25）O_δ（H）是通过在硝酸中超声处理以除去表面活性的CuO物种而获得的，并且制备CuCe_（0.75）Zr_（0.25）O_δ作为参比催化剂。利用CO的程序升温氧化和红外摄像机（CO-TPO FLIR），CO自持燃烧的催化活性不仅由点火温度决定，CuCe 0.75 Zr 0.25 O δ的大小顺序为（81 ℃）> CuCe0.75Zr0.25O δ（H）（131 ℃）> CuCe0.75Zr0.25O δ（167摄氏度）在200毫升/分钟的流速，而且还通过相应的限制稀薄燃烧（当量比Phi）分别为0.06-0.09、0.10-0.13、0.24-0.37。吸附的CO与晶格氧反应的M-K机理，通过程序升温表面活性反应和原位红外分析（TPSR + DRIFT）对所有催化剂进行了表征。活性位的敏感性顺序为：分散均匀的CuO > Cu-Ce固溶体> Ce-Zr固溶体。作为CO自持燃烧的速率控制步骤，CO优先吸附在表面活性剂分散的CuO上生成羰基化合物，然后羰基化合物与晶格氧相互作用形成CO2释放。CO在固溶体中被吸附在铜和铈的表面氧上生成碳酸盐。形成的碳酸盐更稳定，因此CO2的产生速率低于羰基化合物，表明固溶体的活性低于分散的CuO。暴露的Ce 3+有利于在Cu-Ce固溶体表面形成空位，有利于吸附CO和O-2，从而表现出比Ce-Zr固溶体更高的活性。(C)2018燃烧研究所爱思唯尔公司出版All rights reserved.
The self-sustained combustion of carbon monoxide (CO) has been studied over the CuCe0.75Zr0.25O delta catalyst by sol-gel method, and compared with the CuCe0.75Zr0.25O delta (H) and CuCe0.75Zr0.25O delta to investigate sensitivity of different active sites, such as dispersed CuO, Cu-Ce and Ce-Zr solid solution. The CuCe0.75Zr0.25O delta (H) is obtained via CuCe0.75Zr0.25O delta sonicated in nitric acid to remove surficial CuO species, and the CuCe0.75Zr0.25O delta is prepared as the reference catalyst. Using the temperature programmed oxidation of CO together with an infrared camera (CO-TPO FLIR), the catalytic activity for CO self-sustained combustion is determined not only by the ignition temperatures, following the decreasing order CuCe0.75Zr0.25O delta (81 degrees C) > CuCe0.75Zr0.25O delta(H) (131 degrees C) > CuCe0.75Zr0.25O delta (167 degrees C) at the flow rate of 200 mL/min, but also by corresponding limits of lean combustion (equivalence ratio Phi) of 0.06-0.09, 0.10-0.13, 0.24-0.37, respectively, under the flow rate of 100-1000 mL/min. The M-K mechanism, in which adsorbed CO reacts with lattice oxygen, is crucial for all the catalysts via temperature programmed surficial reaction and in situ infrared analysis (TPSR + DRIFT). The sensitivity of active sites as follows: well-dispersed CuO > Cu-Ce solid solution > Ce-Zr solid solution. As rate-determining step for CO self-sustained combustion, CO is preferentially adsorbed on surficial dispersed CuO to yield carbonyls, and then the carbonyls interact with lattice oxygen to form CO2 release. CO is secondly adsorbed on the surficial oxygen of copper and cerium sites in solid solution to yield carbonates. The carbonates formed are more stable and thus CO2 is produced at the lower rate than carbonyls, indicating that the solid solution is less active than dispersed CuO. Exposed Ce3+ favors to form vacancies on the Cu-Ce solid solution surface, which is beneficial to adsorbing both CO and O-2, thus presenting the higher activity than Ce-Zr solid solution. (C) 2018 The Combustion Institute. Published by Elsevier Inc. All rights reserved.