二氧化钛结构对其负载氧化铜催化剂性能的影响。

Effect of titania structure on the properties of its supported copper oxide catalysts.

机构信息

Key Laboratory of Mesoscopic Chemistry of MOE, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China.

出版信息

J Colloid Interface Sci. 2011 May 15;357(2):497-503. doi: 10.1016/j.jcis.2011.02.012.

DOI:10.1016/j.jcis.2011.02.012

PMID:21392779

Abstract

Anatase and rutile have the same chemical composition as TiO(2) but different crystalline structures (space group of D(4h)(19)-I4(1) for anatase and D(4h)(14)-P4(2) for rutile, respectively), which result in different surface structures and can be used ideally to investigate the effects of support and surface structure on the properties of their supported catalysts. In this work, anatase- or rutile-supported copper oxide catalysts (signed as Cu-A and Cu-R, thereafter) prepared by the impregnation method were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area, X-ray photoelectron spectroscopy (XPS), and H(2) temperature-programmed reduction (H(2)-TPR) to study the support effect of titania on the physicochemical properties and catalytic properties for the NO reduction by CO of these supported copper oxide catalysts. The results indicated that (1) copper oxide presented different dispersion capacities on anatase or rutile; (2) dispersed copper oxide species on anatase and rutile also showed different reduction behaviors; i.e., one-step reduction for dispersed copper oxide species in Cu-A and stepwise reduction for that in Cu-R; (3) the NO+CO activity test suggested dispersed copper oxide and small CuO particles on rutile are the main active species under the current reaction conditions and copper oxide supported on rutile is more active than that on anatase, which might result from Cu(+) species in Cu-R sample formed during the reaction due to its stepwise reduction behavior.

摘要

锐钛矿和金红石具有相同的化学组成（TiO(2)），但具有不同的晶体结构（锐钛矿为 D(4h)(19)-I4(1)，金红石为 D(4h)(14)-P4(2)），这导致了不同的表面结构，可以理想地用于研究载体和表面结构对负载催化剂性能的影响。在这项工作中，采用浸渍法制备了锐钛矿或金红石负载氧化铜催化剂（分别标记为 Cu-A 和 Cu-R），并通过 X 射线衍射（XRD）、BET 比表面积、X 射线光电子能谱（XPS）和 H(2)程序升温还原（H(2)-TPR）对其进行了表征，以研究 TiO(2)载体对这些负载氧化铜催化剂的物理化学性质和 CO 还原 NO 催化性能的影响。结果表明：（1）氧化铜在锐钛矿或金红石上具有不同的分散能力；（2）分散在锐钛矿和金红石上的氧化铜物种也表现出不同的还原行为，即 Cu-A 中的分散氧化铜物种为一步还原，而 Cu-R 中的则为分步还原；（3）NO+CO 活性测试表明，在当前反应条件下，分散在金红石上的氧化铜和小的 CuO 颗粒是主要的活性物种，负载在金红石上的氧化铜比负载在锐钛矿上的更活跃，这可能是由于 Cu-R 样品中 Cu(+)物种在反应过程中由于其分步还原行为而形成。