http://libir.tmu.edu.tw/bitstream/987654321/43034/1/4.pdf

Review of second-order models for adsorption systems.

Over the past several years, cerium oxide and CeO2-containing materials have come under intense scrutiny as catalysts and as structural and electronic promoters of heterogeneous catalytic reactions. Recent developments regarding the characterization of ceria and CeO2-containing catalysts are critically reviewed with a special focus towards catalyst interaction with small molecules such as hydrogen, carbon monoxide, oxygen, and nitric oxide. Relevant catalytic and technological applications such as the use of ceria in automotive exhaust emission control and in the formulation of SO x reduction catalysts is described. A survey of the use of CeO2-containing materials as oxidation and reduction catalysts is also presented.

Catalytic Properties of Ceria and CeO2-Containing Materials

Traditional analysis of reactions catalyzed by supported metals involves the structure of the metallic particles. However, we report here that for the class of nanostructured gold- or platinum-cerium oxide catalysts, which are active for the water-gas shift reaction, metal nanoparticles do not participate in the reaction. Nonmetallic gold or platinum species strongly associated with surface cerium-oxygen groups are responsible for the activity.

http://science.sciencemag.org/content/sci/301/5635/935.full.pdf

Active Nonmetallic Au and Pt Species on Ceria-Based Water-Gas Shift Catalysts

The literature treating mechanisms of catalyst deactivation is reviewed. Intrinsic mechanisms of catalyst deactivation are many; nevertheless, they can be classified into six distinct types: (i) poisoning, (ii) fouling, (iii) thermal degradation, (iv) vapor compound formation accompanied by transport, (v) vapor-solid and/or solid-solid reactions, and (vi) attrition/crushing. As (i), (iv), and (v) are chemical in nature and (ii) and (v) are mechanical, the causes of deactivation are basically three-fold: chemical, mechanical and thermal. Each of these six mechanisms is defined and its features are illustrated by data and examples from the literature. The status of knowledge and needs for further work are also summarized for each type of deactivation mechanism. The development during the past two decades of more sophisticated surface spectroscopies and powerful computer technologies provides opportunities for obtaining substantially better understanding of deactivation mechanisms and building this understanding into comprehensive mathematical models that will enable more effective design and optimization of processes involving deactivating catalysts. © 2001 Elsevier Science B.V. All rights reserved.

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Mechanisms of catalyst deactivation

[Xie, Xiaowei; Li, Yong; Shen, Wenjie] Chinese Acad Sci, Dalian Inst Chem Phys, State Key Lab Catalysis, Dalian 116023, Peoples R China. [Liu, Zhi-Quan] Chinese Acad Sci, Inst Met Res, Shenyang Natl Lab Mat Sci, Shenyang 110016, Peoples R China. [Haruta, Masatake] Tokyo Metropolitan Univ, Grad Sch Urban Environm Sci, Dept Appl Chem, Tokyo 1920397, Japan. [Haruta, Masatake] Japan Sci & Technol Agcy, CREST, Kawaguchi, Saitama 3320012, Japan.;Shen, WJ (reprint author), Chinese Acad Sci, Dalian Inst Chem Phys, State Key Lab Catalysis, Dalian 116023, Peoples R China;shen98@dicp.ac.cn

Mordecai Shelef

Papers

Twenty-five years after introduction of automotive catalysts: what next?

Surface interactions in the system Reγ-Al2O3

The oxidation of CO by O2 and by NO on supported chromium oxide and other metal oxide catalysts

Heterogeneous methanation: Steady-state rate of CO hydrogenation on supported ruthenium, nickel and rhenium

Heterogeneous methanation: In situ infrared spectroscopic study of RuAl2O3 during the hydrogenation of CO