Catalysis Today 62 (2000) 249–254 Selective catalytic oxidation of CO in H 2 : fuel cell applications Olga Korotkikh, Robert Farrauto ∗ Engelhard Corporation, 101 Wood Avenue, Iselin, NJ 08830-0770, USA Abstract An essential requirement for the proton exchange membrane (PEM) fuel cell is to deliver clean H 2 to the anode electrode, the kinetics of which are greatly hindered by traces of CO present from the upstream hydrocarbon steam reforming and water-gas shift processes. A technology receiving much attention is the selective oxidation of CO to CO 2 . Ideally the catalyst must selectively oxidize about 1% (10 000 ppm) CO to less than 5 ppm without oxidizing any of the 30–70% H 2 present. This paper describes performance results of a Pt promoted catalyst deposited on a monolith for selective oxidation of CO under simulated fuel processing conditions for PEM fuel cell applications. The effect of space velocity, gas composition and temperature on activity and selectivity is presented. Preliminary mechanism ideas are also presented. © 2000 Elsevier Science B.V. All rights reserved. Keywords: Selective oxidation of CO; Fuel processing; PEM fuel cells; Monolith; Pt catalyst 1. Introduction Development of the proton exchange membrane (PEM) fuel cell has been accelerating during the last 5 years advancing the commercial possibilities for generating clean and efficient power for stationary and mobile source applications [1,2]. It promises to deliver electricity with virtually no emission of harm- ful pollutants with increased efficiency because it di- rectly converts chemical energy to electricity avoiding the thermodynamic mechanical cycle losses associ- ated with combustion in conventional power genera- tion. The electrochemical system operates at about 70–80 ◦ C using H 2 (essentially free of CO which poi- sons the Pt anode reaction) as the anode fuel and O 2 (air) at the cathode. The net reaction generates H 2 O and electricity. In the absence of large capacity hydro- gen storage systems, the H 2 will likely be generated ∗ Corresponding author. Tel.: +1-732-205-5306; fax: +1-732-321-0334. E-mail address: bob.farrauto@engelhard.com (R. Farrauto). on site. Given the extensive infrastructure existing for natural gas (stationary source applications) and gaso- line (mobile source), these are the preferred sources of H 2 . The production of clean H 2 for the chemical in- dustry from hydrocarbon feeds [3] is well known and is accomplished by a series of catalytic steps including desulfurization, steam reforming, water-gas shift and CO removal by pressure swing absorption or methana- tion. All of these technologies are now being reviewed for possible use in the fuel cell, however CO removal by pressure swing absorption requires expensive com- pressors and methanation is complicated by hydro- genation of the CO 2 present. For this reason selective oxidation is now the primary technology of choice. In the early 1960s Engelhard developed and com- mercialized the Selectoxo TM catalyst and process for H 2 plants to remove CO to levels acceptable for the Fe ammonia synthesis catalyst [4–6]. The heart of this technology is a highly selective Pt containing catalyst which oxidizes up to 10 000 ppm CO without significantly oxidizing the 70% H 2 (dry) present in the reformate. 0920-5861/00/$ – see front matter © 2000 Elsevier Science B.V. All rights reserved. PII:S0920-5861(00)00426-0