Selective CO removal over Au/CeFe and CeCu catalysts in microreactors studied through kinetic analysis and CFD simulations

Abstract

Selective CO removal over Au/CeFe and CeCu catalysts in microreactors studied through kinetic analysis and CFD simulations, Chemical Engineering Journal (2010), doi:10.1016/j.cej.2010.08.083 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. E-mail address: lgandia@unavarra.es (L.M. Gandía) AbstractA kinetic study of the preferential oxidation of CO in H 2 rich streams (CO-PrOx) over a cerium-copper oxide (CeCu) and a gold catalyst supported on cerium-iron oxide (Au/CeFe) is presented. The gold catalyst is very active but the CeCu oxide is more selective. A kinetic model describing the CO-PrOx system with CO 2 and H 2 O in the feed has been formulated considering the oxidation of CO and H 2 and the reverse water-gas shift reaction. The rate equations have been implemented in computational fluid dynamics codes to study the influence of the operating variables on the CO-PrOx in microchannels and microslits. TheCeCu catalyst is the only one capable of achieving final CO contents below 10-100 ppmv.Due to the opposite effect of temperature on activity and selectivity there is an optimalPage 2 of 31 A c c e p t e d M a n u s c r i p t 2 temperature at which the CO content is minimal over CeCu. This temperature varies between 170 and 200 ºC as the GHSV increases from 10 000 to 50 000 h -1. Simulations have evidenced the very good heat transfer performance of the microdevices showing that the COPrOx temperature can be controlled using air as cooling fluid although the inlet temperature and flow rate should be carefully controlled to avoid reaction extinction. Both microchannels and microslits behaved similarly. The fact that the microslits are much easier to fabricate may be an interesting advantage in favor of that geometry in this case.

Gold supported on CuOx/CeO2 catalyst for the purification of hydrogen by the CO preferential oxidation reaction (PROX)

“…8) and the R-WGS reactions (Eq. 9) with the gold catalyst, it was observed that the rate equations developed for the CeCu solid [36] remained valid. For obtaining a good description of the experimental data the rate expression for the CO oxidation over AuCeCu must include some adsorption terms (Eq.…”

“…It is intended this way comparing the CO oxidation performance of the catalysts under different O 2 availability conditions which can be interesting to better understand the PROX reaction in the presence of these solids and design more efficient catalysts. Additionally, a kinetic model is formulated for the Au-CuO x /CeO 2 catalyst in the PROX reaction and compared to that for the CuO x /CeO 2 solid that was reported in a previous study [36].…”

“…These experiments consisted in the variation of the CO, O 2 , H 2 O and CO 2 concentrations, and allowed to establish a kinetic model for the gold catalyst based on the principles previously considered for the development of the kinetic model for the CeCu solid [36]. The experimental data of CO conversion and selectivity of the AuCeCu catalyst were fitted to the considered kinetic model according to the methodology presented in the experimental section [36,56].…”

“…The CuO x /CeO 2 (with 10 CuO wt.% and 90 CeO 2 wt.%) catalyst was prepared by coprecipitation method [36,37]. The required amounts of Cu(NO 3 ) 2 •3H 2 O (Fluka®) and Ce(NO 3 ) 3 •6H 2 O (Alfa Aesar®) were dissolved in distilled water forming a 0.5 M solution.…”

“…These reactions are promoted by temperature and reduce the selectivity for CO oxidation of the global process [36,71].…”