WGS systems based in Pt, Ni or Cu over TiO2, CeO2 or other "reducible" oxides are well known. Apart from the key point of increasing the interface between components, some papers suggest that promoting the metal by alloying (PtNi, CuNi, etc.) is more effective than promoting the oxide by cation doping. The contrary has been also reported. My question is if these options have been combined in an effective way and/or which one is more important to enhance activity, particularly at low temperature?
Could I know what is your application. Normally, in industrial scale, they don't use precious metal for this reaction.
Another application related to exhaust emmission control and the temperature is quite high.
Thank you
Thank you for your answer. Yes, we are interesting in low temperature WGS in the context of purification of hydrogen streams. For some caseswe have combined reforming+WGS (+CO-PROX) systems using "single formulation" catalysts.
Professor Fernandez, I haven't worked with WGS, I worked with dry reforming of methane, so, maybe I'm wrong. Ceria and titania are supports with very low surface area; I think a better catalyst would be with metal (Ni or Cu are cheap) supported on a large area oxide and ceria or titania as promoter. What do you think?
CeO2 and Y2O3 supportes are very good in WGS studied by Noronha in Brazil and give good results you may also try the iron oxide as support or use Fe metal as promoters. As promoter to the active phase Ni is best. Some others studied some other noble metals but it is expensive. Fe2O3 is a good support in WGS also
Dear Carlos and Wael, many thanks for your responses. CeO2 and TiO2 (and Fe2O3 although its performance is somehow below the oxides previously mentioned) are "novel" supports with a significant number of researchers working on. Ni and Cu are typical "active" phases. We (and many others) developed stable catalysts by using several stratagies; for us, the most useful was the development of the interface between the two phases ("oxide and metal") in-situ. We have modulated the interface through "intermediate" phases (with presence of other cations) in order to control the chemical state and defect distribution in the contacting zone of the Cu/Ni and Ce/Ti phases. So, the physical problem is rather complex and I have not convincing evidence about which of the mentioned variables is/are the more important one.
Dear Professor Fernandez,
Noronaha studied the effect of CeO2 and doped Ce-Al2O3 for WGS it might be useful for you
To Wael. Thanks for the information. I will revisite the work of Noronha (I remember his Chem Rev. 2012) to learn about the problem.
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