Water-Oxygen Synergy

Another result particular to this mix of reactants used in Prox testing with various water concentrations was evidence of a water-oxygen synergy within the reactor9 (Fig. 7.7). Table 7.2 comprises representative conditions and results from repeat 

Chapter 7 Removal of Trace Contaminants from Fuel Processing Reformate 

Inlet Concentrations Reactor Temperature Conversion Lambda 

This section is focused on the catalyst selection for optimal Prox reactor operation. During the discussion, catalyst formulation will generally cover the active metal (Pt, Rh, Cu, etc.) and support (A1203, ZnO, etc.) with promoters (La, Ce, etc.) however, there are instances in which studies done are more focused on the active metal regardless of the support used and is indicated where appropriate. It should be kept in mind that catalyst formulation selection must be done in the context of the desired performance outcome, or avoidance of certain characteristics and reformate mix. 

Selective oxidation of CO in hydrogen over different catalysts has been extensively examined. Most research to date has occurred with formulations that include a precious metal component supported on an alumina carrier. The catalyst-mediated oxidation of CO is a multistage process, commonly obeying Langmuir-Hinshelwood kinetics for a single-site competitive mechanism between CO and 02. Initially, CO is chemisorbed on a PGM surface site, while an 02 molecule undergoes dissociative chemisorption either on an adjacent site or on the support in order for surface reaction between chemisorbed CO and O atoms to produce C02. 

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Table 7.2. Evidence for a Water-Oxygen Synergy within the Prox Reactor...

Comparison with the free vinoxy radical shows an -1% shift toward the enolate-like structures 19a and 20b (largely at the expense of intramolecular hyperconjugation structures such as 19c and 20c). This resonance shift increases the anionic (Lewis base) character at oxygen, thereby enhancing the donor-acceptor H-bonding interaction with water (which leads to a weak partial bond order of 0.007 between the monomers). Many other examples of such synergy between intra- and intermolecular resonance interactions have been... 

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