Quantification of Reactive CO and H₂ on CuO_x-CeO₂ during CO Preferential Oxidation by Reactive Titration and Steady State Isotopic Transient Kinetic Analysis

Abstract

The molar quantity of adsorbed CO and H2 present on the surface of a mixed CuO x -CeO2 catalyst during CO preferential oxidation in H2 at 353 K was quantified using both the reactive titration method and the steady-state isotopic-transient kinetic analysis (SSITKA). For the reactive titration method, either CO or H2 was replaced by He during steady state reaction while monitoring the residual transient product formation of CO2 or H2O produced from the surface adsorbed CO or H2 via catalytic oxidations. For SSITKA, 12CO was replaced by 13CO during steady state reaction while monitoring the transient product formation of 12CO2. The amount of adsorbed reactive CO increases with increasing CO partial pressure or decreasing H2 partial pressure, while the amount of reactive H2 decreases with increasing CO partial pressure or decreasing H2 partial pressure, showing that the adsorbed CO and H2 compete for active redox sites and prohibit the other’s adsorption. Using reactive CO and H2 amounts, two models of coverage were defined with trends providing insight into the competitive redox mechanism between adsorbed CO and H2. CO oxidation is kinetically preferred over CuO x -CeO2, and the relative CO to H2 coverage is shown to be the determiner for CO2 selectivity. This new depiction of selectivity parameters provides a useful principle for the design of selective PROX catalysts.

Enhanced Photocatalytic Degradation of Organic Pollutants and Anticorrosion of Mild Steel by Vanadium Modified Titanate Nanotubes (X%V‐TiNTs)

“…[4][5][6]8,9] Titanate nanotubes (TiNTs) are one of the popular photocatalysts and their usage has widely been found based on the environmental governance as it shows excellent chemical stability, low cost and non-toxicity. [4,[10][11][12] The potential applications of TiNTs catalyst include water treatment, [13,14] air purification [4] and also as raw material in a coating. [15][16][17][18][19] It is known that V and Ti acquire the same electronic configuration in their outer layer.…”

“…Consequently, there are several methods to reduce its high Eg; the first one is to identify an appropriate dopant (such as: Au, Ag, N, S, Co, Cr, Mn,…) and the second one is to change its shape to more interesting shapes such as: nanotubes, nonorodes, nanosheets… [4–6,8, 9] . Titanate nanotubes (TiNTs) are one of the popular photocatalysts and their usage has widely been found based on the environmental governance as it shows excellent chemical stability, low cost and non‐toxicity [4,10–12] . The potential applications of TiNTs catalyst include water treatment, [13,14] air purification [4] and also as raw material in a coating.…”

Designing Advanced Vanadium‐Based Materials to Achieve Electrochemically Active Multielectron Reactions in Sodium/Potassium‐Ion Batteries

“…Both SIBs and PIBs have attracted intensive research in recent decades, and they both share the same advantages and mechanisms with LIBs, [ 9–14 ] while the overall manufacturing cost can be greatly reduced. [ 15–17 ] Metallic sodium possesses an acceptable redox potential (Na + /Na) of −2.71 V versus standard hydrogen electrode (SHE), while metallic potassium has an even lower redox potential (K + /K) of −2.93 V versus SHE, which are both close to their lithium metal counterpart (−3.04 V vs SHE).…”

Influence of the Hydrothermal Parameters on the Physicochemical Characteristics of Cu−Ce Oxide Nanostructures

“…[1][2][3] It is noteworthy that the distribution and storage problems of pure H 2 have limited its use as a fuel for PEMFCs and therefore, hydrogen reformate gas streams are considered as an alternative fuel source. [7][8][9] Therefore, an additional purification step is required, in order to reduce the concentration of CO to a trace level (below 10 ppm). [5,6] The reformate gas contains approximately 0.5-1 vol.% CO, which can poison the Pt electrocatalyst that is used for the hydrogen oxidation reaction at the anode of PEMFC.…”

“…[5,6] The reformate gas contains approximately 0.5-1 vol.% CO, which can poison the Pt electrocatalyst that is used for the hydrogen oxidation reaction at the anode of PEMFC. [7][8][9] Therefore, an additional purification step is required, in order to reduce the concentration of CO to a trace level (below 10 ppm). CO preferential oxidation (CO-PROX) in H 2 -rich stream has been accepted as the most efficient method to achieve this goal.…”