H2-rich Stream Research Articles

Facile synthesis of Al2O3-Pt nanocomposite and its catalytic activity

Pt nanoparticles were synthesized on γ-alumina support in presence of oleic acid which was found to prevent clustering of Pt nanoparticles on the support. Various percentage of Pt loading on the alumina changed the catalytic activity for preferential oxidation of CO at relatively low temperature in H2 rich stream. Pt nanoparticles when synthesized in absence of oleic acid, were all clustered and did not have any catalytic activity. The presence of oleic acid promoted stability preventing agglomeration of Pt nanoparticles. The catalyst thus prepared was characterized thoroughly and their catalytic activity was studied in details.

Preferential Oxidation of CO in H2-Rich Stream Over Au/CeO2–NiO Catalysts: Effect of the Preparation Method

Two methods, viz., the hydrothermal (HT) and co-precipitation (CP) methods, were used to prepare CeO2–NiO composite oxides; with them as the supports, Au/CeO2–NiO catalysts were prepared by the colloidal deposition method and used in the preferential oxidation (PROX) of CO in H2-rich stream. Various characterization measures such as N2 sorption, XRD, TEM, H2-TPR, Raman spectroscopy and XPS were used to clarify the influence of preparation method on the structure of CeO2–NiO support and the performance of Au/CeO2–NiO catalyst. The XPS and TEM results reveal that the CeO2–NiO(HT) support prepared by hydrothermal method displays a uniform rod-like shape and exposes preferentially the (110) and (100) planes of CeO2, whereas the CeO2–NiO(CP) support prepared by co-precipitation method is composed of nanorods and irregular nanoparticles dominated by (111) facets of CeO2. After deposition of gold, both the Au/CeO2–NiO(HT) and Au/CeO2–NiO(CP) catalysts are alike in the state and size distribution of deposited Au nanoparticles. The H2-TPR results indicate that the presence of Au strongly promotes the reduction of CeO2 in the Au/CeO2–NiO catalyst. Raman spectra illustrate that the incorporation of Ni ions into CeO2 remarkably increases the amount of oxygen vacancies in the CeO2–NiO supports, especially in CeO2–NiO(HT) prepared by hydrothermal method, which is beneficial to the dispersion and stabilization of gold species. The structure of CeO2–NiO support and catalytic activity of Au/CeO2–NiO in CO PROX is strongly related to the preparation method; Au/CeO2–NiO(HT) exhibits much higher activity than Au/CeO2–NiO(CP). The larger fraction of (110) and (100) CeO2 facets in CeO2–NiO(HT) can promote the dispersion of gold species, formation of oxygen vacancies and migration of oxygen species, which are effective to enhance the redox capacity and activity of the obtained Au/CeO2–NiO(HT) catalyst for CO PROX in H2-rich stream. Au supported on CeO2–NiO nanorods prepared by hydrothermal method exhibits much higher catalytic activity for CO PROX in H2-rich stream.

Sustainable photo-assisted CO oxidation in H2-rich stream by simulated solar light response of Au nanoparticles supported on TiO2

In this study the photo-response behaviour of Au/TiO2 systems in the preferential CO oxidation in a H2-rich stream (CO-PROX) was investigated by the first time under simulated solar light irradiation at room temperature and atmospheric pressure. Au nanoparticles, with an average size of 2–5nm, were precipitated-deposited on a mesoporous TiO2, previously synthesized by sol-gel type procedure and thermally treated at different temperatures to obtain anatase/rutile mixed phases. Structural, chemical and optical properties were studied by means of AAS, N2 physisorption, XRD, HR-TEM, DRUV–vis and XPS, investigating the effects of TiO2 polymorphs (anatase, rutile and combination thereof). All samples, containing a very low amount of noble metal (0.5wt%), resulted very active in the photocatalytic CO-PROX at ambient conditions, attaining very high CO conversion and CO2 selectivity values. The Au/TiO2 sample containing both anatase/rutile polymorphs in the support displayed the highest activity, both in dark and under simulated solar light, due to the simultaneous presence of these two titania crystalline phases, capable to lower the effective band gap of the composite system (2.90eV) and improving the photocatalytic activity in the studied reaction. This kind of materials may provide a sustainable and feasible approach to selectively oxidize CO in H2-rich stream under solar light irradiation and ambient conditions.

Promoted the reduction of Cu2+ to enhance CuO[sbnd]CeO2 catalysts for CO preferential oxidation in H2-rich streams: Effects of preparation methods and copper precursors

A series of CuOCeO2 catalyst samples synthesized by using various methods (CuCe-SF-N, CuCe-UGC-N, CuCe-SG-N and CuCe-ST-N) and copper precursors (CuCe-SF-N, CuCe-SF-C, CuCe-SF-A and CuCe-SF-S) were estimated for CO preferential oxidation in H2-rich streams. It was found that both synthesis routes and copper precursors have an important effect on catalytic behaviors of CuOCeO2 catalyst. Compared to CuCe-UGC-N, CuCe-SG-N and CuCe-ST-N, CuCe-SF-N exhibits the lowest temperature and the widest temperature window for 100% CO conversion (about 50 °C), which should be attributed to synergistic effects of smaller crystallite size, the formation of more Cu+ species together with the high ratio of Ce3+/(Ce3++Ce4+). Among the four catalysts prepared with different Cu precursors (CuCe-SF-N, CuCe-SF-C, CuCe-SF-A and CuCe-SF-S), the corresponding CO conversions of them are in the order of CuCe-SF-N > CuCe-SF-A > CuCe-SF-C » CuCe-SF-S. The lowest catalytic activity of CuCe-SF-S should be due to the presence of SO42− species covered on the surface of the catalyst, which not only results in the formation of the less Cu active species but inhibits the interaction between Cu species and CeO2. In addition, the optimal CuCe-SF-N catalyst displays relative stability during the 200 h time-on-stream test even in the presence of H2O and CO2.

Identification of the nano/micro structure of CeO2(rod) and the essential role of interfacial copper-ceria interaction in CuCe(rod) for selective oxidation of CO in H2-rich streams

CeO2(rod) has been found to be exposed four {111} planes and two {100} planes with a hexangular cross section, and the growth mechanism follows to the oriented attachment of the cube-like basic grains with a [110] growth direction and the subsequent Ostwald ripening, corresponding to the increasing lateral size and longitudinal size with prolonging the hydrothermal time. Equal amount of copper oxide totally highly distributed on the surface of CeO2(rod) supports with different abundance of oxygen vacancies facilitate to produce the strongly bound Cu-[Ox]-Ce species to different degrees (supported by XPS, H2-TPR and in situ DRIFTs results), which is encouraged by prolongation of hydrothermal time of CeO2(rod) supports. The essential role of interfacial Cu-Ce interaction in CuCe(rod) catalysts for CO-PROX was identified by the enhanced catalytic performance of CuCe(rod)-48h, on account of much stronger Cu-Ce interaction generated in it. Moreover, we proposed a potential structural model of strongly bound Cu-[Ox]-Ce to interpret the synergetic effect of copper and ceria species in CuO/CeO2 catalysts and generalized the possible reaction mechanism for CO-PROX over the CuCe(rod) catalyst.

Unexpected stability of CuO/Cryptomelane catalyst under Preferential Oxidation of CO reaction conditions in the presence of CO2 and H2O

The catalytic activity of CuO/Cryptomelane for the preferential oxidation of CO in H2-rich streams has been studied in the absence and presence of H2O and CO2, paying special attention to the catalyst stability and to changes on its physical-chemical properties under CO-PROX reaction conditions.For fresh CuO/cryptomelane catalyst, the presence of CO2 and/or H2O in the CO-PROX feed partially inhibits CO oxidation due to chemisorption of H2O and CO2 on the catalyst. H2O chemisorption on CuO/Cryptomelane is stronger than CO2 chemisorption, and simultaneous CO2 and H2O adsorption has a synergetic effect that enhances co-adsorption and significantly hinders CO oxidation.On the contrary, the presence of CO2+H2O in the CO-PROX reaction mixture has a positive effect in the CuO/Cryptomelane stability upon several consecutive reaction cycles in the 25–200°C range. XRD showed that chemisorbed CO2+H2O species partially prevent the catalyst deactivation due to cryptomelane reduction to hausmannite (Mn3O4) under the strongly reductive environment of the CO-PROX reaction, and H2-TPR and Raman spectroscopy characterisation support that the cryptomelane structure is less damaged under CO-PROX conditions in the presence of CO2 and H2O than in the absence of these species. Therefore, interestingly under CO2+H2O environment (realistic CO-PROX conditions) CuO/Cryptomelane catalyst performs an improved catalytic activity.

The Effect of the Ruthenium Crystallite Size on the Activity of Ru/Carbon Systems in CO Methanation

The influence of the ruthenium crystallite size on the catalytic activity of Ru/graphitized carbon systems in carbon monoxide methanation was evaluated. Four graphitized carbon materials differing in their surface area were used as supports for Ru. The average size of Ru crystallites in Ru/C materials was estimated by X-ray powder diffraction, transmission electron microscopy and CO chemisorption. Dispersion of the active phase clearly depends on the carbon texture. The activity tests conducted in H2-rich streams with very low CO concentrations (0.5 vol% CO) have shown that the activity of Ru/carbon catalysts changes with the ruthenium particles size (d). The highest activities were obtained for ruthenium particles in the range 4–8 nm in size.

CuO/CeO2 catalysts synthesized from Ce-UiO-66 metal-organic framework for preferential CO oxidation

We synthesized a CuO/CeO2 catalyst using a copper ions encapsulated ceria metal-organic framework (MOF) Ce-UiO-66 as the precursor. The CuO/CeO2 catalysts derived by calcining the MOF precursor (the x-CuCe catalysts) showed the better activity and selectivity for the preferential CO oxidation in the H2-rich stream than the CuO/CeO2 catalyst prepared by wetness impregnation (CuCe-im). A temperature window to match the CO conversion and O2 to CO2 selectivity higher than 99.5% at the same time appeared using the x-CuCe catalysts as the catalyst. Raman and XPS results indicated that more oxygen vacancies were formed in the bulk of ceria in the x-CuCe catalysts than that in the CuCe-im catalyst, which could promote the mobility of oxygen. Our results indicated that the surface lattice oxygen and the oxygen vacancies in the bulk of ceria could enhance the catalytic performance of the CuO/CeO2 catalysts.

Numerical modeling of an indirect internal CO2 reforming solid oxide fuel cell energy system fed by biogas

High-temperature Solid Oxide Fuel Cells have a flexible fuel supply and high energy performance. When fed with biofuels, such as biogas, they provide an attractive, ecofriendly and efficient energy system.The Internal Reforming that uses the high temperature of the same fuel cell makes them suitable to biogas, whose carbon dioxide content can be exploited.The fuel cell is characterized by an Internal CO2 Dry Reforming that converts the CH4 in the biogas into an H2 rich stream, owing to the role of CO2, acting as reforming promoter.The paper presents the formalization and the implementation in Matlab of a steady state-zero dimensional numerical model which describes the various processes of a global self-sustained Indirect Internal CO2 Reforming Solid Oxide Fuel Cell System fed by biogas. In addition to the energy core of the system with reforming and electrochemical section, the plant scheme considers the preheating of fresh gases, partial recirculation of the fuel cell exhausted gases and combustion of the expelled ones.The model aims at assessing energy performance and at monitoring carbon deposition.

Rapid synthesis of Fe-doped CuO-Ce0.8Zr0.2O2 catalysts for CO preferential oxidation in H2-rich streams: Effect of iron source and the ratio of Fe/Cu

Abstract A facile route (urea grind combustion method) is described for the rapid synthesis of Fe-doped Cu-Ce-Zr catalysts within 30 min through simple grinding and combustion. The effects of iron source and Fe/Cu mass ratio on the performances of the catalysts for CO preferential oxidation (CO-PROX) are evaluated. The influences of H 2 O, CO 2 , and their mixture on the activity as well as stability of the catalysts are also investigated. The samples are characterized by XRD, N 2 adsorption-desorption, H 2 -TPR, TEM, Raman and XPS. Fe(NO 3 ) 3 is found to be superior to FeCl 3 and Fe 2 (SO 4 ) 3 as the iron source for Fe-CuCZ catalyst. Among the different synthesized catalysts, 1/10Fe (N) -CuCZ is found to be the most active catalyst, indicating that the optimal Fe/Cu mass ratio is 1/10. The influences of H 2 O, CO 2 , and H 2 O + CO 2 on the catalytic performance of 1/10Fe (N) -CuCZ are in the order of CO 2 2 + H 2 O 2 O. 1/10Fe (N) -CuCZ exhibits excellent stability during a 228 h time-on-stream test. 1/10Fe (N) -CuCZ shows the highest catalytic activity and excellent stability even in the presence of H 2 O and CO 2. The excellent catalytic performance can be attributed to the synergy between the highly dispersed copper species and ceria, as well as the formation of more oxygen vacancies and reduced copper species.

Effect of crystallite size on the performance and phase transformation of Co3O4/Al2O3 catalysts during CO-PrOx - an in situ study.

The preferential oxidation of carbon monoxide has been identified as an effective route to remove trace amounts of CO (approx. 0.5-1.0 vol%) in the H2-rich reformate gas stream after the low-temperature water-gas shift. Instead of noble metal-based catalysts, Co3O4-based catalysts were investigated in this study as cheaper and more readily available alternatives. This study aimed at investigating the effect of crystallite size on the mass- and surface area-specific CO oxidation activity as well as on the reduction behaviour of Co3O4. Model Co3O4 catalysts with average crystallite sizes between 3 and 15 nm were synthesised using the reverse micelle technique. Results from the catalytic tests revealed that decreasing the size of the Co3O4 crystallites increased the mass-specific CO oxidation activity in the 50-200 °C temperature range. On the other hand, the surface area-specific CO oxidation activity displayed a volcano-type behaviour where crystallites with an average size of 8.5 nm were the most active within the same temperature range. In situ characterisation in the magnetometer revealed that the Co3O4 crystallites are partially reduced to metallic Co above 225 °C with crystallites larger than 7.5 nm showing higher degrees of reduction under the H2-rich environment of CO-PrOx. In situ PXRD experiments further showed the presence of CoO concurrently with metallic fcc Co in all the catalysts during the CO-PrOx runs. In all experiments, the formation of fcc Co coincided with the formation of CH4. Upon decreasing the reaction temperature below 250 °C under the reaction gas, both in situ techniques revealed that the fcc Co previously formed is partially re-oxidised to CoO.

Co/MCM41 catalyst in the COProx reaction prepared by supercritical CO2 reactive deposition

Co/MCM41 catalyst with 4.3 wt % Co (Co/sc) has been prepared by supercritical CO2 reactive deposition (‘scfrd’) and characterized by different physicochemical techniques. This synthesized method was compared with others conventional methodologies such as template-ion exchanged (Co/tie) and incipient wet impregnation (Co/iwi) with similar cobalt content. All the samples were studied as catalysts on the CO total oxidation (COTox) and preferential oxidation of CO on H2-rich streams (COProx). Incorporating cobalt with supercritical CO2 leads to a catalyst which produces values of CO conversion similar to those obtained by conventional methods such as incipient wetness impregnation (Co/iwi) or template-ion exchanged (Co/tie). It has been possible to identify different cobalt species present in catalysts depending on their synthesis methods by Temperature-Programmed Reduction (TPR), X-ray Photoelectronic (XPS), Laser Raman (LRS) and X-ray Absorption (XANES/EXAFS) spectroscopic studies. All samples containing a main cobalt species of cobalt (II) coordinated with Si tetrahedral sites form part of mesoporous structure and lesser extent, cobalt orthosilicate on the surface. In addition, Co3O4 species dispersed over the MCM41 support were detected for the Co/iwi and Co/sc catalysts.Thus, the combination of Co3O4 nanoparticles and Co(II) sites interacting with the siliceous structure, highly dispersed on the surface and inside the mesoporous support obtained by the ‘scfrd’ method resulted in a more active and selective catalyst for the COProx reaction.

High performance and stability of copper loading on mesoporous ceria catalyst for preferential oxidation of CO in presence of excess of hydrogen

Copper (Cu) supported on mesoporous (MSP) ceria catalysts were prepared by deposition-precipitation (DP) method for the preferential CO oxidation of CO in a H2-rich stream (CO-PROX). A MSP ceria support with a high surface area of 293 m2/g and ordered structure was synthesized by a nanocasting process using MCM-48 as template. All copper-MSP ceria catalysts show high dispersion of Cu and still maintain the fluorite structure of MSP ceria. Moreover, TEM imaging confirmed the three dimensional and long-range ordered pore structure of the Cu-catalysts. The reduction temperature of the Cu-catalysts decreases compared to pure MSP ceria and the reduction of Ce4+ to Ce3+ decreases with increasing copper content. An MSP ceria catalyst with 7 wt% Cu loading (7Cu/MSP ceria) shows the highest activity with high stability for over 48 h in various feed components, making it attractive for use as a catalyst in purification of hydrogen.

Au/Cu–Fe–La–Al2O3: A highly active, selective and stable catalysts for preferential oxidation of carbon monooxide

A series of gold-based catalysts supported by Fe–La–Al2O3 composite doped with various amounts of copper were prepared using a modified deposition-precipitation method. Investigations were carried out based on the reaction of the preferential carbon monoxide oxidation (CO-PROX) in H2-rich stream and CO oxidation at low temperatures in an O2-rich stream as a reference to examine the effects of copper on the catalytic performance. The high dispersion of gold nanoparticles in alumina-based support, the formation of Au–Cu alloy, and the close contacts of these neat or alloyed nanoparticles with CuO species, making Au partially positively charged, were examined with H2-TPR, XPS, and HRTEM-FFT techniques. Gold catalysts were obtained with very promising performance for polymer electrolyte membrane fuel cell with positive results in activity, CO2 selectivity, and thermal stability and long-term storage and on-line stability. Although H2 addition decreased the rate of CO oxidation over the studied gold catalysts, the activity and selectivity in CO2 formation were continuously improved with an increase in copper loading.

Structuring CuO/CeO2 Catalyst as Option to Improve Performance Towards CO-PROX

In this work we review our results on the preparation, characterization and testing of copper/ceria structured catalysts for CO abatement in H2-rich streams by preferential oxidation. Copper/ceria wash-coated monoliths were prepared by a modified dip coating procedure. The effect of the substrate properties (cell density and wall thermal conductivity) on the catalytic performances and the effect of the slurry preparation on the wash-coat adhesion were investigated. The role of the temperature profile on the performances was also studied and the dependence of thermal profile on the cell density and the wall thermal conductivity was shown. Monoliths with both high cell density and high thermal conductivity of the substrate represent the best option, providing a very good thermal management of the process due to the reduction of hot spots over the catalyst surface. On the other hand, wash-coat adhesion is significantly improved by the presence of nanometric ceria in the slurry used to dip-coat the monoliths, due to the partial penetration of the wash-coat into the substrate macropores. Moreover, due to the modifications of the specific surface area and the pore size distribution upon addition of nanometric ceria to the slurry, copper dispersion and, then, CO selectivity were enhanced as well.

Well-crystallized ZnCo2O4 nanosheets as a new-style support of Au catalyst for high efficient CO preferential oxidation in H2 stream under visible light irradiation

A kind of high dispersed gold catalyst supported on the spinel ZnCo2O4 nanosheets was readily fabricated by a facile template-free wet chemical method for CO oxidation in H2-rich streams at room temperature under visible light irradiation or not, which was found to be a high performance catalyst. As verified by X-ray powder diffractometry (XRD), Raman spectra, N2 adsorption–desorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscope (XPS), photoelectrochemical measurement and photoluminescence (PL) spectra results, the contribution of high crystallinity, the enhanced mass and charge transport, the longer lifetime of surface electrons as well as the optical absorbance properties on Au/ZnCo2O4 enabled the superior CO preferential oxidation. Notably, electron paramagnetic resonance (EPR) and CO chemisorption (TPD-MS) results indicate that visible light could promote the adsorption and activation of both CO and O2 at Au/ZnCo2O4 due to both the photo-response of Au nanoparticles and the photo-excitation of ZnCo2O4 band gap under visible light irradiation. This study indicates that Au/ZnCo2O4 may be highly desirable for a promising photo-assisted Au catalyst.

Improved Low-Temperature Activity of CuO–CeO2–ZrO2 Catalysts for Preferential Oxidation of CO in H2-Rich Streams

In this work, CuO–CeO2–ZrO2 catalysts for CO preferential oxidation have been prepared by ultrasound assisted reverse coprecipitation and slow coprecipitation, and characterized via BET, XRD, XPS and H2-TPR techniques, respectively. It is found that the catalyst prepared with ultrasound assisted reverse coprecipitation preserves large specific surface area, fine crystalline grain and high dispersion of active copper species. Meanwhile, the reducibility is improved significantly and more active copper species and oxygen vacancies are formed in the copper–ceria boundaries. The ultrasound assisted reverse coprecipitation prepared CuO–CeO2–ZrO2 catalyst exhibits superior low-temperature activity and CO2 selectivity, over which the temperature responding to 50 % CO conversion is as low as 67 °C, and the temperature window of full CO conversion is significantly widen from 100 to 160 °C. The ultrasound assisted reverse coprecipitation prepared CuO–CeO2–ZrO2 catalyst exhibits superior low-temperature activity for CO preferential oxidation and wide temperature window of full CO conversion comparing with the catalyst prepared with slow coprecipitation.

Structural features and catalytic performance in CO preferential oxidation of MWCNT-supported Pt–Fe catalysts

Pt–Fe catalysts supported on multi-walled carbon nanotubes (MWCNT) were prepared by an impregnation method assisted with an ultrasonication treatment. The Pt–Fe/CNT catalysts were extensively examined for the preferential oxidation of CO in a H2-rich stream with respect to the influences of Pt/Fe ratios, different support materials and the presence of CO2 and water vapor in the feed stream. The optimized catalyst with a Pt/Fe ratio of 4/0.8 can attain complete CO conversion in a wider temperature range as well as favorable performance under the simulated reformatted gas mixture. It was noticed that the catalytic performance was greatly enhanced for the MWCNT-supported Pt–Fe catalysts in comparison with those supported on Al2O3, SiO2 and other carbon materials. Based on the structural features of the catalysts characterized by XRD, TGA, H2-TPR, TEM and Raman spectroscopy, the enhanced catalytic performance of Pt–Fe/CNT catalysts was discussed in terms of the interactions between Pt–Fe species and MWCNT, as well as the possible bifunctional surface with the presence of both Fe sites of Pt–Fe species and Pt sites.

Pressure swing adsorption for coproduction of power and ultrapure H2 in an IGCC plant with CO2 capture

The coproduction of power and ultrapure H2 within an Integrated Gasification Combined Cycle (IGCC) plant implementing CO2 capture offers advantages in terms of flexible operation while retaining good efficiency. The common design includes an absorption unit for removing CO2 from a high pressure syngas followed by a Pressure Swing Adsorption (PSA) unit for purifying a part of the resulting H2-rich gas stream. A drawback of this design consists in the necessity for compression of the PSA tail gas in order to recover the energy available in the residual H2 content. This paper presents two novel configurations for power and H2 coproduction with CO2 capture, entirely based on PSA technology. The first relies on two PSA trains in series (Two-train PSA), while the other is able to carry out CO2 separation and H2 purification within a single PSA train (One-train PSA). The two systems were defined and simulated through a composite model of the whole plant. The process simulation results showed that both the configurations proposed are able to shift between the two energy products without compromising the performance of the plant. The load of the plant could be decreased by increasing the ultrapure H2 throughput, while maintaining a constant feed of coal to the gasifier. The Two-train PSA configuration achieved higher performance in terms of energy efficiency and H2 purity. The One-train PSA configuration returned slightly lower but still good performance, while its design includes a single separation stage instead of two. Additionally, both configurations enable the avoidance of PSA tail gas compression giving an advantage against the absorption-based design. A comparative analysis with results taken from the literature seems to confirm this assertion.

Ceria-Praseodymia Mixed Oxides: Relationships Between Redox Properties and Catalytic Activities Towards NO Oxidation to NO2 and CO-PROX Reactions

A series of CexPr1−xO2−δ catalysts was prepared by co-precipitation method in alkali media. These catalysts were characterized by N2 adsorption–desorption isotherms at −196 °C, X-ray diffraction, thermogravimetry combined with mass spectrometry (TG-MS), and temperature-programmed reduction with H2 and CO (H2-TPR and CO-TPR, respectively). Catalytic tests were performed for temperature programmed NO oxidation to NO2 (from 25 to 750 °C) and for the preferential oxidation of CO in H2 rich stream (CO-PROX reaction) in the range of 150–500 °C. The trends in the order of catalytic activities towards NO oxidation and CO-PROX are correlated with the redox properties of the catalysts and their composition. CexPr1−xO2−δ mixed oxides present very different catalytic behaviours towards NO oxidation and CO-PROX reactions. These experimental trends might be explained by the balance of several factors: the acid character of the NO and CO molecules, the different lattice oxygen mobility of the catalysts, the presence of surface carbonates species in the samples, and the catalysts’ reducibility under H2 and CO. The understanding of the features that govern the activity towards these environmentally relevant oxidation reactions is important in the designing of effective catalysts.