NSR Catalyst Research Articles

NOx Storage on BaTi0.8Cu0.2O3 Perovskite Catalysts: Addressing a Feasible Mechanism.

The NOx storage mechanism on BaTi0.8Cu0.2O3 catalyst were studied using different techniques. The results obtained by XRD, ATR, TGA and XPS under NOx storage–regeneration conditions revealed that BaO generated on the catalyst by decomposition of Ba2TiO4 plays a key role in the NOx storage process. In situ DRIFTS experiments under NO/O2 and NO/N2 show that nitrites and nitrates are formed on the perovskite during the NOx storage process. Thus, it seems that, as for model NSR catalysts, the NOx storage on BaTi0.8Cu0.2O3 catalyst takes place by both “nitrite” and “nitrate” routes, with the main pathway being highly dependent on the temperature and the time on stream: (i) at T < 350 °C, NO adsorption leads to nitrites formation on the catalyst and (ii) at T > 350 °C, the catalyst activity for NO oxidation promotes NO2 generation and the nitrate formation.

NOx adsorption and desorption of a Mn-incorporated NSR catalyst Pt/Ba/Ce/xMn/γ-Al2O3.

This study evaluated the NOx adsorption and desorption performance as well as the casual relationship underlying a Mn-incorporated catalyst (Pt/Ba/Ce/xMn/γ-Al2O3). NOx adsorption and desorption are regarded as a prominent index for the NOx removal performance of NOx storage and reduction; we utilized NOx storage experiments with various inlet NO and O2 concentrations and cycling adsorption/desorption experiments with a couple of adsorption time protocols for performance evaluation. In-suit DRIFT and NOx-TPD tests were implemented to reveal the instant stored species and their thermal stability. Eight percent of Mn catalyst at 350°C was adopted in the described experiments for its desirable NOx adsorption characteristics. The optimal NOx storage performance was found under 10% O2, deteriorating when the concentration was further increased. Furthermore, elevating NO concentration impaired the NOx adsorption due to the low NO2/NOx ratio. It was also found that shorter adsorption time facilitated NOx removal via maintaining an unsaturated state for active storage components in terms of a fixed desorption time. The stored species existed as nitrites and nitrates with a good low-temperature thermal stability which however decayed at higher temperatures as exhibited in the DRIFT and NOx-TPD tests. These findings provided invaluable information for the application of Mn-incorporated catalyst for NOx removal in diesel exhaust purification to relieve the aerial pollution.

Influence of H2, CO, C3H6, and C7H8 as Reductants on DeNOx Behavior of Dual Monoliths for NOx Storage/Reduction Coupled with Selective Catalytic Reduction

The effects of feeding hydrogen, carbon monoxide, and propylene as reductants are analyzed in the combined NOx storage and reduction with selective catalytic reduction technology (NSR-SCR), with Pt–Ba/Al2O3 and Pt–Ba–Ce/Al2O3 monoliths as NSR catalysts, and Cu/BETA and Cu/SAPO-34 monoliths as SCR catalysts. Feed streams including CO2 and H2O mimic the real composition of the diesel engine exhaust. Also, the reaction temperature and reductant concentration are analyzed on NOx removal and product distribution at the converter outlet. H2 is the most efficient reductant at low temperature. The reducing capacity of CO is comparable to H2 from 300 °C and onward. Higher temperature (400 °C) is needed for propylene to be as effective reductant as H2 or CO due to the promotion of storage and reduction reaction. Benefits in dual NSR-SCR configurations are enhanced with H2 as reductant, due to higher internal generation of NH3 to be used in the SCR catalyst.

Effect of support preparation with different concentration precipitant on the NO storage performance of Pt/BaO/CeO2 catalysts

Abstract In this study, the CeO2 nanorods as the supports of Pt/BaO/CeO2 catalysts were synthesis by the alkali-assisted hydrothermal method in a solution containing different content of NaOH. Pt/BaO/CeO2 catalyst with 7.5M NaOH pre-added in the support preparation process showed higher NOx storage capacity and NOx removal efficiency than samples derived from other concentration NaOH. Moreover, even under shorter rich time (3s) and more lean-rich cycles (60), Pt/BaO/CeO2-7.5M still maintained above 80% NOx conversion from 250 to 450 °C, exhibiting good fuel economy and durability. A series of characterization techniques including XRD, N2-adsorption, TEM, XPS, Raman, H2-TPR, and NO2-TPD were conducted to investigate the physical, chemical properties. Combining the activity with the structure of catalysts, a linear relationship between the NOx storage capacity (NSC) of NSR catalysts and the amount of oxygen vacancies was drawn. Meanwhile, the strong synergetic effect among Pt and CeO2 attributed to the role of oxygen vacancies in anchoring the active component Pt, promoting the mobility of surface oxygen species, was also related to the NSC value of NSR catalysts. These results indicated that the oxygen vacancies were responsible for the excellent catalytic activity.

Mechanistic insights into a NOx storage-reduction (NSR) catalyst by spatiotemporal operando X-ray absorption spectroscopy

Monitoring the catalytically active state and online mass spectra clarified the fast transient phenomena occurring inside a NSR catalyst.

Effect of the Presence of Ceria in the NSR Catalyst on the Hydrothermal Resistance and Global DeNOx Performance of Coupled LNT–SCR Systems

The global performance of coupled LNT–SCR systems, addressed to high NOx-to-N2 conversion, minimal ammonia slip and null N2O production, as well as the hydrothermal resistance of single NSR and SCR monolith catalysts and their coupling is discussed. Pt–Ba/Al2O3 and Pt–Ce–Ba/Al2O3 were washcoated on cordierite monoliths as NSR catalysts, and Cu/CHA was washcoated on similar monoliths as SCR catalysts. Both monoliths were coupled in two subsequent reactors to conform the LNT–SCR system. Previously to washcoating, the fresh powder catalysts and after severe hydrothermal aging were fully characterized by N2 adsorption–desorption isotherms at 77 K, X-ray diffraction, NH3 temperature-programmed desorption, and H2 chemisorption to relate textural and chemical characteristics with the DeNOx performance. The Cu/CHA catalyst shows an excellent hydrothermal resistance for the NH3–SCR reaction. Incorporation of ceria to the model Pt–BaO/Al2O3is beneficial for the NO-to-NOx oxidation and NO2 storage, improving NO conversion at low temperature and reducing the NH3 slip. However, addition of ceria is detrimental for the hydrothermal resistance of the NSR catalyst. However, this detrimental effect is minimized when the NSR catalyst is coupled with the Cu/CHA monolith downstream of the NSR catalyst, achieving the coupled LNT–SCR device high NO conversion and minimal NH3 slip with superior N2 selectivity for an extended temperature windows, including as low as 220 °C, and maintaining performance even after severe hydrothermal aging.

NOx adsorption on K and Ba loaded on zirconia-titania NSR catalysts: A comparative study by in situ and operando IR spectroscopy

An intensive in situ and operando IR study on NOx adsorption over potassium (K) loaded zirconia-titania NSR catalyst in comparison to a barium (Ba) loaded one is reported. Based on in situ IR experiments, NOx adsorption under heated environment was confirmed to favor potassium bidentate nitrate species rather than ionic nitrate species observed for Ba-loaded NSR catalyst (previously published). Complementary operando IR experiments revealed different mechanisms for NOx adsorption over the two NOx storage materials (NSMs): initial simultaneous NO2− and NO3− formation over K loaded catalyst while over Ba-loaded one, NO2− is first accumulated before being converted to NO3−. Isotopic labelling in combination with operando experiments identified distinct dynamic behaviors regarding the exchange between nitrogen containing species on surface and in gas phase. This work provides beneficial inputs for advanced catalyst converter design, for example with zone-coated washcoat that contains more than one catalyst formulations.

Macroporous carrier-free Sr-Ti catalyst for NOx storage and reduction

A novel concept is presented, consisting of a macroporous carrier-free catalyst. As a proof of concept, a novel Cu-containing Sr-Ti NSR catalyst with a macroporous network has been synthesized, and its maximum NOx storage capacity (1500μmolNOx/gcatalyst) significantly surpasses that of conventional Pt/Ba/Al2O3 formulations (∼600–800μmolNOx/gcatalyst). This high NOx storage capacity is achieved because the active phases (mainly SrCO3 and Cu-containing Sr-Ti perovskites, as deduced by XRD) are not diluted in an inert carrier, and this can be done because the macroporous structure obtained using a polymethylmethacrylate colloidal crystal template allows the access of gases to the particles bulk. In situ DRIFTS experiments showed that NOx were chemisorbed on the novel Cu-containing Sr-Ti macroporous catalyst as a mixture of nitrite and nitro species, and this suggests that several NOx chemisorption pathways are simultaneously taking place probably involving chemisorption of both NO and NO2. Additionally, this novel catalyst is totally selective towards N2 formation as NOx reduction product, without traces of N2O nor NH3. CO2 and H2O compete with NOx for being chemisorbed on the catalyst, and this hinders the utilization of this catalyst in real diesel exhausts. However, we believe that this new concept of macroporous carrier-free catalyst could be extended to other heterogeneous catalyzed reactions or materials to avoid the diluting effect of the catalyst support.

Optimal Operating Conditions of Coupled Sequential NOx Storage/Reduction and Cu/CHA Selective Catalytic Reduction Monoliths

The optimal control of the combined NSR–SCR system has been derived by looking for optimal conditions, namely temperature and H2 concentration during the rich period, under which the NSR catalyst has to be operated in order to generate the adequate amount of NH3 needed to be used as the reductant agent for the NOx reduction reaction on the downstream SCR monolith, with the final objective of producing selectively only-N2 with minimum ammonia slip at the exit of the system. This conceives the so expected “zero emission level”. The analysis has been carried out for a model Pt–BaO/Al2O3 monolith followed by the Cu/CHA monolith, which allows the storing of ammonia to react with NOx leaving the NSR during the subsequent lean phase, establishing the complete “operational map” for any combination of temperature (150–400 °C) and H2 concentration used during the rich period (1–4 %) to know the reached NOx efficiency. Maximum efficiency, with almost total selectivity to N2 and no NH3 slip is achieved at low-intermediate temperature (around 180–200 °C) and high H2 concentration (3–4 %), which generates about 30 % of ammonia in the NSR catalyst to be used in the SCR catalyst.

NOx storage and reduction over copper-based catalysts. Part 1: BaO + CeO2 supports

The performance of noble metal-free copper-based NSR catalysts was studied by rapid-scan operando DRIFTS, using CeO2, BaO and BaO+CeO2 mixtures with different ratios as supports. The maximum temperature for CuO/CeO2 utilization as NSR catalyst was 400°C, as the stored NOx species decomposed above this temperature. At 400°C, CuO/CeO2 showed high NO oxidation capacity and NOx were stored on the catalyst mainly in the form of nitrates and lower populations of nitro groups. CuO/BaO was not suitable for NSR below 250°C, because its oxidation activity was very low and its NOx storage capacity was negligible, but it did not exhibit upper temperature restrictions until 500°C. The effect of temperature on NOx chemisorption on copper catalysts with BaO+CeO2 mixed oxide supports was between those of CuO/CeO2 and CuO/BaO. NSR experiments performed with high frequency H2 or CO pulses (micropulses every 120, 60 or 30s) at 400°C showed that regeneration with H2 was more effective than with CO, and this was attributed to the higher reactivity of H2 rather than to the poisoning effect of the reaction products (H2O and CO2 respectively). Nitrates were the main form of chemisorbed nitrogen oxides on all catalysts in NSR experiments at 400°C, and NOx chemisorption and desorption rates were faster for CuO/CeO2 than for CuO/BaO. The general behavior of all catalysts tested for NSR at 400°C was quite similar, and only certain differences were observed during the highest frequency pulses of CO, where CuO/CeO2 showed the best resistance to deactivation. For all catalysts, N2 was the only NOx reduction product detected during H2 regeneration.

Sulfation and Desulfation Behavior of Pt-BaO/MgO-Al2O3 NOx Storage Reduction Catalyst.

The comparative study between Pt-BaO/Al2O3 and Pt-BaO/MgO-Al2O3 gives the information about the effect of MgO addition to Al2O3 support on the sulfation and desulfation behavior of Pt-BaO/MgO-Al2O3 NOx storage reduction catalyst. The sulfated two samples were analyzed by using element analysis (EA), X-ray diffraction (XRD), H2 temperature programmed reaction (H2 TPRX) and NOx uptake measurement. The amount of sulfur uptake on 2 wt% Pt-20 wt% BaO/Al2O3 and 2 wt% Pt-20 wt% BaO/MgO-Al2O3 are almost identical as 0.45 and 0.40 of S/Ba, respectively, which yields the drastic decrease in NOx uptake for both sulfated samples. However, after desulfa- tion with H2 at 600 degrees C, the residual sulfur amount on MgO-Al2O3 supported catalyst is three times larger than that on Al2O3 supported one, indicating that sulfur species formed on the former are more stable than those on the latter. It is also well corresponding to the H2 TPRX results where the main H2S peak from MgO-Al2O3 supported sample is observed at higher temperature than Al2O3 supported one, resulting in the lower NOx uptake activity of former sample than the latter one. Meanwhile, after desulfation of MgO-Al2O3 supported sample at 700 degrees C and 800 degrees C, the activity is recovered more significantly due to the removal of the large amount of sulfur while Al2O3 supported one decreases monotonically due to the sintering of Pt crystallite and the formation of BaAl2O4 phase. It is summarized that MgO-Al2O3 supported catalyst enhances the thermal stability of the catalyst, however, forms the stable sulfate species, which needs to be improved to develop the more sulfur resistant NSR catalyst system.

Low-Temperature Selective Catalytic Reduction with NH&lt;sub&gt;3&lt;/sub&gt; over MnO&lt;sub&gt;x&lt;/sub&gt;-CeO&lt;sub&gt;2&lt;/sub&gt; Catalysts Supported on Nano Tetragonal Zirconia

The MnOx-CeO2/t-ZrO2 catalyst was prepared by impregnation with nano t-ZrO2 as the support. The influence of active component and reaction temperature on denitration performance of catalyst was investigated. The results showed that denitration efficiency improved as active component increased and reaction temperature rose. The denitration efficiency of 2.5% MnOx-CeO2/t-ZrO2 at 100°C was 68.1% while 15% MnOx-CeO2/t-ZrO2 was 97.4%. The results of XRD, BET and H2-TPR showed that surface structure of loaded catalyst was good for oxidation-reduction and denigration. NH3-TPD test demonstrated that NH3 was mainly adsorbed at Lewis acid sites on the surface of catalysts and became coordination NH3. Intermediate product NH2NO generated from reactions between coordination NH3 and NO which finally changed into N2 and H2O.NOx are potentially harmful to humans as a kind of primary pollutants. And NOx are the main cause of many environment problems, such as acid rain, surface ozone pollution and Particulate Matter 2.5[1]. The emission of NOx was 2337.8 tons in China in 2011 and that was 2275.4 tons[2]. The environmental situation is grim although the emission of NOx had begun decreasing. Emission standard of air pollutants for thermal power plants which came into effect on January 1, 2012 require the emission concentration of NOx under 100mg·m-3. The task is arduous.Selective catalytic reduction (SCR) of NOx with NH3 is the most promising method to remove NOx and catalysts with high activity play a decisive part in low temperature SCR technology. Many researches about metal oxide as SCR catalyst support have been reported recently, such as TiO2[3], Al2O3[4], activated carbon[5] and molecular sieve[6]. Zirconium oxide has attracted considerable attention recently as a catalyst support because of its special characteristics. Takahashi et al.[7] investigated the influence of the various compositions of TiO2 and ZrO2 on the NOx removal ability over a sulfur-treated NSR catalyst and came to a conclusion that ZrO2 support suppressed the solid phase reaction with potassium. Reddy et al.[8, 9] investigated structural characteristics of nanosized ceria-silica, ceria-titania, and ceria-zirconia mixed oxide catalysts and found these mixed oxides exhibit better redox properties than pure CeO2. YAN Zhi-yong et al.[10] reported that the existence of ZrO2 in catalysts can raise its specific area and enhance the dispersion of CeO2 on catalysts which results in high activity of the catalysts. CeO2/TiO2-ZrO2 catalyst has strong tolerance to water vapor and sulfur dioxide.It is well known that ZrO2 exists mainly in three polymorphs with monoclinic (m-ZrO2), tetragonal (t-ZrO2) and (c-ZrO2) cubic structures[11]. ZrO2 polymorphs have different amphoteric character of its surface hydroxyl groups. The crystalline phase of ZrO2 has a great effect on the structure, activity and selectivity of catalysts. Therefore, it is valuable to investigate the effects of nanocrystalline zirconia polymorphs on catalytic properties of MnOx-CeO2/t-ZrO2 Catalysts which few researchers have concerned about. In this study, we try to investigate catalytic activity and microstructure of SCR catalysts with manganese oxide and cerium oxide supported on t-ZrO2.

Cu-zeolite catalysts for NOx removal by selective catalytic reduction with NH3 and coupled to NO storage/reduction monolith in diesel engine exhaust aftertreatment systems

Coupled NSR-SCR systems comprising a Pt-BaO/Al2O3 NSR monolith and Cu/CHA, Cu/ZSM-5 or Cu/BETA SCR catalysts are prepared and tested for NOx removal from diesel and lean burn engines exhaust gases. The Cu/zeolite catalysts are characterized by ICP-AES, XRD, N2 adsorption-desorption, NH3-TPD and H2-TPR. The physico-chemical characteristics of fresh catalysts and aged under 5% steam/Ar at 750°C for 16h and are compared, resulting in the Cu/CHA with much higher hydrothermal resistance to the loss of textural and structural properties. The single-SCR, single-NSR and coupled NSR-SCR catalytic performance is studied including the conversion of NO and NH3, slip of NH3, and N2O and NO2 yields. Cu/CHA presents the SCR wider temperature window, eventually 100% NO conversion from 220 to 380°C, even maintained after severe aging. For application in the NSR-SCR technology, the NH3 generated in the NSR catalyst during the rich period is able to achieve higher NO conversion reducing significantly the slip of NH3 (negligible at 200°C and above), very few amount of N2O at any temperature, and small production of NO2 only at higher temperatures. This improvement of activity and selectivity is particularly enhanced with the coupled NSR-Cu/CHA system, which is also maintained when the catalyst is deposited on the cordierite monolith substrate, as in the case of real application.

Performance of Cu-ZSM-5 in a Coupled Monolith NSR-SCR System for NOx Removal in Lean-Burn Engine Exhaust

The viability of hybrid systems conformed by a combination of Pt–Ba/Al2O3 NSR and Cu-ZSM-5 SCR catalysts is studied with both catalysts over monolithic structures in order to maximize the removal of NOx from lean-burn engines exhaust gases. To optimize performance of these coupled NSR-SCR systems, the NSR catalyst has to work under operational conditions completely different from those optimal when the NSR-only catalyst works, as in the coupled system the intermediate production of ammonia needs to be apparently increased, and then adsorbed in the SCR catalyst (Cu-ZSM-5) which is placed downstream in order to complete elimination of remaining NOx (NO+NO2) selectively to N2 with minimal amounts of other nitrogen derivates, i.e. N2O and NH3. The suitable control of operational conditions, specifically H2 concentration and duration of the rich period, allows establishing the optimal working conditions of the NSR-SCR double system in the practical application, which resulted in temperature around 200 °C and H2 concentration in excess (3–4 %).

AN XPS study of the interaction of model Ba/TiO2 AND Ba/ZrO2 NSR catalysts with NO2

X-ray photoelectron spectroscopy is used to study the interaction of model NO2 storage-reduction catalysts (NSR catalysts) Ba/TiO2 and Ba/ZrO2 with NO2. The catalysts are prepared on the surface of ultrathin Al2O3 film substrates obtained by the FeCrAl alloy oxidation. It is shown that at room temperature the model catalysts react with NO2 with the successive formation of surface barium nitrite and nitrate. The NO2 reduction with the formation of barium nitrite at the initial step of the interaction is assumed to be accompanied by the oxidation of residual metallic barium and amorphous carbon impurity. It is found that the formation of barium nitrate proceeds more efficiently on Ba/ZrO2 rather than on Ba/TiO2.

Influence of ceria loading on the NOx storage and reduction performance of model Pt–Ba/Al2O3 NSR catalyst

The influence of the addition of ceria on the NOx storage and reduction behaviour of model Ba–Pt/Al2O3 catalyst has been studied. Several 15%Ba–1.5%Pt–Ce/Al2O3 catalysts were prepared with increasing ceria loading, from 0 to 20.3wt.%. The prepared catalysts were characterized in terms of specific surface area (N2 adsorption–desorption at −196°C), platinum dispersion (H2-chemisorption), reducibility (H2-TPR) and acidity (NH3 adsorption–desorption experiments). The storage of NOx was followed by FTIR showing that low Ce loaded catalyst, i.e. Ba–Pt–4.5%Ce/Al2O3, was able to promote nitrate formation readily at low temperature (200°C), while nitrites were predominant for model Ba–Pt/Al2O3 and high loaded Ce catalyst, i.e. Ba–Pt–15.4%Ce/Al2O3. Ammonia oxidation experiments confirmed that Ce was able to oxidize NH3 into N2, the reaction extent increasing with temperature and Ce loading. The 4.5% Ce loaded catalyst achieved the highest NOx storage and reduction efficiency. The NOx storage capacity was increased with respect to the model Ba–Pt/Al2O3 catalyst due to the enhancement of NO oxidation conversion and due to the ability of Ce to take part as NOx storage material. On the other hand, NH3 emissions were reduced due to the participation of Ce in the oxidation of NH3 to N2. In contrast, high Ce loaded catalyst penalized NOx storage capacity and increased NH3 selectivity. The limited NOx storage capacity was in concordance with the low NO to NO2 conversion, which was attributed to a possible migration of CeO2 to form an atomic layer over Pt which ultimately covers and blocks its catalytic activity. The increased NH3 emission was attributed to a lower acidity of the doped catalyst which reduced the NH3 adsorption capacity.

The Effect of Hydrogen on the Storage of NOx Over Silver, Platinum and Barium Containing NSR Catalysts

Addition of hydrogen significantly increases the amount of stored nitrogen oxides (NOx) over Pt/Ba/Al2O3 at 100 A degrees C and Ag/Al2O3 between 100 and 200 A degrees C. This increase is unique for hydrogen as reductant. A higher apparent NOx storage capacity is also observed by simultaneous reduction of NO in a selective catalytic reduction (SCR) reaction, where, however, the conversion in H-2-SCR is < 10 % in this study.

Combined Fixed‐Bed Reactor and In Situ DRIFTS Tests of NO Adsorption on a NOx Storage‐Reduction System Catalyst

AbstractThe effect of water on NOx storage performance of a Pt/BaO/Al2O3 catalyst was investigated. The adsorption capacity of a model NOx storage‐reduction system (NSR) catalyst was studied in the presence of NO, oxygen, and water in nitrogen. Fixed‐bed and in situ DRIFTS adsorption tests were carried out in order to evaluate the influence of water on the adsorption capacity of the catalyst, adsorbed species on the surface of the catalyst, and stability of these species. The presence of water slightly reduces the NOx storage capacity of the NSR catalyst. A decrease of platinum oxidation activity was observed which was correlated to a slowdown of surface bidentate nitrate formation, detected by in situ DRIFTS tests. On the other hand, surface monodentate nitrates were favored and formation of bulk nitrates was not affected. A set of reactions corresponding to these observations is proposed.

Effect of reducing agent (C3H6, CO, H2) on the NOx conversion and selectivity during representative lean/rich cycles over monometallic platinum-based NSR catalysts. Influence of the support formulation

NOx storage reduction efficiency was investigated on a Pt–10%BaO/Al2O3 model catalyst using a complex gas feed including reductants and oxidants in both lean and rich mixtures. Three representative reductants have been studied, separately and blended: C3H6, CO, H2 and C3H6+CO+H2. The influence of each reductant was evaluated with a special consideration to the N2O selectivity. The reductant/oxidant ratio was kept constant for the lean and the rich gas mixture, respectively. The N2O emission depends on the introduced reductant(s), and the nature of reductant acts differently depending on the temperature. At 200°C, H2 mainly drives the N2O emission, whereas at 300°C, N2O yields is enhanced by C3H6. In addition, it is demonstrated that NOx reduction also occurs during the lean period, leading to significant amount of N2O. In fact, on Pt–10%BaO/Al2O3 catalyst, 70–90% of the produced N2O come from the lean phase, except with CO as reductant which does not allow any NOx reduction in lean condition. Results were compared with a platinum/ceria–zirconia-based oxide (Pt/CZ) previously studied. Pt/CZ is generally more active at low temperature (200°C). At 300°C, significant differences appear between the two formulations depending on the used reductant, especially concerning the N-compound selectivities in the rich pulses.

Influence of ceria on the NOx reduction performance of NOx storage reduction catalysts

Influence of ceria on the NOx storage and reduction behavior of NSR catalysts was investigated in a systematic manner over γ-Al2O3, Ba/Al, Ce/Al, Ba/Ce/Al, Pt/Al, Pt/Ce/Al and Ba/Pt/Ce/Al systems using BET, XRD, Raman spectroscopy and in situ FTIR. Although ceria promotion does not seem to have a substantial influence on the overall NOx storage capacity, it does have a clearly positive effect on the NOx reduction via H2(g) during catalytic regeneration under rich conditions which is associated with the enhancement in the total amount of activated hydrogen on the catalyst surface and lowering of the thermal threshold for hydrogen activation. A strong metal support interaction (SMSI) between Pt sites and the BaOx/CeOx domains leads to a complex redox interplay including oxidation of the precious metal sites, reduction of ceria, formation of BaO2 species as well as the formation of Pt–O–Ce interfacial sites on the Ba/Pt/Ce/Al surface. Ceria domains also act as anchoring sites for Pt species, limit their surface diffusion, enhance dispersion and hinder sintering at elevated temperatures. On the Ba/Pt/Ce/Al catalyst surface, reduction of the stored nitrates under relatively mild conditions via H2(g) initially leads to the formation of surface –OH and –NHx species and gas phase N2O, as well as the destruction of surface nitrate species, leaving bulk nitrates mostly intact. Reduction proceeds with the conversion of N2O(g) into N2(g) along with the partial loss of surface –OH and –NHx groups, dehydration and the loss of bulk nitrates.