Catalytic Oxidation Of Carbon Monoxide Research Articles

Selective phase transformation of layered double hydroxides into mixed metal oxides for catalytic CO oxidation

Phase transformation from layered double hydroxides (LDHs) into mixed metal oxides (MMOs) has been widely used in various catalytic applications owing to its numerous advantages over conventional synthesis methods. Herein we report the results of selective phase transformation of LDHs into spinels and delafossites for the preparation of phase-pure MMO catalysts. Pure cuprous delafossites and cupric spinels were selectively obtained through heat treatment of Cu-based LDHs followed by post-treatments. This enabled the study of the crystalline-phase-dependent CO oxidation activity of the MMO catalysts and their physicochemical properties. The spinel catalysts exhibited higher CO oxidation activities, in comparison with those of the delafossites, with greater redox properties and improved active sites for CO adsorption. Although the crystalline phases were derived from the same LDH precursors, the catalytic properties of the end product were greatly influenced by their crystal structures. • Preparation of copper-based layered double hydroxides (LDHs) • Selective phase transformation of LDHs into metal oxides • Phase dependence of catalytic carbon monoxide oxidation is studied Synthesis of phase-pure materials is important for studying structure-property relationship. Jang et al. selectively prepared pure copper-based spinels and delafossites exploiting phase transformation of layered double hydroxides in different atmospheric conditions. The spinels exhibit higher CO oxidation activities and improved CO adsorption active sites than those of delafossites.

Illustrating catalysis with a handmade molecular model set: catalytic oxidation of carbon monoxide over a platinum surface

Abstract Catalytic converters (automotive catalysts) and the chemical reactions they catalyze appear in general and introductory chemistry textbooks. Although the detailed mechanisms of the chemical reactions that occur in catalytic converters have been clearly revealed via recent developments in surface and computational chemistry research, the description and illustration of the catalysis are still ambiguous in textbooks. In this paper, we describe an extracurricular lecture whereby a handmade teaching aid was employed to illustrate the basic principle of the catalytic oxidation of carbon monoxide over platinum surface, which is an essential reaction occurring in catalytic converters. The teaching aid, constructed combining easily available materials, can illustrate the positions and motions of the molecules on the platinum surface during catalytic oxidation. The lecture was favorably received by non-chemistry majors and high school students. Despite the difficulty of the topic, the audience displayed a relatively high level of understanding.

Effect of Preparation Methods on the Performance of Pt/TiO2 Catalysts for the Catalytic Oxidation of Carbon Monoxide in Simulated Sintering Flue Gas

A series of Pt/TiO2 catalysts were prepared by the impregnation (IM), dry ball mill (DB), or wet ball mill (WB) methods, and their catalytic activity for the oxidation of CO was evaluated. The structure and redox properties of the catalysts were investigated by N2 desorption, XRD, SEM, TEM, XPS, H2-TPR, SO2-TPD, and CO chemisorption analysis. It was determined that the preparation method affects the physical structure of the catalyst and the particle size and dispersion of Pt on the catalyst surface. The catalyst prepared by the impregnation method had a more suitable physical structure than the other catalysts, with a smaller particle size, a higher dispersion of Pt on the surface, and the lowest strength of SO2 adsorption. Pt/TiO2(IM) catalysts presented the best catalytic activity for the oxidation of CO in simulated sintering flue gas at 140 °C, as well as better sulfur and water resistance with simulated sintering flue gas containing 50 ppm of SO2 and 15% water vapor.

Insight into the Crystal Structures and Surface Property of Manganese Oxide on CO Catalytic Oxidation Performance.

α-MnO2 nanorods and flower-like γ-MnO2 microspheres were synthesized by facile and mild methods to illustrate the effect of crystal structures and surface features on catalytic performance with the help of carbon monoxide (CO) oxidation. It is revealed that the flower-like γ-MnO2 microspheres possess better catalytic oxidation performance (CO complete conversion temperature at 120 °C and long-time stability for 50 h) than α-MnO2 nanorods, which can be attributed to the obvious differences in the chemical bonds and linking modes of [MnO6] octahedra due to the different crystal structures. γ-MnO2 possesses lower Mn-O bond strength that enables γ-MnO2 to present a large amount of surface lattice oxygen and superior oxygen mobility. The disordered random intergrowth tunnel structure can adsorb effectively CO molecules, resulting in excellent catalytic performance for CO catalytic oxidation. In addition, the MnO2 catalyst probably occurred via a Mars-van Krevelen mechanism for CO oxidation. This work provides an insight into the effect of crystal structures and surface property of manganese oxide on catalytic oxidation performance, which presents help for the future design of promising catalysts with excellent catalytic performance.

Catalytic oxidation of CO on noble metal-based catalysts.

Carbon monoxide (CO) catalytic oxidation has gained increasing interest in recent years due to its application prospects. The noble metal catalysts commonly exhibit outstanding CO catalytic oxidation activity. Therefore, this article reviewed the recent research on the application of noble metal catalysts in the catalytic oxidation of CO. The effects of catalyst support, dopant, and physicochemical properties on the catalytic activity for CO oxidation are summarized. The influence of the presence of water vapor and sulfur dioxide in the reaction atmosphere on the catalytic activity in CO oxidation is emphatically discussed. Moreover, this paper discussed several reaction mechanisms of CO catalytic oxidation on noble metal catalysts. Finally, the challenges of removing CO by catalytic oxidation in practical industrial flue gas are proposed.

An Experimental and Theoretical Investigation on the Oxidation of CO over Pd/C Derived from the Spent Pd Catalyst

AbstractDevelopment of novel materials and methodologies for removal of toxic and poisonous carbon monoxide (CO) gas is important to solve serious health and environmental related problems. Existing materials used for the removal of CO gas are quite expensive and therefore, the synthesis of low‐cost and earth‐abundant catalyst for CO oxidation is urgently needed. In the present work, we report the preparation of Pd nanoparticles loaded on porous carbon supports from the spent Pd/C and the subsequent catalytic oxidation of CO. Different Pd based catalysts are prepared by using various reducing agents with different reduction potential such as formaldehyde, green tea, ascorbic acid, and sodium borohydride. The prepared catalysts are characterized and employed for the oxidation of CO. All the prepared catalysts show excellent activity towards CO oxidation at room temperature either in presence or absence of moisture depending on the Pd0/Pd+2 ratio in Pd/C which follows the order Pd/C−NaBH4>Pd/C−HCHO>Pd/C−Ascorbic acid>Pd/C−Green tea. Experimental findings of the present work also reveal that depending on the oxidation state, and moisture plays a critical role in Pd catalytic properties on the oxidation of CO. Theoretical calculations performed using Vienna ab initio Simulation Package (VASP) support the experimental observations and further confirm that the reaction proceeds through Langmuir‐Hinshelwood mechanism.

Metal oxide/CeO2 nanocomposites derived from Ce-benzene tricarboxylate (Ce-BTC) adsorbing with metal acetylacetonate complexes for catalytic oxidation of carbon monoxide.

Herein, a series of metal oxide/CeO2 (M/CeO2) nanocomposites derived from Ce-benzene tricarboxylate (Ce-BTC) adsorbing with different metal acetylacetonate complexes were prepared for CO oxidation under four different CO gas atmospheres. It was demonstrated that Cu/CeO2 exhibited the highest catalytic activity and stability in CO oxidation. Remarkably, both O2 selectivity and CO selectivity to CO2 are 100% in most of the investigated conditions. Several analytical tools such as N2 adsorption–desorption and powder X-ray diffraction, were employed to characterize the prepared catalysts. In addition, the excellent catalytic performance of Cu/CeO2 in CO oxidation was revealed by H2 temperature-program reduction experiment, X-ray photoelectron spectroscopy, and in situ diffuse reflectance infrared Fourier transform spectroscopy. The result showed that high oxygen vacancy and high CO adsorption capacity (Cu+–CO) caused by the electron exchanges of Cu2+/Cu+ and Ce3+/Ce4+ pairs (Ce4+ + Cu+ ⇆ Ce3+ + Cu2+) are two key factors contributing to the high oxidation performance of Cu/CeO2 catalyst.

The kinetic parameters of the smoke gases purification process from carbon monoxide on a zeolite-based manganese oxide catalyst

A modified MnO 2 clinoptillolite was obtained by using the available zeolite rock from the Sokyrnytsia deposit (Khust district of the Zakarpattia region, Ukraine) using a simple technique of mixing solutions containing separately Mn 2+ and MnO 4 - . It was determined that the total manganese content in the air-dry modified thermally untreated clinoptyllolite was 11.42 mg/g, which is 1.8 % in terms of MnO 2 . Structural characteristics, namely, the pore size distribution and specific surface area as the main basic characteristics of the catalyst, were studied, which were obtained from the isotherms of low-temperature nitrogen adsorption-desorption. These studies are necessary to determine the limiting stage of CO oxidation. It has been determined that the kinetics of the oxidation process is described by a first-order equation. Based on the obtained characteristics of the catalyst, the kinetic parameters of the process were calculated, namely, the effective and true rate constants and the activation energy, which is 31 kJ/mol. It has been proved that the oxidation reaction of carbon monoxide on an oxide-manganese catalyst proceeds in the intra-diffusion mode. This makes it possible, using the criterion dependences, namely, the Carberry criterion, which is less than 0.05, to assert that the reaction is not limited by the diffusion of CO from the gas stream to the outer surface of the catalyst. It is shown that the transport of carbon monoxide molecules inside the catalyst granules proceeds in the Knudsen regime. The obtained scientific result in the form of a kinetic description of the catalytic oxidation of carbon monoxide with atmospheric oxygen on a manganese oxide catalyst based on zeolite is interesting from a theoretical point of view. From a practical point of view, the calculated kinetic parameters of this process make it possible to calculate a catalytic CO oxidation reactor

Photocatalytic CO Oxidation over Nanoparticulate Au-Modified TiO2 Aerogels: The Importance of Size and Intimacy

We determine the activity of catalytic carbon monoxide (CO) oxidation as a function of the size of gold nanoparticles (Au NP), their weight loading, and their interfacial intimacy with similarly si...

Catalytic oxidation of CO over V2O5/TiO2 and V2O5-WO3/TiO2 catalysts: A DFT study

Vanadium‑titanium based selective catalytic reduction (SCR) catalysts are commercially applied for the denitrification of nitrogen oxides (NOx) in flue gas. Meanwhile, they are also catalytically effective to the abatements of many contaminants including carbon monoxide (CO) catalytic oxidation. Understanding the catalytic performance on CO oxidation is of great significance to develop modified SCR catalysts for the synergetic control of nitrogen oxides and CO. Two SCR catalyst models were constructed, i.e., V2O5/TiO2(001) and V2O5-WO3/TiO2(001). The mechanisms of CO oxidation over the above two catalyst surfaces were analyzed by density functional theory (DFT) calculations. The results show that the whole oxidation cycle of CO includes two reaction stages. In the first stage, CO reacts with terminal oxygen of VO site, following MvK mechanism, which is also the rate-determining step of the whole reaction process. In the second stage, the redundant oxygen Oe of the absorbed O2 molecule reacts with another CO molecule, which follows E-R mechanism. The activation energy barriers of the CO oxidation on V2O5/TiO2 surface are lower than those on V2O5-WO3/TiO2, indicating that WO3 doping inhibits CO oxidation. Moreover, the established reaction kinetics of elementary reactions would be helpful to model CO catalytic oxidation over the real SCR catalysts.

Combustion and emissions from cerium oxide nanoparticle dosed diesel fuel in a high speed diesel research engine under low temperature combustion (LTC) conditions

Cerium oxide (CeO2) is widely used in three-way-catalysts (TWCs) in the catalytic oxidation of hydrocarbons (HC) and carbon monoxide (CO) as well as the catalytic reduction of NOx. It has also had use as a fuel-borne catalyst in diesel fuel – particularly to promote diesel particulate filter (DPF) regeneration. The literature indicates that the catalytic effect of CeO2 might reduce HC emissions, reduce NOx formation, slow burn rates and reduce fuel consumption. In this work 8–10 nm CeO2 particles in diesel are tested at two dosing levels (5.7 & 19.8 mg/L) as a fuel-borne catalyst (FBC) in a modern high speed single cylinder diesel engine at two operating points, one low load and one high load. The combustion and engine-out emissions are analysed and compared to the undosed diesel fuel. The results show that CeO2 reduces soot and THC emissions by up to 30% at part load under LTC but no significant differences are observed at high load. At high load a minor (2–5%) reduction in NOx for a given EGR level is observed. No significant differences are seen in fuel consumption at either load point. At light load, a significant difference in the particulate size distribution is observed with fuels dosed with CeO2. CeO2 is observed to remove small particles under LTC conditions. In terms of the combustion parameters a reduction in maximum cylinder pressure of 2.5% at part load and an increase in ignition delay of up to 10% at high load are observed.

The Origin of Au/Ce1-xZrxO2 Catalyst’s Active Sites in Low-Temperature CO Oxidation

Gold catalysts have found applications in many reactions of both industrial and environmental importance. Great interest has been paid to the development of new processes that reduce energy consumption and minimize pollution. Among these reactions, the catalytic oxidation of carbon monoxide (CO) is an important one, considering that a high concentration of CO in the atmosphere creates serious health and environmental problems. This paper examines the most important achievements and conclusions arising from the own authorship contributions concerning (2 wt. % Au)/Ce1−xZrxO2 catalyst’s active sites in low-temperature CO oxidation. The main findings of the present review are: (1) The effect of preparing conditions on Au crystallite size, highlighting some of the fundamental underpinnings of gold catalysis: the Au surface composition and the poisoning effect of residual chloride on the catalytic activity of (2 wt. % Au)/Ce1−xZrxO2 catalysts in CO oxidation; (2) The identification of ion clusters related to gold and their effect on catalyst’ surface composition; (3) The importance of physicochemical properties of oxide support (e.g., its particle size, oxygen mobility at low temperature and redox properties) in the creation of catalytic performance of Au catalysts; (4) The importance of oxygen vacancies, on the support surface, as the centers for oxygen molecule activation in CO reaction; (5) The role of moisture (200–1000 ppm) in the generation of enhanced CO conversion; (6) The Au-assisted Mars-van Krevelen (MvK) adsorption–reaction model was pertinent to describe CO oxidation mechanism. The principal role of Au in CO oxidation over (2 wt. % Au)/Ce1−xZrxO2 catalysts was related to the promotion in the transformation process of reversibly adsorbed or inactive surface oxygen into irreversibly adsorbed active species; (7) Combination of metallic gold (Au0) and Au-OH species was proposed as active sites for CO adsorption. These findings can help in the optimization of Au-containing catalysts.

Electrospun La0.8Ce0.2Fe1-xNixO3 perovskite nanofibrous catalysts for CO oxidation

Carbon monoxide (CO) is one of the main pollutants of incomplete gasoline combustion from automotive and engines. Catalytic CO oxidation is an effective way to remove CO. La0.8Ce0.2Fe1-xNixO3 nanofibrous catalysts with high thermal stability were prepared by electrospinning in this study. The influence factors of La0.8Ce0.2Fe1-xNixO3 perovskite properties on CO oxidation were investigated. Calcination temperature affects catalyst crystallinity and hence catalytic activity. Increasing calcination temperature enhances crystallinity while decreases catalytic surface area, resulting in the highest catalytic activity at the calcination temperature of 800 °C. Oxygen vacancy in the perovskite increases catalyst activity. Doping Ni up to 20 mol% increases oxygen vacancy and oxygen storage capacity while excessive doping decreases perovskite crystallinity. The nanofibrous catalyst activity can be improved via reducing fiber diameters so as to increase catalytic surface area. The advantage of nanofibrous catalysts was confirmed by comparing with conventional powder catalysts. Therefore, high CO conversion can be achieved over the nanofibrous perovskite-type catalysts.

Selection of Manganese oxide catalysts for catalytic oxidation of Carbon monoxide at ambient conditions

Abstract Carbon monoxide (CO) is one of the very poisonous gases present in the atmosphere and low temperature complete oxidation CO is very important process for all human being present in the environment. A catalytic converter was an emission control device that converts more toxic gases present in the automobile exhaust into less toxic gases by the catalytic reactions. The manganese oxide catalysts i.e. (XMn2O x , X = Ce, Co, Fe, Cu) are prepared into laboratory by the co-precipitation method followed by calcinations in reactive CO–air mixture and traditional calcinations conditions. The activity order of catalysts for CO oxidation is as follows: CuMn2O2 > CeMn2O2 > CoMn2O2 > FeMn2O2. Among all the prepared catalysts, the CuMn2O2 has showed that the best catalytic activity for CO oxidation at the low temperature. The complete oxidation of CO was achieved at 85 oC over CuMn 2RC catalyst. The calcinations strategies of precursors have great influenced on the activity of resulting catalysts. The CO oxidation activity was recognized to be a combination of factors including high surface area, active surface oxygen species and Mn(IV) cations. These results provide a novel thought to design the highly active CuMn2O2 catalyst.

Study of Transition Zones in the Carbon Monoxide Catalytic Oxidation on Platinum Using the Network Simulation Method

A study of transition zones in the carbon monoxide catalytic oxidation over platinum is presented. After the design of a network model following the rules of the Network Simulation Method, it is run in a standard (free) software providing the fractional coverages of all species for different values of carbon monoxide partial pressure, the main parameter that produces the change between a stationary or periodic response. The design of the model is explained in detail and no assumptions are made concerning the removing of oxidation fractional coverage. The illusory chaotic behavior associated with an inadequate time step in the numerical algorithm is studied. This work provides an explanation for the transition (bifurcation) between the stationary and the periodical response studies making use of Poincaré plane and phase-diagrams. The extinction of variable fluctuation in the transition zone is analyzed to understand its relation with given values of transition partial pressures. Of particular interest is the small time span of the superficial fractional coverage of carbon monoxide fluctuation near the second transition partial pressure.

Synthesis of CuMnOx catalysts by novel routes for selective catalytic oxidation of carbon monoxide

The ambient temperature catalytic oxidation of carbon monoxide (CO) is very important process for all living beings present in the atmosphere. Hopcalite (CuMnOx) is a mixed oxide of copper and manganese has been efficiently applied as a catalyst in the catalytic converter for CO oxidation. All the catalysts are prepared by the Co-precipitation method and characterized by the SEM-EDX, XRD, FTIR, BET and XPS technique. The ratio of Cu:Mn in CuMnOx catalyst was divided into three equal parts (Cu:Mn = 1:2, Cu:Mn = 1:1 and Cu:Mn = 2:1) and their performances for CO oxidation was also measured. The activity order of catalysts for CO oxidation was as follows: Cu2Mn1 < Cu1Mn1 < Cu1Mn2. In these catalysts the Cu1Mn2 has showed that the best catalytic activity for CO oxidation at a lower temperature. The calcinations strategies of precursors have great influences on the activity of resultant catalyst. All the catalysts are prepared in different calcinations conditions like reactive calcinations (RC) and traditional calcinations. The reactive calcinations strategy is one of the best calcinations strategies for the preparation of highly active catalysts. The stability of CuMnOx catalyst is also investigated in this research work.

LUMINESCENCE OF Α-WILLEMITE IN THE CATALYTIC OXIDATION OF CARBON MONOXIDE

The interaction of neutral gas particles of thermal energies (molecules and atoms) with the surface of a solid is accompanied by radiation in the visible and I.R. parts of the spectrum. In this case, the surface of a solid body acts as a catalyst for the recombination reactions of gas particles. In this connection, the possibility of exciting luminescence during the catalytic oxidation of carbon monoxide directly by the atomic form of oxygen pre-adsorbed on the surface of a solid is of interest. Kinetic and spectral methods were used to study the luminescence arising from the catalytic oxidation of carbon monoxide by the atomic form of oxygen preadsorbed on the surface of a solid – a sample of α-willemite Zn2SiO4:Mn2+. The main stages in the mechanisms of recombination between adsorbate particles are established. Electronic transitions in adsorption complexes and the activator ion have been identified. During the filling process, the sample temperature was maintained by a constant high-speed electronic control system of the heater current. This made it possible to avoid thermal side effects. The main stages in the mechanisms of recombination between adsorbate particles are established. Electronic transitions in adsorption complexes and the activator ion have been identified. It was found that luminescence excitation proceeds in two main stages, somewhat time-shifted. The two-stage mechanism for the catalytic oxidation of carbon monoxide on the surface of α-willemite with pre-adsorbed atomic oxygen allows a consistent description of the luminescence observed in this case. This type of luminescence has the prospect of using for studying the mechanisms of catalytic oxidation of carbon monoxide.

Highly Catalytic Electrochemical Oxidation of Carbon Monoxide on Iridium Nanotubes: Amperometric Sensing of Carbon Monoxide.

The nanotubular structures of IrO2 and Ir metal were successfully synthesized without any template. First, IrO2 nanotubes were prepared by electrospinning and post-calcination, where a fine control of synthetic conditions (e.g., precursor concentration and solvent composition in electrospinning solution, temperature increasing rate for calcination) was required. Then, a further thermal treatment of IrO2 nanotubes under hydrogen gas atmosphere produced Ir metal nanotubes. The electroactivity of the resultant Ir metal nanotubes was investigated toward carbon monoxide (CO) oxidation using linear sweep voltammetry (LSV) and amperometry. The anodic current response of Ir metal nanotubes was linearly proportional to CO concentration change, with a high sensitivity and a short response time. The amperometric sensitivity of Ir metal nanotubes for CO sensing was greater than a nanofibrous counterpart (i.e., Ir metal nanofibers) and commercial Pt (20 wt% Pt loading on carbon). Density functional theory calculations support stronger CO adsorption on Ir(111) than Pt(111). This study demonstrates that metallic Ir in a nanotubular structure is a good electrode material for the amperometric sensing of CO.

Urea–nitrate combustion synthesis of CuO/CeO2 nanocatalysts toward low-temperature oxidation of CO: the effect of Red/Ox ratio

The low-temperature catalytic oxidation of carbon monoxide (CO) is the key process to overcome incomplete combustion of fossil fuels for both commercial (e.g., lowering automotive emissions) and domestic (e.g., indoor air quality improvement) applications. So the development of cost-effective and high-active catalysts made from non-noble metals is an actual material science challenge. Ce–Cu–O oxide system is one of the most prospective to investigate due to the feasibility of the Langmuir–Hinshelwood dual-site oxidation mechanism, and, in our previous work, it was shown that solution combustion synthesis using the urea as fuel in stoichiometric ratio with metal nitrates is a most reasonable fuel choice toward the synthesis of CuO/CeO2 nanocatalysts for effective CO oxidation. In this work, the effect of the Red/Ox (urea to nitrates or U/N) ratio on the catalytic oxidation activity of resulting CuO/CeO2 composites is in the spotlight. Series of CuO/CeO2 nanocatalysts were successfully synthesized via the urea–nitrate combustion method with U/N ratios from 0.2 to 1.4 and then were applied for CO oxidation. The samples before and after catalysis were characterized by EDX, SEM, PXRD, N2-ASA, H2-TPR, etc. It was shown that the U/N ratio strongly affects the qualitative and quantitative X-ray phase composition (c-CeO2, m-CuO, and am-CuO, in general), CeO2 and CuO crystallite sizes (4.9–63.0 nm and 14.7–28.3 nm, correspondently), specific surface area (4–46 m2/g) and porosity (0.009–0.033 cm3/g), as well as the morphology of nanocomposites and their catalytic characteristics (t50% = 113–199 °C and t100% = 137–348 °C). The sample synthesized at U/N = 0.2 shows the best oxidative performance (t50% = 113 °C and t100% = 137 °C) explained by the highest surface (46 m2/g), the lowest CeO2 crystallite size (4.9 nm), and the lowest degree of agglomeration of nanocrystals in the CuO/CeO2 composite. Besides, cyclic and water resistivity tests of this sample confirm the high stability of its catalytic activity in the CO oxidation process due to the close conjugation of the CeO2 and CuO components in the resulting nanocomposite, confirmed by the H2-TPR analysis results. Thus, it was shown that the optimization of Red/Ox ratio in the urea–nitrate combustion process contributes to obtaining the stable CuO/CeO2 nanocatalyst with gradual conversion of CO at quite low temperatures (ti ~ 50 °C). We believe that the subsequent reduction of CuO loading in the Ce–Cu–O system allows creating a cost-effective and stable composite nanocatalyst with high activity even at room temperature.

Experimental study of the effect of carbon monoxide on the performance of passive autocatalytic recombiners

Passive autocatalytic recombiners (PARs) have been implemented in water-cooled nuclear reactors to prevent hydrogen explosion during severe accidents. Carbon monoxide (CO) can also be produced in severe accidents from ex-vessel molten core–concrete interaction. Assessment of scenarios involving ex-vessel interactions requires additional attention to the contribution of CO to combustion loads in containments. The risk of CO combustion can be mitigated by catalytic oxidation of CO in parallel with hydrogen recombination; however, the PAR performance may be affected by catalyst poisoning by CO. Tests were performed to examine the PAR self-start behaviour, recombination rate and efficiency, and ignition induced by hot catalyst plates in the presence of hydrogen and CO mixtures. The experiments were conducted in a 120 m3 test facility with a full-sized PAR and in a lab-scale apparatus with catalyst coupons. These measurements demonstrate that the CO poisoning effect strongly depends on the temperature and gas compositions. CO appears to have no adverse effect on PAR recombination rate during operation. This paper presents select experimental results with a focus on the effect of CO on PAR self-start behaviour. These results will help to refine severe accident management guidelines.