Catalysts For Oxidation Of Carbon Monoxide Research Articles

{CeO2/Bi2Mo1−xRuxO6} and {Au/Bi2Mo1−xRuxO6} Catalysts for Low-Temperature CO Oxidation

Nowadays, one of the most important challenges that humanity faces is to find alternative ways of reducing pollutant emissions. CeO2/Bi2Mo1−xRuxO6 and Au/Bi2Mo1−xRuxO6 catalysts were prepared to efficiently transform carbon monoxide (CO) to carbon dioxide (CO2) at low temperatures. The systems were prepared in a two-step process. First, Bi2Mo1−xRuxO6 supports were synthesized through the hydrothermal procedure under microwave heating. Then, CeO2 was deposited on Bi2Mo1−xRuxO6 using the wet impregnation method, while the incipient impregnation method was selected to deposit gold nanoparticles. The CeO2/Bi2Mo1−xRuxO6 and Au/Bi2Mo1−xRuxO6 catalysts were characterized using SEM microscopy and XRD. Furthermore, energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy were used. Tests were carried out for the supported catalysts in CO oxidation, and high conversion values, nearing 100%, was observed in a temperature range of 100 to 250 °C. The results showed that the best system was the Au/Bi2Mo0.95Ru0.05O6 catalyst, with CO oxidation starting at 50 °C and reaching 100% conversion at 186 °C.

Synthesis of hierarchically porous silica aerogel supported Palladium catalyst for low-temperature CO oxidation under ignition/extinction conditions

Abstract Synthesis of well-dispersed palladium nanoparticles within silica aerogel pores with controlled size was carried out using sol-gel synthesis under supercritical ethanol drying. The high concentration of silanol groups on silica (SiO2) surface facilitated a superior palladium (Pd) loading up to 10 wt %. The synthesized Pd/SiO2 nanocomposite aerogels were characterized by X-ray diffraction (XRD), N2 adsorption-desorption, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectroscopic methods. The silica aerogel supported catalysts were found to have a wide pore size distribution. TEM investigations confirmed that Pd nanocrystals were located within the SiO2 microspores and mesopores. The catalyst was evaluated for carbon monoxide (CO) oxidation reaction under ignition/extinction conditions. The synthesized catalyst demonstrated a high catalytic activity at low operating temperatures (

Synthesis and Properties of a Carbon Monoxide Oxidation Catalyst Based on Platinum and Plasma-Chemical Titanium Nitride

A CO oxidation catalyst that includes Pt clusters applied on nanosized TiN supports with a particle size of 18 and 36 nm has been synthesized. The catalyst has been studied using TEM, X-ray powder diffraction, and XPS methods. It has been found that platinum clusters formed on the support surface are covered with a mixture of platinum and platinum oxide. The coherent scattering range of the Pt cluster is close to 8 nm on a support with titanium nitride particles of 18 nm. The catalytic properties in the reaction of CO oxidation at 295 K and low CO concentrations (<100 mg/m3) have been examined. It has been found that when the platinum content in the catalyst is 9 to 15 wt %, the CO oxidation rate is 120 times higher than that on platinum black with a specific surface area of 30 m2/g. The catalysts are promising for use in catalytic systems for air purification.

A Review of Synthesis, Structure and Applications in Hopcalite Catalysts for Carbon Monoxide Oxidation

Carbon monoxide (CO) is a poisonous atmospheric pollutant. It highly affects human beings, plants, animals and environment. Automobile exhaust is the largest source of CO emission in the environment. To control this automobile exhaust pollution, the catalytic converters are used. Many types of catalysts have been investigated for CO oxidation purposes, i.e., noble metal, base metal, rare earth, perovskite, spinel and mixed transient metal oxides. These catalysts are widely used in a catalytic converter. Among the various metal oxide catalysts, hopcalite (CuMnOx) is one of the most efficient catalysts for low-temperature CO oxidation. Hopcalite catalysts have been reported to be good from economical, thermal, activity, selectivity and availability points of view. The activity of hopcalite catalysts is strongly dependent on the surface area, crystallite size and binding energy of the catalysts. This study will provide a scientific basis for designing future application of hopcalite catalysts for low-temperature CO oxidation. This manuscript provides a summary of published information regarding pure and substituted hopcalite catalyst, synthesis methods; properties and application for CO emissions control. A number of papers associated with CO oxidation over the hopcalite catalysts have been available, but no review papers appear in the literature that is dedicated to CO oxidation. Therefore, in an attempt to fill this gap, the present review updates and evaluates the progress and future scope of hopcalite catalyst for purification of exhaust gases.

Ambient temperature complete oxidation of carbon monoxide using hopcalite catalysts for fire escape mask applications

Carbon monoxide (CO) is one of the most poisonous gases present in the atmosphere. It also called the silent killer of twenty-first century. CO is produced into the environment by incomplete combustion of carbon containing compounds. It causes lots of people die every year including the firefighters. The main aim of this work to find out the literature study of standard respiratory escape masks for ambient temperature CO oxidation purposes. The research under concern is applicable for developing respiratory protection systems for military, mining, and space devices. There are many catalysts which are active for this process under different conditions. Among these catalysts, the hopcalite (CuMnOx) is one of the best-known catalysts for low-temperature CO oxidation. It is a low-cost, easily available, and highly stable catalyst. The hopcalite catalyst is active for a longer time and would be tolerant of moisture and impurities in reacting gases. The catalyst surface and reacting gases forever play a key role in catalytic reactions. Hopcalite is an ideal catalyst for use in next-generation respiratory protection devices. Although there are numerous research papers present on this topic until now no one review are present for demanding this issue. So there is a space in this area; it has been made an attempt to seal this hole by this review.

Rational Synthesis of Porous Graphitic-like Carbon Nitride Nanotubes Codoped with Au and Pd as an Efficient Catalyst for Carbon Monoxide Oxidation.

The precise fabrication of efficient catalysts for CO oxidation is of particular interest in a wide range of industrial and environmental applications. Herein, a scalable method is presented for the controlled synthesis of graphitic-like porous carbon nitride nanotubes (gC3N4NTs) codoped with Au and Pd (Au/Pd/gC3N4NTs) as efficient catalysts for carbon monoxide (CO) conversion. This includes the activation of melamine with nitric acid in the presence of ethylene glycol and metal precursors followed by consecutive polymerization and carbonization. This drives the formation of porous one-dimensional gC3N4NT with an outstanding surface area of (320.6 m2 g-1) and an atomic-level distribution of Au and Pd. Intriguingly, the CO conversion efficiency of Au/Pd/gC3N4NTs was substantially greater than that for gC3N4NTs. The approach thus presented may provide new avenues for the utilization of gC3N4 doped with multiple metal-based catalysts for CO conversion reactions which had been rarely reported before.

Synthesis of silver promoted CuMnOx catalyst for ambient temperature oxidation of carbon monoxide

Abstract The present research shows that the addition of silver (Ag), by the deposition-precipitation method, to a mixed CuMnOx catalyst can improve the activity of carbon monoxide (CO) oxidation. The CuMnOx catalyst doped with 3 wt.% Ag shows a higher catalytic activity as compared to the 1, 2, 4 and 5 wt.% Ag doped samples. The loading of Ag could introduce new active sites into the CuMnOx catalyst and reduce its deactivation. The order of the optimal calcination strategies based on the performance of catalysts for CO oxidation is as follows: Reactive Calcination > Flowing air > Stagnant air. All the catalysts were characterized by XRD, FTIR, BET, XPS and SEM-EDX techniques. It was found that the high active surface area was one of the main factors for the high catalytic activity of the Ag-promoted CuMnOx catalyst.

Gold‐Loaded Nanoporous Iron Oxide Cubes Derived from Prussian Blue as Carbon Monoxide Oxidation Catalyst at Room Temperature

AbstractThis work reports the preparation of carbon monoxide (CO) oxidation catalysts based on gold nanoparticles supported on nanoporous iron oxide cubes. By heat‐treating Prussian blue (PB) cubes at various temperatures between 250–450 °C in air, nanoporous iron oxide cubes with surface areas up to 100 m2 g−1 are obtained. Owing to the relatively large surface area and nanoporous structure, the as‐synthesized iron oxide cubes can be loaded with up to 11 wt% of Au nanoparticles without significant aggregation. When employed for CO oxidation, the Au‐loaded nanoporous iron oxide cubes exhibit a high CO conversion rate of over 95% at room temperature under 0.1 L⋅min−1 of CO gas flow, with specific activity of up to 1.79 molCO⋅gAu−1⋅h−1. The high catalytic performance of the Au‐loaded nanoporous iron oxide cubes for CO oxidation is contributed by various factors, including: (i) the high surface area of the iron oxide cubes which leads to the availability of more sites for the adsorption of oxygen molecules to react with carbon monoxide to generate more carbon dioxide (CO2); (ii) the presence of nanopores which enhances the diffusivity of the reactant molecules during the catalytic reaction and improves dispersion of the deposited gold nanoparticles while also preventing their aggregation at the same time and (iii) the small size of the deposited gold nanoparticles (2‐5 nm) which falls within the ideal size of gold nanoparticles for achieving high CO conversion.

A DFT study on the possibility of using a single Cu atom incorporated nitrogen‐doped graphene as a promising and highly active catalyst for oxidation of CO

AbstractUsing dispersion‐corrected density functional theory (DFT) calculations, a single Cu adatom incorporated nitrogen‐doped graphene (CuN3‐Gr) is proposed as a new and highly active noble‐metal‐free catalyst for carbon monoxide (CO) oxidation reaction. According to our results, the Cu adatom can be stably anchored onto the monovavancy site of the nitrogen‐doped graphene, and the resulting large diffusion barrier suggests that the metal clustering is avoided in CuN3‐Gr. Three possible reaction mechanisms for CO oxidation (ie, Eley–Rideal, Langmuir–Hinshelwood, and termolecular Eley–Rideal) are systematically studied. It is found that the activation energy for the rate‐determining step of the termolecular Eley–Rideal mechanism is only 0.13 eV, which is much smaller than those of others. The results of this study may provide a useful guideline for the design of highly active and promising single‐metal catalysts for the CO oxidation reaction based on graphene.

Adsorption Synthesis of Iron Oxide-Supported Gold Catalyst under Self-Generated Alkaline Conditions for Efficient Elimination of Carbon Monoxide

Goethite- and hematite-supported highly dispersed gold catalysts for carbon monoxide oxidation were synthesized by gold precursor adsorption onto the support materials in self-generated alkaline solutions. The support materials were prepared by reacting iron nitrate with excess sodium hydroxide. The residual minor alkali incorporated into the support could provide suitable alkaline conditions at approximately pH 8 for the hydrolysis of tetrachloroaurate anions and the subsequent adsorption process. Gold species underwent autoreduction to achieve activation during the synthesis. An increase in pH or temperature to 80 °C decreased the gold loading of the catalysts. The optimal catalysts could achieve complete oxidation of carbon monoxide at −20 °C.

Effect of various metal oxides phases present in CuMnOx catalyst for selective CO oxidation

Hopcalite (CuMnOx) is a highly efficient catalyst for low temperature oxidation of Carbon monoxide (CO). As synthesized by Co-precipitation method, it shows the high activity for CO oxidation. The coordination between CuO and MnOx in CuMnOx catalyst improves the catalytic activity for CO oxidation. In this research work, we investigate the individual catalytic activity of CuO and MnOx and compare with the multiphase CuMnOx catalyst. The performance of multiphase catalysts CuO and MnO2 were numerous times higher as compared to single phase CuMnOx. The activity order of catalysts for CO oxidation was as follows: CuMnOx> MnOx > CuOx. The success of CuMnOx catalyst has prompted a great deal of research work into each component and nature of active sites. In CuMnOx catalyst, the MnOx acts as an oxygen donor and CuO acts as an oxygen acceptor. The presence of MnOx is possible to assist in the reduction of CuO, due to the coordination between CuO and MnOx. The calcination strategies of precursors highly affect the physicochemical and catalytic properties of the catalysts for CO oxidation. The reactive calcination (RC) conditions (4.5% CO in air) for prepared catalysts showed the best activity result for CO oxidation, as compared to the traditional method of calcination.

The MgO(111) versus MgO(100) supported Au ultrasmall particles as a model catalyst for carbon monoxide oxidation

Adsorption and reaction of carbon monoxide and oxygen on gold ultrasmall particles deposited on MgO(111) and MgO(100) films in ultra-high vacuum have been studied by surface sensitive spectroscopic and structural techniques. The 3 nm thick MgO(111) and MgO(100) films were formed on Mo(110) and Mo(100) supports, respectively, as templates to grow the corresponding oxide structures. It is found that, unlike MgO(100), and many other oxide surfaces, reported in the literature, the Au particles of and average size of c.a. 2–3 nm, deposited on MgO(111), acquire an effective positive charge as a result of charge transfer from the metal as an effect stabilizing the uncompensated dipolar moment of the polar substrate. Gold nanoparticles on both MgO(111) and MgO(100) are active model catalysts for carbon monoxide oxidation by oxygen, as revealed by temperature desorption studies. However the effect of MgO(111) support is markedly more pronounced due to stronger interaction of precursor CO and O2 induced by specific state of supported Au ultrasmall particles.

Transformation of a Pt–CeO2 Mechanical Mixture of Pulsed‐Laser‐Ablated Nanoparticles to a Highly Active Catalyst for Carbon Monoxide Oxidation

AbstractThe pulsed laser ablation (PLA) in alcohol and water media was employed to prepare Pt and CeO2 PLA‐nanoparticles of different sizes and degrees of defectiveness. Interactions of metallic platinum and ceria particles were studied using the thermal activation of Pt–CeO2 mechanical mixtures in the CO+O2 reaction medium or O2 atmosphere. The thermal activation resulted in oxidized Pt2+/Pt4+ states of platinum in the surface solid solutions PtCeOx and/or PtOx clusters. Catalysts formed after calcination of the PLA‐ablated Pt–CeO2 mixtures in oxygen at 450–600 °C revealed CO conversion at very low temperatures up to 70 % depending on the conditions of PLA particles preparation and thermal activation of Pt–CeO2 mechanical mixture.

Room temperature carbon monoxide oxidation based on two-dimensional gold-loaded mesoporous iron oxide nanoflakes

In this work, we fabricate a highly effective catalyst for carbon monoxide oxidation based on gold-loaded mesoporous maghemite nanoflakes which exhibit nearly 100% CO conversion and a very high specific activity of 8.41 molCO gAu-1 h-1 at room temperature. Such excellent catalytic activity is promoted by the synergistic cooperation of their high surface area, large pore volume, and mesoporous structure.

Study of Hopcalite (CuMnOx) Catalysts Prepared Through A Novel Route for the Oxidation of Carbon Monoxide at Low Temperature

Carbon monoxide (CO) is a poisonous gas, recognized as a silent killer. The gas is produced by incomplete combustion of carbonaceous fuel. Recent studies have shown that hopcalite group is one of the promising catalysts for CO oxidation at low temperature. In this study, hopcalite (CuMnOx) catalysts were prepared by KMnO4 co-precipitation method followed by washing, drying the precipitate at different temperatures (22, 50, 90, 110, and 120 oC) for 12 h in an oven and subsequent calcination at 300 oC in stagnant air, flowing air and in a reactive gas mixture of (4.5% CO in air) to do the reactive calcination (RC). The prepared catalysts were characterized by XRD, FTIR, SEM-EDX, XPS, and BET techniques. The activity of the catalysts was evaluated in a tubular reactor under the following conditions: 100 mg catalyst, 2.5% CO in air, total flow rate 60 mL/min and temperature varying from ambient to a higher value, at which complete oxidation of CO was achieved. The order of calcination strategies based on activity for hopcalite catalysts was observed to be as: RC &gt; flowing air &gt; stagnant air. In the kinetics study of CuMnOx catalyst prepared in RC conditions the frequency factor and activation energy were found to be 5.856×105 (g.mol)/(gcat.h) and 36.98 kJ/gmol, respectively.

Kinetics of catalytic oxidation of carbon monoxide over CuMnAgOx catalyst

The CuMnAgOx catalyst was prepared by the deposition-precipitation method and followed by calcination at 300°C, which showed excellent activity and stability for carbon monoxide (CO) oxidation at low temperature. This paper describes the kinetics of catalytic air oxidation of CO over the CuMnAgOx catalyst and their kinetics data were collected in a plug flow tubular reactor. The data were collected under the following reaction conditions: 100mg catalyst, 2.5% CO in air, total flow rate maintained 60ml/min and temperature range 25–30°C. The CO oxidation followed in a different reaction mechanism at a broad range of experimental temperature. A better tool for measuring the performance of CuMnAgOx catalyst for CO oxidation is the activation energy for the process and it’s used for the modeling and design of the catalytic converter. The data were fitted into the power law rate equation. The frequency factor and activation energy were found to be 2.7790×105 (gmol)/(gcath) and 16.977kJ/gmol, respectively.

Thermal Activation of CuBTC MOF for CO Oxidation: The Effect of Activation Atmosphere

High performance catalysts for carbon monoxide (CO) oxidation were obtained through thermal activation of a CuBTC (BTC: 1,3,5-benzenetricarboxylic acid) metal–organic framework (MOF) in various atmospheres. X-ray diffraction (XRD), X-ray photonelectron spectroscopy (XPS), N2 adsorption–desorption measurement, and field emission scanning electron microscopy (FESEM) were adopted to characterize the catalysts. The results show that thermal activation by reductive H2 may greatly destroy the structure of CuBTC. Inert Ar gas has a weak influence on the structure of CuBTC. Therefore, these two catalysts exhibit low CO oxidation activity. Activating with O2 is effective for CuBTC catalysts, since active CuO species may be obtained due to the slight collapse of CuBTC structure. The highest activity is obtained when activating with CO reaction gas, since many pores and more effective Cu2O is formed during the thermal activation process. These results show that the structure and chemical state of coordinated metallic ions in MOFs are adjustable by controlling the activation conditions. This work provides an effective method for designing and fabricating high performance catalysts for CO oxidation based on MOFs.

Nanocrystalline ZrO2 and Pt-doped ZrO2 catalysts for low-temperature CO oxidation.

Zirconia (ZrO2) nanoparticles were synthesized by solution combustion using urea as an organic fuel. Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), transmission electron microscopy (TEM), UV–vis and Fourier transform infrared (FTIR) measurements were performed in order to characterize the catalyst. The calculated crystallite size of ZrO2, calculated with the help of the Scherrer equation, was around 30.3 nm. The synthesized ZrO2 was scrutinized regarding its role as catalyst in the oxidation of carbon monoxide (CO). It showed 100% CO conversion at 240 °C, which is the highest conversion rate reported for ZrO2 in literature to date. It is found that through solution combustion, Pt2+ ions replace Zr4+ ions in the ZrO2 lattice and because of this, oxygen vacancies are formed due to charge imbalance and lattice distortion in ZrO2. 1% Pt was doped into ZrO2 and yielded excellent CO oxidation. The working temperature was lowered by 150 °C in comparison to pure ZrO2. Further, it is highly stable for the CO reaction (time-on-stream ≈ 40 h). This is because of a synergic effect between Pt and Zr components, which results in an increase of the oxygen mobility and oxygen vacancies and improves the activity and stability of the catalyst. The effects of gas hourly space velocity (GHSV) and initial CO concentration on the CO oxidation over Pt(1%)-ZrO2 were studied.

Pd nanoparticles supported on iron oxide nanorods for CO oxidation: Effect of preparation method

In this work, Pd nanoparticles was precipitated over iron oxide that prepared through two basic approaches to look for better dispersion of Pd nanoparticles and robust catalyst for carbon monoxide oxidation. The first involves direct precipitation of iron oxide using sodium hydroxide, and the second involves hydrothermal treatment after precipitation. The catalysts were characterized by many techniques such as, FTIR, XRD, N2 adsorption-desorption, H2-TPR and TEM images. The catalytic activity of the prepared catalysts was tested in CO oxidation reaction. The XRD showed that, α-FeOOH crystalline structure is formed. While, TEM images showed that, α-FeOOH has nanorods structure with different dimensions. The TPR experiment indicated that the reducibility of Pd/FeOOH catalyst was much more enhanced. The results also demonstrate that, as compared with the direct precipitation approach, the hydrothermal treatment after precipitation approach of iron oxide enable better dispersion of Pd nanoparticles as well as hinder the growth of large Pd crystallites which are important to produce outstanding catalysts for carbon monoxide oxidation.

Correlation between catalytic activity of supported gold catalysts for carbon monoxide oxidation and metal–oxygen binding energy of the support metal oxides

The effect of a wide variety of metal oxide (MOx) supports has been discussed for CO oxidation on nanoparticulate gold catalysts. By using typical co-precipitation and deposition–precipitation methods and under identical calcination conditions, supported gold catalysts were prepared on a wide variety of MOx supports, and the temperature for 50% conversion was measured to qualitatively evaluate the catalytic activities of these simple MOx and supported Au catalysts. Furthermore, the difference in these temperatures for the simple MOx compared to the supported Au catalysts is plotted against the metal–oxygen binding energies of the support MOx. A clear volcano-like correlation between the temperature difference and the metal–oxygen binding energies is observed. This correlation suggests that the use of MOx with appropriate metal–oxygen binding energies (300–500 kJ/atom O) greatly improves the catalytic activity of MOx by the deposition of Au NPs.