Catalysts For Oxidation Of Carbon Monoxide Research Articles

Effect of surface acidity modulation on Pt/Al2O3 single atom catalyst for carbon monoxide oxidation and methanol decomposition

With ideal metal utilization efficiency and homogeneous active sites, single atom catalysts (SACs) have attracted extensive attention in heterogeneous catalysis field. The performance of SACs is highly dependent on the local coordination environment of metal single atoms. However, few works reported the effect of surface acidity modification on the performance of SACs such as Pt SACs which have been widely studied nowadays. In this work, a Pt/Al2O3 SAC has been successfully prepared using a bayerite Al(OH)3 as support through simple IWI method for Pt loading. Through post-modification of Pt/Al2O3 with acidic WO3 and basic MgO, the surface acidity of Pt/Al2O3 was tuned. Activity of CO oxidation and methanol decomposition on the modified catalysts has been evaluated. It was found that the catalytic performance was highly related to the surface acidity of Pt SACs. Basic MgO modified Pt/Al2O3 performed better in CO oxidation under the reaction condition with H2O. Acidic WO3 modified Pt/Al2O3 showed superior activity in methanol decomposition. Detailed characterization and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) study suggested that the positive H2O effect on CO oxidation was due to the mitigated formation of bicarbonate species on Pt/Al2O3 and WO3/Pt/Al2O3 catalysts and the promoted desorption of carbonate species from MgO/Pt/Al2O3. The superior methanol decomposition performance on WO3/Pt/Al2O3 was owing to its abundant oxygen vacancies and high resistance to carbonate accumulation. This study highlights the importance of surface acidity modulation of Pt SACs in heterogeneous catalysis and suggests that fine-tuning the surface acidity can be an effective strategy in new SACs development.

Co Anchored B36 Cluster as a Novel Single Atom Catalyst for Removing Toxic CO Molecules: A Mechanistic First‐Principles Study

AbstractThe catalytic oxidation of toxic carbon monoxide (CO) into carbon dioxide (CO2) is one of the most significant reactions in heterogeneous catalysis and industrial chemistry. Hence, finding efficient and cost‐effective catalysts for CO oxidation is very critical. In this study, the electronic and catalytic properties of a Co atom incorporated B36 cluster (Co@B36) are investigated by means of first‐principles calculations. The results show that the Co atom can seriously tune the properties of the B36 cluster due to significant hybridization between the 3d states of the Co atom and the B‐2p states of the surrounding B atoms. This induces a significant positive charge on the Co atom, providing an active site for O2 and CO molecules to attack. Furthermore, the well‐known mechanisms for CO oxidation, namely the Eley‐Rideal (ER), Langmuir‐Hinshelwood (LH), termolecular Eley‐Rideal (TER), and new Eley‐Rideal (NER), are taken into account in this work. According to our findings, the LH and TER mechanisms are the most energetically efficient routes for CO oxidation; however, the favored mechanism may be depending on the relative concentrations of CO and O2 molecules in the reaction mixture. The obtained activation energies through the TER and LH mechanisms are also comparable with those reported on noble metals. The findings of this work might help in the design and manufacture of noble‐metal free single atom catalysts for the removal of harmful CO molecules from the environment.

Structure-activity relationship of Pt catalyst on engineered ceria-alumina support for CO oxidation

In heterogeneous catalysis, the promotion of low temperature activity and enhancement of thermal stability simultaneously especially for precious metal catalysts is always highly demanded but very challenging. Herein we report a novel Pt catalyst on ceria-alumina (CeO2/Al2O3) support (Pt/CA-T) engineered by a two-step ceria deposition strategy, exhibiting superior thermal stability and low-temperature carbon monoxide (CO) oxidation activity after activation. Pt single sites anchored to engineered CeO2 edge sites are much more stable than that to CeO2 (111) surface, and such stable single sites can be transformed into highly active Pt clusters for efficient low-temperature CO oxidation. Active site identification indicates that the CO oxidation activity of different Pt sites follows such sequence: Pt cluster step sites ≈ Pt cluster terrace sites > Pt cluster corner sites ≫ Pt single sites on CeO2. The excellent low temperature activity of activated Pt/CA-T catalyst for CO oxidation is associated with its abundant Pt cluster step and terrace sites as well as rich Pt-CeO2 interfaces, which facilitate the adsorption of active CO species and superior oxygen activation/transfer ability. The present study provides new insights into the structure–activity relationship of Pt-CeO2-Al2O3 catalyst, which can also guide the preparation of other highly robust supported catalysts for important industrial applications.

Cooperative effect between copper species and oxygen vacancy in Ce0.7−xZrxCu0.3O2 catalysts for carbon monoxide oxidation

Cooperative effect between copper species and oxygen vacancy in Ce0.7−xZrxCu0.3O2 catalysts for carbon monoxide oxidation

Influence the performances of hopcalite catalysts by the addition of gold nanoparticle for low temperature CO oxidation

The catalytic conversion of carbon monoxide (CO) into carbon dioxide (CO 2 ) at a low temperature is very important procedure for all living beings present in the environment. The present study represents that the addition of gold (Au) nano-particles, by the deposition-precipitation method into the hopcalite (CuMnOx) catalyst has been improving their performances for CO oxidation. The CuMnOx catalyst loading by 0.75 wt% Au was representing that the best catalytic activity for CO oxidation than the other catalysts loading by 0.25, 0.5 and 1 wt% Au. The small amount of Au doping (0.75 wt%) in CuMnOx catalyst improves their performances for CO oxidation at an ambient conditions. The gold nano-particles will be introducing the new active sites into the CuMnOx catalyst surfaces and decreases the deactivation of catalyst. The lattice oxygen movement was a major important factor which can influences the performances of hopcalite catalyst for CO oxidation. The calcinations strategies (reactive calcinations and traditional calcinations) of the precursor have huge impacts on the performances of resulting catalysts. The reusability of Au promoted CuMnOx catalyst was also measured and found that this catalyst does not have any major changes in its catalytic performances still after the reuses.

Facile synthesis strategy for the development of carbon fiber cloth supported palladium catalyst from spent Pd catalyst for low-temperature CO oxidation

Metal supported catalysts are well-known for the effective conversion of carbon monoxide. Among different support materials that are generally employed, activated carbon-based materials are important because of their well-developed structural characteristics. This paper investigates the development of palladium (Pd) catalyst supported on activated carbon fiber cloth (CFC) as a potential scalable material for mitigation of environmental pollution by studying its carbon monoxide (CO) removal efficiency under ambient conditions. As a Pd source, the deactivated Pd/C catalyst was employed for the development of the Pd/CFC catalyst. Palladium was reduced using reducing agents of different reduction potential, i.e. , sodium borohydride and formaldehyde. The catalysts were characterized using atomic absorption spectrometry, scanning electron microscopy, energy dispersive X-ray spectrometry, X-ray powder diffraction, BET surface area analyzer, temperature-programmed reduction and desorption, X-ray photoelectron spectroscopy, H 2 chemisorption followed by CO efficiency studies. It was observed that the microporous nature of activated CFC affects the surface metal concentration of Pd 0 and Pd +2 and accordingly, the CO conversion activity. The study involves testing the dependency of moisture towards the catalyst and noticed that a higher moisture level causes a reduction in the CO conversion efficiency due to pore blockage. • Carbon Monoxide removal studies using Palladium impregnated activated carbon fiber cloth (Pd/CFC) was conducted. • A spent Pd/C catalyst was re-used as a metal precursor for catalyst preparation to make the process economically viable. • The Pd/CFC catalyst was prepared by incipient wetness impregnation method followed by liquid media reduction. • The effect of different reducing agents on the efficacy of cloth catalyst was studied. • The structural characteristics of Pd/CFC catalysts and its dependency on moisture for the catalytic activity was studied.

CO Oxidation at Near-Ambient Temperatures over TiO2-Supported Pd-Cu Catalysts: Promoting Effect of Pd-Cu Nanointerface and TiO2 Morphology.

Significant improvement of the catalytic activity of palladium-based catalysts toward carbon monoxide (CO) oxidation reaction has been achieved through alloying and using different support materials. This work demonstrates the promoting effects of the nanointerface and the morphological features of the support on the CO oxidation reaction using a Pd-Cu/TiO2 catalyst. Pd-Cu catalysts supported on TiO2 were synthesized with wet chemical approaches and their catalytic activities for CO oxidation reaction were evaluated. The physicochemical properties of the prepared catalysts were studied using standard characterization tools including SEM, EDX, XRD, XPS, and Raman. The effects of the nanointerface between Pd and Cu and the morphology of the TiO2 support were investigated using three different-shaped TiO2 nanoparticles, namely spheres, nanotubes, and nanowires. The Pd catalysts that are modified through nanointerfacing with Cu and supported on TiO2 nanowires demonstrated the highest CO oxidation rates, reaching 100% CO conversion at temperature regime down to near-ambient temperatures of ~45 °C, compared to 70 °C and 150 °C in the case of pure Pd and pure Cu counterpart catalysts on the same support, respectively. The optimized Pd-Cu/TiO2 nanowires nanostructured system could serve as efficient and durable catalyst for CO oxidation at near-ambient temperature.

Synthesis of CuMnOx catalysts by using various precipitants for oxidation of carbon monoxide

Hopcalite (CuMnOx) is one of the best catalysts for carbon monoxide (CO) oxidation at ambient conditions. In present research work we measured the performances of various precipitants (KMnO 4 , Na 2 CO 3 and KOH) used in the CuMnOx catalysts synthesis by the co-precipitation method and calcined at 300°C temperature. The KMnO 4 precipitant used in CuMnOx catalyst has shown that the best catalytic activity, which completely oxidized CO at the lower temperature (T 100 = 83°C). The other precipitants used in CuMnOx catalyst synthesis by Na 2 CO 3 as precipitant for CO oxidation was done at (T 100 =105°C) and KOH used as precipitant in CuMnOx catalyst, which completely oxidized CO (T 100 =115°C). The calcinations conditions of precursors have huge impact on the performances of resulting catalysts for CO oxidation. The reactive calcinations (RC) conditions (1.5% CO in air) prepared CuMnOx catalysts have shown that the best catalytic activity as compared to the tradition calcinations conditions. The RC route is one of the best calcinations strategies for preparation of highly active CuMnO x catalyst for CO oxidation. • The choice of precipitant in precursor has significant effect in the designing of most suitable catalyst. • The KMnO 4 is one of the best precipitant for synthesis of highly active CuMnOx catalyst. • The reactive calcinations condition is produced highly active CuMnOx catalyst for CO oxidation.

To optimized various parameters of Hopcalite catalysts in the synthetic processes for low temperature CO oxidation

Carbon monoxide (CO) is very poisonous gasses present in the atmosphere and lower temperature complete oxidation of CO is very important processes for all life support. The automobile vehicles exhaust is one of the major sources of CO produced into the environment. The application of catalytic converter in automobile vehicles reduces the toxic gasses emission. There are lots of catalysts used in the catalytic converter for CO oxidation purposes among these catalysts the Hopcalite (CuMnOx) is one of the oldest and best-known catalysts for low temperature CO oxidation. The hopcalite catalyst is prepared by the co-precipitation method and preparation parameters like magnetic shaker shaking speed, shaking time, shaking temperature and pH has an influence on the activity of resultant catalysts. The activity of catalyst was measured in reactive calcinations (RC) conditions at the presence of (1.5% CO) and air. The reaction temperature was increased from room temperature to higher temperature at which the total oxidation of CO was achieved. The characterizations of catalysts are done by several techniques like XRD, FTIR, BET and SEM-EDX. These results are interpreted in terms of structure the active catalyst. The reusability of CuMnOx catalyst was also tested and also found that this catalyst does not show any high level of significant change in its catalytic performances even after reuses.

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.

Synthesis and Properties of a Carbon Monoxide Oxidation Catalyst Based on Plasma-Chemical Titanium Carbonitride, Titanium Dioxide, and Palladium

A CO oxidation catalyst based on plasma-chemical titanium carbonitride TiC0.2N0.8 and TiO2 with a palladium content of 10 wt % has been synthesized. The dependence of the reaction rate of CO oxidation at room temperature and low CO concentrations (<100 mg/m3) on the TiC0.2N0.8 content has been studied. It has been found that, at TiC0.2N0.8 concentrations from 8 to 10 wt %, the catalyst exhibited a maximum rate of the CO oxidation reaction, which was 2.5 times higher than the rate of reaction on a catalyst based on pure TiO2 that included palladium clusters. The catalysts are promising for use in catalytic and photocatalytic systems for air purification.

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.

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.

Development of novel nano-hydroxyapatite doped with silver as effective catalysts for carbon monoxide oxidation

A series of novel silver-containing catalysts were synthesized, characterized by X-ray diffraction, infrared spectroscopy, scanning and transmission electron microscopy, N2 adsorption-desorption isotherms, thermogravimetric analysis and then tested for the oxidation of carbon monoxide (CO). The microwave-hydrothermal method was a useful synthesis pathway to structurally incorporate low amounts of silver (2.5–5.0 atomic percentage) to hydroxyapatite (HA) lattice, preserving the crystalline structure of the HA. Specific surface area and particle size (diameter) of the obtained materials were about 52–55 m2/g and 19–47 nm, respectively. Silver-catalysts showed higher catalytic activities than the unmodified HA sample at temperatures between 600 and 850 °C. The best catalytic results were achieved at around 700–800 °C with silver-containing HA samples. However, due to the significant decrease in the crystallinity of the materials exposed to 800 °C; then, 700 °C was established as the best thermal condition for producing CO2 and preserving the HA crystalline structure.Furthermore, cyclic tests demonstrated that silver-containing HA catalysts perform CO oxidation for 3 h through several consecutive catalytic tests at 700 °C without losing neither their activity nor their structural properties, evidencing their high thermal stability under the CO-O2 atmosphere. Thus, the highest reaction rate values (rCO2) were obtained with HA containing 2.5% of silver at 700 °C during the five cycles performed, positioning it as a promissory catalyst with high activity during the CO oxidation at high temperatures. The proposed reaction mechanism was established using these silver-doped materials. This work constitutes the first assessment to add low amounts of silver to increase the activity of this kind of catalytic materials for the CO oxidation reaction.

Synthesis and applications of titanium oxide catalysts for lower temperature CO oxidation

Carbon monoxide (CO) is one of the very poisonous gasses and major sources of CO produced into the environment by the automobile vehicles exhaust. There are various types of catalysts have been used in the catalytic converter for CO oxidation. The titanium dioxide (TiO2) is one of the best transitional metal oxides catalysts for lower temperature CO oxidation. A small amount of TiO2 was deposited on the mesoporous Al2O3 using atomic layer deposition and subsequent oxidation at the different temperatures. The lightly reduced support improves the high catalytic activity of the adparticles, a strongly reduced one quenches the CO oxidation. The quenching is due to thermally activated diffusion of Ti3+ interstitials from the bulk to the surface where they deplete the oxygen adsorbed onto the clusters by the formation of TiOx (x ​≃ ​2) structures. The additions of promoters and support in titanium oxide catalysts improved their performances and reduced their stability. The bulk reduction state of TiO2 strongly affects the catalytic activity of supported metal clusters in the chemical reactions between oxygen and other molecules. The certain attention has been paid on the recovery of TiO2 catalysts from reaction systems and their reuse for various times without losses of catalytic activity in CO oxidation. This investigation will shown scientific basis for potential design of Ti-oxide nano-particle catalysts for lower temperature CO oxidation.

Applications of Rhodium and Ruthenium Catalysts for CO Oxidation: an Overview

The rhodium (Rh) and ruthenium (Ru) are very important catalytic materials in various oxidation reactions. It is the best monometallic catalyst for oxidation of carbon monoxide (CO) and practically used in residential catalytic converters. These catalysts are active for CO oxidation at a low temperature. The activity of Ru/Rh catalysts is strongly dependent on the surface area, pore volume and textural properties of designed catalysts. It could be used as an ideal candidate not only for automobile industry through the cross-coupling reactions but also for low-temperature catalytic oxidation of CO. The chemisorptions of CO over Ru/Rh catalysts and supported catalysts were studied in this review. These studies will provide the scientific basis for future design of Ru/Rh oxidation catalysts. Both Ru and Rh are minor metals and supply risk often increases the price. However, the performance improved and cost-reduced nanoparticles of Rh/Ru system are reviewed by this work.

Ceria doped CuMnOx as carbon monoxide oxidation catalysts: Synthesis and their characterization

The CuMnOx and ceria doped CuMnOx catalysts (with ceria loadings in the range 0.5–3 wt.%)were synthesized by using the Co-precipitation method and characterized by various methods as discussed in the manuscript. Carbon monoxide (CO) is an individual one of the most toxic gases presents in the atmosphere and ambient-temperature complete oxidation of it is an important process for human health protection. According to the results, Ceria was doped successfully into the CuMnOx catalyst lattice. The better catalytic activity was observed 2.50 wt.% of ceria doping in the CuMnOx catalyst was found. The calcinations strategies (reactive calcinations and traditional calcinations) of the precursor have a huge impact on the activity of resulting catalysts. The presence of more number of oxygen vacancies and high specific surface area in ceria promoted CuMnOx catalyst to design highly active catalyst. The reusability of ceria doped CuMnOx catalyst was also tested and observed that this catalyst does not show any high level of major changes in its catalytic activity even after reuses.

Room temperature blooming of CeO2 3D nanoflowers under sonication and catalytic efficacy towards CO conversion.

Carbon monoxide (CO), being a highly toxic gas, bears hazardous effects on human health and contributes majorly to environmental pollution. It is mostly produced by automobile exhausts and incomplete combustion of carbon-containing substances. Thus, the development of catalysts for CO conversion is highly imperative and has always gained interest for real field applications. Besides the high oxygen storage capacity and facile transitions between oxidation states, the huge abundance of cerium on earth makes CeO2 a low-cost and highly effective alternative to noble metal catalysts for CO oxidation. The present work delineates the room temperature synthesis of flower-shaped 3D CeO2 nanostructures using a sonication-assisted simple synthesis method within 2 hours under the pivotal importance of a structure-directing agent, polyvinylpyrrolidone (PVP). The bifunctional contributions of PVP as a surfactant and as a capping agent are discussed with a plausible mechanism. The method leading to the formation of hierarchical CeO2 nanoflowers provides an appreciable surface area of 132.69 cm2 g−1. The morphological and structural characterizations of the catalyst were thoroughly investigated using FESEM, TEM, XRD, UV-visible spectroscopy, photoluminescence spectroscopy, FTIR spectroscopy and X-ray photoelectron spectroscopy. The structural efficacies of flower-like CeO2 nanostructures have also been correlated to the narrowing of the band gap and the generation of the corresponding oxygen vacancies, resulting in surface catalytic properties towards 80% conversion of CO.

Design of Ceria Catalysts for Low‐Temperature CO Oxidation

AbstractA catalyst active to carbon monoxide (CO) oxidation at low temperature is essential for environmental conservation, saving fuel and improvement of the quality of human life. Rational design of CO oxidation catalyst on the basis of comprehensive understanding of physicochemical properties of catalytic materials, rather than simply searching for the catalyst based on trial‐and‐error, is a promising approach to meet the increasingly stringent regulations. This review covers metal‐doped and ‐loaded system based on CeO2 catalysts as strategies to significantly improve CO oxidation activity at low temperature. When incorporated into CeO2 lattice, active metals significantly lower the oxygen vacancy formation energy (Evf) of the catalyst surface, resulting in high catalytic activities at low temperature. When the active metals are loaded on the CeO2 surface, many active sites could be acquired by increasing the dispersion, and the catalytic activity can be dramatically improved by newly introducing the interfacial sites between the metals and the CeO2 support. Doping the support could further improve this loaded system in terms of specific surface area, oxygen vacancy formation, and spillover effects. In this review, based on this knowledge, we propose a rational design approach to a robust low‐temperature CO oxidation catalysts. The desirable CO oxidation catalysts identified from the interplay between theoretical and experimental approaches would ultimately improve the quality of human life, and create potential economic benefits by alleviating air pollution.

Advances in transition metal oxide catalysts for carbon monoxide oxidation: a review

The transition metal catalysts have much concerned over the last two to three decades due to their different properties from their bulk-counterparts, which cover the way for their application in various fields. It has shown superior efficiency in selectivity, performances, and stability to the heterogeneous catalysis. Carbon monoxide (CO) is a very harmful gas that exists in the atmosphere and ambient-temperature complete oxidation of it is an important process for human health protection. The performances of transition metal catalysts are highly dependent on the crystallite size, surface area, and pore volume of the catalysts. The chemisorptions of CO over transitional metal and supported catalysts were studied in this review. The transition metal catalysts have been represented an excellent catalyst from lower cost, thermally, activity, and selectivity point of view. This investigation will show scientific basis for potential design of transition metal oxide catalysts for CO oxidation.