Ability Of CO Research Articles

Cover Feature: In Situ Diffraction of Fischer–Tropsch Catalysts: Cobalt Reduction and Carbide Formation (ChemCatChem 18/2017)

The Cover shows the transition of face centered cubic to hexagonal packed cobalt via the carbide intermediate on a catalyst support. Control of the cobalt structure is vital for Fischer–Tropsch chemistry, which is a highly significant reaction in industry for the gas to liquids fuels process.In their Full Paper, J. Paterson et al. demonstrate the transition to the more active hexagonal phase using in situ X-ray diffraction and present the catalysis results supporting it. Moreover, the effect of CO is studied, showing the effect of partial pressures between 0 and 10 bar, the facile removal under hydrogen and the ability of CO to complete the full reduction of the cobalt oxide precursor. Future catalyst and process designs may benefit from these mechanistic insights, leading to improved performance, greater activity and enhanced selectivity. More information can be found in the Full Paper by J. Paterson et al. on page 3463 in Issue 18, 2017 (DOI: 10.1002/cctc.201700754).

Prussian Blue Analogues for the Separation of Hydrocarbons in Humid Conditions

The relative affinity of a series of Prussian Blue analogues presenting various chemical compositions for the adsorption of different gases, such as water vapor and hydrocarbons, was studied. The ability of Co[CoIII(CN)6]0.66·5.2H2O for the separation of hydrocarbons in a humid atmosphere was demonstrated.

Reactivity Study of Unsymmetrical β-Diketiminato Copper(I) Complexes: Effect of the Chelating Ring.

β-Diketiminato copper(I) complexes play important roles in bioinspired catalytic chemistry and in applications to the materials industry. However, it has been observed that these complexes are very susceptible to disproportionation. Coordinating solvents or Lewis bases are typically used to prevent disproportionation and to block the coordination sites of the copper(I) center from further decomposition. Here, we incorporate this coordination protection directly into the molecule in order to increase the stability and reactivity of these complexes and to discover new copper(I) binding motifs. Here we describe the synthesis, structural characterization, and reactivity of a series of unsymmetrical N-aryl-N'-alkylpyridyl β-diketiminato copper(I) complexes and discuss the structures and reactivity of these complexes with respect to the length of the pyridyl arm. All of the aforementioned unsymmetrical ß-diketiminato copper(I) complexes bind CO reversibly and are stable to disproportionation. The binding ability of CO and the rate of pyridyl ligand decoordination of these copper(I) complexes are directly related to the competition between the degree of puckering of the chelate system and the steric demands of the N-aryl substituent.

Promotion effect of palladium on Co3O4 incorporated within mesoporous MCM-41 silica for CO Oxidation

Co3O4 incorporated within mesoporous MCM-41 silica have been successfully synthesized and promoted with Pd nanoparticles through a microwave irradiation (MWI) approach. Powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), N2-physisorped, X-ray photoelectron spectroscopy (XPS), temperature program reduction of hydrogen (H2-TPR), temperature program desorption of oxygen (O2-TPD) and high resolution transmission electron microscopy (HRTEM) were adapted to characterize these prepared catalysts. Carbon monoxide oxidation as a model reaction was then used to assess the catalytic performance of these materials. In the light of H2-TPR and XPS results, revealed that the coexisting of Co3+ and Co2+ species as well as surface Co3+/Co2+ ratio within the hexagonal mesoporous of MCM-41, could create an ideal environment to accomplish most extreme catalytic activity. On the other hand, the enhanced CO oxidation by Pd nanoparticles deposition has been explained in the light of the enhancement of the redox ability and tuning the electronic structure of Co3O4, which improved the O2 activation and reduced the adsorption ability of CO simultaneously, which significantly boosted the catalytic performance of CO oxidation. This work provides insights into factors that could lead to improved low temperature CO oxidation performance in Pd-based catalysts.

Virus-directed formation of electrocatalytically active nanoparticle-based Co3O4 tubes.

Spinel-type Co3O4 finds applications in a wide range of fields, including clean energy conversion, where nanostructured Co3O4 may provide a cost-efficient alternative to platinum- and iridium-based catalysts for electrocatalytic water-splitting. We here describe a novel strategy in which basic cobalt carbonate - a precursor to Co3O4 - is precipitated as sheet-like structures and microspheres covered with fine surface protrusions, via ammonium carbonate decomposition at room temperature. Importantly, these mild reaction conditions enable us to employ bio-inspired templating approaches to further control the mineral structure. Rod-like tobacco mosaic viruses (TMV) were used as biotemplates for mineral deposition, where we profit from the ability of Co(ii) ions to mediate the ordered assembly of the virus nanorods to create complex tubular superstructures of TMV/ basic cobalt carbonate. Calcination of these tubules is then achieved with retention of the gross morphology, and generates a hierarchically-structured solid comprising interconnected Co3O4 nanoparticles. Evaluation of these Co3O4 materials as electrocatalysts for the oxygen evolution reaction (OER) demonstrates that the activity of Co3O4 prepared by calcination of ammonia diffusion-grown precursors in both, the absence or presence of TMV exceeds that of a commercial nanopowder.

Remediation of waste water by Co–Fe layered double hydroxide and its catalytic activity

Abstract Layered double hydroxide (LDH) nanoparticles have tremendous anion-intercalating property. Co–Fe LDH has been synthesized using the ball milling method. Characterization of Co–Fe LDH was done by XRD, SEM, TEM and FT-IR. The prepared LDH was used, for the first time, as a catalyst for multi-walled carbon nanotubes (MWCNTs) via chemical vapor deposition (CVD) of acetylene at different temperatures (400–700 °C). Also, the ability of Co–Fe LDH as an adsorbent was investigated for the removal of Cd2+ ions from aqueous solutions. Various physicoechemical parameters such as pH, initial metal ion concentration, and time were studied. To get the adsorption isotherms, the concentrations of the metal ions ranging from 6 to 18 mg/l were used. The adsorption process follows pseudo-second-order reaction kinetics, as well as Langmuir adsorption isotherms. Interestingly, Co–Fe LDH demonstrated 95% Cd2+ removal at pH 9 and 6 h which could be applied in wastewater treatment characterized by a high efficiency and low cost.

Tool wear in disk milling grooving of titanium alloy

The work efficiency of grooving machining can be improved by the approach of disk milling. However, the problem of tool wear was serious because of big milling force and high milling temperature in manufacture process, by which the tool life and the machined surface quality were influenced. In this study, disk-milling grooving experiments of titanium alloy were designed and conducted. First, milling force and milling temperature were examined, which provided theory basis to tool wear. Then, the tool life, wear patterns, and its corresponding mechanisms were investigated in detail through scanning electron microscope observation, X-ray energy-dispersive spectrometer, and automatic tool analyzer. By analyzing experimental results, it was found that, for an example of five-stage compressor blisk of a certain type aircraft engine, disk cutter can only remove about 50 tunnels’ volume after five times grinding before wear-out failure, the tool life still needs to be greatly enhanced. The damage morphologies were delamination, thermal fatigue crack, plastic deformation, and tipping. Wear mechanisms were the synergistic interaction among adhesion wear, oxidation wear, and diffusion wear. Thermal crack and tipping were easily found for the cutting edges around the keyway. The oxidation degree of major cutting edge was higher than minor cutting edge; rake face was severe compared to flank face. The element W easily diffused into the titanium alloy, the diffusion ability of Co and C were weaker than W, and the element Ti was dead in diffusion process.

Effect of temperature on the removal of cobalt by Friedel´s salt

The performance of Friedel’s salt (FS: 3CaO·Al2O3·CaCl2·10H2O), a layered double hydroxide (LDHs), as an adsorbent for cobalt (Co2+) removal from its solution was investigated. Friedel’s salt was synthesized by reaction of tricalcium aluminate with calcium chloride. The stability of FS at different pHs was studied. Also, the adsorption behaviors of Friedel’s salt for cobalt (Co2+) from its solution at different concentrations and pH=4 at room temperature and 50oC was examined. The results showed that, high stability for FS in neutral medium (pH=6) than in basic (pH=8) and acidic medium (pH=4). In addition, the results indicated that the adsorbent FS had an outstanding ability for Co(II) adsorption. The maximum adsorption capacity of the FS for Co (II) removal can reach to 1903.44 mg/g. Furthermore, the increase in the temperature (50o C) effect positively on the rate of adsorption.

Co and Ni extraction and separation in segmented micro-flow using a coiled flow inverter

The segmented micro-flow extraction and separation of the adjacent elements of Co from Ni sulphate solution with Cyanex 272 is developed using a micro-scale coiled flow inverter (CFI). This is compared with the conventional batch extraction in parallel. Continuous operation of a process involving liquid-liquid extraction and then two-phase separation is achieved instantly. For the latter a micro-scale separator is used. Compared with batch extraction, the segmented micro-flow extraction process shows order-of-magnitude faster extraction times, higher extraction ability for Co, lower extraction for Ni, and then a better selectivity between Co and Ni at industrial-matching concentration. Regular columnar slugs are observed at low flow rates and found to be a Gaussian function of the flow rates. Matched in- and outlet flows indicates that extraction in micro-flow is dependent on mass transfer by molecular diffusion. Extraction efficiency is enhanced by the internal circulation flow generated within slugs. Additionally, the characteristic parameters, overall volumetric mass transfer coefficient kLα and overall mass transfer coefficient kL, are measured to determine the mass transfer performance. Compared with batch, much higher kLα of Co (0.26–0.017s−1) and smaller of Ni (0.053–0.013s−1) are investigated in CFI. Meanwhile, 4.5 times increasement of the kL value of Co to Ni is observed in CFI indicating the asynchronous extraction between Co and Ni.

Design of a Gas Sensor Transducer Circuitry With Calibration Ability for CO2 Concentration Detection

In this paper, a gas sensor and the proposed calibration chip are presented. For this paper, a commercially available MG811 CO2 gas sensor is used. The output of the CO2 gas sensor was inputted to the proposed chip, and the output signal of the chip is a pulse stream with its frequency corresponding to gas concentration. All functions of the CO2 gas sensor and the proposed chip have been validated experimentally. After calibration, the concentration range of 426–1359 ppm corresponded to the output frequency range of 285–242 kHz. The measured maximum frequency error was 1.3%.

Dual stimulation of antigen presenting cells using carbon nanotube-based vaccine delivery system for cancer immunotherapy.

Although anti−cancer immuno−based combinatorial therapeutic approaches have shown promising results, efficient tumour eradication demands further intensification of anti−tumour immune response. With the emerging field of nanovaccinology, multi−walled carbon nanotubes (MWNTs) have manifested prominent potentials as tumour antigen nanocarriers. Nevertheless, the utilization of MWNTs in co−delivering antigen along with different types of immunoadjuvants to antigen presenting cells (APCs) has not been investigated yet. We hypothesized that harnessing MWNT for concurrent delivery of cytosine−phosphate−guanine oligodeoxynucleotide (CpG) and anti-CD40 Ig (αCD40), as immunoadjuvants, along with the model antigen ovalbumin (OVA) could potentiate immune response induced against OVA−expressing tumour cells. We initially investigated the effective method to co−deliver OVA and CpG using MWNT to the APC. Covalent conjugation of OVA and CpG prior to loading onto MWNTs markedly augmented the CpG−mediated adjuvanticity, as demonstrated by the significantly increased OVA−specific T cell responses in vitro and in C57BL/6 mice. αCD40 was then included as a second immunoadjuvant to further intensify the immune response. Immune response elicited in vitro and in vivo by OVA, CpG and αCD40 was significantly potentiated by their co−incorporation onto the MWNTs. Furthermore, MWNT remarkably improved the ability of co−loaded OVA, CpG and αCD40 in inhibiting the growth of OVA−expressing B16F10 melanoma cells in subcutaneous or lung pseudo−metastatic tumour models. Therefore, this study suggests that the utilization of MWNTs for the co−delivery of tumour−derived antigen, CpG and αCD40 could be a competent approach for efficient tumours eradication.

Synergistic Effects in Nanoengineered HNb3O8/Graphene Hybrids with Improved Photocatalytic Conversion Ability of CO2 into Renewable Fuels.

Layered HNb3O8/graphene hybrids with numerous heterogeneous interfaces and hierarchical pores were fabricated via the reorganization of exfoliated HNb3O8 nanosheets with graphene nanosheets (GNs). Numerous interfaces and pores were created by the alternative stacking of HNb3O8 nanosheets with limited size and GNs with a buckling and folding feature. The photocatalytic conversation of CO2 into renewable fuels by optimized HNb3O8/G hybrids yields 8.0-fold improvements in CO evolution amounts than that of commercial P25 and 8.6-fold improvements than that of HNb3O8 bulk powders. The investigation on the relationships between microstructures and improved photocatalytic performance demonstrates that the improved photocatalytic performance is attributed to the exotic synergistic effects via the combination of enhanced specific BET surface area, increased strong acid sites and strong acid amounts, narrowed band gap energy, depressed electron-hole recombination rate, and heterogeneous interfaces.

Citrate Effect on Reaction Kinetics of Pt Deposition on Pd(hkl) Via Surface Limited Redox Replacement of Cu UPD Monolayer

The effect of citrate ions in reaction solution on reaction kinetics of Pt deposition on Pd via SLRR of Cu UPD monolayer has been studied[i]. Experiments involving both, single crystal Pd and Pd-nanoparticle substrates were performed. The results suggest that citrate has a suppressive role on Pt deposition kinetics which is manifested through the zero order reaction kinetics during red-ox process[ii]. The citrate adsorbed phase on Pd surface has mainly transport hindering role for upcoming Pt ions. The IR data suggest that Pt monolayers produced from citrate containing electrolyte have weaker electrosorption ability for CO than bulk Pt and Pd. This information should be useful in further application of citrates as reactant and additive for Pt deposition via SLRR which can be used to fine tune Pt monolayer reactivity on different substrates[iii]. The reaction kinetics model was developed to analyze our kinetics data where the citrate effect was described as an extra barrier for the Pt ion transport. The model is capable of predicting the reaction rate constants from known concentrations of the citrate and platinum ions in the solution using only two model parameters, X and B3. Both parameters have the real physical meaning which could be directly visualized as the additional diffusion path for Pt ions due to the presence of adsorbed citrate layer on CuUPD/Pd-NP surface. The analytical work could be further applied in design and development of more sophisticated apparatus for Pt-shell Pd-core catalyst synthesis. This aspects will be discuss in the conclusion of the talk. The authors acknowledge the private funding of this work and the support from NSF Chemistry division under the contract # 0955922.

Calcium silicates synthesised from industrial residues with the ability for CO2 sequestration.

This work explored several synthesis routes to obtain calcium silicates from different calcium-rich and silica-rich industrial residues. Larnite, wollastonite and calcium silicate chloride were successfully synthesised with moderate heat treatments below standard temperatures. These procedures help to not only conserve natural resources, but also to reduce the energy requirements and CO2 emissions. In addition, these silicates have been successfully tested as carbon dioxide sequesters, to enhance the viability of CO2 mineral sequestration technologies using calcium-rich industrial by-products as sequestration agents. Two different carbon sequestration experiments were performed under ambient conditions. Static experiments revealed carbonation efficiencies close to 100% and real-time resolved experiments characterised the dynamic behaviour and ability of these samples to reduce the CO2 concentration within a mixture of gases. The CO2 concentration was reduced up to 70%, with a carbon fixation dynamic ratio of 3.2 mg CO2 per g of sequestration agent and minute. Our results confirm the suitability of the proposed synthesis routes to synthesise different calcium silicates recycling industrial residues, being therefore energetically more efficient and environmentally friendly procedures for the cement industry.

Density Functional Theory study of electric field effects on CO and OH adsorption and co-adsorption on gold surfaces

A Density Functional Theory (DFT) study of CO and OH adsorption on Au(111) and Au(110) surfaces is presented. The analysis includes the effect of an external negative electric field on adsorption characteristics such as binding energies, binding geometries, charge distribution and vibrational frequencies, both on CO and OH individually and in co-adsorbed geometries. The minimal energy pathways for COOH formation from CO and OH co-adsorbed on Au(111) and Au(110) were also calculated. The ability of CO to enhance the adsorption of OH on gold is discussed in relation to the surface structure of gold and changes in the work function as induced by the adsorption of CO.

Lighting up Carbon Monoxide: Fluorescent Probes for Monitoring CO in Living Cells

All aglow: Both a fluorescent biosensor, composed of a circularly permuted yellow fluorescent protein (cpYFP), and a small-molecule fluorescent probe (1) for the detection of CO in living cells have been recently reported. Though different these novel probes were designed based on the unique binding ability of CO to transition-metal ions.

Oxidation Ability of CO2 for the Transformation of Cinnamic Aldehydes to Acids Catalyzed by N‐Heterocyclic Carbene: Combining Computational and Experimental Studies

AbstractThe mechanism of the CO2 splitting reaction with N‐heterocyclic carbene (NHC) as a catalyst and cinnamic aldehydes as the oxygen acceptor was thoroughly investigated at the B3LYP/6‐31G(d,p) level. Owing to its nucleophilicity, NHC can initiate the reaction through two distinct channels (I and II) by nucleophilic attack. The results reveal that without the assistance by H2O, channel II is slightly more favorable than channel I, and the reaction path II‐D is the optimum reaction path. However, the reaction is difficult to conduct at room temperature because of its high activation energy barrier. Although the results suggest that most of the high activation energy barriers involved in proton transfer decrease if the reaction is assisted by H2O, all highest energy barriers for all reaction channels are still above 40 kcal mol−1. This indicates that this reaction cannot be performed at room temperature, which is also proven by experiments.

The contamination and transfer of potentially toxic elements and their relations with iron, vanadium and titanium in the soil-rice system from Suzhou region, China

A regional scale investigation was performed to study the contamination and transfer of Ni, Cr, Co, Al, Cd and Hg and their relations with Fe, V and Ti in the soil-rice system under actual field conditions from a typical developed industrial area. Thirty-two pairs of rice and soil samples were collected in Suzhou region, China. The results show that the transfer abilities of potentially toxic elements (PTEs) were generally in the order of Cd > Hg > Co > Ni > Cr > Al from soil to root, Hg > Cr > Al > Ni > Cd > Co from root to straw and Ni > Hg > Cr > Cd > Al > Co from straw to grain. Compared with the relevant criterion, the major pollutants in rice grains were Al and Ni. 18.8 and 12.5 % of grain samples were contaminated by Al and Ni, respectively. Besides the increased soil PTEs concentrations, the enhanced transfer of Ni and Al from rice root to grain via straw may play another crucial role in Ni and Al contamination of rice grain. The relatively weaker transfer ability of Co in the rice plant may be conducive to the rice grain keeping an uncontaminated level of Co. Additionally, Al, Ni, Cr and Co showed high correlations with each other, and they also had a close association with Fe, V and Ti in soil and rice. These correlations imply that Fe, V and Ti may play an important role in the transfer, accumulation and speciation of Al, Ni, Cr and Co in the soil-rice system.

Synthesis Strategy for Protected Metal Nanoparticles

A method for synthesizing metal nanoparticle catalysts with a structured environment using atomic layer deposition (ALD) has been developed. The method involves growing uniform, dispersed Pd nanoparticles, protecting the particles with a blocking agent, growing a metal oxide structure around the nanoparticle using ALD, and removing the blocking agent. Using CO adsorption and diffuse reflectance infrared Fourier transform spectroscopy, possible blocking agents for metal nanoparticles have been evaluated based on the ability of CO to adsorb to the blocking agent–Pd nanoparticle complex. Ethylenediamine and decanethiol were found to be effective blocking agents, while acetonitrile, 1-(3-mercapto)propyl-3,5,7,9,11,13,15-isobutylpentacyclo[9.5.1.13,9.15,15.17,13]octasiloxane, and hexafluoroacetylacetonate were less effective. Octadecanethiol was proven to be effective in protecting Pd nanoparticles during Al2O3 ALD.

Fischer–Tropsch Synthesis over Ordered Mesoporous Carbon Supported Cobalt Catalysts: The Role of Amount of Carbon Precursor in Catalytic Performance

Ordered mesoporous carbon supported cobalt-based catalysts (Co/MC) were synthesized via incipient wetness impregnation with different amounts of furfuryl alcohol (FA) as carbon precursor. The characterizations of obtained Co/MC were subjected to N2 adsorption, XRD, XPS, TEM, H2-TPR, H2-TPD and H2-TPSR. The results indicate that the reducibility and dispersion of Co active species vary significantly due to the difference of FA amount. By simply tuning the FA content from 25 to 100 wt%, the reduction temperature of deriving metallic Co shifts gradually to lower. The catalytic performance of Co/MC was evaluated for Fischer–Tropsch (FT) synthesis. The observed FT activity exhibits a volcano-type curve with the amount of FA due to the effect of both reducibility and dispersion of active species. As the precursor concentration overweighs 50 wt%, the ability of CO to dissociate over the active surface and the selectivity to the C5+ products level off after experiencing an initial increase. Substantially, the catalysts with higher concentration of FA render the larger crystallites having an average size of more than 6 nm, which facilitates the CO hydrogenation by way of carbon chain propagation. It seems that the sample with FA content of 50 wt% is optimum in terms of FT activity and C5+ selectivity. By simply tuning the carbon precursor furfuryl alcohol (FA) content from 25 to 100 wt%, the textural property of mesoporous carbon varies significantly, which further induces the different reducibility and dispersion of Co active species and the temperature of deriving metallic Co shifts gradually to lower. The catalytic performance of as-synthesized catalysts was evaluated for Fischer–Tropsch synthesis (FTS). The observed FT activity exhibits a volcano-type curve with the amount of FA due to the effect of both reducibility and dispersion of active species. At the FA concentration of support over 50 wt%, the selectivity to the C5+ heavy molecular maintain invariant after experiencing an initial increase. It seems that the sample with respect to 50 wt% FA is optimum in terms of FT activity and C5+ selectivity.