201230-82-2

Basic information

• Product Name: Methylene, oxo-
• CAS NO: 201230-82-2
• Molecular Formula: CO
• Molecular Weight: 28.0104
• Mol File: 201230-82-2.mol
• Article Data: 2075

Chemical Properties

• CAS DataBase Reference: Methylene, oxo-(CAS DataBase Reference)
• NIST Chemistry Reference: Methylene, oxo-(201230-82-2)
• EPA Substance Registry System: Methylene, oxo-(201230-82-2)

Safety Data

• Hazardous Substances Data: 201230-82-2(Hazardous Substances Data)

Upstream product

• 109-99-9 tetrahydrofuran 
• 86457-85-4 5-diazotetrazole 
• 289-14-5 1,2,4-trioxolane 
• 930-21-2 2-azetidinone 
• 96-48-0 4-butanolide 
• 100-42-5 styrene 
• 67-56-1 methanol 
• 50-00-0 formaldehyd 
• 563-79-1 2,3-Dimethyl-2-butene 
• 79-37-8 oxalyl dichloride 
• 100-41-4 ethylbenzene 
• 91-16-7 1,2-dimethoxybenzene 
• 577-85-5 3-hydroxyflavone 
• 187737-37-7 propene 

Downstream Products

• 4136-86-1 dimethyl 2-butylsuccinate 
• 10420-33-4 dimethyl 2-acetylsuccinate 
• 40745-20-8 dimethyl 2-cyclohexylsuccinate 
• 71195-17-0 dimethyl ester of trans-2'-carboxycyclohexanepropanoic acid 
• 68826-23-3 methyl 1,3,4-trimethylcyclohex-3-enecarboxylate 
• 15760-37-9 1-Methyl-3-methylen-cyclobutancarbonsaeure-methylester 
• 7367-81-9 methyl (E)-oct-2-enoate 
• 14952-06-8 methyl (2E)-2-nonenoate 
• 41343-59-3 3-ethoxyacrylic acid methyl ester 
• 623-95-0 1,3-dipropylurea 
• 5343-52-2 2-methyl-2-ethylpentanoic acid 
• 813-72-9 2,2-dimethylhexanoic acid 
• 149-57-5 2-Ethylhexanoic acid 
• 116454-37-6 2-methylheptanoic acid 

Relevant articles and documents

A Ru(II)-Mn(I) Supramolecular Photocatalyst for CO2 Reduction

Supramolecular photocatalysts for CO2 reduction, constituted of redox photosensitizer, catalyst, and bridging ligand, play crucial roles in constructing hybrid systems with solid materials and photoelectrochemical cells for artificial photosynthesis. We report the first supramolecular photocatalysts with a Mn(I) catalyst [MnBr(CO)3(BL)] and photosensitizer unit(s) [Ru(dmb)2(BL)]2+ (dmb = 4,4′-dimethyl-2,2′-bipyridine, BL = bridging ligand). A 1:1 ratio between the redox photosensitizer and catalyst units showed higher activity for HCOOH formation in comparison to the corresponding mixed system of mononuclear complexes.

Investigation of the thermal decomposition of ketene and of the reaction CH2 + H2 ? CH3 + H

Using frequency modulation (FM) spectroscopy singlet methylene radicals have been detected for the first time behind shock waves. The thermal decomposition of ketene served as source for metylene radicals at temperatures from 1905 to 2780 K and pressures around 450 mbar. For the unimolecular decomposition reaction, (1) CH2CO+M → CH2 +CO+M, the rate constants obtained are: k1 = (9.5±5.7) · 1015 · exp[(-244±25) kJ mol-1/RT] cm3mol-1 s-1. As a first study of a methylene reaction at high temperatures by diretly tracing methylene the reaction of methylene with hydrogen, (8+9) 1.3CH2 + H2 → CH3 + H, was investigated at temperatures from 1930 to 2455 K and pressures around 500 mbar. For the total rate constant of the singlet and triplet methylene reaction a temperature independent value was obtained: log(kg+9/(cm3mol-1s-1)) = 13.89±0.26. A comparison with low temperature literature data and the systematics of activation energies of triplet methylene reactions allowed a consistent description of singlet and triplet contributions and of the forward and reverse reaction. by Oldenbourg Wissenschaftsverlag, Muenchen.

Photoactivity of mono- and dicarbonyl complexes of ruthenium(II) bearing an N,N,S-donor ligand: Role of ancillary ligands on the capacity of CO photorelease

One monocarbonyl and one dicarbonyl complex of ruthenium(II), namely, [Ru(Cl)(CO)(qmtpm)(PPh3)]BF4 (2) and [Ru(Cl)(CO) 2(qmtpm)]ClO4 (3), derived from the tridentate ligand 2-quinoline-N-(2′-methylthiophenyl)methyleneimine (qmtpm) have been synthesized and structurally characterized. The qmtpm ligand binds in a meridional fashion in these carbonyl complexes, and in 3, the two carbon monoxide (CO) ligands are cis to each other. Solutions of 2 in ethanol, chloroform, or acetonitrile rapidly release CO upon illumination with low-power (3-15 mW) light in the 300-450 nm range. Loss of CO from 2 brings about a dramatic color change from yellow to magenta because of the formation of [Ru(Cl)(MeCN)(qmtpm)(PPh3)]BF4 (4). In acetonitrile, photorelease of CO from 3 under 360 nm light occurs in two steps, and the violet photoproduct [Ru(Cl)(MeCN)2(qmtpm)]+ upon reaction with Ag+ and PPh3 affords red [Ru(MeCN)2(qmtpm) (PPh3)](ClO4)2 (5). The structure of 5 has also been determined by X-ray crystallography. Reduced myoglobin assay confirms that 2 and 3 act as photoactive CO-releasing molecules (photoCORMs) that deliver 1 and 2 equiv of CO, respectively. The results of density functional theory (DFT) and time-dependent DFT studies confirm that electronic transitions from molecular orbitals with predominantly Ru-CO character to ligand-based π* orbitals facilitate CO release from these two photoCORMs. Complexes 2-5 have provided an additional opportunity to analyze the roles of the ancillary ligands, namely, PPh3, Cl-, and MeCN, in shifting the positions of the metal-to-ligand charge-transfer bands and the associated sensitivity of the two photoCORMs to different wavelengths of light. Collectively, the results provide helpful hints toward the future design of photoCORMs that release CO upon exposure to visible light.

CO2 hydrogenation to methanol on Ga2O3-Pd/SiO2 catalysts: Dual oxide-metal sites or (bi)metallic surface sites?

A series of palladium (2 wt.%) catalysts supported on silica (301 m2/g) and loaded with increasing amount of gallium – ratio of Ga/Pd = 2, 4 and 8 atom/atom – were investigated for CO2 hydrogenation to methanol. The turnover frequency to methanol (H2/CO2 = 3; 523 K, 3 MPa), based on surface palladium, showed a 200-fold enhancement as compared to the monometallic Pd/SiO2 catalyst. Additionally, the apparent activation energy for methanol synthesis decreased from 60 kJ/mol on Pd/SiO2 to ～40 kJ/mol on the supported Ga-Pd catalysts. Characterization of the Pd-Ga catalyst series by X-ray absorption spectroscopy and high resolution transmission electron microscopy indicates the formation of Pd2Ga bimetallic nanoparticles partially covered by a thin layer of Ga2O3 on the silica surface. In situ infrared spectroscopy was employed to examine the reaction mechanism during the CO2 adsorption and hydrogenation at 0.7 MPa. It is proposed a bifunctional pathway where the carbonaceous species bound to the gallium oxide surface are hydrogenated, stepwise, to formate and methoxy groups by atomic hydrogen, which spillovers from the Pd-Ga bimetallic nanoparticles.

Click and Release: A Chemical Strategy toward Developing Gasotransmitter Prodrugs by Using an Intramolecular Diels–Alder Reaction

Prodrug strategies have been proven to be a very effective way of addressing delivery problems. Much of the chemistry in prodrug development relies on the ability to mask an appropriate functional group, which can be removed under appropriate conditions. However, developing organic prodrugs of gasotransmitters represent unique challenges. This is especially true with carbon monoxide, which does not have an easy “handle” for bioreversible derivatization. By taking advantage of an intramolecular Diels–Alder reaction, we have developed a prodrug strategy for preparations of organic CO prodrugs that are stable during synthesis and storage, and yet readily release CO with tunable release rates under near physiological conditions. The effectiveness of the CO prodrug system in delivering a sufficient quantity of CO for possible therapeutic applications has been studied using a cell culture anti-inflammatory assay and a colitis animal model. These studies fully demonstrate the proof of concept, and lay a strong foundation for further medicinal chemistry work in developing organic CO prodrugs.

HEI PHOTOELECTRON SPECTRA OF UNSTABLE MOLECULES: MONO- AND DIHALOGENOKETENES

HeI Photoelectron spectra are reported for the mono- and di-chloro-and-bromo-ketenes (XHC=C=O and X2C=C=O, X=Cl,Br) generated in high yield as unstable molecules from thermolysis of acid halides.The spectra are discussed and assigned by reference to the parent ketene molecule, orbital trends, and comparison with theoretical calculations.

Morphology Modulation-Engineered Flowerlike In2S3 via Ionothermal Method for Efficient CO2 Electroreduction

Electroreduction of carbon dioxide (CO2) to chemicals is a promising route to convert and utilize CO2 under atmospheric conditions. However, the relative poor reaction efficiency seriously hinders the practical applications of this route. In this work, flowerlike In2S3 assembled by nanoflakes was synthesized via ionothermal method and exhibited a high Faradaic efficiency (FE) of 86 % with excellent formate formation rate of 478 μmol h?1 cm?2 in ionic liquid (IL) electrolyte. Flowerlike structure can provide large electrochemically active surface area and enhance mass transfer rate. Additionally, density functional theory (DFT) calculations reveal that the origin of the improved performance can be attributed to the large adsorption energy of CO2 * and OCHO* intermediate on the (440) facet which is the main exposed crystal facet of flowerlike In2S3.[f1].

Reaction volume and enthalpy changes in photochemical reaction detected by the transient grating method; photodissociation of diphenylcyclopropenone

A method for the measurement of reaction volume (ΔV) and enthalpy (ΔH) changes of a photochemical reaction is presented based on the transient grating technique.Since ΔV and ΔV contributions are detected separately by the time-resolved manner, this new me

Fuel composition and diluent effect on gas transport and performance of anode-supported SOFCs

Anode-supported solid oxide fuel cells (SOFCs) with Ni+yttria-stabilized zirconia (YSZ) anode, YSZ-samaria-doped ceria (SDC) bilayer electrolyte, and Sr-doped LaCoO3 (LSC)+SDC cathode were fabricated. Fuel used consisted of H2 diluted with He, N2, H2O, or CO2, mixtures of H2 and CO, and mixtures of CO and CO2. Cell performance was measured at 800°C with the above-mentioned fuel gas mixtures and air as oxidant. For a given concentration of the diluent, cell performance was higher with He as the diluent than with N2 as the diluent. Mass transport through porous Ni-YSZ anode for H2-H2O, CO-CO2 binary systems, and H2-H2O-diluent gas ternary systems was analyzed using multicomponent gas diffusion theory. At high concentrations of diluent, the maximum achievable current density was limited by the anodic concentration polarization. From this measured limiting current density, the corresponding effective gas diffusivity was estimated. Highest effective diffusivity was estimated for fuel gas mixtures containing H2-H2O-He mixtures (～0.55 cm2/s), and the lowest for CO-CO2 mixtures (～0.07 cm2/s). The lowest performance was observed with CO-CO2 mixture as a fuel, which in part was attributed to the lowest effective diffusivity of the fuels tested and higher activation polarization.

Laser-Induced Activation of Methane at Oxide Surfaces: A Probe of Radical-Surface Interactions

C-H bond activation was studied via pulsed laser irradiation of oxides in a methane atmosphere.Carbon monoxide was the major product observed at low power densities and room temperature.Significant amounts of C2 products, ethane, ethylene, and acetylene were formed.CO, C2H6, C2H4, and C2H2 are assigned as primary products of the reaction.Laser-induced methane activation produces *CH3 and :CH2 radical species in the gas phase via a plasma mechanism and is utilized as a tool to study radical-oxide surface interactions.These reactions are surface sensitive as evidenced by the changes in conversion and product selectivity as a function of oxide pretreatment and oxides used.

Sn(101) Derived from Metal-Organic Frameworks for Efficient Electrocatalytic Reduction of CO2

The synthesis of a specific Sn plane as an efficient electrocatalyst for CO2 electrochemical reduction to generate fuels and chemicals is still a huge challenge. Density functional theory (DFT) calculations first reveal that the Sn(101) crystal plane is more advantageous for CO2 electroreduction. A metal-organic framework (MOF) precursor Sn-MOF has been carbonized and then etched to successfully fabricate Sn(101)/SnO2/C composites with good control of the carbonization time and the concentration of hydrochloric acid. The Sn(101) crystal plane of the catalyst could enhance the faradaic efficiency of formate to as high as 93.3% and catalytic stability up to 20 h. The promotion of the selectivity and activity by Sn(101) advances new possibilities for the rational design of high-activity Sn catalysts derived from MOFs.

Electrocatalytic Reduction of CO2 to Ethylene by Molecular Cu-Complex Immobilized on Graphitized Mesoporous Carbon

The electrochemical reduction of carbon dioxide (CO2) to hydrocarbons is a challenging task because of the issues in controlling the efficiency and selectivity of the products. Among the various transition metals, copper has attracted attention as it yields more reduced and C2 products even while using mononuclear copper center as catalysts. In addition, it is found that reversible formation of copper nanoparticle acts as the real catalytically active site for the conversion of CO2 to reduced products. Here, it is demonstrated that the dinuclear molecular copper complex immobilized over graphitized mesoporous carbon can act as catalysts for the conversion of CO2 to hydrocarbons (methane and ethylene) up to 60%. Interestingly, high selectivity toward C2 product (40% faradaic efficiency) is achieved by a molecular complex based hybrid material from CO2 in 0.1 m KCl. In addition, the role of local pH, porous structure, and carbon support in limiting the mass transport to achieve the highly reduced products is demonstrated. Although the spectroscopic analysis of the catalysts exhibits molecular nature of the complex after 2 h bulk electrolysis, morphological study reveals that the newly generated copper cluster is the real active site during the catalytic reactions.

Carbon Dioxide Hydrogenation over Au/ZrO2 Catalysts from Amorphous Precursors: Catalytic Reaction Mechanism

An active catalyst for carbon dioxide hydrogenation is obtained by exposing an amorphous Au25Zr75 alloy to CO2 hydrogenation conditions.During this in situ activation, metallic gold particles of 8.5 nm mean size are formed, and the zirconium component of the catalyst is oxidized to ZrO2.For comparison, a further Au/ZrO2 catalyst was synthesized by coprecipitation, followed by calcination of the amorphous precipitate.The calcination step strongly enhances the activity of the catalyst; gold segregation and zirconia crystallization are found to occur in this process.The structural and chemical changes are characterized by gas adsorption, X-ray diffraction and thermal analysis. The main products of CO2 hydrogenation over these catalysts, as identified by gas chromatography, are methanol and CO.To investigate the reaction mechanism, diffuse reflectance FTIR spectroscopy has been used.Observed surface species are correlated with the formation of gas-phase products.Adsorption of CO2-H2 results in rapid formation of formate as the primary surface intermediate; two types of formate species are clearly detected on the coprecipitated catalyst, and are assigned by means of formic acid adsorption experiments.CO formation from CO2 appears to proceed via surface carbonate, in a surface reaction that corresponds to a 'basic variant' of the reverse water-gas-shift reaction.The CO formed in this process is, in turn, the starting point for a series of surface hydrogenation steps that yield ?-bonded formaldehyde, surface-bound methylate and finally methanol.This sequence of reactions is confirmed by separate CO-H2 adsorption experiments.

Preparation, characterization and crystal structure of lead(II) tricyanomethanide

The so far unknown lead tricyanomethanide, Pb[C(CN)3] 2, was obtained from a saturated aqueous solution of PbCl2 and solid AgC(CN)3. Its IR spectrum and thermal behaviour are described. The crystal structure was determined by single-crystal X-ray diffraction (trigonal, P31m, Z = 3, a = 1414.4(5), c = 409.02(6) pm, R 1 = 0.0249, wR2 = 0.0527). Two crystallographically independent ninefold coordinated Pb atoms are connected by planar tricyanomethanide ions in two distinct bridging coordination modes. The Pb-N distances range between 254 and 293 pm.

The difference of roles of alkaline-earth metal oxides on silica-supported nickel catalysts for CO2 methanation

The roles of alkaline-earth metal oxides on CO2 methanation over modified Ni/SiO2 catalysts were investigated. Ni/MO/SiO2 catalysts with variable elements (M = Mg, Ca, Sr and Ba) were prepared by the sequential impregnatio

Selective Hydrogenation of Carbon Dioxide to Methanol on Cu-ZnO/SiO2 Catalysts Prepared by Alkoxide Method

Hydrogenation of CO2 to methanol was carried out on Cu-ZnO/SiO2 catalysts at 493 K and 3 MPa with a flow rate of 100 cm3min-1 (H2/CO2=2).Higher selectivity (>90percent) was observed on the catalysts prepared by the alkoxide method than on a conventional catalyst prepared by the impregnation method.The selectivity was higher on the catalysts pretreated with H2 at a higher temperature, except at 873 K.The activity of the catalyst pretreated at 873 K was extremely low, probably because of alloy formation.The results of XRD, XPS, and EXAFS demonstrate that the active species for methanol formation is a large metallic Cu particle covered with a partially oxidized layer interacting with highly dispersed ZnO.

Photosensitive iron(II)-based CO-releasing molecules (CORMs) with vicinal amino and diphenylphosphino substituted chelating ligands

The reactions of [Fe(H2O)6] [BF4] 2 with aminoethyl-diphenylphosphane and 2-(diphenylphosphino)aniline lead to the formation of trans-[Fe(NC-Me)2(H2NCH 2CH2PPh2)2] [BF4] 2 (1a) and trans-[Fe(NC-Me)2(H2NC 6H4-2-PPh2)2] [BF4] 2 (1b), respectively. One acetonitrile ligand can be substituted by CO yielding [Fe(CO)(NC-Me)(H2NCH2CH2PPh 2)2] [BF4]2 (2a, CORM-P1) and [Fe(CO)(NC-Me)(H2NC6H4-2-PPh2) 2] [BF4]2 (2b, CORM-P2). Upon irradiation with visible light, CO is liberated making especially 2a a promising photo-CORM whereas for 2b a slow and incomplete CO release is observed.

Strong Evidence of the Role of H2O in Affecting Methanol Selectivity from CO2 Hydrogenation over Cu-ZnO-ZrO2

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Epoxidation of Ethylene with Products of Thermal Gas-Phase Oxidation of n-Butane

Abstract: Epoxidation of ethylene with the reactive products formed during thermal gas-phase oxidation of n-butane has been carried out under flow conditions with the separation of the zones of generation of radicals and their interaction with ethylene. Butane is oxidized in the first section of a two-section reactor, and ethylene is fed to the second section. It has been found that increasing the residence time of a butane–oxygen mixture in the first section of the reactor from 7 to 13 s increases the ethylene oxide accumulation rate. A further increase in the contact time leads to a decrease in the rate. Similarly, increasing the C4H10/O2 ratio in the range of 0.05–0.25 leads to an increase in the rate of accumulation of ethylene oxide. A further increase in this ratio decreases the rate of epoxidation. It has also been found that the temperature dependences of the ethylene oxide accumulation rate in both sections of the reactor pass through a maximum. The obtained data give evidence for the occurrence of the ethylene epoxidation reaction initiated by the n-butane oxidation products under the conditions when ethylene itself is slightly oxidized.

Laser photofragmentation time-of-flight mass spectrometric study of acetophenone at 193 and 248 nm

The photodissociation of acetophenone (C6H5COCH3) at 193 and 248 nm is studied using the time-of-flight mass spectrometric technique. It is found that the dissociation is dominated by processes (1) and (2): C6H5COCH3+hν→C6H5CO+CH3 (1), C6H5+CH3CO (2) and, C6H5CH3+CO. At 193 nm, processes (1) and (2) occur with comparable cross sections. The cross section for process (3) at 193 nm is estimated to be 3CO and C6H5CO radicals initially formed at 193 nm by processes (1) and (2) are found to undergo further dissociation according to processes (6) and (8). At 248 nm, process (1) is overwhelmingly the dominant channel. The branching ratios for process (1) : process (2) : process (3) are estimated as 1.0:0.01:0.0008. The energy releases for these dissociation processes are also determined.

Comparative study of CO2 hydrogenation to methanol on cubic bixbyite-type and rhombohedral corundum-type indium oxide

Hydrogenation of CO2 to value-added chemicals has attracted much attention all through the world. In2O3 with cubic bixbyite-type (denoted as c-In2O3) is well known for its high CO2 hydrogenation activity and CH3OH selectivity at high temperature. However, the other structure of In2O3 with rhombohedral corundum-type (denoted as rh-In2O3) rarely been investigated as catalyst. Herein, c-In2O3 and rh-In2O3 were prepared and comparatively studied for CO2 hydrogenation. The results indicated that c-In2O3 showed higher CO2 conversion activity than rh-In2O3 due to the impressive reducibility and reactivity. Whereas rh-In2O3 had higher CH3OH selectivity due to weaker CH3OH and stronger CO adsorption on rh-In2O3. Although c-In2O3 and rh-In2O3 catalysts showed different CO2 hydrogenation performance, in-situ diffuse reflectance infrared Fourier transform spectroscopy showed CO2 can be reduced to CO through redox cycling and hydrogenation to CH3OH through formate path.

Lewis Acid Strength of Interfacial Metal Sites Drives CH3OH Selectivity and Formation Rates on Cu-Based CO2 Hydrogenation Catalysts

CH3OH formation rates in CO2 hydrogenation on Cu-based catalysts sensitively depend on the nature of the support and the presence of promoters. In this context, Cu nanoparticles supported on tailored supports (highly dispersed M on SiO2; M=Ti, Zr, Hf, Nb, Ta) were prepared via surface organometallic chemistry, and their catalytic performance was systematically investigated for CO2 hydrogenation to CH3OH. The presence of Lewis acid sites enhances CH3OH formation rate, likely originating from stabilization of formate and methoxy surface intermediates at the periphery of Cu nanoparticles, as evidenced by metrics of Lewis acid strength and detection of surface intermediates. The stabilization of surface intermediates depends on the strength of Lewis acid M sites, described by pyridine adsorption enthalpies and 13C chemical shifts of -OCH3 coordinated to M; these chemical shifts are demonstrated here to be a molecular descriptor for Lewis acid strength and reactivity in CO2 hydrogenation.

An Investigation of the end-products of CO2-laser irradiation of the ethene gas

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Oxidation of Allyl Radicals: Kinetic Parameters for the Reactions of Allyl Radicals with HO2 and O2 between 400 and 480 deg C

The decomposition of 4,4-dimethylpent-1-ene (DMP) in the presence of O2 has been used as a source of allyl and HO2 radicals between 400 and 480 deg C.Propene was added to the mixtures of DMP and O2 in order to monitor from the yields of propene oxide by use of the known value of k14.HO2 + C3H6 -> C3H6O + OH (14).From measurements of the initial yields of CO, hexa-1,5-diene and propene oxide over a range of mixture composition, rate constants have been obtained for reaction (9) and (10). CH2CHCH2 + HO2 -> CO + product (9); CH2CHCH2 + HO2 -> C3H6 + HO2 (10).At 400 deg C, k9 = 3.95 x 109 and k10 = 1.42 x 109 dm3 mol-1 s-1 and both show a slight increase (within experimental error) with temperature, 15percent and 30percent, repectively, at 480 deg C.Strong evidence is obtained for the formation of CO in the reaction between allyl radicals and O2 and values of A15 = 109.4 +/- 0.6 dm3 mol-1 s-1 and E15 = 79 +/- 8 kJ mol-1 are obtained. CH2CHCH2 + O2 -> CO + products (15).The mechanism of reactions (10) and (15) are discussed.Based on current thermochemistry it is shown by calculation that reaction (10) probably occurs only to a minor extent through a direct H-atom abstraction route which is reverse of the chain initiation reaction (16).C3H6 + O2 -> CH2CHCH2 + HO2 (16).The available kinetic data for the reaction between allyl radicals and O2 are summarised.

Effect of active and inert oxide on catalytic partial oxidation (CPO) of methane over supported Ni catalysts

The effects of preparation method, types of carrier and different catalyst and support structures on the CH4 catalytic partial oxidation (CPO) activity of supported Ni catalysts are reviewed with respect to selected results obtained by this research group during the last five years. In particular, different preparation methods and structural effect of Ni supported on La2O3, on CeO2 and on mixed CeO2-La2O3 are discussed. The effects of the peculiarity of an active (redox) and of an inert oxide carrier, influencing the metal dispersion, the metal reducibility and the carbon formation, are considered by comparing the catalytic performance of nickel catalysts supported on CeO2 and on SiO2. Ni supported over a high surface area silica will be compared with a corresponding ceria-doped nickel catalyst. The results of a detailed material characterization attained by several techniques as XPS, XRD, TPR/TPO are described, aiming to elucidate the structure - activity relationship. The reviewing of the different case studies illustrates the importance of the interaction between support and active metals ultimately determining the surface distribution of the active sites and their final catalytic activity.

Oxygen-vacancy generation in MgFe2O4 by high temperature calcination and its improved photocatalytic activity for CO2 reduction

MgFe2O4 spinel with abundant oxygen vacancy was synthesized by a simple precipitation method, and tested in photocatalytic reduction of CO2 with water vapor as reductant. A series of characterization including XRD, XPS, EPR, PL spectrum, UV–vis DRS and TPD-CO2 were performed to investigate the influence of calcination temperature on morphology, optical and electronic properties of MgFe2O4 spinel. The results demonstrated that the oxygen vacancy concentration increases first and then decreases with the increase of calcination temperature. By introducing oxygen vacancies, the recombination of photogenerated electron-hole pairs was significantly suppressed, visible light absorption and chemisorption capacity of CO2 were dramatically boosted. Mg-Fe-750 with the richest oxygen vacancies exhibits the highest photocatalytic activity, for which the production rate of CO and H2 was 24.4 and 34.3 μmol/gcat/h, respectively.

Rational Design of Zinc/Zeolite Catalyst: Selective Formation of p-Xylene from Methanol to Aromatics Reaction

The production of p-xylene from the methanol to aromatics (MTA) reaction is challenging. The catalytic stability, which is inversely proportional to the particle size of the zeolite, is not always compatible with p-xylene selectivity, which is inversely proportional to the external acid sites. In this study, based on a nano-sized zeolite, we designed hollow triple-shelled Zn/MFI single crystals using the ultra-dilute liquid-phase growth technique. The obtained composites possessed one ZSM-5 layer (≈30 nm) in the middle and two silicalite-1 layers (≈20 nm) epitaxially grown on two sides of ZSM-5, which exhibited a considerably long lifetime (100 % methanol conversion >40 h) as well as an enhanced shape selectivity of p-xylene (>35 %) with a p-xylene/xylene ratio of ≈90 %. Importantly, using this sandwich-like zeolite structure, we directly imaged the Zn species in the micropores of only the ZSM-5 layer and further determined the specific structure and anchor location of the Zn species.