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In order to understand the transformations of the Keggin-type H4-xCsxPV-Mo11O40 (x = 0, 2) compounds with rising temperature over a long time in a stream of different gas atmospheres, in situ UV/Vis/near-IR spectroscopic studies were carried out. Diffuse reflectance spectra were recorded using an improved spectrometer and a suitable microreactor. Visible and near-IR peak intensities, peak positions and the band gap energies were determined from apparent absorption spectra. Propene, isopropanol, water and the oxidation products were analyzed by GC. The experimentally observed blue shift of the visible absorption band in the region of crystal water loss and the increase in the near-IR absorption were explained on the basis of quantum-mechanical calculations of the shapes and positions of the charge transfer and d-d bands arising from Mo5+-Mo6+ and V4+-Mo6+ pairs in intact and ill-defined fragments of the Keggin structure. It was concluded that with removal of crystal water during the action of He, He/H2O, propene, O2/propene and increasing temperature, reduced species with protons located at the bridging oxygens promote a blue shift of the visible band, while a large number of ill-defined species form the near-IR part of the spectra in the temperature range 326-600 K.

Oxidation of propene on a Mo4Pr0.5Bi0.5Ox/SiO2 catalyst was studied in order to establish the reaction network.In the temperature range 598-653 K the primary reaction products were propenal (main product), acetone, acetaldehyde, and carbon dioxide.Other products (mainly aldehydes and acids) could be classified as secondary reaction products.From studies of oxidation of the primary unstable products and the kinetics of formation of minor primary products it is concluded that both, acetaldehyde and carbon dioxide, are formed through parallel and consecutive reactions.Acetone formation is strongly influenced by reaction temperature, probably due to changes in the active centers of the catalyst.

The effect of different type of heteropolyacid/Zr-MCM-41 catalysts on the catalytic amination of glycerol with dimethylamine to produce Dimethylamino-3-propanal was researched. Under the premise of their respective optimum loading amount, the specific sur

Results obtained from studies of the oxidation of propene between 400 and 520 deg C have been used to obtain the first Arrhenius parameters for the important chain initiation reaction RH + O2 -> R + HO2, where RH is a hydrocarbon.A full product analysis in the early stages of reaction has been made for a number of mixtures at 400, 440, 480 and 520 deg C.It has been shown that hexa-1,5-diene is a major initial product and that its formation in reaction (8) represents the major termination process.By use of measurements of the initial rate of formation of hexa-1,5-diene HDE)O>, so that secondary initiation is negligible, then in the absence of radical branching the simple relationship k7 = (RHDE)O holds.Values of k7 at a constant temperature obtained from the relationship vary by less than a factor of two over a wide range of mixture composition, and the average values at each temperature give A7 = 109.2 dm3 mol-1 s-1 and E7 = 162 kJ mol-1.CH3CH=CH2 + O2 -> CH2CHCH2 + HO2 (7) 2CH2CHCH2 -> CH2=CHCH2CH2CH=CH2 (8) When allowance is made for minor termination processes and for the radical-branching reaction (17), the values of A7 and E7 change only slightly, confirming the essential validity of the interpretaion and of the simple relationship above.Final values of A7 = 109.29 +/- 0.41 dm3 mol-1 s-1 and E7 = 163.5 +/- 6 kJ mol-1 are obtained for reaction (7).The interpretation also gives reliable Arrhenius parameters of A17 = 108.21 +/- 0.60 dm3 mol-1 s-1 and E17 = 72.5 +/- 8.3 kJ mol-1 for the radical-branching reaction (17).No previous estimates are available for either reaction.CH2CHCH2 + O2 -> 2 radicals + products (17)

An iridium(III) pentamethylcyclopentadienyl catalyst supported by 6,6'-dihydroxy-2,2'-bipyridine displays exquisite selectivity in acceptorless alcohol dehydrogenation of cyclic α,β-unsaturated alcohols over benzylic and aliphatic alcohols under mild aqueous reaction conditions. Hydrogenation of aldehydes and ketones occurs indiscriminately using the same catalyst under hydrogen, although chemoselectivity could be achieved when other potentially reactive carbonyl groups present are sterically inaccessible. This chemistry was demonstrated in the reversible hydrogenation and dehydrogenation of the A ring of glucocorticoids, despite the presence of other alcohol/or carbonyl functionalities in rings C and D. NMR studies suggest that an iridium(III) hydride species is a key intermediate in both hydrogenation and dehydrogenation processes.

Gas-phase dehydration of glycerol to produce acrolein was investigated at 315 °C over Nb2O5 catalysts calcined in the temperature range of 350-700 °C. The catalysts were characterized by nitrogen physisorption, TG-DTA, XRD, and n-butylamine titration using Hammett indicators to gain insight into the effect of calcination temperature on catalyst texture, crystal structure, and acidity. Calcination at 350 and 400 °C produced amorphous Nb2O5 catalysts that exhibit significantly higher fractions of strong acid sites at - 8.2 ≤ H0 ≤ - 3.0 (H0 being the Hammett acidity function) than the crystallized Nb2O5 samples obtained by calcination at or above 500 °C. Glycerol conversion and acrolein selectivity of the Nb2O5 catalysts were dependent of the fraction of strong acid sites (- 8.2 ≤ H0 ≤ - 3.0). The amorphous catalyst prepared by the calcination at 400 °C, having the highest fraction of acid sites at - 8.2 ≤ H0 ≤ - 3.0, showed the highest mass specific activity and acrolein selectivity (51 mol%). The other samples, having a higher fraction of either stronger (H0 ≤ - 8.2) or weaker acid sites (- 3.0 ≤ H0 ≤ 6.8), were less effective for glycerol dehydration and formation of the desired acrolein.

Highly dispersed vanadia species on SBA-15 mesoporous silica have been found to exhibit a highly efficient catalytic performance for the oxidative dehydrogenation (ODH) of propane to light olefins (propene + ethylene).

To obtain thermally stable copper-based catalysts with excellent catalytic performance in the selective propene (C3H6) oxidation reaction, amorphous silicon nitride (Si3N4) was selected to anchor active copper species using a deposition–precipitation approach followed by air calcination at different temperatures. We found that the thermal treatment temperature remarkably modified the reactivity of the copper catalyst, and the 800 °C-calcined 10 wt% Cu/Si3N4 showed superior catalytic activity with 24.0% propene conversion and 86.2% acrolein selectivity at 325 °C, featuring a turnover frequency as high as 80.6 h?1. With the help of transmission electron microscopy, X-ray absorption fine structure, and in situ X-ray diffraction, we have identified that the larger Cu2O species account for the highly efficient formation of acrolein at 325 °C. From the CO temperature-programmed reduction results, we have confirmed that the presence of surface copper hydroxyls (Cu–OH) was closely related to the acrolein selectivity, since they favored CO2 generation at the beginning of the reaction. Furthermore, surface copper hydroxyls can be effectively tuned by optimizing the air calcination temperature and thus improve the catalytic activity.

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Acrolein is a widely used intermediate of synthesis for value-added compounds in a number of domains of application. This work reports on the sustainable synthesis of acrolein by oxidative coupling of bio-alcohols, which constitutes a very promising alternative to fossil fuel-based production. The synthesis is performed in two sequential reactors, using an iron molybdate catalyst for oxidation and then a magnesium aluminate spinel where magnesium is partly or totally substituted by transition metals (Fe, Zn, Co, Cu, Mn) as a catalyst for cross-aldolization. The acid-base properties of the latter catalysts were determined using SO2 and NH3 adsorption microcalorimetry. Adsorption microcalorimetry was also used to study the adsorption properties of the reactants, with formaldehyde, acetaldehyde and propionaldehyde as probe molecules, and was complemented by a FT-IR investigation of reactant adsorption in order to better understand the mechanisms of adsorption and reaction. Acrolein production was found to be correlated to the ionic radius of the transition metals used in the catalysts, indicating that electronic effects are likely a factor influencing the acrolein production.

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Mesoporous silica (FSM-16) was found to exhibit a much higher activity for propene photooxidation than amorphous silica and to give different products distribution from those on silica, thus proposing FSM-16 as a new type of photooxidation catalyst.

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Stoichiometric reactions between superoxide ions on MgO and simple hydrocarbons were observed at 175 deg C, although the O2- ions were much less reactive than either O- or O3- ions.Several types of oxygen-containing products were formed, as well as other hydrocarbons and CO2.The reaction of propylene with O2- gave no gaseous product at 175 deg C; however, at elevated temperatures acetaldehyde and methanol were obtained.Following the reaction of propane with O2-, acetone was detected at 175 deg C in addition to acetaldehyde and methanol which were observed at higher temperatures.With 1-butene as the reactant, 2-butanol was formed together with methanol, acetaldehyde, and acrolein above 300 deg C.Infrared spectra of surface intermediates indicate that the reaction of O2- with propylene at 175 deg C resulted in the simultaneous formation of formate and acetate ions which are consecutively converted to carbonate ions at elevated temperatures.It is proposed that hydrogen atom abstraction is the initial step in the reaction of O2- with simple hydrocarbons.The resulting radicals react with lattice oxygen ions forming carboxylate ions or with HO2- ions forming alkoxy or epoxide intermediates.

A new and convenient method is described to oxidize primary alcohols into the corresponding aldehydes utilizing chromium trioxide-dimethyl sulfoxide system.

Oxygenates are formed in the propane oxidation over silica catalysts supporting a very small amount of Fe. Alkali addition to the catalysts can enhance the activity as well as the selectivity to acrolein and acetone.

A series of vanadium-substituted phosphomolybdic acid (HPA) catalysts supported on zirconia were prepared by impregnation method with varying the HPA active phase content from 10 to 50 wt% on the support. The calcined catalysts were characterized by X-ray diffraction, Raman spectroscopy, temperature-programmed desorption of NH3, FT-IR spectra of pyridine adsorption and surface area measurements. XRD results suggest that the active phase of heteropolyacid is present in a highly dispersed state at lower loadings and as a crystalline phase at higher HPA loadings and these findings are well-supported by the results of FT-IR and Raman spectra. Calcination of the samples did not affect the Keggin ion structure of HPA. The ammonia TPD results suggest that acidity of the catalysts was found to increase with increase of HPA loading up to 40 wt% and decreases at higher loadings. FT-IR spectra of pyridine adsorption show that the Bronsted acidic sites increase with increase of HPA loadings up to 40 wt% catalyst. However, Lewis acid sites decrease with increase of HPA loading. Catalytic properties were evaluated during vapour phase dehydration of glycerol to acrolein. The catalyst with 40 wt% HPA has exhibited excellent selectivity towards acrolein formation with complete conversion of glycerol at 225°C under atmospheric pressure. Catalytic performances during dehydration of glycerol are well-correlated with acidity of the catalysts.

Glycerol A by-product of biodiesel industry, could be utilized for the production of synthesis gas or hydrogen via steam reforming. Ni/Al2O3 catalysts are efficient for this process but could be improved regarding their activity at low temperatures, selectivity toward hydrogen production and stability with time-on stream. In the present work, the effects of addition of Β2Ο3 and La2O3 on Ni/Al2O3, on the physicochemical characteristics and catalytic performance are investigated. N2 adsorption-desorption, XRD, UV-vis DRS, TPR, NH3-TPD and HR-TEM were employed for the evaluation of the textural and structural properties of the catalysts, while quantitative assessment of the carbonaceous deposits was performed using TPH-TPO. Catalytic behavior was investigated in the temperature range of 400-800 °C. In the absence of metal, the support presents considerable activity for the dehydration reactions and influences selectivity to oxygenate products. The catalytic behavior of the bare carriers seems to be dictated by their surface acidity. The presence of Ni enhances significantly catalytic activity and promotes the production of gaseous products, mainly carbon oxides and hydrogen. Conversion to gas-phase products and hydrogen yield are enhanced by the addition of La2O3 to the support while the opposite is observed upon addition of B2O3. These differences are more pronounced at lower temperatures. Lower amount of graphitic carbon was formed on NiLaAl at all temperatures. However, this catalyst has not been proven more stable than the unmodified NiAl, mostly due to its poorer textural properties.

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The thermal decomposition of 3,4-dihydro-2H-pyran (DHP, C5H8O) has been investigated by two methods: in shock waves with the laser-schlieren technique using mixtures of 5 and 10percent DHP in krypton over 900-1500 K, 110-560 torr; in a flow tube having a reaction pressure 0.5 torr above atmospheric, using the decomposition of allylethyl ether as an internal standard, and covering 663-773 K.The retro-Diels-Alder dissociation to the stable acrolein and ethylene is the dominant channel for all conditions.Precise rate constants (rms deviation of 10percent) were obtained for this process over the indicated temperature ranges.Unimolecular falloff is evident in the shock-tube results, and RRKM calculations also predict a slight falloff at the lower temperatures.These RRKM calculations use a routine vibration model transition state and agree closely with the high-temperature data when (ΔE)down is a fixed 400 cm-1.Arrhenius expressions for kinfinite derived from the two measurements are in close accord and also consistent with most previous studies of this reaction.

The catalytic gas-phase oxidation of propylene on a multicomponent Mo-Co-Fe-Bi-K-O catalyst gives up to 85percent yield of acrolein and acrylic acid along with undesirable side products - formaldehyde and acetaldehyde.Effect of four factors have now been studied with the aim of suppressing of formation of the by-product viz. the effect of potassium content in the catalyst, that of final annelating temperature of the catalyst, and those of addition of other components (tungsten, nickel).It has been found that a charge in potassium content in catalyst affect distinctly its activity and also selectivity for products of total oxidation of propylene but does not practically affect the yields of formaldehyde and acetaldehyde.The yields of the said side products decreased with increasing annelating temperature, however, with concominant considerable decrease in the catalytic activity.Whereas a partial substitution of molybdenum atoms in the catalyst by tungsten atoms is accompanied by an increase in production of formaldehyde and acetaldehyde, some catalysts with nickel gave acrolein as the only aldehyde.

The laser flash photolysis technique, coupled with UV absorption spectroscopy, has been used to investigate the UV spectra and kinetics of reactions of the allyl radical (CH2=CHCH2) and the allyl peroxy radical (CH2=CHCH2O2) at 296 K and total pressures near atmospheric.CH2=CHCH2 radicals were generated by the 193 nm photolysis of hexa-1,5-diene-N2 mixtures, or the 248 nm photolysis of allyl iodide-N2 mixtures.The 193 nm photolysis of hexa-1,5-diene-O2-N2 mixtures was used to generate CH2=CHCH2O2.The low resolution spectrum of CH2=CHCH2 was characterised in the range 210-232.5 nm.The absolute absorption cross-section near the maximum, ? (220 nm) = 5.8 +/- 0.8) * 10-17 cm2 molecule-1, calibrated relative to the loss of allyl iodide, is in good agreement with the single published determination.The observed time dependence of CH2=CHCH2 in the various chemical systems allowed measurement of rate coefficients for the following reactions 2CH2=CHCH2 (+M) -> CH2=CHCH2CH2CH=CH2 (+M) (10), CH2=CHCH2 + I (+M) -> CH2=CHCH2I (+M) (12), CH2=CHCH2 + O2 (+M) -> CH2=CHCH2O2 (+M) (7).The parameters obtained were k10 = (3.0 +/- 0.5) * 10-11, k12 = (1.6 +/- 0.6) * 10-10, and k7 = (6 +/- 2) * 10-13 cm3 molecule-1 s-1.The UV absorption spectrum of CH2=CHCH2O2, characterised in the wavelength range 210-300 nm, is typical of an organic peroxy radical, with a peak cross-section of (6.2 +/- 0.9) * 10-18 cm2 molecule-1 at 235 nm.CH2=CHCH2O2 displayed second-order kinetic behaviour indicative of its removal via the self-reaction: 2CH2=CHCH2O2 -> 2CH2=CHCH2O + O2 (13a) -> CH2=CHCHO + CH2=CHCH2OH + O2 (13b).The observed rate coefficient, k13obs = (1.1 +/- 0.2) * 10-12 cm3 molecule-1 s-1, is greater than the elementary coefficient, k13, owing to secondary removal of CH2=CHCH2O2.The observed and elementary coefficients are related by the expression k13obs = (1 + α13)k13, where α13 = k13a/k13.Associated long pathlength Fourier transform infrared (FTIR) measurements of the products of the 253.7 nm initiated photo-oxidation of allyl iodide, allowed the product channels of reaction (13) to be identified and quantified, and a value of α13 = 0.61 +/- 0.07 was determined, leading to k13 = (6.8 +/- 1.3) * 103 cm-13 molecule-1 s-1.The kinetic and mechanistic data obtained for CH2=CHCH2O2, and those measured previously in this laboratory for HOCH2CH2O2, are used to infer average rate coefficients for peroxy radicals (RO2) formed in the OH-initiated oxidation of isoprene.A simple box model of the planetary boundary layer is used to demonstrate the potential impact of elevated concentrations of isoprene on ambient levels of OH, HO2, RO2, O3 and NOx.

A heterogeneous recoverable catalyst was prepared via the complexation of palladium onto the surface of magnetic nanoparticles coated by a poly(1-vinyl imidazole) brush. The stable, active and reusable catalyst was proven to be highly active in aerobic oxidation of primary and secondary alcohols with excellent yields. Only 0.1 mol% of the catalyst was used to oxidize 1 mmol of primary and secondary alcohols. The catalyst was readily recovered and reused up to 10 times under the described reaction conditions without significant loss of activity.

A fast, mild, and reasonable oxidizing agent, pyridinium sulfonate chlorochromate (VI), C5H5NSO3H[CrO 3Cl] (PSCC) is synthesized. Its reactions with primary, secondary, benzylic, and allylic alcohols under very mild conditions give the corresponding carbonyl compounds. These are obtained with relatively short reaction times. The oxidant/substrate ratios of 1:1 are employed.

The addition of phosphoric acid to WNbO catalyst active for glycerol transformation to acrolein and to WVNbO catalyst active for direct transformation of glycerol to acrylic acid appreciably improved their catalytic performance. The phosphoric acid-added WNbO catalyst gave acrolein yield of 81.8%, and the phosphoric acid-addedWVNbO catalyst gave acrylic acid yield of 59.2% in the direct glycerol transformation. The improvement of the catalytic performance seems due to the increases of the acid amount and the Bronsted acidity.

The adsorption and reaction of allyl alcohol on clean and atomic oxygen covered Ag(110) has been investigated with temperature programmed reaction spectroscopy (TPRS).Allyl alcohol adsorbs and desorbs molecularly from the clean Ag(110) surface.When the surface is covered with 0.1 monolayer (ML) of atomic oxygen, allyl alcohol forms an intermediate that reacts further to yield hydrogen, water, acrolein, and allyl alcohol at 310 K in a single rate-limiting first-order reaction.Increasing the oxygen coverage to 0.25 ML increases the amount of products formed as expected for activation of the allyl alcohol by the predosed oxygen.The results obtained are consistent with the formation of an alkoxy intermediate, which has also been observed for methanol and ethanol on this surface.

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Supported nickel sulfate was proved to be an efficient catalyst for gas-phase dehydration of glycerol to acrolein at 340 °C in the presence of oxygen. At a GHSV of glycerol of 873 h-1, glycerol conversion over 17NiSO4-350 was still higher than 90% even after 10 h of reaction, with selectivity to acrolein always higher than 70 mol.%. It was demonstrated that Lewis acid sites were responsible for heavy compounds formation, and that Bronsted acid sites with medium and high strength were active sites for acrolein production from glycerol dehydration. The acidity of supported nickel sulfate was associated with one metastable structure, NiSO4· xH2O (0 x 1). Furthermore, not only nickel cations but also sulfate groups exhibited oxidizability during reactions, and loss of sulfur was the main reason for irreversible deactivation of supported nickel sulfate.

The solution combustion method (SCS) is demonstrated as an easy and fast alternative method allowing the synthesis of mixed oxides with thermally sensitive metals, still keeping a good control on their stoichiometry and phase composition. Bismuth molybdates with different theoretical Bi/Mo atomic ratios, namely α-Bi2Mo3O12, β-Bi2Mo2O9, and γ-Bi2MoO6 were synthesized by the SCS, fully characterized by XRD, Raman, SEM/EDX, BET and XPS analyses, and tested in the partial oxidation of propene to acrolein. The SCS method allowed obtaining crystalline catalysts with Bi/Mo atomic ratios close to the theoretical values and very good catalytic properties namely high propene conversion (from 13.4 to 23.4%) and acrolein selectivity (from 71.5 to 80.0%) at 425°C. A high purity of the SCS prepared bismuth molybdates was obtained by means of a subsequent calcination treatment. Such treatment did not alter the high catalytic activity of the catalysts, which slightly increased (from 12.3 to 25.5%), but induced a marked loss of acrolein selectivity (from 66.2 to 48.4%) at 425°C. This effect is due to a strong increase of the oxidation states of Mo and Bi and reduction of the specific surface area during the calcination.

The impact of acid/base properties (determined by adsorption microcalorimetry) of various catalysts on the cross-aldolization of acetaldehyde and formaldehyde leading to acrolein was methodically studied in oxidizing conditions starting from a mixture of methanol and ethanol. The aldol condensation and further dehydration to acrolein were carried out on catalysts presenting various acid/base properties (MgO, Mg–Al oxides, Mg/SiO2, NbP, and heteropolyanions on silica, HPA/SiO2). Thermodynamic calculations revealed that cross-aldolization is always favored compared with self-aldolization of acetaldehyde, which leads to crotonaldehyde formation. The presence of strong basic sites is shown to be necessary, but a too high amount drastically increases COx production. On strong acid sites, production of acrolein and carbon oxides (COx) does not increase with temperature. The optimal catalyst for this process should be amphoteric with a balanced acid/base cooperation of medium strength sites and a small amount (?1) of very strong basic sites (Qdiff>150 kJ mol?1).

Zirconia-supported tungsten oxide (WO3/ZrO2 or WZ) is known as an efficient catalyst for selective acrolein (AC) production from gas-phase dehydration of glycerol (GL). Two catalysts (WZ-CP and WZ-AN) were prepared herein using, respectively, a ZrO(OH)2 hydrogel (ZrO(OH)2-CP) and its derived alcogel (ZrO(OH)2-AN) for a precursor of ZrO2. To optimize the reaction variables and improve the catalyst performance, the WZ-CP catalyst was employed to show the effects of (A) reaction variables (temperature, partial pressures of GL and H2O, and co-feeding H2 or O2); (B) catalyst modification with alkali and alkali earth metal ions (Na+, K+ and Mg 2+), or transition metals (Pt, Pd, Rh and Ni). The reaction at 315 °C always produced the highest AC selectivity, and this temperature was then used to investigate the effects of the other variables and catalyst modifications. Increasing the molar GL/H2O ratio led to lower AC selectivity and accelerated the catalyst deactivation. Introducing 4-8 kPa O2 to the reaction feed significantly reduced the catalyst deactivation rate but the AC selectivity was only slightly lowered. However, an addition of 4 kPa H2 produced almost no effect on the reaction. The modified catalysts performed no better during the reaction unless the modifier was Pt or Pd, whose catalytic stabilities in the O2-containing (4 kPa) feed were significantly higher and their selectivity for AC production slightly lowered. Working under the conditions optimized with WZ-CP, the WZ-AN catalyst offered a high AC yield (62-68%) for longer than 30 h, during which the GL conversion remained higher than 93%.

Liquid phase dehydration of glycerol to acrolein commonly suffers from a low acrolein yield because of severe side reactions of chemically active acrolein with itself or glycerol in the reaction system. Rapid separation of acrolein from the reaction system is one of the effective strategies to increase the yield of acrolein. Herein, a renewable water-in-oil Pickering emulsion with silica nanoparticle cages as microreactors was designed for liquid phase glycerol dehydration to acrolein. The influences of the oil phase types on the droplet size of the Pickering emulsion and the yield of acrolein were investigated in a microreactor. The smaller Pickering emulsion droplet showed a superior ability to intensify the separation of chemically unstable acrolein molecules from the nanoparticle cages and thus improved the yield of acrolein. A droplet size of about 11 μm was obtained with peony seed oil as the oil phase, in which 84.6% of acrolein yield was achieved. This journal is

Allyl alcohol can be converted into hydrocarbons, acrolein and diallyl ether and control of product selectivity can be achieved by selection of the cation exchanged form of zeolite Y used as catalyst.

V-containing mesoporous silica with 3D structure was prepared by a hydrothermal procedure using NH4VO3 as the vanadium precursor and with varied reaction mixture pH values (pH = 3 and pH = 5). The combined use of DR UV-vis and H2-TPR techniques confirmed the successful incorporation of vanadium into the structure of the mesoporous silica material. The number of acid sites, evidenced by ammonia TPD, strongly correlates with the vanadium content. Propene oxidation with N2O revealed the noticeable activity of the synthesised vanadium-containing mesoporous materials in epoxidation reactions. The activity of the synthesized vanadosilicates is compared with the performance of vanadium-supported catalysts (on mesoporous silica of 3D structures) prepared by wet-impregnation method. On the basis of TOF analysis indicating the activity of particular vanadium ions, it was evidenced that although the presence of isolated V species is crucial in propene epoxidation, the availability of the active species is of paramount importance for proper vanadium utilization.

Vanadium oxide has been deposited by a grafting technique onto TiO2 anatase, both pure and doped with potassium [(1.2 and 2.5) atoms nm-2]. The V content varied between 0.1 and 20 atoms nm-2 [0.01-2 V2O5 monolayers (ML)]. The prepared samples were characterized by X-ray photoelectron spectroscopy (XPS), 51V magic-angle spinning (MAS) NMR and a surface potential (SP) technique and tested as catalysts in the oxidative dehydrogenation (ODH) of propane and propan-2-ol decomposition, a probe reaction for acid-base properties. From the XPS and SP data it has been inferred that VOx are located beside the K centres on the bare surface of TiO2 with the lower K content sample, whereas they cover the K-doped fraction of the surface for the sample with higher K content. Monomeric and polymeric VOx species and V2O5 were detected by 51V NMR on pure and K-doped catalysts. For the K-doped samples the polymeric species were observed only at high V content and new tetrahedral VOx species and traces of KVO3 appeared. It has been found that the presence of K on the TiO2 surface leads to (a) a decrease in the reducibility of the vanadia phase at low V content; (b) a decrease in the surface potential (electronic work function); (c) a decrease in acidity and increase in basicity and (d) a decrease in the total activity for ODH of propane. The pattern of the activity and selectivity changes with the total V content depends on the amount of K on the support surface: with K 2O5 ML. At higher K content, higher amounts of vanadium (> 1 ML) are required to obtain the same catalytic performance. Polymeric [VOx] species seem to be more active and selective in the ODH of propane than monomeric species or bulk V2O5.

Partial oxidation of propene by oxygen species transported electrochemically on MoO3-Bi2O3 via yttria-stabilized zirconia at 450 deg C revealed that the oxygen atoms bound to molybdenum insert into an allylic intermediate of propene to form acrylaldehyde while bismuth species are responsible for oxygen incorporation into the catalyst.

MoO3-Bi2SiO5/SiO2 catalysts with a Mo/Bi molar ratio of 5, prepared by a two-step hydrothermal and simple impregnation method, were investigated for the epoxidation of propylene by O2 and characterized by XRD, N2 absorption-desorption isotherms, thermogravimetric analysis (TGA), temperature-programmed reduction, NH3 temperature-programmed desorption (TPD), and IR, Raman, and X-ray photoelectron spectroscopy (XPS). On MoO3-Bi2SiO 5/SiO2 with Mo/Bi=5 calcined at 723K, a propylene conversion of 21.99 % and a propylene oxide selectivity of 55.14 % were obtained at 0.15MPa, 673K, and flow rates of C3H6/O 2/N2=1/4/20cm3 min-1. XRD, IR spectroscopy, and XPS results show that Bi2SiO5 and MoO3 are crystalline nanoparticles. NH3-TPD results indicate that the surface acid sites are necessary for the high catalytic activity. The results of TGA and N2 absorption-desorption isotherms reveal that a reasonable calcination temperature is 723K. The reaction mechanism of propylene epoxidation on MoO3-Bi2SiO 5/SiO2 catalysis is hypothesized to involve an allylic radical generated at the molybdenum oxide species and the activation of O 2 at the bismuth oxide cations. A new sensation in epoxidation: We describe the probable synergistic effects of MoO3 and Bi 2SiO5 in propylene epoxidation. The reactive centers consist of nanoparticulate species of crystalline MoO3 to activate the propylene and bismuth oxide cluster cations to activate O2.

H3PW12O40 catalysts supported on mesoporous titania (XH3PW12O40/MT (X = 5, 10, 15, 20, 25, and 30)) were prepared with a variation of H3PW12O40 content (X, wt%), and they were applied to the dehydration of glycerin to acrolein. The prepared catalysts were characterized by FT-IR spectroscopy, X-ray diffraction, N2 adsorption-desorption, and pyridine-adsorbed in-situ FT-IR spectroscopy analyses. The effect of H3PW12O40 content on the physicochemical properties and catalytic activities of XH3PW12O40/MT catalysts was investigated. It was found that surface area and pore volume of XH3PW12O40/MT catalysts decreased with increasing H3PW12O40 content. Br?nsted acidity of XH3PW12O40/MT catalysts showed a volcano-shaped trend with respect to H3PW12O40 content. The catalytic performance of XH3PW12O40/MT catalysts was closely related to the Br?nsted acidity of the catalysts. It was revealed that yield for acrolein over XH3PW12O40/MT catalysts increased with increasing Br?nsted acidity of the catalysts. Among the catalysts tested, 20H3PW12O40/MT catalyst with the largest Br?nsted acidity showed the highest yield for acrolein.

The effect of silylation on a series of Au/Ti-SiO2 catalysts for the direct epoxidation of propylene in the presence of H2 and O2 was studied. It was found that silylation significantly improved catalyst performance: propylene conversion, propylene oxide (PO) selectivity, and H2 efficiency increased. The extent of improvement depended on the Au and Ti content of the catalysts. The catalyst showing the best activity (Au(0.1)/Ti(1)-SiO2) exhibited an average PO formation rate of 121 gPO kgcat?1 h?1 and a PO selectivity of 92% at 473 K, while the catalyst having the maximum Au and Ti loading (Au(1)/Ti(5)-SiO2) showed the most significant improvement in performance with a 78% increase in the rate of PO formation upon silylation. The catalysts were characterized by contact angle measurements, FTIR, TGA, TEM, ICP-OES and these observations were used to elucidate the key factors governing the enhanced catalytic performance upon silylation. It was found that the silylated catalyst exhibited superior performance due to increased hydrophobicity, which aids product desorption, a decrease in acidic sites that are responsible for side-product formation, and a possible redistribution of the Au particles.

Gas-phase dehydration of aqueous propane polyols including glycerol, 1,2- and 1,3-propanediols was investigated over various solid catalysts with a wide range of acid-base properties. Fairly high selectivity (40-75 mol%) for propanal formation from 1,2-propanediol, and acrolein from glycerol was obtained over the catalysts with high fractional acidity in the range of -8.2 0 ≤-3.0, in which Br?nsted acidity appeared advantageous over Lewis acidity. The dehydration of 1,3-propanediol produced quite scattered products and a clear relationship between its product selectivity and the catalyst acidity could not be established. Mechanistic implications of these observations are discussed, which point to that the dehydration reactions of both 1,2-propanediol and glycerol are initiated by activation of the hydroxyl group bonded with the central carbon atoms.

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The rate of oxidation of C//3H//6, C//2H//4, C//3H//8, and CO has been investigated over V-Sn oxides of various compositions. The rate shows two maxima at V-Sn(V/Sn equals 2/1) and (1/8) oxides. Comparison between the rate of reduction of the oxides with C//3H//6 and that of the corresponding catalytic oxidation suggests that the oxygen species responsible for oxidation differs for V-Sn(2/1) and V-Sn(1/8) oxides. The amount of oxygen desorbed in the temperature range 400-530 degree C varies with the composition of the V-Sn oxides, showing a maximum at V-Sn(2/1) oxide. With V-Sn(1/8) oxide, little or no oxygen desorption is observed. On the basis of these results together with those of structural studies, it is concluded that the rate maximum with V-Sn(2/1) oxide arises from formation of an amorphous material from which lattice oxygen is easily released, while the rate maximum with V-Sn(1/8) oxide is associated with the presence of V**4** plus ions dissolved in SnO//2.

A series of laboratory and modelling experiments on the oxidation of propene in the gas phase has been undertaken to determine conditions which give high yields of propene oxide.The conditions under which the experiments were conducted were 505 - 549 K and up to 4 bar pressure.It is proposed that propene oxide is formed from propene by reaction with several peroxy radicals including HO2 and CH3CO3.However, one of the more important radicals is hydroxypropylperoxy.Its reaction with propene, under these conditions (107) HOCH2CHO2CH3 + C3H6 -> HOCH2CHOCH3 + C3H6O is more important than concerted decomposition to formaldehyde and acetaldehyde.

Among alkali metal ions, Cs+ was found to be the most efficient promoter of the CuOx/SiO2 catalyst for the epoxidation of propylene to propylene oxide (PO) by O2. Stronger interactions between Cs+ and CuOx nanoparticles were proposed to favor the selective formation of PO. Kinetic studies indicated that PO was formed as a primary product in parallel with acrolein over the CuOx/SiO 2 catalyst, but PO readily underwent isomerization to allyl alcohol, followed by oxidation to acrolein, without Cs+ modification. The modification by Cs+ inhibited the isomerization of PO because of the weakened acidity, contributing to the increase in PO selectivity. The inhibition of the reactivity of the lattice oxygen in the presence of Cs+ also promoted PO selectivity by suppressing the allylic oxidation route. In situ X-ray diffraction, CO-adsorbed Fourier-transform infrared, and pulse-reaction studies suggest that CuI sites generated during the reaction account for the epoxidation of propylene by O2.

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Abstract: Highly dispersed silica-supported CuOx/SiO2 catalysts were synthesized via solution-phase deposition and studied for their activity, selectivity, and stability in catalyzing the selective oxidation of propylene to acrolein. Strategies for ensuring high metal dispersion included controlling the surface density of silanols (via covalent silanol-capping) or by pre-installing different “promoter” transition metals at submonolayer coverages. A comparison of the effect of first row transition metal promoters showed that V and Cr significantly boost catalyst performance and stabilize CuOx sites against aggregation. Graphic Abstract: [Figure not available: see fulltext.].

The present invention relates to a 6-(isooxazolidin-2-yl)-N-phenylpyrimidin-4-amine derivative, and a pharmaceutical composition for preventing or treating cancer comprising the compound as an effective component. The compound exhibits high inhibitory activity against an epidermal growth factor receptor (EGFR) variant, or wild-type or variants of one or more of ERBB2 and ERBB4, and thus may be usefully used in the treatment of cancers in which same are expressed. In particular, the compound exhibits excellent inhibitory activity on proliferation of lung cancer cell lines, and can thus be usefully used in the treatment of lung cancer.

Conversion of glycerol to acrolein is a useful reaction for value-added application of biodiesel-derived glycerol and bioenergy development. The high-performance solid acid catalyst is essential to this dehydration reaction. In this paper, tungsten-based heteropolyacids (HPA) were supported on non-ordered mesoporous silica (MSU-x) to increase their dispersion and used as catalysts for glycerol dehydration to acrolein. Aiming to reveal the surface structure of HPA and resulting acidic properties, as well as the relationship between acidic properties and dehydration activity, different loadings of H3PW12O40 were supported on MSU-x (10–50 wt%) and the catalysts were characterized by X-ray diffraction (XRD), BET, SEM/TEM, UV–vis diffuse reflectance spectra (DRS), Raman and FT-IR techniques. Their acidic properties were studied by NH3-Temperature Programmed Desorption (NH3-TPD) and Pyridine adsorption methods. The molecular structure and dispersion of H3PW12O40 supported on the catalysts was revealed. The Keggin unit preserved well but with different hydration level for various loadings. The total acid concentration and respective Br?nsted/Lewis acid identification were calculated. The acrolein yield increased with H3PW12O40 loading until 30 wt% and showed less change with higher loadings. Based on the correlation of acrolein formation rate with acidic properties, the active role of Br?nsted acid and the cooperative role of Br?nsted/Lewis acid sites for glycerol dehydration to acrolein were discussed. This work provides new insight into the structure evolution of heteropolyacids and the catalyst design for the glycerol to acrolein.

Industrially-applied mixed metal oxide catalysts often possess an ensemble of structural components with complementary functions. Characterisation of these hierarchical systems is challenging, particularly moving from binary to quaternary systems. Here a quaternary Bi?Mo?Co?Fe oxide catalyst showing significantly greater activity than binary Bi?Mo oxides for selective propylene oxidation to acrolein was studied with chemical imaging techniques from the microscale to nanoscale. Conventional techniques like XRD and Raman spectroscopy could only distinguish a small number of components. Spatially-resolved characterisation provided a clearer picture of metal oxide phase composition, starting from elemental distribution by SEM-EDX and spatially-resolved mapping of metal oxide components by 2D Raman spectroscopy. This was extended to 3D using multiscale hard X-ray tomography with fluorescence, phase, and diffraction contrast. The identification and co-localisation of phases in 2D and 3D can assist in rationalising catalytic performance during propylene oxidation, based on studies of model, binary, or ternary catalyst systems in literature. This approach is generally applicable and attractive for characterisation of complex mixed metal oxide systems.

A method for the simple and efficient microwave radiation-assisted hydrothermal synthesis of Fe2(MoO4)3 has been developed. Several factors such as pH, addition rate, molybdenum precursor, type of solvent and various other microwave synthesis parameters are studied. The catalysts were characterized using X-ray diffraction, scanning electron microscopy, M?ssbauer spectroscopy and specific surface area measurements. The results show that different morphologies can be obtained, depending on the conditions under which the iron molybdate is prepared. Nevertheless, in all cases the solid particles appear to be covered by an amorphous oxide layer, which is less rich in iron than in the case of a crystallized oxide layer. The presence of this amorphous layer was revealed on all facets of the molybdate, with approximately the same composition and thickness. In an effort to evaluate the relationship between the morphology of iron molybdate particles and their catalytic properties, several samples exhibiting different morphology were tested for the oxidation of propene to acrolein. These samples were tested for the oxidation of propene to acrolein. The catalysts with platelets morphology and exhibiting larger surface of (100) planes appeared more active. This was attributed to a faster re-oxidation due to the preferential diffusion of oxygen anions in the bulk structure channels perpendicular to these planes.

Abstract: Novel Mo-V-PMMA and Mo-V-PS catalysts are prepared by addition of hard polymethyl methacrylate (PMMA) and polystyrene (PS) nanospheres into Mo/V compounds in the preparation process, respectively. The catalytic tests in selective oxidation of acrolein reveal that Mo-V-PMMA catalyst shows very high acrolein conversion (99.1%) and the yield of acrylic acid (90.7%). The BET, DLS, SAXS, XRD, XPS, H2-TPR and NH3-TPD measurements reveal that the addition of PMMA and PS nanospheres causes the obvious changes of porous structure, crystal phases composition and chemical properties of catalysts. These differences between Mo-V-PMMA and Mo-V-PS catalysts are attributed to the totally different “real” nano–environment during heat treatment in the high–concentration component mixture. PS nanospheres are in a state of adhesion or agglomeration or not uniformly distributed in the active component solution, while PMMA nanospheres with much better hydrophilicity and monodispersed state promote Mo and V ions more easily and uniformly dispersed in the mixture. Graphic abstract: Novel Mo-V catalysts are prepared by addition of hard polymethyl methacrylate (PMMA) and polystyrene (PS) nanospheres into Mo/V mixture. Obvious changes of porous structure, crystal phases and chemical properties of catalysts are caused by the nanospheres introduction, showing very high acrolein conversion (99.1%) and the yield of acrylic acid (90.7%) in selective oxidation of acrolein.[Figure not available: see fulltext.].

A total synthesis of the marine macrolide biselide A is described that relies on an enantiomerically enriched α-chloroaldehyde as the sole chiral building block. Several strategies to construct the macrocycle are presented including a macrocyclic Reformatsky reaction that ultimately provides access to the natural product in a longest linear sequence of 18 steps. Biological testing of synthetic biselide A suggests this macrolide disrupts cell division through a mechanism related to the regulation of microtubule cytoskeleton organization. Overall, this concise synthesis and insight gained into the mechanism of action should inspire medicinal chemistry efforts directed at structurally related anticancer marine macrolides.

A new bismuth molybdate, obtained by means of microwave-assisted hydrothermal synthesis, is described by the chemical formula: β(L)-Bi2Mo2O9, in accordance with its low crystallization temperature and transition to β-Bi2Mo2O9 at 532 °C. Its structure, solved ab initio using powder diffraction data, crystallizes in the monoclinic system (space group P21/c), with a = 8.11413(5), b = 8.54445(5), c = 13.43623(6) ?, and β = 123.5085(2)°. This phase has been tested as a catalyst for the oxidation of propene. It appears to be highly stable on stream, with a specific rate of propene conversion comparable to that of α-Bi2Mo3O12 and a slightly higher selectivity to acrolein. A possible active site for the abstraction of the first hydrogen from propene has been identified, by analogy with that proposed for α-Bi2Mo3O12 and seems to correspond to a molybdenyl Mo = O oxygen that is weakly coordinated to a neighboring Bi cation.

The present invention relates to a process for producing methacrylic acid or methacrylic acid esters. The present invention is directed to a new process for the production of methacrylic acid or alkyl methacrylate starting from Acrolein, which is available from glycerol or propane.

The invention relates to the field of pesticides, and discloses a preparation method of a quinclorac herbicide intermediate 7-chloro-8-methylquinoline, wherein the method comprises: carrying out a contact reaction on 2-methyl-3-chloroaniline, a monobasic inorganic acid, acrolein and a dehydrogenation reagent in the presence of an organic solvent to obtain 7-chloro-8-methylquinoline. According to the method, sulfuric acid can be prevented from being used in the cyclization reaction, so that the consumption of liquid caustic soda is reduced, and the amount of wastewater is reduced.

Abstract: The activity of catalytic systems based on polyoxometalates in the gas-phase dehydration of glycerol into acrolein has been investigated. The catalysts synthesized have been characterized using FTIR spectroscopy, X-ray phase analysis, scanning electron microscopy, and low-temperature nitrogen adsorption/desorption (BET method). It has been shown that the nature of the surface acid sites of catalysts has a significant effect on the direction of glycerol transformation. An increase in the fraction of Br?nsted acid sites in the catalyst leads to an increase in the yield of acrolein. At the same time, an increase in the fraction of Lewis acid sites in the catalyst leads to an increase to the yield of acetol, which is formed through a competing route. Among the catalytic systems considered, the best results have been obtained with the silicomolybdic acid anion supported onto alumina (SiMo/A). The main patterns of the gas-phase glycerol dehydration have been studied using SiMo/A as a catalyst, and the conditions responsible for the highest yield of acrolein have been determined.

Two different supports containing zinc (ZnO and Zn/SBA-15) were used to prepare mono- and bimetallic gold, silver and gold-silver catalysts. Zinc was used for two different purposes in these materials: (i) as a support in the form of zinc oxide and (ii) as a dopant introduced to short-channel SBA-15 by wetness impregnation. Short channel SBA-15 was used as the reference support. The materials obtained were characterized by: N2 physisorption, XRD, TEM, UV–vis, XPS, XAS and their activity was tested in the reactions of propene and methanol oxidation in the gas phase. The state of metals (Au, Ag, Zn) and the composition of gold-silver alloy formed on the catalysts surface were considered in terms of thermal activation of catalysts in inert gas and in hydrogen flow as well as interaction with reagents and products of methanol and propene oxidation. It was found that silver species were responsible for the activity in propene oxidation and its total combustion to CO2, whereas (Au0)δ? metallic particles were active in methanol oxidation. Selectivity to acrolein in propene oxidation was achieved thanks to the presence of Au-Ag alloy whose composition depended on the presence of zinc oxide and activation conditions. The alloy was not stable and separated into metals upon propene oxidation conditions. In methanol oxidation, zinc species took part in selective oxidation to methyl formate.

The present disclosure relates to a catalyst for dehydration of glycerin, a preparation method thereof, and a production method of acrolein using the catalyst. Particularly, the catalyst according to an embodiment of the present disclosure is used in a dehydration reaction of glycerin to exhibit high catalytic activity, a high yield, and high selectivity to acrolein and acrylic acid, and has a longer lifetime compared to the conventional catalysts due to a characteristic that coke carbon cannot be easily deposited on the surface of the catalyst.

Gas phase conversion of glycerol to acrolein over a variety of aluminum phosphate (AlP) catalysts synthesized by a simple replacement reaction method with a variation in calcination temperature (300-700 °C, AlP-300, AlP-400, AlP-500, AlP-600, and AlP-700, respectively) has been investigated. The textural properties, acidities and coke contents of the samples were also determined. The catalysts were presented in an amorphous state when the AlP sample was calcined below 500 °C. Further increasing the calcination temperature promoted the formation of orthorhombic α-AlPO4 crystal. The weak acid sites increased when the calcination temperature was raised from 300 to 500 °C. However, the weak acid sites decreased when the AlP was calcined above 500 °C. The acidity of the catalyst played a crucial role in the glycerol dehydration reaction. The maximum acrolein selectivity of 66% at 98% glycerol conversion was obtained over AlP-500 catalyst, due to the largest number of acid sites and appropriate textural properties. AlP-700 exhibited the lowest glycerol conversion, owing to the formation of orthorhombic α-AlPO4 crystalline phase and the lowest amount of acid sites under high calcination temperature. The significant reduction in the acidity of the used sample led to a decrease of glycerol conversion.

Mesoporous aluminas were prepared using different precipitants at different pH of precipitation and evaluated in the gas phase dehydration of glycerol. Samples were characterized by thermal analysis techniques (TGA, NH3-TPD and TPO), specific surface area measurements, XRD and SEM. The gas phase dehydration of glycerol was performed in a fixed bed quartz tubular reactor at 773?K using a 10% glycerol aqueous solution. Thermogravimetric analysis has revealed the temperature regions of decomposition for the prepared alumina catalyst precursors. The specific surface area and the crystallinity of the samples were dependent on both the pH and the used precipitating agent. Samples precipitated with NaOH presented higher density of acid sites than the samples prepared with Na2CO3, regardless of precipitation pH. The catalytic properties of the prepared aluminas are mainly related to the specific surface area and to acidic characteristics. Conversions of glycerol above 85% were obtained for all samples. The selectivity for glycerol dehydration was strongly related to the amount and strength of acid sites. The best result for dehydration was obtained for samples prepared with NaOH and precipitated at pH = 5. These results are related to the higher specific surface area, greater amount of acid sites and the higher ratio of weak acid sites. TPO revealed the amount of carbon deposited on the catalysts. Samples that showed higher carbon formation also showed a higher production of light olefins, indicating that the formation of carbon is related to the formation of these byproducts. NH3-TPD has shown the ratio of different acid sites on the surface of alumina samples that makes possible to estimate the correlation between the acidity and the catalytic properties.

Oxidative debenzylation of N-benzyl aromatic amines using DMSO as a non-toxic oxidant and catalyzed by TsOH gave Nphenylimines, which were spontaneously hydrolyzed to form anilines and benzaldehydes in good yields. This reaction employs mild, metal-free conditions. The conditions are also suitable for the debenzylation of benzylphenylethers.

Selective transformation of glycerol to propanal (PA) provides a feasible route towards the sustainable synthesis of high value-added chemicals. In this work, zirconium phosphate (ZrP) was studied as support and Ru and Co as metal sites for glycerol hydrogenolysis in a continuous-flow reactor. It was found that ZrP-supported Co?O species had a moderate selectivity to PA (49.5 %) in glycerol hydrogenolysis. Notably, once Ru species were doped into CoO/ZrP, the resulting catalyst exhibited not only an outstanding catalytic performance for glycerol hydrogenolysis to PA (a selectivity of 80.2 % at full conversion), but also a high stability at least a 50 h long-term performance. The spent catalyst could be regenerated by calcining in air to remove carbonaceous deposits. Characterization indicated that the acid sites on ZrP played a very critical role in the dehydration of glycerol into acrolein (AE), that the distribution of Co was uniform, basically consistent with that of Zr, P and Ru, and that an especially close contact between Co?O and Ru species was formed on Ru/CoO/ZrP catalyst. The further activity tests and characterizations confirmed that there was a strong interaction between the dispersed Co?O species and Ru0 nanoparticles, which endowed Ru sites with high electronic density. This effect could play a role in facilitating the dissociation of H2, and thus in promoting the hydrogenation reaction. Besides, DFT calculations suggested that the Co?O species can adsorb more strongly the C=C bond of the intermediate AE on a highly coordinatively unsaturated Co (Cocus) site and thus lead to preferential hydrogenation at the C=C bond of AE to PA.

Direct epoxidation of propylene by molecular oxygen alone is one of the dream reactions in heterogeneous catalysis. Despite much effort, the yield of propylene epoxide is still too low to be commercially attractive due to the trade-off between conversion and selectivity. Here, we demonstrate that doping Cl into the lattice of Cu2O nanocrystals by the intergrowth method not only can enhance the catalytic selectivity and conversion of direct propylene epoxidation but also can solve the long-existing Cl loss problem. In particular, Cl-doped rhombic dodecahedral Cu2O with (110) exposing facets exhibited 63% PO selectivity with a 12.0 h-1 turnover frequency at 200 °C, outperforming any other coinage metal-based catalysts under mild conditions. Comprehensive characterization and theoretical calculations revealed that the Cl-decorated Cu(I) facilitated formation of electrophilic oxygen species, thus boosting the production of propylene oxide. This work provides a general strategy to develop catalysts and explore the promoter effect by creating uniform isolated anion doping to activate a nearby metal center by virtue of well-defined nanocrystals.

Tungstated metal phosphate (WOx/MP; M = Al, Zr and Ti) solid acid catalysts were examined for vapor phase glycerol dehydration to acrolein and hydroxyacetone. The physico-chemical characteristics of the samples were explored using X-ray diffraction (XRD), N2 sorption, Fourier-transform infrared spectroscopy (FT-IR), UV-visible diffuse reflectance spectroscopy (UV-DRS), and ex situ FT-IR investigation of the adsorbed pyridine and ammonia temperature programmed desorption (NH3-TPD) analysis to gain an understanding of the impact of the structural and acidic nature of the catalysts upon changing the metal component. The catalytic activity and selectivity functionalities were interpreted in terms of the acidity and structural properties of the WOx/MP catalysts. The outcomes demonstrated that WOx/TiP was the most selective and stable catalyst during the catalytic dehydration of glycerol owing to the acceptable amount of surface acidity and the substantial number of pores available on its surface. A detailed study on WOx/TiP was also performed to understand the interaction between the tungsten and the TiP support.

1,2-Ethylene-bis(para-methyl pyridinium) dichromate, (C 14 H 18 N 2) [Cr 2 O 7 ], is used as a new oxidizing agent in conversion of some alcohols to their corresponding carbonyl compounds in CH 3 CN solvent and also under solvent-free conditions. In both procedures, high conversion percentages are observed. However, a much shorter reaction time is achieved in solvent-free conditions. For allylic alcohols, the C = C bond is not oxidized and the examined saturated alcohol in this work (i.e. cyclo-hexanol) remains intact, which illustrates the mild nature of reagent used. The structure of the reagent is investigated by single-crystal X-ray diffraction analysis. The C–H · · · O and O · · · π interactions are the most important features of crystal packing, which are visualized by the Hirshfeld surface map.

V-containing silica SBA-3 mesoporous catalysts were prepared by means of one-pot hydrothermal procedure with NH4VO3 or VOSO4 as vanadium precursors under various acidic medium of the reaction mixture (pH 2-TPR allowed to determine the nature of vanadium species in the studied samples. A successful incorporation of vanadium into the structure of silica SBA-3 was attained for the samples with low V content (5 wt%) exhibited the presence of isolated vanadium and also of polynuclear surface species. The resulting V-bearing samples contain the Br?nsted and Lewis acidic centres evidenced by FTIR spectra of adsorbed pyridine and by catalytic activity for 2-propanol decomposition and cumene cracking. Ammonia TPD allowed to estimate the number and strength of acid sites in regards to the vanadium content. Propene oxidation with N2O revealed noticeable activity of the synthesised V-SBA-3 samples in epoxidation reaction. On the basis of TOF analysis indicating the activity of particular vanadium ions it seems that not all of the introduced V atoms take part in the formation of mild electrophilic oxygen species responsible for propene oxide formation.

Mixed iron and molybdenum oxide catalysts supported on nanostructured silica, SBA-15, were synthesized with various Mo/Fe atomic ratios ranging from 0.07/1.0 to 0.57/1.0. Structural characterization of as-prepared MoxOy_FexOy/SBA-15 samples was performed by nitrogen physisorption, X-ray diffraction, and DR-UV-Vis spectroscopy. Adding molybdenum resulted in a pronounced dispersion effect on supported iron oxidic species. Increasing atomic ratio up to 0.21Mo/1.0Fe was accompanied by decreasing species sizes. Strong interactions between iron and molybdenum during the synthesis resulted in the formation of Fe?O?Mo structure units, possibly Fe2(MoO4)3-like species. Reducibility of MoxOy_FexOy/SBA-15 catalysts was investigated by temperature-programmed reduction experiments with hydrogen as reducing agent. The lower reducibility obtained when adding molybdenum was ascribed to both dispersion and electronic effect of molybdenum. Catalytic performance of MoxOy_FexOy/SBA-15 samples was studied in selective gas-phase oxidation of propene with O2 as oxidant. Adding molybdenum resulted in an increased acrolein selectivity and a decreased selectivity towards total oxidation products.

Shaping is a crucial step to produce technical catalysts that remains as some sort of dark art for catalytic researchers in academia. This contribution discusses aspects concerning the fabrication of technical catalysts based on MnO2 powders ai

Endogenous histidyl dipeptides such as carnosine (β-alanine-l-histidine) form conjugates with lipid peroxidation products such as 4-hydroxy-trans-2-nonenal (HNE and acrolein), chelate metals, and protect against myocardial ischemic injury. Nevertheless, it is unclear whether these peptides protect against cardiac injury by directly reacting with lipid peroxidation products. Hence, to examine whether changes in the structure of carnosine could affect its aldehyde reactivity and metal chelating ability, we synthesized methylated analogs of carnosine, balenine (β-alanine-Nτ-methylhistidine) and dimethyl balenine (DMB), and measured their aldehyde reactivity and metal chelating properties. We found that methylation of Nτ residue of imidazole ring (balenine) or trimethylation of carnosine backbone at Nτ residue of imidazole ring and terminal amine group dimethyl balenine (DMB) abolishes the ability of these peptides to react with HNE. Incubation of balenine with acrolein resulted in the formation of single product (m/z 297), whereas DMB did not react with acrolein. In comparison with carnosine, balenine exhibited moderate acrolein quenching capacity. The Fe2+ chelating ability of balenine was higher than that of carnosine, whereas DMB lacked chelating capacity. Pretreatment of cardiac myocytes with carnosine increased the mean lifetime of myocytes superfused with HNE or acrolein compared with balenine or DMB. Collectively, these results suggest that carnosine protects cardiac myocytes against HNE and acrolein toxicity by directly reacting with these aldehydes. This reaction involves both the amino group of β-alanyl residue and the imidazole residue of l-histidine. Methylation of these sites prevents or abolishes the aldehyde reactivity of carnosine, alters its metal-chelating property, and diminishes its ability to prevent electrophilic injury.

MoFe-N, MoFe/c–CeO2, MoFe/p1–CeO2, and MoFe/p2–CeO2 (where N, c, and p stand for non-supported, nanocube, and nanoparticle) oxide catalysts were designed for gas-glycerol direct catalytic conversion into allyl alcohol. The catalysts also were characterized by XRD, TEM, BET, H2-TPR, and NH3-TPD. Mo–Fe oxides were highly dispersed on the surface of c-CeO2 and p-CeO2 supports, different with the MoFe-N consist of crystalline Fe2(MoO4)3 and Fe2O3 crystalline phase. The support effect and special natural property of CeO2 significantly improve the allyl alcohol selectivity from gas-glycerol over MoFe/CeO2. The p-CeO2 with low particle sizes and crystalline degree was superior to high-crystalline nanocube c-CeO2 to promote its interaction with the MoFe oxide active components, and improve the surface acid site concentration and reducibility of MoFe/CeO2 as well as catalytic activity and stability for allyl alcohol synthesis from gas-glycerol without any extra hydrogen donors. Over the MoFe/p2–CeO2, the glycerol conversion reached 97.1%, and the selectivity of allyl alcohol, enthanal, propanoic acid, and acrylic acid were 23.3%, 8.6%, 12.6%, and 7.8%, respectively, yielding allyl alcohol of 22.6%.

Dimethylsulfoniopropionate (DMSP) is one of the most abundant sulfur metabolites in marine environments. The biosynthesis of DMSP and its degradation to dimethylsulfide are important links in the planetary sulfur cycle. Herein, the first complete description of a DMSP biosynthetic pathway is provided by the in vitro reconstitution of four enzymes from Streptomyces mobaraensis. The isolation of DMSP from S. mobaraensis cells grown at high salinity confirmed that this actinobacterium is indeed is a DMSP-producing organism. The described DMSP biosynthesis follows the same route as that previously described for angiosperm plants. Despite this chemical congruence, limited sequence similarity between plant and bacterial enzymes suggests that the two biosynthetic activities emerged by convergent evolution.

Aqueous glycerol solutions of up to 50 wt% were reacted over magnesium oxide catalysts at temperatures greater than 300 °C, the reactivity of which was compared to catalyst-free reactions. Under catalyst-free conditions, modest levels of dehydration to hydroxyacetone were observed at temperatures >400 °C in a steel reactor tube and >320 °C over silicon carbide. For reactions over MgO, the product distribution becomes more diverse, resulting in the formation of methanol, acetaldehyde, ethylene glycol, 1,2-propanediol and acetic acid. The methanol space-time-yield over MgO catalyst samples (0.5 g) was found to be highest at 400 °C (205 g h-1 kgcat-1) with a 50 wt% solution of glycerol, or with a glycerol concentration of 10 wt%; 255 g h-1 kgcat-1 over 0.1 g of catalyst. Despite the high glycerol conversion achieved, the MgO catalyst was found to be stable over 48 h, following a modest decrease in glycerol conversion during the initial 2 h of reaction. Post-reaction characterisation revealed that the level of coking at high glycerol conversions (>90%) was ≥120 mg gcat-1. The carbon mass balance determined by GC analysis for a typical reaction was 75% and so the carbon lost from catalyst coking only represents a modest quantity of the missing carbon; typically 10%. MgO was also found to promote the formation of high molecular weight products via condensation reactions, which were responsible for the remainder of the missing carbon; ca. 15%. Therefore, the total organic content of the post-reaction mixture and coke was calculated to be 94% of the starting solution. We conclude that the catalyst surface directs the formation of methanol, however, the results indicate that the reaction conditions are crucial to obtain optimum yields.

Abstract: Hydrogen production by glycerol steam reforming is an attractive alternative, as it represents the conversion of a waste in a high-added value product. In this work, three catalysts were synthesized by wet impregnation of nickel precursor in different supports: γ-Al2O3 prepared by boehmite calcination, α-Al2O3 and 15 wt% CaO-γ-Al2O3 prepared by wet impregnation of calcium oxide precursor in γ-Al2O3. A commercial catalyst for methane steam reforming was also evaluated. Catalytic tests were performed at 500?°C, glycerol feed of 20% v/v and GHSV of 200,000?h?1. The calcium oxide incorporation reduced the formation of nickel aluminate phase (NiAl2O4) and the amount and strength of catalyst acidity, while increasing the amount and strength of basic sites. Furthermore, it was the only catalyst that has not presented deactivation in 30?h of reaction, showing the highest glycerol conversion and hydrogen yield after 24?h of reaction. Ni/γ-Al2O3 and Ni/α-Al2O3 presented a severe deactivation, which was associated with coke formation. The synthesized catalysts presented better catalytic performance for glycerol steam reforming in comparison with commercial catalyst, in terms of higher glycerol conversion, glycerol conversion to gas and hydrogen yield. Graphical Abstract: [Figure not available: see fulltext.]

Crystalline “MoVO”, “MoVCuO”, “MoVFeO” and “MoVWO” catalysts with a trigonal symmetry were successfully synthesized and characterized. The influence of the as-obtained structures on catalytic performances in selective oxidation reactions was investigated. MoVFeO and MoVCuO accomodated Fe and Cu species inside heptagonal channels, while W in MoVWO was incorporated in pentagonal {Mo6O21}6? units. Whereas MoVO and MoVWO showed catalytic activity in the selective oxidation of ethane and acrolein, MoVFeO and MoVCuO performed very poorly in the same reaction, suggesting that the presence of empty heptagonal channels is related to ethane and acrolein activations. In the selective oxidation of allyl alcohol, substantial amounts of acrolein (formed by oxidative dehydrogenation) and propanal (formed by isomerization) were formed as primary products over MoVO and MoVWO, whereas MoVFeO and MoVCuO preferentially promoted the formation of acrolein. It was found that the local crystal structure around the heptagonal channel was related with a modification of the reaction pathway for the selective oxidation of allyl alcohol. Due to the prevention of isomerization over MoVFeO, a high acrylic acid yield of 83.1% from allyl alcohol was achieved at 350 °C over this sample.

The gas-phase oxidehydration (ODH) of 1,2-propanediol to propionic acid has been studied as an intermediate step in the multi-step transformation of bio-sourced glycerol into methylmethacrylate. The reaction involves the dehydration of 1,2-propanediol into propionaldehyde, which occurs in the presence of acid active sites, and a second step of oxidation of the aldehyde to the carboxylic acid. The two reactions were carried out using a cascade strategy and multifunctional catalysts, made of W-Nb-O, W-V-O and W-Mo-V-O hexagonal tungsten bronzes, the same systems which are also active and selective in the ODH of glycerol into acrylic acid. Despite the similarities of reactions involved, the ODH of 1,2-propanediol turned out to be less selective than glycerol ODH, with best yield to propanoic acid no higher than 13percent, mainly because of the parallel reaction of oxidative cleavage, occurring on the reactant itself, which led to the formation of C1-C2 compounds.

The present invention relates to: a catalyst for glycerin dehydration; a preparation method therefor; and an acrolein preparation method using the catalyst. According to one embodiment of the present invention, the catalyst is used in glycerin dehydration so as to exhibit high catalytic activity, a high yield and high acrolein selectivity, and has a characteristic in which carbon is not readily deposited, thereby having a long lifetime compared with that of a conventional catalyst.

The present invention relates to a method for preparing acrylic acid from glycerin. More specifically, the present invention provides a method which can improve the selectivity of acrolein by applying a specific catalyst composition and process conditions to minimize the generation of coke carbon of the catalyst, and can prepare acrylic acid with higher productivity for a longer duration of time because a dehydration reaction can be performed for a longer working period while maintaining catalyst activity at a high level during the reaction.

Abstract: Vapour phase catalytic dehydration of glycerol to acrolein was studied over phosphotungstic acid (PTA) supported (with different loadings of PTA) on Y-zeolite catalysts. The active component PTA was varied between 10 and 40% w/w on the support Y-zeolite and was synthesized by the wet impregnation method. The physico-chemical characterization of the catalyst samples was investigated by X-ray diffraction (XRD), FT-IR, Raman and by the gas adsorption measurements. The XRD results showed that active component PTA is highly dispersed in an amorphous form at lower loadings of PTA and attained a crystalline state beyond 20?wt% of PTA. Both Raman and FT-IR spectra indicated that the Keggin ion structure of PTA was present in a highly dispersed state in the supported PTA/zeolite catalysts as compared to the bulk form of PTA. Temperature programmed desorption (TPD) of ammonia and FT-IR spectra of pyridine adsorption were used to determine the acidic properties of the PTA catalysts. The TPD of ammonia showed the presence of moderate acidity on the catalyst surface. The total acidity increased with raise in PTA loading up to 20?wt% and beyond this, it had decreased. The FT-IR results suggested the presence of Br?nsted acidity. The Pore size increased with PTA loading until 20?wt%. Finally, the PTA/zeolite catalysts were tested for the gas phase dehydration of glycerol in a fixed-bed, micro-reactor in the temperature range between 250 and 300 °C. Among all the catalysts tested, PTA (20?wt%)/zeolite showed a total conversion of 100% glycerol and a selectivity of 79% for acrolein. These results are correlated with surface acidity, textural and structural properties of the PTA/zeolite catalysts. Graphical Abstract: Glycerol dehydration products over Lewis and Bronsted acidic sites. [Figure not available: see fulltext.].

The oxidative dehydrogenation of allyl alcohol to acrolein over bulk alloyed and supported silver catalysts has been studied, with the aim of designing optimal Ag-based catalysts for this specific reaction. All of the tested catalysts were highly active and selective to acrolein at temperatures ranging between 340 and 380 °C. The results show that the alloying of Ag with Au or Cu leads to alloys with upper surface compositions comprising approximately between 35 and 65% silver. Although these elements improve the activity of Ag catalysts, they decrease their selectivity, leading to lower acrolein yields. Various different Ag catalyst supports were prepared (LaPO4, Carbon nanotubes CNT, TiO2, Al2O3 and SiO2) using the impregnation method, and subsequently tested. This study reveals that the catalyst with the best performance is Ag/SiO2 with a yield in acrolein of 87.2% at 360 °C. The results obtained with the tested catalysts are discussed, and the reasons of performance improvement or degradation caused by the presence of Au or Cu on the active silver sites, or by the presence of the supports, are raised.

Abstract: Processes of catalytic homocondensation of propanal and its cross-condensation with ethanal and methanal in the presence of aniline and amino acids have been studied. The dependence of the conversion of the reactants and selectivity of the homo/heterocondensation process on the catalyst nature and temperature has been revealed. It has been shown that the maximum acrolein selectivity is reached in the case of using benzoyl-substituted derivatives in water, with the proportion of the products of further condensation decreasing. The selectivity for the ethanal homocondensation product 2-butenal decreases simultaneously as a result of the formation of linear and branched oligomers of successive condensation.

A direct synthetic route was developed to prepare mesoporous-silica-nanoparticle-supported copper catalysts featuring ordered mesostructures with extensive intraparticle voids, a high degree of silica condensation, and a high dispersion of copper species. After hydrogen reduction, the catalysts containing nanosized metallic copper showed superior and stable catalytic activity for the selective oxidation of propylene by dioxygen, with high conversion of both reactants and high yield and formation rate of acrolein. The best catalyst outperformed the state-of-the-art silica-supported copper catalysts, representing one of the most active acrolein-production catalysts. Results of in situ X-ray absorption spectroscopy, in situ diffuse reflectance infrared Fourier transform spectroscopy, and other characterizations suggested that the metallic copper transformed and mainly stayed in the 1+ oxidation state under reaction conditions and that factors including the small size of copper and the presence of silanol groups on the silica support were crucial for the catalytic performance of the catalysts.

The one-step reaction of glycerol with hydrogen to form propene selectively is a particularly challenging catalytic pathway that has not yet been explored thoroughly. Molybdena-based catalysts are active and selective to C?O bond scission; propene is the only product in the gas phase under the standard reaction conditions, and further hydrogenation to propane is impeded. Within this context, this work focuses on the exploration of the reaction pathways and the investigation of various parameters that affect the catalytic performance, such as the role of hydrogen on the product distribution and the effect of the catalyst pretreatment step. Under a hydrogen atmosphere, propene is produced primarily via 2-propenol, whereas under an inert atmosphere propanal and glycerol dissociation products are formed mainly. The reaction most likely proceeds through a reverse Mars–van Krevelen mechanism as partially reduced Mo species drive the reaction to the formation of the desired product.

Modified H-ZSM-5 zeolite catalysts were studied for the dehydration of glycerol to acrolein in gas phase. The modifications were made by alkaline treatment using Na2CO3 solutions in different concentrations, followed by consecutive i

A series of W–V–O catalysts with different m-WO3 and h-WO3 phase contents were hydrothermally synthesized by employing different tungsten, vanadium, and ammonium precursors and characterized by powder XRD, N2 adsorption, SEM, X-ray energy-dispersive spectroscopy, thermogravimetric analysis, Raman and FTIR spectroscopy, NH3 temperature programmed desorption, H2 temperature-programmed reduction, and XPS. Finally, the acid/redox properties were analyzed by using aerobic transformation of methanol as a characterization reaction. A correlation between phase composition as well as acid and redox properties was observed, which were correlated to the catalytic performance of the title materials in a one-pot oxydehydration reaction of glycerol. The hexagonal tungsten bronze (h-WO3) phase shows a significantly higher concentration of acid sites than monoclinic m-WO3, so that the acid properties of W–V–O oxides are directly related to the presence of h-WO3 crystals. The presence of a higher concentration of acid sites in V-containing h-WO3 crystals is a key factor to achieve high selectivity to both acrolein and acrylic acid during one-pot glycerol oxydehydration. Also, V sites in h-WO3 show higher selectivity in the consecutive reaction (partial oxidation of acrolein to acrylic acid), while V sites in the m-WO3 phase fundamentally lead to the formation of carbon oxides.

A vanadium-catalysed deoxydehydration (DODH) of neat glycerol has been developed. Cheap and readily available ammonium metavanadate (NH4VO3) affords higher yields of allyl alcohol than the well-established catalyst methyltrioxorhenium. A study in which deuterium-labelled glycerol was used was undertaken to further elucidate the dual role of glycerol as both an oxidant and reductant. This study led to the proposal of a metal-catalysed DODH mechanism for the production of allyl alcohol and a deeper understanding of the formation of the byproducts acrolein and propanal.

In this study, modified niobium oxide were prepared to study the addictive effects on the catalytic performance for gas-phase glycerol dehydration. The catalysts were characterized by N2 adsorption/desorption, XRD, NH3-TPD, FT-IR. The amount of phosphoric acid was up to 50 wt% in niobium. As a result, the highest glycerol conversion was achieved over 20 wt% PO4/Nb2O5. It indicates that the optimal amount of phosphoric acid leads the catalyst to have appropriate acidity which is an important factor for gas-phase glycerol dehydration.

Abstract: Vanadium modified mesocellular silica foams (MCF) materials (V content ca. 3 and 5 wt%) prepared by the impregnation method show mainly isolated or low-polymeric VOx species, which was confirmed by means of Raman spectroscopy and DR UV–Vis. Textural measurements, and also XRD and TEM results indicate that the characteristic mesocellular structural features of MCFs are preserved after vanadium incorporation. The MCF-supported vanadia catalysts exhibit much higher propene conversion and propene oxide productivity when compared to vanadium modified mesoporous silicas of 2D structure, demonstrating that apart from the presence of highly dispersed isolated vanadium species, internal molecular transport within three-dimensional ultra large pores of MCF materials also plays an important role in gas-phase propene epoxidation. Graphical Abstract: [Figure not available: see fulltext.]

Information on the volume of production of biodiesel and crude glycerol is discussed. The possibility of using crude glycerol as a feedstock for preparing solketal is demonstrated. The specific features of the solketal synthesis from crude glycerol and of separation of the reaction products are described. A catalytic process is suggested for selective decomposition of solketal to glycerol to obtain purified glycerol of any required concentration up to 99.8 wt.%. A flowsheet is provided for processing of crude glycerol to obtain solketal and subsequently converting it to obtain pure glycerol.

Abstract: The effect of the nature of zeolite catalysts H-ZSM-5, H-BETA, and SAPO-34 on the activity and selectivity in the conversion of glycerol into aromatic hydrocarbons, acrolein, and oxygenates (various glycerol ethers) was studied. H-ZSM-5 was foun

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