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Propane to propene oxide (PO) oxidation over V-containing mesoporous silica of SBA-3 structure has been studied using different oxidants (nitrous oxide, oxygen, and their mixture) in the temperature range 673–773 K. Electron spin resonance spectroscopy, ultraviolet–visible spectroscopy, and X-ray photoelectron spectroscopy (XPS), as well as X-ray diffraction, temperature-programmed reduction with hydrogen (H2 TPR), and low-temperature N2 adsorption/desorption, were applied for characterization of fresh and spent catalysts. XPS spectra and H2 TPR profiles revealed a significant reduction of V-species as a result of propane oxidation with N2O alone, which leads to a decrease in both propane conversion and the space–time yield (STY) of PO. The use of an N2O–oxygen mixture as an oxidant of propane allows the vanadium valence to be stabilized at a level similar to the initial sample, which results in stable activity with time on stream. Propane conversion of 40%, propylene selectivity of 45%, and propylene oxide selectivity of 11%, corresponding to a STY of propylene oxide of about 15 g kgcat-1h?1, have been obtained, which makes these results very promising compared with the data reported in the literature. Vanadium catalyst used with only oxygen results in stable propane conversion with high total oxidation and stable propene selectivity, although the STY of PO is 10 times lower. N2O applied as the only oxidant results in rapid catalyst deactivation, and after 2 h on stream, STY of PO is only 2.5 g kgcat-1h?1.

A method for producing propylene oxide involves an oxidation step, a distillation step, an epoxidation step, and a separation step. The distillation step involves distilling the reaction mixture containing cumene hydroperoxide to separate it into a concentrate containing cumene hydroperoxide and a distillate. The reaction mixture is continuously distilled so that the ratio of the flow rate of the distillate to the flow rate of the reaction mixture to be distilled is 0.037 to 0.13. The epoxidation step involves obtaining a reaction mixture containing propylene oxide and cumyl alcohol by contacting the concentrate with propylene in the presence of a catalyst in one or more reactors to cause a reaction between propylene and cumene hydroperoxide in the concentrate, in which the outlet temperature of the final reactor is adjusted to 115° C. or more and less than 140° C.

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.

A Schiff-base molybdenum complex (MoO2–salen) supported on mesostructured cellular foam (MCF) was initially prepared by an in situ synthesis method under acidic conditions. Following silanization modification, a MoO2–salen?MCF-S sample with improved surface hydrophobicity was obtained. The ligand environment of molybdenum within the samples has been analyzed by Fourier-transform infrared spectroscopy, ultraviolet/visible spectroscopy, and X-ray photoelectron spectroscopy. Furthermore, the textural and structural properties of the corresponding materials have been characterized by nitrogen adsorption–desorption isotherms and transmission electron microscopy. Despite of the presence of fewer MoO2 species, the results showed that MoO2–salen?MCF-S has more active Mo centers than MoO2–salen and MoO2–salen?MCF on the basis of maintaining the mesoporous structure. The catalytic performances of the synthesized samples were assessed in the epoxidation of propylene with tert-butyl hydroperoxide (TBHP) as an oxidant, and the mechanism of propylene epoxidation under MoO2–salen?MCF was given. The prepared MoO2–salen?MCF-S material showed the best epoxidation performance with 1,2-dichloroethane as a solvent and a molar ratio of propylene to TBHP of 10:1 at 120 °C, giving a TBHP conversion of up to 100% after 1 h, with selectivities for propylene oxide and tert-butyl alcohol reaching 94.7% and 84.6%, respectively.

Disclosed are gas-phase ODH and OCP processes for converting alkanes (e.g., C2H6 and C3H8) to alkenes (e.g., C2H4 and C3H6) or oxygenates (e.g., methanol, ethanol, isopropanol, or propylene oxide) or converting alkenes (e.g., ethylene and propene) and oxygenates (e.g., methanol, ethanol, isopropanol or propylene oxide) to longer carbon-chain alkenes or longer carbon-chain alkanes with or without solid catalysts.

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.

Abstract: The gas-phase propylene epoxidation for noble metal system as a green process has confronted a great challenging task in metal utilization and stability. In this work, we realize the enhancement of Au capture efficiency and high-dispersed Au nanoparticles by supports modification and interfacial regulation to construct Au–Fe–TS-1 interface coupling structure. The Au capture efficiency of the optimum catalyst arrived at 69percent and it displayed a 7.3percent C3H6 conversion with a PO selectivity of 89.9percent, giving a H2 efficiency of about 25.7percent. Then some typical characterizations systematically elucidate that Fe is not only incorporated into TS-1 framework and captures Au species with high dispersion and stability, but also inhibits the losing of Ti species. Furthermore, Fe-modified catalysts change the property of Au active site and maintain lower apparent activation energy. This report may provide a new strategy to design advanced catalysts for enhancing metal utilization efficiency by the construction of interface coupling structure. Graphic Abstract: [Figure not available: see fulltext.].

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.

Au?Pd bimetallic catalyst has attracted significant research interests due to its fascinating properties. Herein, Au?Pd nanoparticles (NPs) supported on titanium silicalite-1 (denoted as Au?Pd/TS-1) were prepared by the alcohol reduction method. The Au?Pd alloy structure was proven via multiple characterization. This Au?Pd/TS-1 bimetallic catalyst showed improved activity compared with monometallic catalyst for propylene epoxidation with H2 and O2. The synergistic enhancement over Au?Pd/TS-1 could be elaborated by H-spillover process, which reduced the apparent activation energy significantly. The insights in this work are of referential importance to understanding the effect of interaction between bimetallic components on reaction system.

The invention provides a method for synthesizing propylene epoxide and co-producing ketal (acetal) by taking a by-product PG as a raw material in propylene epoxidation in the presence of heteropoly acid as a catalyst. Negative effects of alcohol substances to the activity of the catalyst in epoxidation reaction are eliminated, the activity of the catalyst is improved, the catalyst is used stably,meanwhile, downstream application of the by-product PG is expanded, and a preparation method for ketal (acetal) is provided. The method has the advantages of gentle reaction conditions, good catalyzing stability, good catalyst using effect, and resource utilization of the by-product.

Ce0.05Zr0.95O2 (denoted as CZ) was prepared by using a precipitation method to support tungsten oxide. For comparison, ZrO2 (denoted as Z) and CeO2 (denoted as C) supports were also prepared with the same method. The WOx/Z, WOx/CZ, and WOx/C catalysts were characterized by XRF, nitrogen adsorption–desorption, FE-SEM, SEM-EDX, XRD, Raman, H2-TPR, NH3-TPD, and CO2-TPD analyses. Propylene epoxidation by oxygen was carried out over WOx/Z, WOx/CZ, and WOx/C catalysts in a continuous flow reactor. In the propylene epoxidation by oxygen, WOx/CZ catalyst showed the desirable conversion of propylene (3.8%) and selectivity for propylene oxide (46.8%). Such superior catalytic performance of WOx/CZ catalyst compared to the other catalysts (WOx/Z and WOx/C) was attributed to the moderate reduction ability and the optimum ratio of acidity/basicity.

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.]

Mesoporous silica was prepared with the use of low-cost and environmentally friendly sucrose as a porogeneous agent. It was found that the presence of sucrose as well as the products of its chemical transformation upon the synthesis procedure (i.e., furfural polymer) affected markedly the structure and morphology of the resulting porous silica. The influences of the sucrose content and the source of the silicon as well as the synthesis conditions (pH, temperature) were very significant. The samples obtained in an acidic medium of the initial mixture formed from TEOS and treated at room temperature gave rise to products with a high surface area and narrow pore size distribution. Despite the lack of pore ordering, their catalytic activity in propene epoxidation after vanadium modification was remarkable in comparison to the activity of the vanadium catalyst supported on ordered mesoporous materials.

Au–Ag bimetallic nanoparticle-supported microporous titanium silicalite-1 catalysts were prepared via a hydrothermal-immersion method, and their structures were examined. These materials serve as efficient catalysts for the photosynthesis of propylene oxide via the epoxidation of propene. The Au/Ag mass ratio and reaction temperature were demonstrated to have significant effects on the catalytic activity and selectivity of propylene oxide. The optimal formation rate (68.3 μmol/g·h) and selectivity (52.3%) toward propylene oxide were achieved with an Au:Ag mass ratio of 4:1. Notably, the strong synergistic effect between Au and Ag resulted in superior photocatalysis of the bimetallic systems compared with those of the individual systems. A probable reaction mechanism was proposed based on the theoretical and experimental results.

Reactions of anion-radical α-oxygen (FeIII–O??)α with propylene and 1-butene on sodium-modified FeZSM-5 zeolites were studied in the temperature range from ?60 to 25 °C. Products were extracted from the zeolite surface and identified. It was found that main reaction pathway was the epoxides formation. Selectivity for epoxides at ?60 °C was 59–64%. Other products were formed as a result of secondary transformations of epoxides on the zeolite surface. According to IR spectroscopy, the oxidation of propylene over the entire temperature range and 1-butene at ?60 °C were not accompanied by the formation of (FeIII–OH)α groups, in distinction to methane oxidation. This testifies that hydrogen abstraction does not occur. In case of 1-butene reaction with α-oxygen at 25 °C, hydrogen abstraction occurred but was insignificant, ca 7%. According to DFT calculation ferraoxetane intermediate formation is preferable over hydrogen abstraction. Following decomposition of this intermediate leads to the propylene oxide (PO) formation. The results may be relevant to the low selectivity problem of the silver catalyst in propylene epoxidation and raise doubts about the presently accepted mechanism explaining an adverse effect of allylic hydrogen.

In the propylene epoxidation reaction with Fe-SiO2 catalysts the presence of iron oxide particles has a detrimental effect due to the total combustion of propylene on these iron species. Thus, the complete elimination of the iron oxide particles is presented as a preliminary strategy in order to increase the selectivity towards propylene oxide in iron-based catalysts. In this sense, a simple post-treatment of the catalysts with alkali or alkaline-earth elements (such as K or Ca, respectively) has proven effective in the total elimination of these iron oxide particles. Furthermore, the addition of K and Ca has modified the physico-chemical properties of the catalysts, decreasing their superficial acidity and (for higher K or Ca loadings) masking/blocking the active sites responsible for the catalytic reaction. With all this, it is shown that K has a higher efficiency removing the iron oxide particles compared with Ca (for the same molar ratios) and that a higher amount of K (compared to Fe) is required for the complete elimination of the iron oxide particles. A considerable propylene oxide selectivity enhancement (up to 65%) has been obtained for the K-promoted Fe0.005SiO2 and Fe0.01SiO2 catalysts using O2 as sole oxidant.

Ag-Cu-Cl/BaCO3catalysts with different Cl and Cu loadings, prepared by the reduction deposition impregnation method, were investigated for gas-phase epoxidation of propylene by molecular oxygen and characterized by X-ray diffraction, X-ray photoelectron spectroscopy and O2temperature programmed desorption. Ag-Cu-Cl/BaCO3catalyst with 0.036 wt% Cu and 0.060 wt% Cl exhibited the highest catalytic performance for gas-phase epoxidation of propylene by molecular oxygen. A propylene oxide selectivity of 83.7% and propylene conversion of 1.2% were achieved under the reaction conditions of 20% C3H6-10% O2-70% N2, 200 °C, 0.1 MPa and 3000 h?1. Increasing the Cl loading allowed Ag to ensemble easier, whereas changing the Cu loading showed little effect on Ag crystallite size. The appropriate Cl loading of Ag-Cu-Cl/BaCO3catalyst can reduce the dissociation adsorption of oxygen to atomic oxygen species leading to the combustion of propylene to CO2, which benefits epoxidation of propylene by molecular oxygen. Excessive Cl loading of Ag-Cu-Cl/BaCO3catalyst decreases propylene conversion and propylene oxide selectivity remarkably because of Cl poisoning. The appropriate Cu loading of Ag-Cu-Cl/BaCO3catalyst is efficient for the epoxidation of propylene by molecular oxygen, and an excess Cu loading decreases propylene oxide selectivity because the aggregation of Cu species increases the exposed surfaces of Ag nanoparticles, which was shown by slight increases in atomic oxygen species adsorbed. The appropriate loadings of Cu and Cl of Ag-Cu-Cl/BaCO3catalyst are important to strike the balance between molecular oxygen and atomic oxygen species to create a favorable epoxidation of propylene by molecular oxygen.

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.

Nucleic acids encoding cytochrome P450 variants are provided. The cytochrome P450 variants of have a higher alkane-oxidation capability, alkene-oxidation capability, and/or a higher organic-solvent resistance than the corresponding wild-type or parent cytochrome P450 enzyme. A preferred wild-type cytochrome P450 is cytochrome P450 BM-3. Preferred cytochrome P450 variants include those having an improved capability to hydroxylate alkanes and epoxidate alkenes comprising less than 8 carbons, and have amino acid substitutions corresponding to V78A, H236Q, and E252G of cytochrome P450 BM-3. Preferred cytochrome P450 variants also include those having an improved hydroxylation activity in solutions comprising co-solvents such as DMSO and THF, and have amino acid substitutions corresponding to T235A, R471A, E494K, and S1024E of cytochrome P450 BM-3.

Different bi-functional materials (Pd(Au)@TS-1) based on metallic nanoparticles supported onto active nanocrystalline titanium silicalite (TS-1) zeolites were synthesized, characterized and used as recyclable heterogeneous catalysts for direct propylene oxide production from hydrogen, oxygen and propylene through one-pot two-step consecutive process. These catalysts allowed carrying out the combined reaction where metallic nanoparticles catalyzed the formation of in situ H2O2 that was the necessary intermediate for propylene epoxidation catalyzed by active TS-1 nanocrystalline support. Several variables were considered such as use of supercritical CO2 conditions, modifiable content of metallic species, and presence of additional co-solvents, surface acidity inhibitors and H2O2 stabilizers. Reusability and stability of the bi-functional catalyst was showed through consecutive catalytic cycles.

A process for preparing epoxypropane by catalyzing propylene epoxidation with a phase-transfer catalyst under reaction control comprises a hydrogen peroxide dehydration part, a reaction part, a separation part, and a tail gas treatment part. Phosphotungstic heteropoly acid quaternary ammonium salt is used as a catalyst; an anhydrous H2O2 organic solvent produced by azeotropic dehydration of hydrogen peroxide and an organic solvent is used as an oxidizing agent; and propylene epoxidation is carried out at 40-160 DEG C and 0.25-10.0 MPa in the presence of inert gas to prepare epoxypropane. The process provided in the invention realizes continuous production of epoxypropane by catalyzing propylene epoxidation with a phase-transfer catalyst, is simple and easy to operate, and is mild in reaction conditions.

The invention relates to a method for co-production of epoxide and dicumyl peroxide to mainly solve the problems of the prior art that a large amount of wastewater and offscum containing chlorine and sulphur is generated, pollution is serious, product quality is poor, energy consumption is high, production efficiency is low, and labor intensity is high. The method comprises the steps that a, cumyl hydroperoxide and olefin react, and reaction products are separated to obtain epoxide and alpha, alpha-dimethyl benzyl alcohol; b, cumyl hydroperoxide reacts with alpha, alpha-dimethyl benzyl alcohol generated in the step a to generate dicumyl peroxide. The method can be used for industrial co-production of epoxide and dicumyl peroxide.

PROBLEM TO BE SOLVED: To provide a method for producing epoxides capable of enhancing the selectivity of epoxides, in reactions for forming epoxides from glycols.SOLUTION: The method for producing epoxides is a method for producing epoxides by the vapor-phase dehydration reaction of glycols in the presence of a catalyst. The catalyst is a catalyst including an alkali metal (A)-containing salt or a catalyst composed of a carrier on which the alkali metal (A)-containing salt is carried. In the method, each glycol and a carrier gas containing carbon dioxide are introduced into a reactor filled with the catalyst, and the glycol is reacted at a reaction temperature of the cloud point or higher of the glycol and 500°C or less.

The invention provides a technique and a system for preparing propylene oxide by directly oxidizing propylene with oxygen and hydrogen. The technique comprises the following steps that: (1) propylene, circulation propylene, and high-boiling-point organic sulfide are added to a mixed solvent of methanol and hydrazine hydrate, hydrogen and oxygen are accessed, and raw propylene oxide is produced; (2) raw propylene oxide is cooled and pumped into a rough separation tower by a pump, and organic sulfide and a few of high-boiling-point by-products in raw propylene oxide are removed; (3) a balance mixture of propylene and propylene oxide enters a propylene stripping tower, and unreacted propylene and a little propylene oxide in the mixture are removed; and (4) balance propylene oxide mixed liquor enters an extraction purification tower containing cumin and an alkaline solution, and is further extracted and rectified to form propylene oxide with high purity. The technique and the system are energy-saving and environmentally friendly, can increase the purity and the yield of propylene oxide significantly, reduce the losses of propylene oxide, and are suitable for industrialized production.

The invention relates to a method for preparing epoxy propane from ethylbenzene hydroperoxide and propylene, and is used for mainly solving the problems in the prior art that reaction temperature rising is higher and higher molar ratio of propylene to ethylbenzene hydroperoxide is needed for maintaining higher reaction efficiency. The problems are better solved through adopting the technical schemes that raw materials of ethylbenzene hydroperoxide and liquid propylene go into a multistage adiabatic reactor, and under conditions of the reaction temperature of 15-160 DEG C, the pressure of 1.0-12.0 MPa and the total molar ratio of propylene to ethylbenzene hydroperoxide of 1-20, the raw materials make contact with a Ti-silica catalyst and subjected to an epoxidation reaction to generate epoxy propane, wherein the raw material ethylbenzene hydroperoxide goes into catalyst bed layers of the multistage adiabatic reactor in a sectionalized manner, and a part of epoxidation reaction products containing epoxy propane circulate to an inlet of the reactor. The method can be used in industrial production of preparation of epoxy propane through epoxidation of ethylbenzene hydroperoxide and propylene.

The invention discloses a method for oxidation of olefin. The method comprises the following steps: under the condition of oxidation reaction, subjecting a liquid mixture and a titanium-silicon molecular sieve to contact reaction, and removing reaction heat with a heat-exchange medium in the process of contact reaction, wherein the liquid mixture comprises olefin and at least one oxidant and optionally comprises at least one solvent; and when a target oxidation product is reduced lower than an expected value, the method also comprises the following steps: regulating the condition of heat exchange so as to reduce the amount of the removed reaction heat, and optionally improving the quality of the oxidant in the liquid mixture so as to improve the selectivity of the target oxidation product until the expected value is met. The method provided by the invention can remain the selectivity of the target oxidation product at a high level in the process of long-time continuous operation, effectively prolongs the single-way service life of the titanium-silicon molecular sieve used as a catalyst, and reduces regeneration frequency of the catalyst.

The kinetics of propylene oxidation into propylene oxide in the presence of extruded titanium silicalite was studied. Based on the experimental data, a kinetic model of the process was designed and the activation energies of the target and side reactions, the rate constants, and the adsorption equilibrium constants were determined. The adequacy of the proposed kinetic model was verified on a continuously-operated test bench laboratory unit.

RuO2-CuO/SiO2 catalysts doped with Cs2O and TiO2 were investigated for the direct gas phase epoxidation of propylene to propylene oxide (PO) using molecular oxygen under atmospheric pressure. The optimal catalyst was achieved at Ru/Cu/Cs/Ti = 8.3/4.2/0.6/0.8 by weight and total metal loading of 21 wt% on SiO2 support. NH3 and CO2 temperature programmed desorption measurements of RuO2-CuO/SiO2 catalyst modified with Cs2O showed that the surface's acidity decreased, resulting in enhanced PO selectivity. The addition of TiO2 increased the PO formation rate by promoting the synergy effect between RuO2 and CuO. Using the Box-Behnken design of experiments on the RuO2-CuO-Cs2O-TiO2/SiO2 catalyst, an extraordinarily high optimal PO formation rate of 3015 gPO h-1 kgcat-1 was obtained with a feed comprised of O2/C3H6 at a volume ratio of 3.1 and (O2 + C3H6)/He at a volume ratio of 0.26, all at 272 °C and 34 cm3 min-1. To the knowledge of the authors, this is the highest PO formation rate ever reported for direct propylene epoxidation via O2.

Ag-MClx/BaCO3 catalysts with different chloride promoters, prepared by reduction-deposition-impregnation method, were investigated for gas-phase epoxidation of propylene to propylene oxide (PO) by molecular oxygen. Ag-CuCl2/BaCO3 catalyst with 360?ppm of Cu and 400?ppm of Cl exhibits the best initial catalytic performance, in which PO selectivity of 71.2% and propylene conversion of 1.3% are achieved, but only PO selectivity of 13.9% is obtained at propylene conversion of 3.2% after reaction for 500?min. The catalytic reaction mechanism over Ag-CuCl2/BaCO3 catalyst follows Rideal-Eley mechanism, in which propylene in the gas phase reacts with molecular oxygen species adsorbed on the surface of Ag at the interface in close contact with CuCl2 to produce PO, and with atomic oxygen species adsorbed on the surface of Ag nanoparticles to produce CO2 and H2O. One oxygen atom of molecular oxygen species reacts with propylene to form a PO molecule, and the left insufficient oxygen atoms react with propylene to produce oxygen-containing intermediates and then to form coke deposition which covers the active sites and thus results in the catalyst deactivation. The deactivated Ag-CuCl2/BaCO3 catalyst can be completely regenerated by combustion of coke deposition and then impregnation with appropriate amount of Cl.

Ag/BaCO3 catalysts with different Ag crystallite sizes, prepared by the reduction-deposition method, were developed for gas-phase epoxidation of propylene to propylene oxide (PO) by molecular oxygen. Effects of preparation conditions, such as pretreatment of organic amines of BaCO3 support, pretreatment way of ethylene diamine, reduction temperature of HCHO and calcination temperature, on the catalytic performance and Ag crystallite size of Ag/BaCO3 catalyst were investigated. Ag/BaCO3 * catalyst, with pretreatment of BaCO3 support by ethylene diamine and prepared at the reduction temperature of HCHO of 10 °C and the calcination temperature of 250 °C, exhibited better catalytic performance and good durability, in which 12.5% of propylene conversion and 36.9% of PO selectivity were achieved under the reaction conditions of 20%C3H6–10%O2–70%N2, 200 °C, 0.1 MPa and GHSV of 3000 h?1. Both lower reduction temperature of HCHO and lower calcination temperature can get smaller Ag crystallite sizes, which is more effective for epoxidation of propylene over Ag/BaCO3 * catalyst. The catalytic reaction mechanism of Ag/BaCO3 * catalyst for epoxidation of propylene is that propylene in the gas phase reacts with molecular oxygen species adsorbed on the catalyst surface to produce PO and follows Rideal–Eley mechanism.

Single turnover epoxidation of propylene by α-complexes (FeIII-O?)α on the surface of FeZSM-5 zeolite was studied in the temperature range from +25 °C to -60 °C. After extraction, the reaction products were identified by gas chromatography (GC), gas chromatography-mass spectrometry (GC-MS), and nuclear magnetic resonance (NMR). The reaction C3H6 + (FeIII-O?)α was shown to proceed in a similar way as the oxidation of propylene by the enzyme methane mono-oxygenase sMMO, i.e., via the addition of active oxygen over C=C bonds to yield propylene oxide, not affecting a weakly bound allylic hydrogen. This result, together with the previous results on the hydroxylation of methane and other hydrocarbons, shows the (FeIII-O?)α to be the unique functional model of compound Q, the key intermediate of sMMO. In another aspect, the results relate to the low selectivity problem of the silver catalyst in propylene epoxidation and raise doubts about the presently accepted mechanism explaining an adverse effect of allylic hydrogen.

In this work, the effects of co-feed species, namely, H2O or H2, on the photocatalytic epoxidation of propylene over V-Ti/MCM-41 are examined. A promoting effect on the C3H6 consumption rate is found under 0.6 kPa H2O co-feed when the PO (propylene oxide) formation rate is not proportionally promoted, resulting a slightly decreased PO selectivity. With increasing H2O concentration, the reaction activity decreases and this can be attributed to surface site blocking by excess H2O. The presence of H2O also increases the stability of photocatalyst during reaction. Similar observation of the enhanced C3H6 consumption rate and the improved stability is found when 5.6 kPa H2 is used as co-feed. We found that the catalyst stability is improved when the AA (acetaldehyde) is increased. This suggests that AA accumulation on the catalyst surface may lead to surface fouling and the observed deactivation. The presence of H2O or H2 co-feed, which can lead to hydroxyl radical (OH?), may impose a shift in the production formation of photocatalytic reaction.

PROBLEM TO BE SOLVED: To provide a new method for producing an epoxy compound, capable of producing it in high activity and in high selectivity even if necessarily using no peroxide, and enabling the reaction to be conducted safely as a result of non-use of peroxide. SOLUTION: The new method for producing an epoxy compound comprises: conducting a catalytic reaction between an olefin, a secondary alcohol and molecular oxygen in the presence of a palladium complex and a MWW-type crystalline titanosilicate as catalysts. COPYRIGHT: (C)2013,JPOandINPIT

Process for manufacturing an epoxide by reacting at least one chlorohydrin with at least one dehydrochlorinating agent in order to give the epoxide and at least one chlorinated co-product, said process comprising regenerating the dehydrochlorinating agent from the chlorinated co-product by a treatment which does not comprise an electrolysis operation.

Two titanium silicalite-1 samples with different crystal sizes were synthesized in the tetrapropylammonium bromide (TPABr) and tetrapropylammonium hydroxide (TPAOH) hydrothermal systems. The small-crystal TS-1 with a size of 600 nm was then treated with different organic bases. These TS-1 samples were evaluated in the epoxidation of propene, and characterized by ultraviolet-visible diffuse reflectance (UV-vis), X-ray absorption near edge structure (XANES) and Raman spectroscopies. The Ti L-edge absorption spectra show that a new Ti species, pentahedrally coordinated Ti, appears in some of the samples. This pentahedrally coordinated Ti species is correlated with the catalytic oxidation activity of TS-1, closely. Tetrahedrally coordinated Ti in TS-1 is the primary active center for selective oxidation reactions, but the existence of a small amount of pentahedrally coordinated Ti can further improve the catalytic activity. A high molar ratio of Si/Ti (n(Si/Ti)) in the synthesis process (n(Si/Ti) = 92.78) was beneficial for the generation of pentahedrally coordinated Ti. The improved catalytic activity of the TPAOH treated TS-1 is mainly due to the increasing amount of pentahedrally coordinated Ti, besides the elimination of diffusion limitation. Slowing down the crystallization rate can also increase the content of pentahedrally coordinated Ti. This journal is

The oxidation of propene has been studied with O2 as the terminal oxidant using a carbon-supported gold palladium catalyst at 90 °C. The reaction is carried out in acetonitrile as solvent in an autoclave. Propene oxidation is only observed in the presence of benzoyl peroxide acting as a radical initiator, but the presence of O2 is essential to observe oxidation. The addition of aldehydes enhances the formation of the epoxide.

Direct propylene epoxidation by O2 is a challenging reaction because of the strong tendency for complete combustion. Results from the current study demonstrate that by generating highly dispersed and stabilized Cu+ active sites in a TiCuOx mixed oxide the epoxidation selectivity can be tuned. The TiCuOx surface anchors the key surface intermediate, an oxametallacycle, leading to higher selectivity for epoxidation of propylene.

A facile method for the size-controllable synthesis of titanium silicalite-1 (TS-1) is presented. A tetrapropylammonium bromide hydrothermal system was used, and the amount of seeds (silicalite-1 suspension) and crystallization time were tuned to control the crystal size. The crystal size could be adjusted from 200 to 1200nm by varying the seed amount from 12 to 0.05wt%. Crystallization time plays a less important role than the seed amount on the crystal size. TS-1 samples with different crystal sizes were characterized and evaluated in propene epoxidation. The catalytic activity and selectivity of propene oxide are enhanced by decreasing the crystal size from 1200 to 200nm because the diffusion limitation is eliminated gradually. The seed is significant for this system, as a lack of seeds leads to poor crystallization and low catalytic activity. The mechanism of the seed function was studied by simulating the transformation process of the seed in the TS-1 synthesis system.

A novel type of dehydration reaction that produces epoxides from vicinal diols (dehydrative epoxidation) using a basic catalyst is reported. Epoxyethane, 1,2-epoxypropane, and 2,3-epoxybutane were produced from the dehydrative epoxidation of ethylene glycol, 1,2-propanediol, and 2,3-butanediol, respectively. Among a number of tested basic catalysts, the Cs/SiO2 catalyst showed outstanding performance for the dehydrative epoxidation of 2,3-butanediol and is considered to be the most promising catalyst for this type of reaction. In order to identify the superiority of the Cs/SiO2 catalyst and a mechanism of the reaction, structure-activity relationships were studied along with density functional theory (DFT) calculations. The following features are found to be responsible for the excellent activity of the Cs/SiO2 catalyst: i) strong basic sites formed by Cs+, ii) low penetration of Cs+ into SiO2 which permits basic sites to be accessible to the reactant, iii) stable basic sites due to the strong interactions between Cs+ and SiO2 surface, and iv) mildly acidic surface of SiO2 which is advantageous for the elimination to H2O. In addition, the dehydrative epoxidation involves an inversion of chirality (e.g. meso-2,3-butanediol (R,S) to trans-2,3-epoxybutane (R,R or S,S)), which is in agreement with DFT results that the reaction follows a stereospecific SN2-like mechanism.

It was found that Ti-modified MoO3-Bi2SiO5/SiO2 exhibited excellent catalytic performance for the epoxidation of propylene by molecular oxygen. The effect of Ti on the performance of the catalysts was investigated, and the results showed that the high surface area, greater pore size, and moderate acidity of the Ti-modified catalyst were favorable to the selective formation of propylene oxide (PO). Interactions between MoO3, bismuth oxide clusters, and Ti species were proposed to favor PO formation. The presence of Ti not only enhanced the dispersion of MoO3 nanoparticles but also inhibited the reactivity of the lattice oxygen and reduced the strong acidity of the catalyst, contributing to the increase in C3H6 conversion and PO selectivity, respectively. Kinetic studies indicated that a high space velocity or low reaction temperature was beneficial for improving the selectivity to PO by decreasing the deep oxidation of PO.

Novel catalysts consisting of gold nanoparticles (NPs) supported on the titanosilicate pillared MCM-36 (Si/Ti-MCM-36) with 2 nm mesopores were prepared. The influences of the Ti coordination environment on the particle size of the anchored Au NPs and their catalytic performances in propylene epoxidation with mixtures of H2 and O2 were investigated. The catalyst materials were characterized with Electron Probe Micro Analysis, X-ray diffraction, nitrogen sorption, UV-visible diffuse reflectance spectroscopy, transmission electron microscopy, and X-ray absorption spectroscopy. The coordination environment of Ti(iv) in Si/Ti-MCM-36 was found to be a mixture of octahedral (Oh) and tetrahedral (Td). The Au loading was proportional to the amount of Ti incorporated in the porous silica. The higher loading of Ti in Si/Ti-MCM-36 anchored more Au and resulted in the formation of larger Au particles. The deposition-precipitation (DP) with NH3 as a DP agent seemed to give Au NPs larger than those loaded by NaOH. The most efficient Au NPs size was about 1 nm, and Au NPs with sizes larger than 2 nm were not efficient for the propylene epoxide (PO) formation. By adjusting the Au and Ti synergy, the optimal PO formation rate over Au loaded Si/Ti-MCM-36 was 28.9 gPO h-1 gcat-1.

We identified and characterized a novel halohydrin dehalogenase HHDH-PL from Parvibaculum lavamentivorans DS-1. Study of substrate specificity indicated that HHDH-PL possessed a high activity toward ethyl (S)-4-chloro-3-hydroxybutanoate ((S)-CHBE). After optimizations of the pH and temperature, whole cell catalysis of HHDH-PL was applied to the synthesis of ethyl (R)-4-cyano-3-hydroxybutyrate (HN) at 200 g L-1 of (S)-CHBE, which gave 95% conversion and 85% yield in 14 h.

The catalytic epoxidation of olefins by an iron(II) complex bearing a tetradentate bis(pyridyl-N-heterocyclic carbene) ligand was investigated. This is the first example of the use of an organometallic iron compound (i.e., with a Fe-C bond) as an olefin epoxidation catalyst. The catalyst system, used without additives, showed good epoxide yields and selectivity for various olefins after a reaction time of 5 min. It was found that the epoxide yield strongly depended on the amount of the peroxide used and its nature and noticeably increased at lower temperatures.

The epoxidation of propene is performed in homogeneous phase using various molecular catalysts and H2O2 or tert-butyl hydroperoxide as oxidants. A comparison between some molybdenum catalysts and methyltrioxorhenium (MTO) shows that the well known Re catalyst is the best among the examined catalysts. This journal is

The present invention relates to a micropowder, wherein the particles of the micropowder have a Dv10 value of at least 2 micrometer and the micropowder comprises mesopores which have an average pore diameter in the range of from 2 to 50 nm and comprise, based on the weight of the micropowder, at least 95 weight-% of a microporous aluminum-free zeolitic material of structure type MWW containing titanium and zinc.

The low-temperature oxidation of the five hexane isomers (n-hexane, 2-methyl-pentane, 3-methyl-pentane, 2,2-dimethylbutane, and 2,3-dimethylbutane) was studied in a jet-stirred reactor (JSR) at atmospheric pressure under stoichiometric conditions between 550 and 1000 K. The evolution of reactant and product mole fraction profiles were recorded as a function of the temperature using two analytical methods: gas chromatography and synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS). Experimental data obtained with both methods were in good agreement for the five fuels. These data were used to compare the reactivity and the nature of the reaction products and their distribution. At low temperature (below 800 K), n-hexane was the most reactive isomer. The two methyl-pentane isomers have about the same reactivity, which was lower than that of n-hexane. 2,2-Dimethylbutane was less reactive than the two methyl-pentane isomers, and 2,3-dimethylbutane was the least reactive isomer. These observations are in good agreement with research octane numbers given in the literature. Cyclic ethers with rings including 3, 4, 5, and 6 atoms have been identified and quantified for the five fuels. While the cyclic ether distribution was notably more detailed than in other literature of JSR studies of branched alkane oxidation, some oxiranes were missing among the cyclic ethers expected from methyl-pentanes. Using SVUV-PIMS, the formation of C 2-C3 monocarboxylic acids, ketohydroperoxides, and species with two carbonyl groups have also been observed, supporting their possible formation from branched reactants. This is in line with what was previously experimentally demonstrated from linear fuels. Possible structures and ways of decomposition of the most probable ketohydroperoxides were discussed. Above 800 K, all five isomers have about the same reactivity, with a larger formation from branched alkanes of some unsaturated species, such as allene and propyne, which are known to be soot precursors.

Propylene oxide (PO) is a versatile chemical intermediate, and by volume it is among the top 50 chemicals produced in the world. The catalytic conversion of propylene to PO by molecular oxygen with minimum waste production is of high significance from an academic as well as an industrial point of view. We have developed a new synthesis strategy to prepare 2-5 nm metallic silver nanoparticles (AgNPs) supported on tungsten oxide (WO3) nanorods with diameters between 30 and 40 nm, in the presence of cationic surfactant (cetyltrimethylammonium bromide: CTAB), capping agent (polyvinylpyrrolidone: PVP), and hydrazine. The synergy between the surface AgNPs and WO3 nanorods facilitates the dissociation of molecular oxygen on the metallic Ag surface to produce silver oxide, which then transfers its oxygen to the propylene to form PO selectively. The catalyst exhibits a PO production rate of 6.1 × 10-2 mol gcat-1h-1, which is almost comparable with the industrial ethylene-to-ethylene oxide production rate.

The selective oxidation of propylene with O2 to propylene oxide and acrolein is of great interest and importance. We report the crystal-plane-controlled selectivity of uniform capping-ligand-free Cu 2O octahedra, cubes, and rhombic dodecahedra in catalyzing propylene oxidation with O2: Cu2O octahedra exposing {111} crystal planes are most selective for acrolein; Cu2O cubes exposing {100} crystal planes are most selective for CO2; Cu2O rhombic dodecahedra exposing {110} crystal planes are most selective for propylene oxide. One-coordinated Cu on Cu2O(111), three-coordinated O on Cu2O(110), and two-coordinated O on Cu2O(100) were identified as the catalytically active sites for the production of acrolein, propylene oxide, and CO2, respectively. These results reveal that crystal-plane engineering of oxide catalysts could be a useful strategy for developing selective catalysts and for gaining fundamental understanding of complex heterogeneous catalytic reactions at the molecular level.

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.

High dispersed 10% MoO3/SiO2 catalysts were prepared by the sol-gel method using a precipitant (ammonium hydroxide) with different pH values, and investigated by XRD, FT-IR spectroscopy of pyridine adsorbed and Raman spectroscopy techniques, and so on. The results show that the catalytic performance of MoO3/SiO2 for the epoxidation of propylene with cumene hydroperoxide (CHP) is affected by pH value of precipitant, and MoO3/SiO2 prepared with precipitant of pH 9 exhibits the highest yield of propylene oxide (PO). It has been found that the weak Lewis acidic sites on MoO3/SiO2 are the active sites of the propylene epoxidation with CHP, total amount of Lewis acid sites on the catalyst surface is related with the CHP conversion, and the weaker Lewis acid sites is in favor of the propylene epoxidation. When the amount of Lewis acid sites on the catalyst surface is more and their acid strength is higher, the CHP degradation and PO acid-catalytic hydrolysis would be speeded up, resulting in a reduction of the PO selectivity. The concentration and strength of the Lewis acid sites on MoO3/SiO2 are affected by pH of precipitant, and the catalyst prepared with precipitant of pH 9.0 possesses the most weakly Lewis acidic sites and the highest selectivity to PO (91.5%). Besides, the addition of certain amount of Nd can increase the weakly acidic sites to enhance CHP conversion and reduce the Lewis acidity of the catalyst thus suppress PO hydrolysis.