TS-1 Catalyst Research Articles

Epoxidation of allyl alcohol to glycidol over the microporous TS-1 catalyst

The results of the epoxidation of allyl alcohol with 30% hydrogen peroxide over the TS-1 catalyst have been presented. The studies were carried out under the atmospheric pressure and at the presence of methanol as a solvent. The influence of the following technological parameters on the course of epoxidation was examined: the temperature of 20–60 °C, the molar ratio of AA/H 2O 2 1:1–5:1, the methanol concentration of 5–90 wt%, the catalyst content of 0.1–5.0 wt% and the reaction time 5–300 min. The main functions describing the process were the selectivity to glycidol in relation to allyl alcohol consumed, the conversion of substrates, and the selectivity of transformation to organic compounds in relation to hydrogen peroxide consumed. The parameters at which the functions describing the process reached the highest values were determined.

Gas Phase Epoxidation of Propylene with TS-1 and in Situ H2O2 Produced by a H2/O2 Plasma

Gas phase epoxidation of propylene was performed by directly contacting propylene and gaseous H 2 O 2 on the surface of TS-1 catalyst in an integrated reactor. The gaseous H 2 O 2 was produced in situ by a H 2 /O 2 plasma. The H 2 O 2 formation rate can be enhanced by increasing the power density of the H 2 /O 2 plasma reactor. The yield and selectivity for propylene oxide (PO) can be increased by optimizing the reaction conditions and using suitable TS-1 catalysts. With a power injection of 3.5 W, flow rates of H 2 , O 2 , and propylene of 170, 8, and 18 ml/min, respectively, catalyst loading of 0.8 g, and epoxidation temperature of 110 °C, the yield and selectivity for PO and the utilization rate of H 2 O 2 were 246.9 g/(kg·h), 95.4%, and 36.1%, respectively. During the gas phase reaction, no decline of TS-1 activity was observed. ： 将 H 2 /O 2 非平衡等离子体现场产生的气态 H 2 O 2 和丙烯与耦合反应器中钛硅沸石 TS-1 直接接触, 实现了丙烯气相环氧化反应. 结果表明, 非平衡等离子体生成气态 H 2 O 2 的速率由介质阻挡放电的输入功率决定, 环氧丙烷的生成速率和选择性取决于钛硅沸石催化剂和反应条件. 在 H 2 和 O 2 进料流量分别为 170 和 8 ml/min, 介质阻挡放电输入功率为 3.5 W, 环氧化反应温度为 110 °C, 丙烯进料量为 18 ml/min, 催化剂用量为 0.8 g 的条件下, 生成环氧丙烷产率达 246.9 g/(kg·h)、环氧丙烷选择性和 H 2 O 2 有效利用率分别为 95.4% 和 36.1%, 反应 36 h 内未见催化剂失活. Gas phase propylene epoxidation was performed by contacting plasma generated gaseous H 2 O 2 and propylene over a TS-1 catalyst. The important feature is the use of gaseous H 2 O 2 for PO production.

Kinetics studies and mechanism evolution of the epoxidation of styrene over nanoporous Au doped TS-1

Kinetics studies and mechanism evolution of the epoxidation of styrene over nanoporous Au doped TS-1 A kinetic investigation of the slurry phase epoxidation of styrene with hydrogen peroxide has been carried out, for the first time, over nanoporous Au doped TS-1 catalyst, in a batch reactor, in the temperature range of 313-333 K. It was found that product selectivity and the rate of reaction are greatly influenced by concentrations of styrene and hydrogen peroxide. Kinetics studies reveal that the mechanism of the reaction is of the "Redox" type. The rate equation, r = k1 k2 PO PH / (k1 PO + k2 PH) deduced, assuming a steady state involving two stage oxidation-reduction process, represent the data most satisfactorily for the conversion of styrene to styrene oxide. A tentative mechanism of the process has also been suggested.

Frontiers in Catalysis and Materials Chemistry: The 3rdIDECAT Conference on Catalysis

Frontiers in Catalysis and Materials Chemistry: The 3^rdIDECAT Conference on Catalysis

Enhanced reactivity of direct propylene epoxidation with H 2 and O 2 over Ge-modified Au/TS-1 catalysts

The epoxidation of propylene with H 2–O 2 mixtures was studied over a gold catalyst supported on a Ge-modified TS-1 catalyst at 170 °C. Shifts of X-ray diffraction lines to lower angle showed that the Ge was incorporated into the structure of the TS-1. The presence of Ge more than doubled the conversion from 1.6% to 4% while increasing selectivity from 87% to 91%. Density functional theory calculations indicated that the origin of the enhanced activity was a ligand effect of Ge on Ti, which lowered the activation energy for the critical epoxidation step.

Synthesis of Mesoporous TS-1 for Catalytic Oxidative Desulfurization

Mesoporous TS-1 catalysts were prepared via a nanocasting route using two different carbon template sources of CMK-3 and commercial carbon black. Products were characterized by XRD, UV-Vis spectroscopy, SEM, TEM, and <TEX>$N_2$</TEX> adsorption- desorption measurement. The catalytic performances of the samples for allylchloride epoxidation and oxidative desulfurization of the representative refractory sulfur compounds, dibenzothiophene and 4,6-dimethyldibenzothiophene, were compared against those of conventional TS-1. Whilst the allychloride epoxidation activity for the mesoporus TS-1 samples were similar, mesoporous TS-1 exhibited significantly higher catalytic activities than conventional TS-1 in oxidative desulfurization.

Effect of ammonium salts on the synthesis and catalytic properties of TS-1

Effects of ammonium salts on the synthesis and characteristics of TS-1 were studied by adding different ammonium salts (NH 4F, NH 4Cl, NH 4Br, NH 4I, CH 3COONH 4, NH 4NO 3, (NH 4) 2CO 3, (NH 4) 2SO 4 and (NH 4) 3PO 4) to the synthesis gel. It was shown that the fine structure and crystal morphology of the synthesized materials depended on the type of ammonium salts. Except for NH 4F, the ammonium salts, and particularly (NH 4) 2SO 4 and (NH 4) 3PO 4 significantly decreased the crystallization rate as a result of remarkably reducing the pH value of the crystallization mixture. Nevertheless, all of these ammonium salts were favorable for the incorporation of Ti in the framework, and the beneficial effect was dependent on the type of ammonium salts. In addition, the ammonium salt also has a strong influence on the catalytic properties of the prepared catalyst. It is worth noting that the catalytic performance of TS-1 was closely related to the substrate molecules. TS-1 catalyst prepared in the presence of (NH 4) 2SO 4 gave the highest conversion in the epoxidation of 1-hexene, whereas that prepared with (NH 4) 2CO 3 was suitable for the oxidation of phenol.

Phenol Hydroxylation over Alkaline Treated TS-1 Catalysts

Alkaline treatment on TS-1 can selective remove silica from the framework while MFI zeolitic framework remains intact, which creates new large micropores or even mesopores and increases Si/Ti ratio in the alkaline treated TS-1. Among various alkaline hydroxide, CsOH treatment leads to partial destruction of MFI structure. All the desilicated TS-1 samples show enhanced phenol conversion and dihydroxylbenzene (DHB) yield in acetone solvent by two folds, which can be attributed to the higher Ti/Si ratio and improved diffusivity. Pore structure modified with alkaline treatment affects significantly reaction pathway and product selectivity. The initial product over the parent TS-1 and NaOH treated TS-1 is mainly 4-hydroxycyclohexa-2,5-dienone and catechol enriched DHB, respectively.

Synthesis and characteristics of titanium silicalite TS-1, Ti-Beta and Ti-MWW catalysts

Synthesis and characteristics of titanium silicalite TS-1, Ti-Beta and Ti-MWW catalysts The synthesis methods of the following titanium-silicalite catalysts: TS-1, Ti-Beta and Ti-MWW were presented. The results of the analyses of the catalysts by XRD, SEM and IR, UV-vis methods were also shown. A brief description of the catalytic performances of these catalysts in the oxidation process of olefins, alkenes, alcohols and aromatic compounds was presented.

Direct Gas-Phase Epoxidation of Propene with Hydrogen Peroxide on TS-1 Zeolite in a Microstructured Reactor

Direct epoxidation of propene with hydrogen peroxide vapor was conducted in a microstructured reactor containing TS-1 catalyst coatings. At 140 °C, 1 bar, 5 vol % hydrogen peroxide, and 15 vol % propene, productivities of more than 1 kg of propene oxide per kg of catalyst and hour are obtained in lab scale, which is in an industrially highly relevant range. Excellent selectivities to propene oxide based on propene of >90% were reached. Potential and need for improvement lie in the propylene oxide selectivity based on hydrogen peroxide, which was observed to be about 25%. By increasing the molar excess of propene to about 6.6, propylene oxide selectivities related to hydrogen peroxide of up to 60% have been observed in the pilot plant.

Effect of solvents on propylene epoxidation over TS-1 catalyst

Solvents have an important effect on the epoxidation of propylene catalyzed by TS-1. The experimental results show that, in different solvents, the catalytic activity of epoxidation is in the following order: methanol > 2-propanol > 2-butanol > acetonitrile > acetone > tetrahydrofuran. Based on the reaction mechanism, the effects of solvents on the epoxidation were studied from eight aspects, which included the electronic effect, the steric effect, the polarity of solvent, the effect of solvent on sorption and diffusion of reactant, the oxidation of alcohol, the etherification of PO, the deactivation of TS-1 and the solubility of propylene in the solvents. The electronic effect, steric effect and the polarity of solvent were considered to be the main aspects. This work may provide theoretical guidance for choosing solvents for these kinds of reactions and also may serve as basis for further industrialization.

One-pot green synthesis of propylene oxide using in situ generated hydrogen peroxide in carbon dioxide

In the one-pot green synthesis of propylene oxide using in situ generated hydrogen peroxide, a propylene oxide yield of 23% with 82% selectivity was achieved over a (0.2%Pd + 0.02%Pt)/TS-1 catalyst by using compressed (supercritical or liquid) carbon dioxide as the solvent and small amounts of water and methanol as co-solvents. The addition of an inhibitor effectively suppressed a number of common side-reactions, including the hydrogenation of propylene, the hydrolysis of propylene oxide and the reaction between propylene oxide and methanol. This suppression effect is due to the interaction between the inhibitor and TS-1 leading to the neutralization of its surface acidity.

Influence of process parameters on the epoxidation of 2-buten-1-ol over titanium silicalite TS-1 catalyst

AbstractThe influence of process parameters on the epoxidation of 2-buten-1-ol with 30 % hydrogen peroxide using the titanium silicalite TS-1 is presented. The studies were carried out under autogenic pressure (in autoclave). Methanol was used as a solvent in this process. The influence of temperature, 2-buten-1-ol to hydrogen peroxide mole ratio, amount of solvent used, TS-1 catalyst content, and reaction time on the reaction was studied. The major product of this reaction, 2,3-epoxybutan-1-ol (EB), has numerous applications in chemical industry.

Green catalysis by microwave synthesized nanostructured materials

MFI type zeolite with incorporated titanium and/or aluminum was successfully prepared by microwave method. MFI type zeolite with incorporated titanium (NSTS-1) which was prepared by microwave had the stacking morphology whereas MFI type zeolite incorporated with titanium and aluminum (NSAlTS-1) gave stacked morphology with arrayed structure. UV–vis spectra and 27Al-MAS-NMR revealed that Ti and/or Al species were incorporated in tetrahedral position. The NSTS-1 catalyst exhibited an enhanced catalytic activity in the epoxidation of 1-dodecene compared with the conventional TS-1 catalyst. The NSAlTS-1 had two catalytic active sites which could carry out both ammoximation of cyclohexanone and Beckmann rearrangement of cyclohexanone oxime, simultaneously.

Eco-friendly, Selective Hydroxylation of C-7 Aromatic Compounds Catalyzed by TS-1/H2O2System under Solvent-free Solid−Liquid−Liquid-Type Triphase Conditions

Direct ring hydroxylation of aromatics, namely, anisole, toluene, and benzylchloride, using TS-1 catalyst, a MFI-type titanium silicate molecular sieve, dilute H2O2 as oxidizing agent, and water as reaction medium, was investigated under solid−liquid−liquid (SLL)-type triphase conditions. The aim was to study the relative influence of commonly used organic solvents, under solid−liquid (SL)-type biphase reaction conditions, as compared to that of water, on the conversion and product selectivity. Under solvent-free triphase conditions, the ring hydroxylation of anisole, toluene, and benzylchloride leads to significant enhancement in the conversion, turn-over frequency, and para-selectivity. However, in the case of benzyl chloride, no ring hydroxylation took place under biphase conditions (using acetone as solvent) contrary to significant ring hydroxylation (ca. 60% H2O2 efficiency) under triphase aqueous medium conditions. The simple product recovery (phase separation of organic and aqueous layers) and use ...

Development and Industrialization of the Vapor-Phase Beckmann Rearrangement Process

Abstract The development of a new catalyst effective for the vapor-phase Beckmann rearrangement of cyclohexanone oxime has made it possible to establish a commercial process for the production of ε-caprolactam without producing any ammonium sulfate. Through fundamental studies of the catalyst, it was discovered that an MFI-type zeolite composed exclusively of silica had a high selectivity and activity for the vapor-phase Beckmann rearrangement. Based on acidity measurements and on the reactivity of oximes with different sizes as well as the calculation results of the deprotonation energies of some silanols, we have suggested that the active sites are nest silanols located close to their mouth of the micro pores. By addition of methanol into the reaction system, the selectivity for ε-caprolactam was markedly improved to the levels required for industrialization. A fluidized bed reactor was used for the reaction system in order to maintain a continuous production. By combining the ammoximation process for production of cyclohexanone oxime using the TS-1 catalyst and the vapor-phase Beckmann rearrangement, a commercial plant has been operating on a 60000 tons per year scale since April 2003, without any troubles.

Highly selective synthesis of methyl ethyl ketone oxime through ammoximation over Ti-MWW

The liquid-phase ammoximation of methyl ethyl ketone (MEK) with ammonia and hydrogen peroxide was conducted on Ti-MWW, TS-1, Ti-MOR and Ti-Beta catalysts in order to produce methyl ethyl ketone oxime (MEKO) cleanly. Compared with other titanosilicates, Ti-MWW produced MEKO more efficiently and selectively, achieving a conversion and selectivity both over 99% under optimized conditions. Ti-MWW was particularly superior to TS-1 in MEKO selectivity, as TS-1 co-produced easily 2-nitrobutane byproduct as a result of consecutive oxidation of MEKO unless the ammonia/MEK molar ratio was increased to 4. The catalyst deactivated in repeated ammoximation, mainly owing to a partial dissolution of framework silicon in basic reaction media. Efforts were thus made in order to develop practicable regeneration methods. By adding a controlled amount of silica source into the reaction mixture, we could suppress the deactivation of Ti-MWW catalyst and then the lifetime was prolonged effectively.

Deactivation and regeneration of titanium silicalite catalyst for epoxidation of propylene

Continuous epoxidation of propylene with 30-wt% hydrogen peroxide in isopropyl alcohol solvent over titanium silicalite (TS-1) zeolite was carried out and the good selectivity to propylene oxide and stability of TS-1 were obtained. After the reaction of 263 h, the deactivation of the TS-1 catalyst occurred. The spent catalysts were regenerated by calcinations at 550 °C for 5 h, washing with isopropyl alcohol solvent or washing with dilute hydrogen peroxide, and the activity evaluation of the regenerated catalysts were studied. The deactivated and regenerated catalysts were characterized by scanning electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, 29Si magic angle spinning nuclear magnetic resonance, thermogravimetric analysis and Brunauer–Emmett–Teller method. The compositions deposited on the surface of the catalysts were collected by solvent extraction and were analyzed by gas chromatography–mass spectrometry (GC–MS). The results showed that calcination and washing with dilute hydrogen peroxide were highly effective regeneration methods and the catalytic activity of TS-1 catalysts can be mostly recovered after these treatments. Washing with isopropyl alcohol had a subtle effect in recovering the catalytic activity of the TS-1 catalyst. The major cause of the deactivation of the TS-1 catalyst for epoxidation is blocking micropores induced by bulky organic by-products formed by consecutive reactions of target reaction, such as dimerization or oligomerization of propylene oxide, etherification of propylene oxide with isopropyl alcohol. In addition, leaching of framework titanium also contributes to the deactivation of the catalyst.

Ammoximation of cyclohexanone over nanoporous TS-1 using UHP as an oxidant

Abstract Ammoximation of cyclohexanone to cyclohexanone oxime has been carried out using ammonia and urea hydrogen peroxide adducts as the oximation reagents. Effect of catalyst concentration, temperature, and molar ratio of reactants and effect of doping TS-1 with Fe has been studied to obtain the optimum conversion of cyclohexanone (CH) and selectivity to cyclohexanone oxime. The catalyst has been characterized employing the techniques of XRD, FT-IR, EDAX, SEM, AAS and Mossbauer spectroscopy with a view to confirm phase purity, stoichiometry, particle size distribution and oxidation state of Fe. The BET surface area of TS-1 catalyst was found to be 680 m2/g. A maximum conversion of about 70% of cyclohexanone with cyclohexanone oxime selectivity of 99.72% was obtained over TS-1 doped with Fe at a temperature of 40 °C and cyclohexanone to UHP molar ratio of 1:1. Reaction seems to proceed through a redox mechanism and follow hydroxylamine as well as imine routes. According to hydroxylamine route ammonia and UHP react within the TS-1 pores and produce hydroxylamine. The hydroxylamine thus formed reacts with cyclohexanone outside the pores to produce cyclohexanone oxime. In the imine route cyclohexanone and ammonia react to produce cyclohexanone imine, which is oxidized to cyclohexanone oxime. A tentative mechanism for the process has been proposed.

Epoxidation of 1-butene-3-ol with Hydrogen Peroxide under Autogenic and Atmospheric Pressure

AbstractThe influence of the technological parameters on the course of the epoxidation of 1-butene-3-ol (1B3O) over the TS-1 catalyst has been presented. A 30 wt% H