Isomerization Of Propylene Oxide Research Articles

Identification of potential technologies for 1,4‐Butanediol production using prospecting methodology

Abstract1,4‐Butanediol (1,4‐BDO) is a four‐carbon diol used for industrial applications such as organic solvents, and the production of adhesives, fibers and polyurethanes. 1,4‐BDO currently is produced through several petrochemical routes: hydrogenation of maleic anhydride, isomerization of propylene oxide, acetoxylation of butadiene, and the reaction between formaldehyde and acetylene. The current trends in 1,4‐BDO production involve the utilization of renewable sources such as biomass. In this context, the present study aimed to identify promising technologies of 1,4‐BDO production through prospecting methodology based on the analyses of patents and scientific article, describing the most relevant aspects of those emerging technologies. An increasing amount of 1,4‐BDO production focused on biotechnological routes has been reported, with the US heavily involved in the development of new technologies. This study tracked three promising technologies which have potential for application in a biorefinery context because those processes involve (i) production of 1,4‐BDO from sugars, classified herein as the biotechnological route; (ii) production of intermediates from sugar fermentation followed by catalytic conversion into 1,4‐BDO, classified herein as the hybrid route, and (iii) furan/furfural conversion into 1,4‐BDO. © 2020 Society of Chemical Industry

Direct Gas-Phase Oxidation of Propylene to Acetone in the Presence of H2 and O2 over Au/TS-1 Catalyst.

A novel process for the preparation of acetone is reported by gas-phase oxidation of propylene in the presence of H2 and O2 with Au supported TS-1 catalyst (Au/TS-1). By elevating the reaction temperature to 280°C, Au/TS-1 catalyzes 11.6% propylene generating acetone with 70.6% selectivity, and 8.2% acetone in onepass yield. Acetone is originated from propylene oxide isomerization, which is mainly attributed to the surface of the Lewis base and high reaction temperature. Furthermore, small Au nanoparticle size promotes the reaction.

Catalytic Performances of Hollow Li3PO4 Spheres for Propylene Oxide Isomerization

Three Li3PO4 catalysts with hollow structure were prepared: N-Li3PO4 (Na3PO4 added to Li3PO4), L-Li3PO4 (LiOH added to Na3PO4), and S-Li3PO4 (LiOH and Na3PO4 added simultaneously). As a catalyst for propylene oxide isomerization, L-Li3PO4 exhibits the highest conversion and selectivity among the three samples. And the change of Li during the isomerization reaction was discussed. There are two Li ions in the crystal lattice (Li1s1 and Li1s2) based on the X-ray photoelectron spectroscopy (XPS) spectra. After catalytic reaction, the ratio of the surface atomic Li1s1/Li1s2 concentration changes from 1:1 to 1.32:1, indicating the motion and shift of Li ions.

Reactions of Propylene Oxide on Supported Silver Catalysts: Insights into Pathways Limiting Epoxidation Selectivity

The reactions of propylene oxide (PO) on silver catalysts were studied to understand the network of parallel and sequential reactions that may limit the selectivity of propylene epoxidation by these catalysts. The products of the anaerobic reaction of PO on Ag/α-Al2O3 were propanal, acetone and allyl alcohol for PO conversions below 2–3%. As the conversion of PO was increased either by increasing the temperature or the contact time, acrolein was formed at the expense of propanal, indicating that acrolein is a secondary reaction product in PO decomposition. With addition of oxygen to the feedstream the conversion of PO increased moderately. In contrast to the experiments in absence of oxygen, CO2 was a significant product while the selectivity to propanal decreased as soon as oxygen was introduced in the system. Allyl alcohol disappeared completely from the product stream in the presence of oxygen, reacting to form acrolein and CO2. The product distribution may be explained by a network of reactions involving two types of oxametallacycles formed by ring opening of PO: one with the oxygen bonded to C1 (OMC1, linear) and the other with oxygen bonded to C2 (OMC2, branched). OMC1 reacts to form PO, propanal, and allyl alcohol. OMC2 can give rise to acetone and PO. (DFT) calculations have verified accessibility to the two oxametallacycle structures from propylene and PO, and have provided energy barriers for each of the steps involved in PO isomerization. This work illustrates the complex manifold of sequential reactions that contribute to the difficulty of achieving high selectivity in direct propylene epoxidation with silver catalysts.

Structures and Catalytic Properties of Lithium Phosphates

Basic lithium phosphate and stoichiometric lithium phosphate were prepared and their catalytic properties were compared. Using basic lithium phosphate as the isomerization catalyst for propylene oxide led to higher selectivity in allyl alcohol and better propylene oxide conversion than stoichiometric lithium phosphate. The fresh and deactivated basic lithium phosphates were also characterized by X-ray diffraction. Results showed that new phases appeared in the deactivated catalyst. An isomerization mechanism for propylene oxide catalyzed by basic lithium phosphate was proposed. Results of temperature programmed desorption of CO2 showed that the surface basicity of the catalysts had a great effect on their catalytic properties and that the catalyst with pH = 12 had two basic centers and its catalytic properties were the best. Basic lithium phosphate had better catalytic properties for isomerization of propylene oxide to allyl alcohol than stoichiometric lithium phosphate. Results of CO2-TPD showed that surface basicity of the catalysts had much effect on catalytic properties. And a mechanism was proposed.

Isomerization of Propylene Oxide. Quantum Chemical Calculations and Kinetic Modeling

The mechanism of propylene oxide isomerization, to yield four isomerization products, was calculated by the B3LYP/cc-pVDZ method. Coupled cluster CCSD(T) calculations for the reactant, products, transition states, and intermediates were carried out to estimate the activation energies. The vibrational frequencies, calculated using B3LYP method, were used to estimate transition state theory frequency factors. The potential energy profiles of the isomerization of propylene oxide to acetone, propanal, and allyl alcohol contain one transition state each, indicating that these reactions proceed via concerted mechanisms with simultaneous C−O bond rupture and 1,2- or 1,4-H-atom shift. The potential energy surface of the isomerization of propylene oxide to methyl vinyl ether contains three transition states and two intermediates. The initial step of the process is a C−C bond cleavage with a relatively low barrier. The first intermediate has a trans structure, and the second intermediate on the surface has a cis st...

Carbon dioxide fixation in the metabolism of propylene and propylene oxide by Xanthobacter strain Py2.

Evidence for a requirement for CO2 in the productive metabolism of aliphatic alkenes and epoxides by the propylene-oxidizing bacterium Xanthobacter strain Py2 is presented. In the absence of CO2, whole-cell suspensions of propylene-grown cells catalyzed the isomerization of propylene oxide (epoxypropane) to acetone. In the presence of CO2, no acetone was produced. Acetone was not metabolized by suspensions of propylene-grown cells, in either the absence or presence of CO2. The degradation of propylene and propylene oxide by propylene-grown cells supported the fixation of 14CO2 into cell material, and the time course of 14C fixation correlated with the time course of propylene and propylene oxide degradation. The degradation of glucose and propionaldehyde by propylene-grown or glucose-grown cells did not support significant 14CO2 fixation. With propylene oxide as the substrate, the concentration dependence of 14CO2 fixation exhibited saturation kinetics, and at saturation, 0.9 mol of CO2 was fixed per mol of propylene oxide consumed. Cultures grown with propylene in a nitrogen-deficient medium supplemented with NaH13CO3 specifically incorporated 13C label into the C-1 (major labeled position) and C-3 (minor labeled position) carbon atoms of the endogenous storage compound poly-beta-hydroxybutyrate. No specific label incorporation was observed when cells were cultured with glucose or n-propanol as a carbon source. The depletion of CO2 from cultures grown with propylene, but not glucose or n-propanol, inhibited bacterial growth. We propose that propylene oxide metabolism in Xanthobacter strain Py2 proceeds by terminal carboxylation of an isomerization intermediate, which, in the absence of CO2, is released as acetone.

Zeolite catalysis for a better environment

To meet the regulations of The Clean Air Acts, solid acid alkylation and isomerization of alkanes and naphthenes have become important processes for producing high-octane blending components in gasoline. To reduce the costs associated with filtration and disposal of chemical waste, the chemical industry has to switch from homogeneous or unsupported heterogenous catalysts to supported catalysts. Zeolite catalysts are playing an ever-increasing role in the petroleum refining and chemicals manufacturing processes. In the areas of acid catalysis by zeolites, recent publications on isobutane alkylation, alkane isomerization, alkene interconversion and isomerization, phenol alkylation and oxygenate production are reviewed. Also reviewed in the areas of basic zeolite catalysis is the patent literature on isomerization of propylene oxide to allyl alcohol, double-bond isomerization of alkenes and ethoxylation of glycol.

Characterization of chlorine-treated alumina surfaces

In order to prepare solid Lewis acid catalysts, γ-alumina was first dehydrated at 773 K and was then exposed to chlorine gas for 1 h at 773–1373 K. The aluminas chlorinated above 973 K had no hydroxyl group and, in the adsorption of pyridine, yielded the typical and enhanced four IRabsorption peaks assigned to pyridine coordinated on Lewis acid sites. The absence of b was ascertained by IR spectroscopic studies of adsorbed carbon dioxide and by the absence of the formation of allyl alcohol and acrolein in propylene oxide isomerization. With an increase in chlorination temperature, the intensity of the 1628 cm −1 peak of coordinated pyridine decreased from a maximum at 973 K, but the difference in the peak intensity between the chlorinated and dehydrated aluminas increased. A similar temperature dependence was obtained in the chlorine content. Further, from ESCA data, the chlorine on the treated alumina was concluded to exist in the form of a chloride ion linked to an aluminium cation. Consequently, the enhanced Lewis acid sites, which changed the yellow colour of 2,4-dinitrofluorobenzene (p K a = −14.52) to yellow-orange, were concluded to be induced by the chloride ions. In addition, the chlorinated alumina adsorbed 1-chloropropane to form π-allyl and isopropyl cations simultaneously, in addition to the propyl cation, and yielded a high cis/trans ratio of 6.2 in 1-butene isomerization at 273 K.

Solid acidity of higher temperature-treated kaolin and isomerization of propylene oxide.

Solid acidity of higher temperature-treated kaolin and isomerization of propylene oxide.

On the isomerization of propylene oxide during tetrahydrofuran polymerization by the catalyst system BF 3-propylene oxide

The initiation of THF polymerization by the catalytic system BF 3-propylene oxide is shown to be accompanied by propylene oxide isomerization to propionic aldehyde. An assumption that there are differing rate constants of deactivation of active centres for initial and advanced stages in the process made it possible to satisfy the propylene oxide balance. Additions of polar compounds (water and sodium perchlorate) significantly influence the kinetics of propionic aldehyde formation.

Effect of polar compounds on copolymerization of propylene oxide and tetrahydrofuran

Propionaldehyde and sodium perchlorate have a marked effect not only on kinetics of copolymerization of propylene oxide and tetrahydrofuran (THF) initiated by BF 3, and also on molecular weight characteristics of the copolymer obtained. The ability of polar compounds to solvate BF 3 complexes and growing centres slows down all the reactions in which they take part. For example, the rate of isomerization of propylene oxide and the formation of a cyclic tetramer decreases, while the concentration of the latter during the process passes through the maximum. This is explained by the existence of chain transfer to a cyclic tetrameter with ring opening.

The Isomerization of Propylene Oxide on Metal Oxides and Silica-Magnesia Catalysts

Abstract The isomerization of propylene oxide was carried out over silica-magnesia catalysts and metal oxides at 260–270°C using a pulse reactor. The main products of the reaction were propionaldehyde, acetone, allyl alcohol, 1-propanol, and acrolein. Propionaldehyde and acetone are produced on acidic and basic sites respectively. Allyl alcohol is formed over acid-base bifunctional catalysts. 1-Propanol and acrolein are mainly produced through hydrogen-transfer reactions between allyl alcohol and propionaldehyde and propylene oxide. As regards these reactions, acid-base bifunctional catalysts are favorable and the reaction rate depends on the electron-donating power of the hydrogen acceptor and the basic strength of the catalyst. The acid sites on silica-magnesia catalysts are attributed to the forsterite produced by the reaction of magnesium oxide and silica gel, and the basic sites, to the magnesium oxide remaining. The metal oxides, such as magnesium and calcium oxides, are considered to have very weak acid sites.

The Isomerization of Propylene Oxide on Zeolite Catalysts

Abstract The selectivity and activity of propylene oxide isomerization have been investigated over zeolite catalysts at 100°C. It has been found that the acid strength of a catalyst is a dominant factor in the selectivity and activity. The stronger the acid strength, the larger the ratio of acetone to propionaldehyde. The reaction intermediates are deduced to be a propylene oxide protonated or that adsorbed on a Lewis-acid site. It has also been found that, in the cases of HY, Silnex (SiO2), and HY treated with pyridine, the selectivity and activity correlate with the strength of the interaction between the propylene oxide and the surface hydroxyl group. Moreover, it has been clarified that the H0 value of the surface hydroxyl group observed at 3660 cm−1 on HY is −8.2–−5.6, while that found at 3540 cm−1 is +4.0–+4.8.

The Isomerization of Propylene Oxide on Metal Phosphate Catalysts

Abstract The isomerization of propylene oxide was carried out on metal phosphate catalysts. The main products were allyl alcohol, propionaldehyde, acetone, and 1-propanol. It was found that allyl alcohol is produced by acid-base bifunctional catalysts, acetone, by basic-site catalysts only, and propionaldehyde, by acid-site catalysts. 1-Propanol may be produced by the hydrogen-transfer reaction of allyl alcohol. The conversion to propionaldehyde is proportional to the acidity of the catalyst, the strength of which is stronger than H0=+4.8. The sum of the conversions to allyl alcohol, acetone, and 1-propanol correlate linearly with the observed basicity (H0≥+7.2) of the catalyst. The selectivity and activity are determined by the basic and acidic properties of the catalyst. The mechanisms of the propylene oxide isomerization are also discussed.

Studies of the Organic Reactions of Metal Carbonyl. III. The Hydroformylation of Olefin Oxides

Abstract The hydroformylation reactions of ethylene oxide and propylene oxide have been carried out; the character of this type of reaction may be summarized as follows: 1) Propylene oxide reacts with water gas, in the presence of dicobalt octacarbonyl serving as a catalyst, to give β-hydroxy-n-butyraldehyde as the major product, but it is important to keep the reaction temperature between 80 to 100°C in order to hold the high selectivity of this reaction. 2) At temperatures below 80°C, the reaction does not take place; on the other hand, at temperatures above 100°C, the isomerization of propylene oxide to acetone predominates, and the other side-reactions, such as the dehydration of the hydroformylation products, hydrogenation, condensation and polymerization, take place simultaneously. 3) Ethylene oxide seems to undergo hydroformylation under the same conditions as those used for the propylene oxide, but only a small amount of acrolein is obtained as the hydroformylation product. The expected product, i.e., β-hydroxypropionaldehyde, is formed, but this compound is easily converted into acrolein and the latter seems to polymerize to give a large amount of a resinous or oily material.

Allyl Alcohol - Isomerization of Propylene Oxide over a Chromic Oxide Catalyst

Allyl Alcohol - Isomerization of Propylene Oxide over a Chromic Oxide Catalyst