Lower olefin oxidation

Catalytic epoxidation of olefins by various forms of bound oxygen (ROOH, H202, peroxy acids) in the liquid phase was comprehensively studied in a review [132, 133] in which 

Of special attention is the single-stage method of olefm oxide production by their conjugated oxidation with another, more easily oxidizing compound (aldehyde, ketone, etc.) [134,139], For the epoxidation of an olefm, active oxygen of peroxy radicals is used in such a system  

The principal possibility of olefm epoxidation by peroxy radicals is indicated. The simplest representative of this class can be obtained from H202. 

The gas-phase propylene oxidation with hydrogen peroxide according to the conjugated mechanism is one of the major ways of synthesizing such valuable products as propylene oxide, acrolein and allene [124, 141,142], 

Conjugated propylene epoxidation with hydrogen peroxide is the main reaction proceeding in the temperature range of 500-580 °C under optimal conditions the average propylene oxide yield reaches 50%. 

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The usual procedures of fractional, azeotropic, or extractive distillation under inert gases, crystallization, sublimation, and column chromatography, must be carried out very carefully. For liquid, water-insoluble monomers (e.g., styrene, Example 3-1), it is recommended that phenols or amines which may be present as stabilizers, should first be removed by shaking with dilute alkali or acid, respectively the relatively high volatility of many of these kinds of stabilizers often makes it difficult to achieve their complete removal by distillation. Gaseous monomers (e.g., lower olefins, butadiene, ethylene oxide) can be purified and stored over molecular sieves in order to remove, for example, water or CO2. 

The literature on liquid-phase olefin oxidation has been well reviewed (1, 2, 3, 5, 6, 8,12,14,15, 16,17, 18,19,20). Recent attention has been focused on the effects of structure and reaction conditions on the proportions of alkenyl hydroperoxy radical reaction by the abstraction and addition mechanisms at lower temperatures and conversions. The lower molecular weight cyclic and acyclic olefins have been extensively studied by Van Sickle and co-workers (17, 18, 19, 20). These studies have recently been extended to include higher molecular weight alkenes (16). 

Catalytic oxidation and ammoxidation of lower olefins to produce a,/3-unsaturated aldehyde or nitrile are widely industrialized as the fundamental unit process of petrochemistry. Propylene is oxidized to acrolein, most of which is further oxidized to acrylic acid. Recently, the reaction was extended to isobutylene to form methacrylic acid via methacrolein. Ammoxidation of propylene to produce acrylonitrile has also grown into a worldwide industry. 

During the history of a half century from the first discovery of the reaction (/) and 35 years after the industrialization (2-4), these catalytic reactions, so-called allylic oxidations of lower olefins (Table I), have been improved year by year. Drastic changes have been introduced to the catalyst composition and preparation as well as to the reaction process. As a result, the total yield of acrylic acid from propylene reaches more than 90% under industrial conditions and the single pass yield of acrylonitrile also exceeds 80% in the commercial plants. The practical catalysts employed in the commercial plants consist of complicated multicomponent metal oxide systems including bismuth molybdate or iron antimonate as the main component. These modern catalyst systems show much higher activity and selectivity... 

Some progress has been made in explaining the splendid catalytic performance of multicomponent bismuth molybdates that are used widely for the industrial oxidations and ammoxidations of lower olefin. We have seen that the catalytic activity and selectivity are greatly enhanced by the multifunctionalization of the catalyst systems. Many functions newly introduced are... 

The oxidative dimerization has recently attracted attention, both from a fundamental viewpoint and as a means for synthesizing aromatics from lower olefins. The reaction is essentially a combination of allyl radicals, by which the oxidation is limited to the abstraction of one hydrogen atom. Typically, the catalysts applied here do not contain Mo03 or a similar component that promotes the selective incorporation of oxygen. 

The catalytic oxidation in the presence of various heteropoly compounds of lower olefins to unsaturated aldehydes and subsequent conversion into unsaturated nitriles are described in Ref.225-231. Copper phthalocyanine is produced in 92% yield from phthalic anhydride in the presence of 12-molybdophosphoric acid232. ... 

Until recently, information on alkylation studies reported in the Russian chemical literature was limited to laboratory work. The work of Butlerov and his students on triptene induced one member of their group, El tekov, to study alkylation as a method of preparation of triptene from lower olefins (99,100). Moldavskii and co-workers recently improved this method in an apparent effort at commercial preparation of triptene which is readily hydrogenated to the high antiknock fuel, triptane (242). The alkylation of pentene was accomplished by El tekov with methyl iodide over lead oxide, whereas Moldavskii used methyl chloride and magnesia. Moldavskil s work was probably carried out simultaneously with similar researches in this country. 

The first polymerizations were free radical reactions. In 1933 researchers at ICI discovered that ethene polymerizes into a branched structure that is now known as low density polyethene (LDPE). In the mid- 50s a series of patents were issued for new processes in which solid catalysts were used to produce polyethene at relatively low pressures. The first was granted to scientists at Standard Oil (Indiana) who applied nickel oxide on activated carbon and molybdenum oxide on alumina. Their research did not lead to commercial processes. In the late 40s Hogan and Banks of Phillips were assigned to study the di- and trimerization of lower olefins. The objective was to produce high octane motor fuels. When they tried a chromium salt as promoter of a certain catalyst (Cr was a known reforming... 

Rare earth oxides are useful for partial oxidation of natural gas to ethane and ethylene. Samarium oxide doped with alkali metal halides is the most effective catalyst for producing predominantly ethylene. In syngas chemistry, addition of rare earths has proven to be useful to catalyst activity and selectivity. Formerly thorium oxide was used in the Fisher-Tropsch process. Recently ruthenium supported on rare earth oxides was found selective for lower olefin production. Also praseodymium-iron/alumina catalysts produce hydrocarbons in the middle distillate range. Further unusual catalytic properties have been found for lanthanide intermetallics like CeCo2, CeNi2, ThNis- Rare earth compounds (Ce, La) are effective promoters in alcohol synthesis, steam reforming of hydrocarbons, alcohol carbonylation and selective oxidation of olefins. 

The reaction, usually carried out in aqueous acetone and with an amine oxide as the oxidant RO, is catalyzed by osmium tetroxide, activated by an alkaloid ligand, L. To explain the higher enantio-selectivity achieved at lower olefin concentrations, a network with two cycles having a common member has been proposed [63,64] ... 

Barbier-Wieland degradation. Stepwise carboxylic acid degradation of aliphatic acids (particularly in sterol side chains) to the next lower homo log. The ester is converted to a tertiary alcohol that is dehydrated with acetic anhydride, and the olefin oxidized with chromic acid to a lower homologous carboxylic acid. 

The subjects presented span a wide range of oxidation reactions and catalysts. These include the currently important area of lower alkane oxidation to the corresponding olefins, unsaturated aldehydes, acids and nitriles. In this manner, the abundant and less expensive alkanes replace the less abundant and more expensive olefins as starting materials for industrially important intermediates and chemicals. In the oxidative activation of methane the emphasis is shifting towards the use of extremely short contact times and newer more rugged catalysts. In the area of olefin oxidations, of particular note are the high efficiency epoxidation of propylene, and new detailed mechanistic insights into the... 

One overall approach currently receiving much attention is the direct coupling of methane to yield higher hydrocarbons. This coupling may be carried out catalytically in the presence of oxygen or other oxidizing agent or by the pyrolysis of methane over a suitable catalyst. Should such a route prove successful the likely products will be rich in lower olefins. 

Natural gas, by direct partial oxidation, can provide olefins suitable for oligomerisation using the Mobil Olefin to Gasoline and Diesel process. Alternatively, synthesis gas routes to olefins can be via methanol or Fischer-Tropsch synthesis. In the Fischer-Tropsch option, the hydrogen-rich nature of the synthesis gas requires that the catalyst should have poor shift activity and produce a narrow range of lower olefins. 

On many supports, ruthenium converts synthesis gas with high selectivity into lower alkanes, notably methane.. However, when ruthenium is supported on certain basic oxides, such as lanthana and ceria, highly selective production of lower olefins has been reported (1,2). One of the aims of this research was to improve the activity and selectivity of ruthenium supported on rare earth oxides (REO). As commercially available REO are of low surface area (<15m2g"l), routes to higher surface area materials have also been developed (3). 

It has been presented here that there is not a unique Ti-Beta material, but the characteristics and catalytic performance strongly depend on chemical composition and synthesis procedure. Then, new synthesis procedures which allow to prepare samples with much lower A1 content than any one reported before have been developed. Moreover, by using highly reactive and stable seeds, crystals of Ti-Beta zeolite have been produced, which have an inner core of aluminosilicate composition, covered by an outer shell of Titanosilicate which accounts for about 98 % of the mass. These synthesis methods have lead to samples which present an improved catalytic behaviour for reactions such as olefin oxidation and phenol hydroxylation using H202 as oxidant. 

Vapor-phase aerobic oxidations of lower olefins, e. g. propylene to acrolein or acrylic acid and isobutene to methacrolein or methacrylic acid, are well-established bulk chemical processes [1,2], They are usually performed over oxidic catalysts, such as bismuth molybdate or heteropoly compounds, although the scope of these allylic oxidations is limited to olefins that cannot form 1,3-dienes via oxidative dehydrogenation. Thus 1- and 2-butene are converted to butadiene, and methylbutenes to isoprene, and with higher olefins complex mixtures result from further oxidation. Hence, such methodologies are not relevant in the context of fine chemicals. 

The present chapter is limited to oxidation of lower olefins, especially those with two to five carbon atoms, over solid catalysts in the vapor phase. Patent literature is given scant attention, but journal literature is covered through 1965. Liquid phase oxidation with homogeneous catalysts has recently grown in importance, but such studies are excluded from this chapter. A review of the oxidation of ethylene to acetaldehyde with PdClg solutions is given by Smidt (3). 

Cuprous chloride tends to form water-soluble complexes with lower olefins and acts as an IPTC catalyst, e.g., in the two-phase hydrolysis of alkyl chlorides to alcohols with sodium carboxylate solution [10,151] and in the Prins reactions between 1-alkenes and aqueous formaldehyde in the presence of HCl to form 1,3-glycols [10]. Similarly, water-soluble rhodium-based catalysts (4-diphenylphosphinobenzoic acid and tri-Cs-io-alkylmethylam-monium chlorides) were used as IPTC catalysts for the hydroformylation of hexene, dodecene, and hexadecene to produce aldehydes for the fine chemicals market [152]. Palladium diphenyl(potassium sulfonatobenzyl)phosphine and its oxide complexes catalyzed the IPTC dehalogenation reactions of allyl and benzyl halides [153]. Allylic substrates such as cinnamyl ethyl carbonate and nucleophiles such as ethyl acetoactate and acetyl acetone catalyzed by a water-soluble bis(dibenzylideneacetone)palladium or palladium complex of sulfonated triphenylphosphine gave regio- and stereo-specific alkylation products in quantitative yields [154]. Ito et al. used a self-assembled nanocage as an IPTC catalyst for the Wacker oxidation of styrene catalyzed by (en)Pd(N03) [155]. 

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