Styrene development ethylbenzene catalysts

EBMax A continuous, liquid-phase process for making ethylbenzene from ethylene and benzene, using a zeolite catalyst. Developed by Raytheon Engineers and Constructors and Mobil Oil Corporation and first installed at Chiba Styrene Monomer in Japan in 1995. Generally similar to the Mobil/Badger process, but the improved catalyst permits the reactor size to be reduced by two thirds. 

In the C4 coproduct route isobutane is oxidized with oxygen at 130-160°C and under pressure to tert-BuOOH, which is then used in epoxidation. In the styrene coproduct process ethylbenzene hydroperoxide is produced at 100-130°C and at lower pressure (a few atmospheres) and is then applied in isobutane oxidation. Epoxidations are carried out in high excess of propylene at about 100°C under high pressure (20-70 atm) in the presence of molybdenum naphthenate catalyst. About 95% epoxide selectivity can be achieved at near complete hydroperoxide and 10-15% propylene conversions. Shell developed an alternative, heterogeneous catalytic system (T1O2 on SiOi), which is employed in a styrene coproduct process.913 914... 

Styrene, one of the world s major organic chemicals, is derived from ethylene via ethylbenzene. Several recent developments have occurred with respect to this use for ethylene. One is the production of styrene as a co-product of the propylene oxide process developed by Halcon International (12). In this process, benzene is alkylated with ethylene to ethylbenzene, and the latter is oxidized to ethylbenzene hydroperoxide. This hydroperoxide, in the presence of suitable catalysts, can convert a broad range of olefins to their corresponding oxirane compounds, of which propylene oxide presently has the greatest industrial importance. The ethylbenzene hydroperoxide is converted simultaneously to methylphenyl-carbinol which, upon dehydration, yields styrene. Commercial application of this new development in the use of ethylene will be demonstrated in a plant in Spain in the near future. 

Alkylation of benzene for the production of ethylbenzene, the raw material for making styrene and subsequently synthetic rubber, was also greatly expanded during the war because of the shortage of natural rubber. The catalyst in most of the original ethylbenzene units was aluminum chloride, but other catalysts are now preferred by many refiners. Alkylation for the production of ethylbenzene was the first large-scale alkylation process used for the production of petrochemicals. Since that time, others, such as cumene, dodecylbenzene, alkylated phenols, diisopropylbenzene, and secondary butylbenzene, have been added to the list, and others have been developed and should soon be in commercial production. 

POSM [Propylene Oxide Styrene Monomer] A process for making propylene oxide from ethylbenzene. The ethylbenzene is reacted with oxygen and propylene in the presence of a proprietary catalyst. Developed in Russia by JSC Nizkhnekamskneftkheim and licensed exclusively by Dow Chemical Company. In 2006, 36% of the world production of propylene oxide was made by this process. See also SMPO. 

The Sud-Chemie Group and Criterion Catalysts are the major catalyst developers and manufacturers for the styrene industry. Both companies offer a wide range of catalysts to suit individual processing needs. Ethylbenzene conversion, styrene selectivity, catalyst activity, and catalyst stability can be optimized by selecting the best catalyst or a combination of catalysts for a particular application. Dow and BASF manufacture proprietary catalysts, which have been mainly for use in their own respective technologies. 

Shell subsequently developed a heterogeneous, silica-supported titania catalyst [11,12] which forms the basis of the commercial process for the epoxidation of propylene with ethylbenzene hydroperoxide. The co-product alcohol is dehydrated, in a separate step, to styrene. Ti(IV)Si02 was the first truly heterogeneous epoxidation catalyst useful for continuous operation in the liquid phase. 

We have developed an effective method for the selective autoxidation of alky-laromatic hydrocarbons to the corresponding benzylic hydroperoxides using 0.5 mol% NHPI as a catalyst and the hydroperoxide product as an initiator. Using this method we obtained high selectivities to the corresponding hydroperoxides, at commercially viable conversions, in the autoxidation of cyclohexylbenzene, cumene and ethylbenzene. The highly selective autoxidation of cyclohexylbenzene to the 1-hydroperoxide product provides the basis for a coproduct-free route to phenol and the observed inq)rovements in ethylbenzene hydroperoxide production provide a basis for in roving the selectivity of the SMPO process for styrene and propene oxide manufacture. 

By far the largest outlet for benzene (approx. 60%) is styrene (phenyl-ethene), produced by the reaction of benzene with ethylene a variety of liquid and gas phase processes, with mineral or Lewis acid catalysts, are used. The ethylbenzene is then dehydrogenated to styrene at 600-650°C over iron or other metal oxide catalysts in over 90% selectivity. Co-production with propylene oxide (section 12.8.2) also requires ethylbenzene, but a route involving the cyclodimerization of 1,3-butadiene to 4-vinyl-(ethenyl-) cyclohexene, for (oxidative) dehydrogenation to styrene, is being developed by both DSM (in Holland) and Dow. 60-70% of all styrene is used for homopolymers, the remainder for co-polymer resins. Other major uses of benzene are cumene (20%, see phenol), cyclohexane (13%) and nitrobenzene (5%). Major outlets for toluene (over 2 5 Mt per annum) are for solvent use and conversion to dinitrotoluene. 

D. Ardissone, A. Bachiller, M. Ponzi, J. Orejas, Oxidehydrogenation of ethylbenzene to styrene on P-O-Ni-Mn/Alumina catalysts , to be presented m Reaction Kinetics and the Development and Operation of Catalytic Processes s Symposium , Oostende (Belgium), April, 2001... 

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