Chemistry of hydrocarbon compounds – Aromatic compound synthesis – Having alkenyl moiety – e.g. – styrene – etc.
Patent
1997-06-18
1999-04-20
Yildirim, Bekir L.
Chemistry of hydrocarbon compounds
Aromatic compound synthesis
Having alkenyl moiety, e.g., styrene, etc.
585445, 585654, 585658, 585662, 585663, 208134, 208136, 208141, C07C 542
Patent
active
058958290
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a process for preparing olefinically unsaturated compounds by catalytic oxygen transfer from a previously oxidized oxygen transferer acting as catalyst to corresponding hydrocarbons (dehydrogenation) in the absence of molecular oxygen. The invention preferably relates to the catalytic oxidative dehydrogenation of alkylaromatics and paraffins to give the corresponding alkenylaromatics and olefins, in particular the dehydrogenation of ethylbenzene to give styrene, with water being formed.
styrene and divinylbenzene are important monomers for industrial plastics and are used in large quantities.
Styrene is prepared predominantly by non-oxidative dehydrogenation of ethylbenzene over modified iron oxide catalysts, with one mole of hydrogen being formed per mole of styrene. A disadvantage of this reaction is that it is an equilibrium reaction which typically proceeds at from 600 to 700.degree. C. and gives a conversion of about 60% at a styrene selectivity of about 90%. As the conversion and concentration of the target product rise, the reverse reaction occurs and limits the conversion.
Oxidative dehydrogenation, in which the hydrocarbon is reacted with molecular oxygen, enables, in contrast, a virtually quantitative conversion to be achieved, since water is formed in this reaction. In addition, this reaction proceeds at a lower temperature than the non-oxidative dehydrogenation. A disadvantage of this procedure is that carbon monoxide and dioxide are formed in a secondary reaction (total oxidation).
It has therefore been proposed that, instead of using molecular oxygen, use be made of an oxygen transferer comprising a reducible metal oxide which acts as catalyst, ie. steers the reaction. In the process the oxygen transferer gradually becomes exhausted and is regenerated in a second step. This principle, which is frequently used in classical process engineering, is called the regenerative principle or non-steady-state method. In the case of the oxidative dehydrogenation, the enthalpy balance of the overall reaction, ie. the sum of the two sub-steps, is negative. By decoupling the reduction and oxidation steps, the selectivity can be significantly increased.
The regenerative principle using a reducible and regenerable catalyst was first described for the oxidation or ammonoxidation of propene to give acrolein and acrylic acid or acrylonitrile (GB 885 422; GB 999 629; K. Aykan, J. Catal. 12 (1968) 281-190), with arsenate and molybdate catalysts being used. The use of the regenerative process in the oxidative dehydrogenation of aliphatic alkanes to give monoolefins and diolefins using ferrite catalysts (eg. U.S. Pat. No. 3,440,299, DE 21 18 344, DE 17 93 499) is likewise known, as is its use for the oxidative coupling of methane to give higher hydrocarbons; catalysts having various structures are used here (Mn/Mg/Si oxides in U.S. Pat. No. 4,795,849, DE 35 86 769; ruthenium oxide in U.S. Pat. No. 4,568,789; Mn/B oxides on MgO in EP 254 423; Mn.sub.3 O.sub.4 spinels in GB 2 156 842). Also known is the dehydrodimerization of toluene to give stilbene in the absence of free oxygen by means of reducible catalysts such as Bi/In/Ag oxides (EP 30 837). Finally, the principle has also been used in the dehydrogenation, dehydrocyclization and dehydroaromatization of paraffin hydrocarbons for upgrading gasoline (U.S. Pat. No. 4,396,537, using Co/P oxide catalysts).
EP 397 37 and 403 462 disclose the use of the process principle for the oxidative dehydrogenation of paraffinic hydrocarbons and alkylaromatics. According to these disclosures, use is made of reducible oxides of metals selected from the group V, Cr, Mn, Fe, Co, Pb, Bi, Mo, U and Sn applied to supports of clays, zeolites and oxides of Ti, Zr, Zn, Th, Mg, Ca, Ba, Si, Al.
The listing above is only an extract from the extensive literature and relates only to processes which are relatively similar chemically. Without going into more detail, further information is to be found in the following publications: EP 558 148; EP 556489; EP 543535; U.S. Pa
REFERENCES:
patent: 3440299 (1969-04-01), Woskow et al.
patent: 3488402 (1970-01-01), Michaels et al.
patent: 3567793 (1971-03-01), Colling et al.
patent: 3686347 (1972-08-01), Dean et al.
patent: 4568789 (1986-02-01), Withers, Jr.
patent: 4581339 (1986-04-01), Bhatt et al.
patent: 4704497 (1987-11-01), Gottlieb et al.
patent: 4795849 (1989-01-01), Gaffney et al.
Jr. of Catalysis 12, 281-290 (1968) Reduction of Bi.sub.2 O.sub.3 -MoO.sub.3 Catalyst during the Ammoxidation . . . Aykan.
Buchele Wolfgang
Deimling Axel
Hagemeyer Alfred
Hoffmann Wolfgang
Popel Wolfgang Jurgen
BASF - Aktiengesellschaft
Yildirim Bekir L.
LandOfFree
Preparation of olefinically unsaturated compounds, in particular does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Preparation of olefinically unsaturated compounds, in particular, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Preparation of olefinically unsaturated compounds, in particular will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2248430