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    32.
    发明专利
    未知

    公开(公告)号：DE3868360D1

    公开(公告)日：1992-03-26

    申请号：DE3868360

    申请日：1988-06-24

    Applicant: BASF AG

    Inventor： KRABETZ RICHARD DR ,  DUEMBGEN GERD DR ,  MERGER FRANZ DR ,  JAEGER MICHAEL ,  THIESSEN FRITZ DR ,  VOGEL HERBERT DR

    IPC: B01J27/19 ,  C07B63/04 ,  C07C51/00 ,  C07C51/235 ,  C07C51/25 ,  C07C57/05 ,  C07C57/055 ,  C07C57/07 ,  C07C67/00

    Abstract: Prodn. of methacrylic acid (I) by gas phase oxidn. of methacrolein (IIA) or isobutyraldehyde (IIB) with gas mixts. contg. O2 and steam is carried out on catalysts (III) contg. Mo and P at 250-400 deg.C. The hot reaction gas is cooled to under 100 deg.C and passed to an absorption column operating with water below 100 deg.C for absorption of the (I) formed, then partly recycled to the reactor after adding the reqd. amt. of (II) and O2. The novel features are that: (a) (II) in an amt. equal to the amt. consumed is added in liq. form to the reaction gas in the lower two-thirds of the absorption column, in conjunction with polymerisation inhibitors (IV); and (b) a side stream of the reactor gas is taken before addn. of (II) or after the absorption column, and scrubbed in a scrubbing column operating with water at 0 to under 10 deg.C to remove unreacted (II) and this is passed to the top of the absorption column as aq. soln.

    33.
    发明专利
    未知

    公开(公告)号：DE3800991A1

    公开(公告)日：1989-07-27

    申请号：DE3800991

    申请日：1988-01-15

    Applicant: BASF AG

    Inventor： WILLERSINN CARL-HEINZ DR ,  MARTAN HANS DR ,  KRABETZ RICHARD DR ,  ENGERT GERD-JUERGEN DR

    IPC: C07C57/05 ,  C07C51/00 ,  C07C51/25 ,  C07C57/055 ,  C07C67/00

    Abstract: A process for the manufacture of alpha , beta -monoolefinic unsaturated carboxylic acids containing 3 to 4 C atoms by gas phase oxidation of alkylenes containing 3 to 4 C atoms and the corresponding alpha , beta -monoolefinic unsaturated aldehydes using oxidic catalysts containing molybdenum and customary therefor in two oxidation steps at pressures from 0.5 to 10 bar, removal of the unsaturated carboxylic acids after the second oxidation step by absorption and return of unreacted starting substances, in which the pressure after the second oxidation step is adjusted to 0.3 to 1.0 bar.

    34.
    发明专利
    未知

    公开(公告)号：DE3721865A1

    公开(公告)日：1989-01-12

    申请号：DE3721865

    申请日：1987-07-02

    Applicant: BASF AG

    Inventor： KRABETZ RICHARD DR ,  DUEMBGEN GERD DR ,  MERGER FRANZ DR ,  JAEGER MICHAEL ,  THIESSEN FRITZ DR ,  VOGEL HERBERT DR

    IPC: B01J27/19 ,  C07B63/04 ,  C07C51/00 ,  C07C51/235 ,  C07C51/25 ,  C07C57/05 ,  C07C57/055 ,  C07C57/07 ,  C07C67/00

    Abstract: Methacrylic acid can be prepared with advantage by gas phase oxidation of methacrolein or isobutyraldehyde over Mo- and P-containing catalysts at from 250 DEG to 400 DEG C. with cooling of the hot reaction gas to below 100 DEG C., absorption of the methacrylic acid in a water-operated absorption column, at below 100 DEG C. and partial recycling into the oxidation reactor after admixture of methacrolein or isobutyraldehyde and oxygen by feeding a quantity of methacrolein or isobutyraldehyde equal to the quantity of methacrolein or isobutyraldehyde consumed in the reaction in liquid form together with a polymerization inhibitor into the reactor gas in the lower two-thirds of the absorber column and upstream of the feed point for the fresh methacrolein or isobutyraldehyde or down-stream of the absorption column splitting off the reactor off-gas a side stream which is washed in a wash column operated with water at

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