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    Manufacture of melamine
    2.
    发明授权
    Manufacture of melamine 失效
    制造三聚氰胺

    公开(公告)号：US3895007A

    公开(公告)日：1975-07-15

    申请号：US35309973

    申请日：1973-04-20

    Applicant: BASF AG

    Inventor： SCHWARZMANN MATTHIAS ,  WIDMANN ALFRED ,  VOGEL LUDWIG ,  FROMM DIETER

    IPC: C07D251/60 ,  C07D20060101 ,  C07D55/28

    CPC classification number: C07D251/60

    Abstract: Catalytic manufacture of melamine from urea by thermal cracking of urea and converting the resulting cracked gases to melamine in the presence of catalysts. The thermal decomposition is carried out in a fluidized bed, the necessary heat being applied by heat exchangers located in the fluidized bed. Conversion of the cracked gases to melamine is effected either in the same fluidized bed, in which case the fluidized solid consists of conventional catalysts, or in a reaction zone remote from said fluidized bed. In the latter case, the solids fluidized consist of catalytically inactive particles, the conversion being carried out in the presence of catalysts in said reaction zone remote from the fluidized bed. In both cases, the urea is fed to the fluidized bed at a point above the heat exchangers.

    Abstract translation: 通过尿素热裂解从尿素催化制备三聚氰胺，并在催化剂存在下将产生的裂化气转化为三聚氰胺。 热分解在流化床中进行，所需的热量由位于流化床中的热交换器施加。 裂化气体转化为三聚氰胺在同一流化床中进行，在这种情况下，流化固体由常规催化剂组成，或在远离所述流化床的反应区中。 在后一种情况下，固体流化由催化非活性颗粒组成，转化是在催化剂存在下在远离流化床的所述反应区中进行的。 在这两种情况下，尿素在热交换器上方的一点加入流化床。

    Process for the purification of crude dimethyl terephthalate
    4.
    发明授权
    Process for the purification of crude dimethyl terephthalate 失效
    纯化粗对苯二甲酸二甲酯的方法

    公开(公告)号：US3073754A

    公开(公告)日：1963-01-15

    申请号：US383360

    申请日：1960-01-21

    Applicant: BASF AG

    Inventor： AROYAN HARRY JAMES ,  SINN RICHARD ,  SCHERF KARL ,  VOGEL LUDWIG

    IPC: B01D9/00 ,  C07C69/82

    CPC classification number: B01D9/0013 ,  B01D9/0059 ,  C07C67/54 ,  C07C69/82

    Abstract: Pure dimethyl terephthalate is recovered from mixtures of the ester with methanol, water and other impurities by a process in which a distillation column 1 is maintained at a pressure at which the condensation temperature of the vaporized methanol-water mixture is above the solidification temperature of the ester, i.e. at least 8 atmospheres, an overhead fraction of methanol, water and low-boiling impurities is led off by line 5 to a second, dehydrating, distillation column 10 from which pure methanol is obtained overhead by line 11 and water and impurities are drained off by line 35, the ester mixed with high-boiling impurities is led by line 9 into a third distillation column 14 maintained at atmospheric or slightly elevated pressure up to 1 atmosphere gauge, to which column methanol vapour is also fed by line 13, and the pure ester is separated from methanol after the fraction consisting of ester and methanol distilled off by line 18 is condensed. High-boiling impurities are discharged by line 16. Crude mixtures preferably contain 1.5 to 8 parts of methanol per part of ester and the water content is between 1 and 30% of the methanol content. Two columns instead of column 1 may be used. The vapours in line 18 are condensed at atmospheric or reduced pressure in a vessel 20 and the condensate is cooled further, e.g. to between 40 DEG C. and -10 DEG C., in a container 21 to crystallize the ester, which is then separated from methanol in a centrifuge 24. The ester, after washing, if desired, with methanol from line 26, is passed to a drier 28 while excess methanol is passed to a reservoir 25 for use in the esterification of terephthalic acid or for circulation to the second column 10 by line 33.

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