| 摘要 |
The process involves (1) Adding a mixture of C4 hydrocarbons (I) of which >=50% are linear and olefinically unsatd. to air, heated to 100-200 degrees C. (2) Adding a volatile organic or mineral phosphorus cpd (II). (3) Passing the mixture through a tubular reactor at 420-600 degrees C lined with catalyst contg. 45-95% TiO2, 0.2-20% V2O5 and 3-53% P2Ok. (4) HEat exchange being carried out by a circulated salt bath at 350-440 degrees C supplied at one end of the reactor at constant flow through an annular tube and discharging from the other end of the reactor through a second annular tube. (5) Cooling the reacted mixture to 160-180 degrees C and washing it to extract maleic anhydride using cold aqs. maleic acid soln. which is obtained at concn. 30-50%. (6) Evaporating the soln. to >90% conc. in thin film evaporators. (7) Splitting maleic anhydride and water vapour in another evaporator. (8) Refining the crude product by continuous fractionation. (I) may contain 0-30% butadiene, 20-100% n-butenes, 0-50% isobutene and 10-50% butanes where the total of butadiene and n-butenes is >=50%. (II) is a trialkyl 1-4C phosphate. Content of (I) is 25-40g/m3 normal of the heated air. - The process uses cheaper raw materials, than known maleic anhydride production precesses, and is simpler to control, more trouble free, and gives improved yields of high quality product.
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