Maleic Acid → Dimethyl maleate

Participants

Reaction Steps

This example relates particularly to FIG. 3 and illustrates use of a side heater in the reaction column. In this example a 95 wt % solution of aqueous maleic acid is provided as described in Example 1. The aqueous maleic acid feed is mixed with recycle methanol from the refining section (line 38/16a′) and fed to a plug flow, mono-ester reactor (36), where more than 80% of the maleic acid is converted to mono-methyl maleate. The product from this is fed to reaction column (19′) to react to the mono-methyl maleate with methanol to produce di-methyl maleate. This reaction column includes a heater near the feed point. The heater helps to drive off water from the column. 350 moles per hour of methanol (lines 42 and 41) are fed to the bottom of the reaction column (19′). Essentially water free, fully converted di-methyl maleate (line 26′) is fed to hydrogenation (20). Recycle methanol from the refining section is fed to the top of the reaction column as wash (line 16b′) to minimize the di-methyl maleate and maleic acid in the overhead of the column. Methanol or water from the overhead (line 31′) of the reaction column is fed to the methanol column (25′) where the methanol is separated and recycled to the reaction column (line 39). Water and a small amount of recovered maleic acid and di-methyl maleate from the bottom of the methanol column are recycled to the absorber (2) in line 3′.

Provenance & Evidence