Process for processing ethylene oxide streams containing nox or organic nitrogen compounds

A technology of ethylene oxide and alkylene oxide, which is applied in the field of preparation of alkylene glycol, and can solve problems such as foaming and decolorization of solids

Inactive Publication Date: 2009-10-28
DOW TECH INVESTMENTS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Discoloration, solids formation, and foaming can be particularly severe in these purge stream treatment units

Method used

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Examples

Experimental program
Comparison scheme
Effect test

comparative test A

[0034] Water containing about 2% by weight ethylene oxide condensed from the outlet of the ethylene oxide reactor was fed to a coiled 18 feet (5.5 meters) long by 1 / 4 inch (6.25 mm) diameter stainless steel Tubular reactor. The reaction mixture contains ethylene oxide, dissolved NO x and dissolved organic nitrogen compounds. Conditions in the tubular reactor included an operating pressure of 300 psig (2068 kPa) and an operating temperature of 180°C. The residence time is 10 minutes. Ethylene oxide contained in the feed is converted to ethylene glycol in the tubular reactor. The process stream leaving the reactor was black and foamy. The solids are separated from the exiting process stream as the process stream passes through a tar coated fine mesh filter by filtering through the filter and measuring the weight gain on the filter. The process stream contained 116 ppm suspended solids.

Embodiment 1

[0036] Comparative Experiment A was repeated except that 0.14% by weight of sodium bisulfite was added to the process stream entering the tubular reactor. The outlet fluid was black and frothy, but contained only 7 ppm suspended solids. This represents a 94% reduction in solids compared to Comparative Test A.

Embodiment 2

[0038] Comparative Experiment A was repeated except that 0.42% by weight of sodium bisulfite was added to the process stream entering the tubular reactor. The outlet fluid was much lighter in color than Comparative Test A and produced little foam. The outlet fluid contained only 20 ppm suspended solids, which represents an 82% reduction in solids compared to Comparative Test A.

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PUM

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Abstract

Crude aqueous alkylene oxide streams are converted to the corresponding alkylene glycol. The crude alkylene oxide stream contains NOx or organic nitrogen compounds. The hydrolysis reaction is conducted in the presence of water-soluble reducing agents, of which an alkali metal bisulfite is a preferred type.

Description

field of invention [0001] The present invention relates to a process for the preparation of alkylene glycols by the reaction of alkylene oxides and water. More specifically, the present invention relates to methods of reducing the amount of certain types of impurities and / or by-products that may be produced during alkylene glycol-forming reactions. Background of the invention [0002] The 1,2-alkylene glycols are prepared by heating a mixture of the corresponding alkylene oxide and water to an elevated temperature where the water reacts at the site of the epoxy group to form a vicinal hydroxyl group. Thus, ethylene oxide and water react to form 1,2-ethanediol, while propylene oxide and water react to form 1,2-propanediol. [0003] Various unwanted side reactions can occur during such processes. Carbonyl compounds are generally formed via various mechanisms. For example, alkylene glycols can be oxidized to form the corresponding aldehyde and water molecules. Other impurit...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C29/10C07C31/20C07D301/32
CPCC07C29/106
Inventor 约翰·P·德弗威廉姆·C·霍夫曼詹姆斯·H·麦凯恩
Owner DOW TECH INVESTMENTS
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