Licensed Processes

n-Methyl-2-Pyrrolidone (NMP)

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Introduction

Our technology generates high-quality NMP by reacting gamma-butyrolactone (GBL) and monomethylamine (MMA), which are products of our butanediol and methylamines processes, respectively.

This NMP production route extends the value of two established Davy technologies while offering feedstock flexibility and efficiency with product quality.

Process Flowsheet

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Key Reactions

The simplified set of reactions below yield the NMP product.

Esterification and subsequent hydrogenolysis of maleic anhydride produces gamma-butyrolactone:

In a separate process stream, amination converts ammonia and methanol to monomethylamine (MMA):

Finally, GBL and MMA react to yield the NMP product:

Process Description

The Davy NMP flowsheet separately generates two compounds, gamma-butyrolactone (GBL) and monomethylamine (MMA), before reacting them together to form NMP.

Process feedstocks

The process feedstock for producing GBL is molten maleic anhydride (MAH), obtainable by the oxidation of butane or benzene.

The amination process, which yields the MMA reactant, requires liquid methanol and liquid ammonia, which mix with a composite stream of recycled methanol, ammonia and methylamines from downstream distillation.

GBL production

Molten maleic anhydride reacts with methanol vapour in the Davy esterification reaction column to produce liquid-phase dimethyl maleate (DMM):

NMP small equation1-sm

Vapour-phase hydrogenolysis follows to produce gamma-butyrolactone (GBL):

NMP small equation2-sm

Some GBL also hydrolises to butanediol (BDO), which subsequently dehydrates to tetrahydrofuran (THF). Distillation separates these compounds to yield high-grade liquid GBL.

Amination

The amination feed stream, comprising methanol, ammonia and methylamines, passes through several heat exchangers, first vaporising and then superheating before entering the methylamines converter.

Here, the vapours pass over catalyst, facilitating an exothermic reaction between the methanol and ammonia to produce MMA, dimethylamine (DMA) and trimethylamine (TMA):

Additional disproportionation and transmethylation reactions create amines from other amines.

NMP small equation4-sm

The hot vapour product stream exiting the converter contains the three methylamine products, reaction water and unreacted ammonia and methanol.

The individual quantities of each amine produced are determined by the converter’s feed composition. This in turn is a function of the amounts of each reactant and methylamine product recycled from distillation to join the fresh methanol and ammonia feed.

After passing through a heat recovery system and then a condenser, the process stream, now a liquid, progresses to the distillation stage.

Distillation

The distillation system, comprising a number of columns in series, purifies and separates the crude methylamine products firstly by separating unreacted ammonia and recycling it to the amination stage.

Subsequent distillation then produces a pure anhydrous MMA stream which proceeds to NMP conversion, and water-free DMA and TMA streams that recycle back to amination.

Residual methanol is extracted from the water and also recycles to the amination stage.

NMP synthesis

Stoichiometric quantities of GBL and MMA proceed to the specialised NMP synthesis reactor, in which they undergo non-catalysed liquid-phase reaction.

The reaction takes place in two stages. First, the GBL and MMA combine to form a long-chain amide by cleavage of the GBL ring and attachment of the MMA. The resulting intermediate is 4-hydroxy-n-methylbutylamide (HMB):

NMP small equation5-sm

In the second stage, cylisation restores the cyclic molecular structure as the HMB molecule dehydrates to form NMP:

NMP small equation6-sm

Purification and separation

Distillation separates organic heavies, MMA and reaction water to yield solvent-quality NMP, which is sent to storage.

The reaction heavies and MMA are recycled back to synthesis.

+Process option: anhydrous or aqueous feed

The Davy NMP process can utilise either anhydrous or aqueous MMA feestock.

The JM Davy Advantage

The Davy NMP process utilises our world-leading technologies from our butanediol and methylamines processes. Explore the advantages they offer here:

+Low material and equipment costs:

  • The esterification step neutralises the acidic feed. This enables the hydrogenolysis and refining systems to be made of inexpensive carbon steel.

+Net savings over conventional processes:

  • The combined savings of cheaper construction materials and catalysts more than compensate for the cost of the added esterification step.

+Optimised heat integration:

  • For improved efficiency and reduced operating costs, the amination process includes a heat recovery system that recycles exothermic reaction heat to the incoming feed streams.
  • This reduces required energy input.

+Lower environmental impact:

  • Flowsheet includes numerous features to prevent atmospheric emissions and to ensure the plant should fall within legislative limits worldwide.

+Simplified catalysis, process efficiency:

  • The esterification and hydrogenolysis catalysts remain in their respective reaction vessels, eliminating the need for catalyst separation and neutralisation at any stage of the process.
  • The esterification catalyst can also be changed at 100% load without any downtime or loss of production.

+Low-cost, higher-performance catalyst:

  • The non-acidic hydrogenolysis environment also allows use of a base-metal catalyst instead of a high-grade precious metal catalyst. This delivers superior performance at lower cost.

+Easy process integration:

  • Our process can easily integrate with maleic anhydride facilities which use abundant, low-cost butane feedstock as their raw material.

+Large capacities:

  • High process output available in a single train.
Core Technologies & Related Processes

Our NMP process comprises several Davy core technologies. Find more detail on each here:

The Davy NMP process employs technologies used in our butanediol (BDO) flowsheet to generate the GBL reactant. Learn more about our BDO process here:

Additionally, our NMP flowsheet is one of several we offer to further enhance our methylamines process. Explore Davy methylamines here, along with our additional value-adding flowsheets:


Core Technologies

Our NMP process comprises several Davy core technologies. Find more detail on each here:


Related Processes

The Davy NMP process employs technologies used in our butanediol (BDO) flowsheet to generate the GBL reactant. Learn more about our BDO process here:

Additionally, our NMP flowsheet is one of several we offer to further enhance our methylamines process. Explore Davy methylamines here, along with our additional value-adding flowsheets: