Licensed Processes

Choline Chloride

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Introduction

This Davy flowsheet reacts trimethylamine (TMA), hydrochloric acid (HCl) and ethylene oxide (EO) in a continuous, single-stream process to produce choline chloride (ChCl).

This highly efficient technology adds value to our well-established methylamines process, which produces the TMA reactant. Alternatively, if a pre-existing TMA source is available, we can provide the flowsheet for stand-alone conversion to ChCl.

Process Flowsheet

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Key Reactions

The simplified set of reactions shown below yield the choline chloride product.

The amination stage first converts methanol and ammonia to trimethylamine (TMA):

Choline chloride is then produced in a liquid-phase reaction between HCl, TMA and ethylene oxide:

Process Description

The Davy choline chloride process comprises two main steps: vapour-phase methylamines production which yields the key substrate trimethylamine (TMA); then a two-stage reaction system for the liquid-phase conversion of TMA to ChCl.

Process feedstock

The process feedstocks are liquid methanol and liquid ammonia, which mix with a composite stream of methanol, ammonia and methylamines recycled from downstream distillation.

The ChCl reaction system employs aqueous hydrochloric acid (HCl) and pure ethylene oxide (EO) feeds.

Amination

The feed stream 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 monomethylamine (MMA), dimethylamine (DMA) and TMA:

Amination-equations-1

Additional disproportionation and transmethylation reactions create amines from other amines.

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 TMA stream which proceeds to ChCl conversion, and a water-free MMA/DMA mixture that recycles back to amination.

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

ChCl synthesis

The ChCl reaction system consists of a single continuous reaction stream proceeding through two reactors in series, both of which operate under mild conditions.

In the first reaction stage, aqueous HCl and anhydrous liquid TMA react exothermically to yield the intermediate trimethylamine hydrochloride (TMA-HCl):

Proceeding to the second reactor, the TMA-HCl solution mixes with pure liquid ethylene oxide, resulting in another exothermic reaction to this time produce the final ChCl product:

Concentration, purification and dosing

Excess TMA, water and trace organics are flashed from the crude product, and subsequent heating concentrates the solution by evaporation. The recovered TMA recycles to the ChCl synthesis stage.

In storage, chemical dosing controls the final product pH and prevents oxidation and discolouring.

The JM Davy Advantage

By adding a simple, continuous reaction system to our world-leading methylamines (MA) process, the Davy ChCl flowsheet further enhances our already established technology. Explore the advantages below:

+Highly flexible technology:

  • Allows plant design to deliver optimal product ratios, which can be adjusted online to match future requirements.

+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.

+Large capacities:

  • High process output available in a single train.

+Lower environmental impact:

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

Our amination technology is the cornerstone of our ChCl process, realising the full potential of the Leonard process efficiently, cleanly and productively. Learn more here:

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


Core Technologies

Our amination technology is the cornerstone of our ChCl process, realising the full potential of the Leonard process efficiently, cleanly and productively. Learn more here:


Related Processes

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