Core Technologies

Esterification

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Esters

Esters are organic compounds characterised by the RCOOR’ functional group, and are most commonly derived from the reaction of carboxylic acids with alcohols.

In this process, the hydrogen from the acid’s carboxylic group (COOH) is replaced by the hydrocarbon section (R’) of the alcohol molecule. The reaction products are the ester and water:

In Context

The Davy esterification process reacts liquid-phase carboxylic acids (R-COOH) with alcohol (R’-OH, e.g. methanol CH3OH) to produce non-acidic esters. Some examples are provided here:

The JM Davy natural detergent alcohol (NDA) licensed process esterifies fatty acids of various chain lengths to their corresponding fatty acid methyl esters (FAME):

in-context-left

Also, JM Davy’s butanediol and derivatives (tetrahydrofuran & γ-butyrolactone) and n-methyl-2-pyrrolidone (NMP) processes employ two-stage esterification to convert maleic anhydride feed to dimethyl maleate, or succinic acid feed to dimethyl succinate:

In each of these processes, the purpose of esterification is to convert an acidic feedstock to a non-acidic ester intermediate, which is much easier to process downstream using lower-grade materials of plant construction.

However, in some Davy processes the ester itself is the final product and undergoes no further processing. An example is the Davy biodiesel process, which echoes the NDA flowsheet by converting fatty acids to FAMEs.

In this case, the resulting mixed fatty esters serve as biodiesel fuel.

Esterification Flowsheet

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Process Description

Esterification proceeds by a simple, continuous process in a reactive distillation column.

Alcohol vapour enters the base of the column and travels upwards, performing three functions:

  • Firstly, it provides the necessary reactant for esterification.
  • Secondly, it strips the reaction by-product water from the organic liquid, thus driving the equilibrium reaction virtually to completion. This is particularly important as the esterification reaction is reversible.
  • Thirdly, it provides physical agitation at each reaction stage, ensuring good contact between reactants and catalyst.

The liquid acid reactant enters the top of the column and travels downwards, counter-current to the alcohol vapour.

The liquid travels via a series of proprietary design reaction trays which provide sufficient liquid residence time to ensure virtually complete equilibrium conversion to the ester product.

The solid catalyst remains on each reaction tray, eliminating the need for its downstream separation from the ester product stream.

Additionally, the catalyst can be replaced while the plant is online without any interruption of the process or loss of production.

Vapour leaving the top of the column contains the bulk of the excess alcohol and all the reaction water. These are subsequently separated, with the dry alcohol recycling to esterification.

A liquid ester stream, which also contains residual alcohol, exits the bottom of the esterification column for downstream processing or refining.

If no further reaction steps are required, the alcohol can be removed from the process stream to yield product-grade liquid ester.

In several Davy processes, however, the liquid ester proceeds to hydrogenolysis. In such cases, the residual alcohol can remain in the process stream as it does not interfere with the hydrogenolysis reaction.

The JM Davy Advantage

JM Davy’s esterification technology offers many advantages, when used either as a stand-alone chemical conversion step or in conjunction with downstream hydrogenolysis.

Learn more here:

+Process efficiency:

  • Water removal by alcohol vapour in the esterification reaction column eliminates the need for an additional removal step.

+Low material and equipment costs:

  • Esterification neutralises the acidic feed, which eliminates the need for downstream process equipment to be constructed from expensive, high-grade stainless steel.

+Minimised side reactions:

  • The optimised reaction conditions employed in JM Davy’s esterification reaction column minimise side reactions. This achieves close to 100% selectivity to esters.

+High esterification yield:

  • Excess alcohol vapour removes water vapour by-product, driving the esterification equilibrium forward.

+Low-cost catalyst in downstream processes:

  • Esterification neutralises acidic process feedstocks. This allows downstream processes to employ a superior copper-based catalyst, whereas an acidic environment would require an expensive precious metal-based catalyst.

+No catalyst separation required:

  • A proprietary solid catalyst remains in the reaction column and so does not mix with the final liquid ester product. This eliminates the need for catalyst separation prior to downstream processing.
  • The catalyst can also be changed at 100% load without any downtime or loss of production.

+Reduced effluent:

  • Using a solid catalyst means there is no need to treat used liquid-phase catalyst.
Related Processes & Core Technologies

We use our esterification technology in a number of licensed processes to make a range of compounds. Click on the panels to find out more:

In some Davy processes, esterification is used in conjunction with our hydrogenolysis technology. Explore here:


Related Processes

We use our esterification technology in a number of licensed processes to make a range of compounds. Click on the panels to find out more:


Core Technologies

In some Davy processes, esterification is used in conjunction with our hydrogenolysis technology. Explore here: