Core Technologies


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Hydrochlorination involves adding hydrogen chloride across the multiple bond of an unsaturated hydrocarbon.

JM Davy’s technology focuses on alkyne (triple-bonded) reactants:

hydrochlorination big equation

This exothermic process yields a chlorinated alkene.

In Context

Davy hydrochlorination technology forms the core of our vinyl chloride monomer (VCM) licensed process.

To make VCM, we react the alkyne acetylene with hydrogen chloride:

hydrochlorination small equation

Facilitating this reaction is Johnson Matthey’s PRICATTM MFC (mercury-free catalyst).

PRICAT MFC is strongly selective towards VCM formation and underpins the high product purity of the Davy licensed process.

In addition PRICAT MFC makes Davy hydrochlorination the only mercury-free technology of its kind currently offered for license.

As such it is the only process ready for the expected complete ban on mercury catalysts for plants started up after 2016 (as per the 2013 Minamata convention between 150 countries including China).

PRICATTM is a trade mark of Johnson Matthey Plc.

Hydrochlorination Flowsheet

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Process Description

The Davy hydrochlorination system consists of several parallel reactors, the number of which is variable to suit desired capacity.

Alkyne reactant and HCl, both gases, are pre-dried and mixed before entering the reactors.

Each reactor contains multiple tubes packed with Johnson Matthey’s mercury-free PRICAT MFC catalyst.

In each tube, the gas mixture passes downwards through the catalyst bed, which drives the reaction to crude chlorinated alkene with a high conversion rate.

The process is highly exothermic, and to accommodate the reaction heat each vessel has its own dedicated vaporising cooling system.

Liquid coolant passes through the reactor on the shell side, some of which vaporises upon contact with the hot reactor tubes.

The vaporised coolant exits the vessel, passes through a condenser and cycles back to the reactor.  Make-up coolant also joins the condensed stream.

Any excess coolant overflows from the reaction vessel into a level pot, which sends the liquid to coolant storage.


Johnson Matthey’s PRICAT family of catalysts serve a range of industries for the production of olefins, oleochemicals, fats & oils, oxo alcohols, aniline capro, specialty amines, fluorochemicals and chlorochemicals.

Davy hydrochlorination technology employs a special PRICAT mercury-free catalyst (MFC) formulation, the advantages of which are outlined below:

Traditionally, VCM production from hydrochlorination of acetylene has accounted for the largest intentional use of mercury in the world.

Johnson Matthey’s PRICAT MFC has the potential to transform the acetylene-to-VCM industry, and hydrochlorination generally, by completely eliminating the use of mercury from the process.

PRICAT MFC is guaranteed non-toxic and not harmful for the environment as it does not contain any volatile components that can be released to atmosphere or contaminate ground water.

Additional advantages of PRICAT MFC include:


  • No risk of mercury poisoning to VCM plant personnel.

High selectivity

  • PRICAT MFC’s high selectivity ensures efficient use of the HCl and alkyne reactants.
  • The low by-product formation that results means that little separation is required to produce high-purity chlorinated alkene.
  • Fewer reactors are required due to the high reaction yield delivered by PRICAT MFC.

Reduced equipment costs

  • Less process equipment required due to the absence of any steps for mercury capture and handling, and treatment of mercury-contaminated waste water.
The JM Davy Advantage

Davy hydrochlorination offers the combined advantages Davy reactor design with a mercury-free catalyst from Johnson Matthey.  Read more below:


+Low investment cost:

  • Our hydrochlorination technology has a low equipment count due to a high single-reactor capacity driven by the PRICAT MFC catalyst.
  • Additionally, as our hydrochlorination process is mercury-free, it requires no process equipment for mercury removal.
  • This low equipment count requires only a small plot size.
  • The hydrochlorination reactor is of simple design and constructed of inexpensive carbon steel. The process requires very few vendor-designed special packages.

+High raw material efficiency and
product purity:

  • Davy hydrochlorination uses a much lower alkyne/HCl ratio than employed elsewhere, which reduces raw material consumption.
  • PRICAT MFC delivers high selectivity with little by-product formation.
  • The low by-product formation delivers a crude chlorinated alkene which requires less purification.

+PRICAT catalyst delivers a high-purity, mercury-free hydochlorination process:

  • Johnson Matthey’s PRICAT MFC (mercury-free catalyst) is guaranteed non-toxic and not harmful to the environment.
  • Our process is the only mercury-free hydrochlorination technology offered for license anywhere in the world.
  • Davy hydrochlorination is ready for the expected complete ban on the use of mercury catalysts for new plants started up after 2016.
Related Processes

Our hydrochlorination technology forms the core of our vinyl chloride monomer (VCM) process, which can be explored by clicking the panel below:

Related Processes

Our hydrochlorination technology forms the core of our vinyl chloride monomer (VCM) process, which can be explored by clicking the panel below: