SCR systems

Johnson Matthey SCR systems prevent air pollution from stationary diesel and natural gas engines for cleaner energy and cleaner air.

SCR systems are essential for producing clean energy from internal combustion engines. Johnson Matthey has supplied over 3 GW of stationary SCR systems on engines which range in power from 500 kW to 20 MW. Our turnkey SCR systems are supplied with all of the components necessary for guaranteed performance. When the SINOX® honeycomb SCR catalyst is coupled with an ammonia slip catalyst or oxidation catalyst, the SCR system can achieve high reductions of CO, hydrocarbons and other VOCs to produce very clean energy.

SCR systems can be used on engines fuelled by natural gas, biogas and landfill gas, as well as engines running on liquid fuels such as ultra-low sulphur diesel (ULSD), biodiesel and heavy fuel oil (HFO). This versatility and high NOx reduction efficiency makes SCR systems ideal for many applications such as prime and standby power generation, irrigation pumps, combined heat & power (CHP) plants, landfills, dairy farms, greenhouses, oil & gas drilling and compression, and marine engines.

Our SINOX SCR systems achieve NOx reductions of 95% for both diesel engines and gas engines using urea or ammonia (aqueous or anhydrous) as the reducing agent. Urea is often the ideal reducing agent because it can be shipped and stored easily and it is bio-friendly, however, ammonia can be preferable for the SCR process in many applications.

Typical emission and noise reductions achieved by SINOX SCR system with silencing.

NOx CO HC Noise
80%-95% 70%-98% 70%-95% 25-35 db(A)


Complete SINOX SCR systems are available from Johnson Matthey in either pre-engineered or custom designed configurations. The standard SCR system includes SCR catalyst, durable housing, mixing duct, injection system components and control panel. Turnkey SCR systems are also available as fully integrated, skid-mounted packages.

At the heart of the SCR system is a PLC-based control system with HMI that is exceptional for its performance, construction and versatility. The built-in software is flexible and can be easily modified right from the HMI screen by Johnson Matthey’s field service engineers to implement different control strategies as needed. Load-based control, feedback control, load-based control coupled with NOx feedback, feed- forward control and feed-forward control coupled with NOx feedback are strategies that can be adopted quickly and easily to optimize performance and achieve compliance with new clean air regulations.

The SINOX honeycomb SCR catalyst is mounted in sturdy catalyst element frames (E-frames) for easy installation and maintenance. The scope of supply of the SCR system that is provided by Johnson Matthey can be adjusted for each situation depending on the requirements of a given project. An optional silencer can be included in the SCR system for additional sound attenuation.


Most SCR systems include the following key components:

  • SINOX honeycomb SCR catalyst
  • Durable stainless steel catalyst housing
  • Stainless steel reagent injection lance
  • Stainless steel reagent mixing duct
  • System control panel and reagent dosing pump

General enquiries

Joseph McCarney

Betty Ann Keen