johnson matthey logo


Standard Systems

This page features descriptions and literature for:

• Modulex™ Converters & Converter Silencers

• SCR Systems

• CRT® Diesel Particulate Filters

• Engine Oxidation Catalyst Systems



Modulex™ Converters & Converter Silencers

The new Modulex™ converter and converter silencer can accommodate multiple 3-way NSCR or 2-way oxidation catalyst elements. They can be installed on rich burn or lean burn gas engines and are pre-engineered for a wide range of engine sizes and can be customized for engines outside of this range. The flexibility of the modular design allows for the use of different flange sizes and the addition of a silencer section now or in the future.

modulex converters and silencers
modulex converters and silencers


Customers have depended on Johnson Matthey's pioneering converter design for decades. This latest generation of converters serves multiple new or retrofit applications: gas compression, power generation, irrigation, pumping, standby equipment and pump jacks.

Modulex W Features:

  •  For IC Engines 250-2,000 HP
  •  All welded design to reduce the potential for leaks and bypass to meet the most stringent emission regulations
  •  Improved flow distribution for maximum utilization of catalyst
  •  Easier catalyst removal for cleaning
  •  Fuels: Natural gas, LPG, propane, diesel, biodiesel, dual fuel
  •  Lock-in element retaining ring for secure seal
  •  3-Way or 2-Way Conversion
  •  Available in carbon or stainless steel
  •  Ability to add more catalysts

modulex converters and silencers

Modulex C Features:

  •  For IC engines 50-500 HP
  •  Multiple applications: Gas compression, power generation, irrigation, pumping, standby equipment, pump jacks
  •  3-Way or 2-Way conversion
  •  Easy access to the catalyst
  •  Compact, lightweight and flexible design
  •  Stainless steel construction
  •  Fuels: Natural gas, LPG, propane, diesel, biodiesel, dual fuel

modulex converters and silencers

Modulex Q Features:

  •  All features of the Modulex W plus the addition of a critical or hospital grade silencing module

modulex converters and silencers


Download information below for Modulex Catalytic Converters & Silencers in PDF format:

modulex literature

Stationary Emissions Control Modulex™ Catalytic Converters
Sales Brochure

modulex literature

Modulex™ Catalytic Converters & Converter - Silencers
Sales Brochure


SCR Systems

Johnson Matthey's SCR technology delivers an economical and effective solution that has achieved 15,000 hours of operation before any maintenance is required.

To insure reliability, each SCR System incorporates the most reliable components available. It allows your engine to comply with the most stringent air emission standards and is the most reliable and durable emissions control solution you can buy for your lean burn engine.

Designed for flexibility and adaptability, the Johnson Matthey SCR System offers three NOX control options:

  •  Load-based curve
  •  Closed-loop feedback
  •  Load-based curve with NOX trim

Using urea (or aqueous ammonia), Johnson Matthey's SCR systems achieve NOX reductions of 90%+ for diesel or gas engines. Urea serves as the ideal reducing agent since it can be shipped and stored easily and is colorless, odorless, nontoxic and bio-friendly. Both aqueous solutions of ammonia and urea have proven their suitability for the catalytic reduction of NOX in many applications. The advantage of the SCR process is the achievement of high NOX reduction rate and low ammonia slip. (Ammonia "slips" through the catalyst unreacted.)

The standard SCR System includes SCR catalyst, durable housing, mixing duct, injection system components and control panel or an optional fully integrated skid-mounted package. The skid-mount option includes a converter, injection system components, electronic controls, urea day tank, air compressor and freeze protection. In addition, the skid is assembled at the Johnson Matthey plant and is delivered ready for installation, minimizing installation labor and time.

voc catalysts

The JM catalyst housing is much more compact than others in the marketplace. So, while the Johnson Matthey SCR catalyst packs maximum punch in performance, its smaller size makes it much easier to install, especially in tight spaces.

At the heart of the SCR System is a PC-based control system that is exceptional for its performance, construction and versatility. With no moving parts, the risk of a breakdown is minimal. The software logic in the Johnson Matthey SCR system is the most efficient self- diagnostic software available. It continuously monitors process parameters such as urea flow, pressure, temperature and performance with the optional NOX analyzer. If a problem is diagnosed, the software is designed to make adjustments, fix the problem and safeguards against urea plugging. Upgrades are done simply by modifying the software, which means quick and easy compliance with new regulations.

In the SCR system, the exhaust gas flows through the catalyst, an integral part of the exhaust gas line, with a precisely dosed injection of ammonia or urea. The chemical reactions proceed rapidly and selectively, i.e. without undesired side reactions, as described by these equations:

4 NO + 4 NH3 + O2 → 4 N2 + 6 H2O

6 NO2 + 8 NH3 → 7 N2 + 12 H2O

Our experienced engineers will help you select the best NOX Control option to meet your requirements. Since every Johnson Matthey SCR System is built on cutting-edge technology, your SCR System can be customized to ensure the most effective and efficient performance while allowing for easy upgrades if conditions should change in the future.

voc catalysts




Download information below for SCR Systems in PDF format:


voc catalyst literature

SCR Stationary Emissions Control
Sales Brochure

voc catalyst literature

SINOx for Stationary Diesel and Gas Engines
Technical Bulletin

voc catalyst literature

SINOx Catalysts for Fossil Fired Power Plants
Sales Bulletin

voc catalyst literature

SINOx CO2 System 701 for Greenhouse Applications
Sales Bulletin


CRT® Diesel Particulate Filters

Our CRT®(+) Diesel Particulate Filter (DPF) is CARB verified to reduce PM by 85%. It also reduces CO and HC. The CRT is Johnson Matthey's patented technology, which utilizes the NO in the engine exhaust to oxidize the collected soot in the filter.

The CRT(+) Diesel Particulate Filter System contains a platinum catalyst that converts part of the NO in the engine exhaust to NO2. In turn, the NO2 combusts the carbon soot that has been collected on the filter, thus regenerating the filter. NO2 can combust the soot more effectively than O2 at a lower temperature. Regeneration of the filters is continuous and at typical engine loads. Using the exhaust gas heat, the CRT(+) does not require any supplemental heat source.

crt diesel catalysts

The compact design and hatch allows access to the catalysts and filters for cleaning or replacement. The CRT(+) can be built to accommodate any engine size. It is compact, easy to install and the lowest cost option.

crt diesel catalysts


Download information below for the CRT®(+) Diesel Particulate Filter System in PDF format:

crt diesel catalyst literature

CRT®(+) Diesel Particulate Filter System
Sales Bulletin



Engine Oxidation Catalyst Systems

Johnson Matthey oxidation catalysts systems are designed for very small to very large diesel and gas engines. Our Diesel Oxidation Catalytic Converters (DOC) can be applied to diesel engines of all sizes, while our DualOx® catalytic converters are used on very large diesel or gas engines.

Our DOC is CARB verified and for smaller engines, it is a fit-and-forget technology requiring very little maintenance. To be effective in reducing PM, use of ultra-low sulfur diesel (ULSD) fuel is recommended.

dual ox catalyst systems

Our DualOx® converters are resistant to thermal and mechanical shock and can accommodate multiple catalyst elements that can be easily replaced or removed for cleaning. If you want the easiest installation and access in a catalytic converter, DualOx is the choice for you. Its built-in enhancements make this a very maintenance-friendly product. For catalyst access, simply unbolt the hinged cover, slide each existing catalyst element out along its supporting track, remove and then slide in the replacement catalyst element.



Download information below for DualOx® Catalytic Converters in PDF format:

dual ox catalyst literature

DualOx® Pre-Engineered or Custom Catalytic Converters
Sales Bulletin