How catalytic converters work

European Exhaust and Catalyst (EEC) says its catalytic converters are designed for durability, performance, and environmental responsibility. According to the company, they reduce harmful exhaust emissions, helping vehicles operate efficiently and comply with increasingly stringent emissions standards – but what exactly does a catalytic converter do, and how does it work in practice? EEC Marketing Coordinator, Laura Pashley, tells all.

A catalytic converter transforms toxic exhaust gases, such as carbon monoxide, nitrogen oxides, and hydrocarbons, into less harmful substances, like carbon dioxide, nitrogen, and water vapor.

At the heart of the converter is a honeycomb structure, coated with a wash coat containing precious metals, like platinum, palladium, and rhodium. These metals act as catalysts, triggering chemical reactions that break down pollutants as exhaust gases pass through. The wash coat also incorporates rare earth minerals, such as aluminium oxide, cerium oxide, and zirconium oxide, which enhance efficiency and durability. This carefully engineered combination ensures a catalytic converter performs optimally under all driving conditions.

Importance of maintenance and regular servicing 

Maintaining a catalytic converter correctly is essential to ensure long-term performance and reliability. Using the correct fuel helps prevent contamination, while addressing engine issues promptly, such as misfiring, can avoid overheating and costly converter damage.

Regular servicing also plays a crucial role. While unusual smells may not always indicate a serious issue – this could also be down to sulphur in fuel – noticeable dips in performance often do. It is important to ensure that oxygen sensors and the ECU are functioning correctly to maintain the proper fuel-air balance. As these checks require specialist diagnostic tools, motorists should consult a qualified technician.

In addition, monitor dashboard warning lights, such as the “check engine” light, and keeping a detailed log of maintenance and repairs will also help motorists schedule servicing at the right intervals and maintain optimal vehicle efficiency.

Different engine types and vehicle applications require specific emissions – each designed to target harmful exhaust gases and particulates in distinct ways.

Three-way catalysts (TWCs) are designed for petrol-powered vehicles and are responsible for reducing three major harmful emissions: nitrogen oxides, carbon monoxide, and hydrocarbons. These pollutants are converted into less harmful substances through carefully controlled chemical reactions. These catalysts typically feature either ceramic or metallic honeycomb substrates, which provide a large surface area to maximise contact between exhaust gases and the catalyst coating.

The substrate is coated with precious metals, such as platinum, palladium, and rhodium, which act as catalysts to accelerate the chemical conversion process. Our petrol catalytic converters are manufactured to meet stringent type approval standards.

Diesel oxidation catalysts (DOCs) are engineered for diesel applications. Unlike TWCs, DOCs primarily focus on oxidising carbon monoxide and hydrocarbons into carbon dioxide and water. They also help reduce visible exhaust smoke and odour.

DOCs use ceramic or metallic substrates coated mainly with platinum and palladium to facilitate oxidation reactions at lower exhaust temperatures. Our diesel oxidation catalysts are developed to provide durable performance under high-load operating conditions typical of diesel engines, particularly in CVs.

Diesel particulate filters (DPFs) are designed to capture and remove particulate matter (soot) produced during diesel combustion. These filters use a wall-flow honeycomb structure that traps soot particles within porous channel walls.

DPFs are usually manufactured from robust materials, such as cordierite or silicon carbide, both chosen for their excellent thermal resistance and filtration properties. Many systems include a catalytic coating to assist with regeneration, a process in which trapped soot is burned off at high temperatures to prevent blockage.

Our DPF range is engineered to provide efficient filtration while maintaining correct exhaust back pressure.

LCVs operate under heavier loads and longer duty cycles, meaning their emissions systems must be robust and efficient. LCV catalytic converters are tailored to meet the specific emissions requirements of vans and minibuses, often combining durability with high thermal resistance.

These units use ceramic or metallic substrates coated with platinum, palladium, and rhodium to ensure effective gas conversion under demanding conditions. We provide coverage for LCV applications, supporting workshops with direct fit, type-approved solutions designed for high-mileage vehicles.

With the introduction of gasoline direct injection engines, particulate emissions from petrol vehicles have become a greater focus. Gasoline particulate filters (GPFs) are designed to capture fine particulate matter in a similar way to DPF systems.

GPFs feature a wall-flow honeycomb structure and are commonly manufactured from cordierite ceramic material, offering effective filtration while maintaining exhaust flow. As emissions regulations continue to evolve, we are committed to expanding our GPF range to ensure modern petrol vehicles remain compliant with the latest standards.