OXYGEN STORAGE CAPACITY TEST (OSC)
The CATAGEN OSC measurement procedure involves cycling the catalyst between lean and rich conditions, with full oxidation and reduction of the ceria at each condition. The OSC value is calculated through several different methods across both oxidation and reduction reactions, including analysis of the λ signals, analysis of raw emissions data and analysis of the reactant delivery.
Measuring oxygen storage on a vehicle is often challenging as recorded data can have a wide measurement spread and is influenced by driving style, ECU mode, fuel type and exhaust mass flow amongst others. CATAGEN can replicate vehicle conditions as long as our partners can share the mass flow rate and engine out temperature at the measurement point on the vehicle. This allows for very strong correlation on OSC measurement between CATAGEN & our partners.
This paper will consider:
- With more stringent emissions legislation, oxygen storage capacity (OSC) measurements for automotive catalysts are more important than ever during the vehicle calibration phase.
- This paper outlines a new, modern approach to complete OSC measurements at a laboratory standard on full scale aftertreatment systems.
- The approach offers precise control over gas composition, temperature and flow rate, providing a pure measurement of performance
Written by Liam McGrane, Senior Engineer
LIGHT OFF TEST (FAST/SLOW)
Catalyst degradation can be tracked through measurement of light-off performance. Two separate reproducible light-off tests are carried out at CATAGEN – a fast and a slow composite light-off (CO, HC and NO). The difference in light-offs is the inlet temperature ramp rate, a fast light-off ramp rate is 10°C per second and a slow light-off ramp rate is 10°C per minute. The light-off tests are complete across the full system.
Emission conversion is measured across the full system using Horiba MEXA ONE analysers, with the 50% conversion point of greatest interest. An example slow composite light-off shift throughout the ageing process is shown, with the dashed line representing the aged catalyst.
LAMBDA / AIR FUEL RATIO SWEEP (AFR)
Lambda sweep tests are used to assess PGM and washcoat degradation. These tests are carried out on the CATAGEN flow-through reactor, facilitating excellent control of gas composition. The test protocol follows a cyclic oscillation of lambda, with fixed HC and NO, and variable CO and O2 concentrations as specified in the table.
Fixed lambda ramp rates are employed, facilitating an assessment of the impact of OSC on emissions conversion. As with the light-off tests, emissions conversion is measured across the starter brick only with Horiba MEXA ONE analysers.
DRIVE CYCLE TEST (WLTC)
The CATAGEN After Treatment Development Path is a proprietary approach delivering an advanced model using unique testing methodology, metrics, performance analysis and data interpretation. The benefits extend beyond compliance and cost reduction creating a roadmap for optimal powertrain development.
Find out more about our Golden Drive Cycle Test below
Knowledgebase Advanced Offering
‘Golden Catalyst replication’ – cloning on-road vehicle aged catalysts
Virtual testing services & modelling
PGM Thrifting Services (Precious Group Metals)
Catalyst poisoning – doping with multiple compounds
Fuel & Lubricants – understanding catalyst performance
Collaborative Research & Development Projects to Clean Air Development Partnership
Advanced Characterisation Services
Precious Metal Loading Measurement
Transmission Electron Microscopy (TEM)
Scanning electron microscopy (SEM)
Brunauer, Emmett and Teller (BET) surface area measurements