Bridging the gap between lab scale and full scale catalysis experimentation
Conference poster, 2012
The transfer of knowledge (bridging) between lab scale and full scale catalyst research may sometimes be hindered by various reasons. These reasons include phenomena in the full scale that were not encountered at the lab scale or model parameters that were not precisely fit from the lab scale experiments. Also, when moving to full scale (engine bench) experimentation, other issues become important such as transport phenomena including heat losses (not to mention cost for engine rig experiments). The benefits of using real engine emissions in a reactor system that also possesses the lab scale benefits can be exemplified with two important issues:
• Model hydrocarbon (HC) used in lab scale (often propene) is seldom a very good representative for real HC emissions (incl. acetylene and aromatics).
• Engine Particulate Matter (PM) is very difficult to mimic using synthetic PM for studies of particulate oxidation and filter performance.
This paper presents a reactor system design and discusses various aspects of reactor design of an Emission After Treatment System (EATS) to be used as a bridge between lab scale and full scale research. It will be exemplified for a study in particulate trapping for open filters but also discussed for other applications.
Materials and Methods
Most of the materials were standard components crafted at the department workshop. The process of the reactor system design included several practical aspects: engine rig environment, scope of objectives, requirements on robustness and accuracy as well as time and resources. The most important aspect is to enable efficient Design of Experiments (DoE) requiring independent variations in reactor conditions. The resulting design is presented in figure 1 below.
Figure 1. A schematic picture of the reactor system.
Results and Discussion
The resulting design enables the following experimental features:
• Independent residence time: By gas flow restriction (~0.1 % of the total flow), by adding gases (air or any other gas) or a combination of both. By using catalysts of different size (10 cm3 – 2.5 dm3).
• Independent gas temperature: Either by applying cooling or by heating or a combination of both.
• Almost independent gas phase concentrations: By using the raw exhaust in combination with ad-gases (e.g. NO/NO2, NH3/HC/H2) preferably in combination with flow restriction.
The system is capable of collecting various types of data including flows, temperatures and concentrations (gas phase components as well as PM). The reactor system can thus decouple the phenomena connected to residence time, temperature and gas composition which is of significant value.
By performing catalysis research at both scales, improved quality is achieved e.g. by: Relevant issues from the full scale can be pursued at the lab scale and findings from the lab scale can be precisely reproduced at the full scale. This kind of research bridges between the two research areas of Heterogeneous catalysis and Internal Combustion engine research. Research is planned in collaboration with industry (member companies of the competence centre for catalysis, KCK at Chalmers) and will contribute to more efficient development of aftertreatment systems.