Ionic bombardment for catalyst creation – BicNanoCat

The more and more severe laws on environmental protection, as well as society concerns on life quality and sustainable development, oblige industrial entities and institutions to a strict control of exhaust emissions from vehicles equipped with combustion engines. To face the forecast rules on tolerate emissions, abatement catalysts for car exhaust are necessary. Nowadays, to be effective, a catalytic exhaust system must reach a working temperature of about 250°C. This device for NOx, HC and CO conversion emissions is, as a consequence, ineffective during the cold start.
The present project concerns environmental protection catalysts, based on platinum-series elements, to be applied to exhaust abatement systems from vehicle thermal engines. One of the main goals is to decrease their working temperature for the catalytic reaction, increasing in parallel their durability towards temperature ageing. The expected consequence should be a significant decrease of the time necessary to reach steady conditions in the exhaust control system after the cold engine start (particularly when the vehicle is driven in a town centre), and that stabilized towards ageing with time.
Catalysts are generally synthesized by conventional methodologies, such as ionic exchange or impregnation of platinum or palladium precursors on metal oxide supports. These synthesis methods are generally unable to provide an optimal dispersion of noble metals. Moreover, metal particles are affected by sintering phenomena and removal from the support due to system ageing. That obliges impregnators to increase noble metal loading, which provokes important extra-costs for the vehicles car exhaust control systems. Car constructors are interested to study a modification process of the surface composition and/or morphology of post-treatment catalysts, in collaboration with academic laboratories. Preliminary tests have in fact encouraged this project. They have shown that ionic bombardment leads to: 1) a better dispersion of the metallic phase and to the creation of nanoparticles on a silicon support; 2) a better catalytic activity of a commercial shaped catalyst.
In the frame of this project, these investigations must continue on two parallel axes:
• Fundamental research (ILV, LCS): determination of the phenomena correlating the ionic bombardment with metal nano-dispersion, depending on the nature and energy of the ion, towards the nature of the treated metal. Application to the catalytic activation of platinum-group metals and other metals on different supports.
• Industrial research (PCA, Renault): tests and validation of the ionic bombardment process on prototypes of catalytic exhaust systems, analyzed on a synthetic gas bench and on a motor bench. Study and development of ionic bombardment methods adapted to the industrial production.