Professor Robbie Burch OBE

Research

Robbie Burch’s research is concerned with developing a fundamental understanding of processes of industrial importance.

Automotive Emission Control

Three-way catalysts have been used in catalytic converters for almost 30 years but although there have been many publications on this subject there is very little information that can be used to model real systems. CenTACat is using state-of-the-art experimental and theoretical tools to investigate the basic reactions of importance in three-way catalysis: CO and hydrocarbon oxidation; NOx reduction; oxygen storage. In particular, intrinsic kinetics are being determined that take account of the complex interdependencies between the individual reactions so that data can be obtained as input to a full reactor engineering model of a real three-way catalyst system.

 

Removal of NOx

Hydrogen powered fuel cell vehicles are still some way from commercial production, in the meantime gasoline and diesel powered vehicles are being subjected to increasingly stringent emissions legislation, especially with regard to NOx emissions. Vehicle manufacturers are approaching the problem from two fronts; improved engine design to decrease NOx emissions and catalytic removal of NOx from the engine exhaust. NOx can be efficiently removed from the exhausts of conventional combustion engines that use a stoichiometric fuel/air mix by using three-way catalysts. However, these catalysts do not work in the conditions of excess oxygen found in the exhausts of diesel and lean-burn gasoline engines. Two methods can be adopted to remove NOx from these exhausts, the first method (NOx storage/reduction) involves storing NOx during lean burn conditions usually as a nitrate of an alkali-earth metal such as barium and then decomposing and reducing the stored NOx during short fuel rich pulses using conventional three way catalyst technology.

The second method of removing NOx in lean-burn engines involves the selective catalytic reduction of NOx using low levels of unconsumed hydrocarbons in the exhaust. Much of our research has focused on metals such as Ag and Co supported on Al2O3. These materials have been found to be active and selective for the reaction, considerable effort has been and continues to be devoted to understanding the reaction mechanism over these materials. The transient kinetics of the overall SCR reaction and the proposed simple constituent reactions such as NO dissociation and hydrocarbon activation are currently be explored using the Temporal Analysis of Products (TAP) technique. This powerful technique allows the experimentalist to perform pulse experiments with a time resolution of 1ms, sufficient time resolution to study complex multistep reactions.

 

Hydrogen Production

The goal of environmental legislators is the zero emission vehicle (ZEV) and hydrogen fuel has been identified as a means of achieving this goal. Hydrogen is an attractive fuel in several important ways; it is the least polluting fuel that can be used in an internal combustion engine, it can be used in a highly efficient hydrogen/oxygen fuel cell to produce electricity, it is potentially available wherever there is water and a clean source of power. However hydrogen storage is currently a problem in mobile applications, one way of overcoming this problem is to store hydrogen in the form of a liquid such as methanol, ethanol and even pyrolysis oil which can readily be converted back to hydrogen on-board by means of a catalytic converter. The challenge lies in developing catalysts which are sufficiently active for hydrogen production with good long term stability. Research into the production of hydrogen for use in fuel cells is on going in the Catalysis Research Group at Queens University, in this instance the catalytic reforming of bio-ethanol and pyrolysis oil over precious metal catalysts are being investigated.

 

Clean Organic Synthesis

The synthesis of many organic compounds can be achieved using heterogeneous catalysts. CenTACat is researching novel bimetallic catalysts for the hydrogen of difficult molecules such as organic acids and esters, and unsaturated organosulphur compounds. The catalysts are evaluated using high pressure kinetic techniques and characterised using a range of structural and analytical techniques (XRD, TEM, EXAFS, XPS).