This article reviews the 21st Century Emissions Technology conference held by Institute of Mechanical Engineers (in December 2000) and summarises the latest developments in emissions control

Warren, James P.

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Open Research OnlineThe Open University’s repository of research publicationsand other research outputs21st Century emissions technology - a reviewJournal ItemHow to cite:Warren, James P. (2001). 21st Century emissions technology - a review. Platinum Metals Review, 45(1) pp.31–33.For guidance on citations see FAQs.c© [not recorded]Version: [not recorded]Link(s) to article on publisher’s website:http://www.platinummetalsreview.com/pdf/pmr-v45-i1-031-033.pdfCopyright and Moral Rights for the articles on this site are retained by the individual authors and/or other copyrightowners. For more information on Open Research Online’s data policy on reuse of materials please consult the policiespage.oro.open.ac.ukPlatinum Metals Rev., 2001, 45, (1), 31–33 31The Combustion Engines Group of theInstitution of Mechanical Engineers (IMechE)held a conference on ‘21st Century EmissionsTechnology’ at their London headquarters on the4th and 5th December 2000. Nearly 100 partici-pants from the U.S.A., Japan and most Europeancountries gathered to hear 23 excellent talks and todiscuss engine and aftertreatment technologies.The major theme of the conference was theneed for ongoing research in emissions reductionstrategies and technologies for both on-highwaytransport and off-road mobile machinery. Theconference was thus a forum for the leadingexperts from motor manufacturers, oil companies,vehicle testing houses and universities to discussthe reduction of particulate matter and nitrogenoxides, NOx, in order to meet the forthcomingstringent European and U.S. federal emissions leg-islation. Vehicle emissions can form a large part ofthe measured pollutant levels in ambient air, thus,this review examines the role that catalyst systems,based on platinum group metals (PGMs) play inensuring the continual global lowering of vehicleemissions. Emissions Control Technology for2000–2010Robert Searles (AECC, Belgium) addressed thechallenges to and opportunities for catalyst tech-nology in the 21st century. He highlighted the needfor cleaner fuels, with lowered sulfur levels, whichenhance and make possible the use of moresophisticated catalyst systems, such as NOx trapsand particulate filters. He mentioned the launch ofthe new Peugeot 607 diesel passenger car, which isan industry first for a European diesel passengercar to have a particulate filter system. There wasspeculation about whether a strategy of using non-continuous regeneration with a fuel-borne catalyst,and an appropriate conventional platinum-basedcatalytic converter would be a realistic way forwardfor all classes of passenger cars. He reported grow-ing interest in the selective catalytic reduction(SCR) of NOx for use in the aftertreatment ofheavy-duty diesel emissions. Searles also sum-marised work on hydrocarbon-absorbers, electricallyheated catalysts, and on active and passive NOx.The technologies currently available for passen-ger cars and larger vehicles were reviewed byTimothy Johnson (Corning, U.S.A.). He discusseddevelopments in various catalyst supports (madeof cordierite) and trends, such as: advanced integration of catalyst and enginemanagement lower ammonia emissions from gasoline vehicles better cold start response hybrid (or layered) catalysts and PGM flexibility.Johnson noted that flexibility in using the PGMs isan important new concept for major automobilemanufacturers. This will help to ease cost volatilityby substitution of one metal for an equally activeone, where possible. This might lead to a need forcertification of multiple catalyst systems at the ini-tial design phase and production testing ofvehicles, and would ultimately result in cost sav-ings for most parties.The costs of various SCR systems were assessedby James Warren (The Open University, U.K.) forEuro 5 heavy-duty diesel trucks. It was shown thatmost long-haul transportation trucks can ‘payback’ the complete cost of the catalyst systemwithin one to two years if fuel savings of 3 to 5 percent are achieved, by tuning the engine for higher,raw (precatalyst) NOx emissions, and then choos-ing an appropriate catalyst and control system.A possible way of reducing NOx via enginemethod alone was presented by Patrick Flynn(Cummins Engines, U.S.A.). He described workon exhaust gas recycling (EGR) which clearly indi-cates that combustion chemistry is the limitingfactor in determining the minimum NOx pro-duced in both gasoline and diesel engines (heavyduty, cylinders > 1 litre). The minimum levels ofNOx achievable are listed in the Table, along withthe proposed European and U.S. federal limits. His21st Century Emissions TechnologyREVIEW OF AN INSTITUTION OF MECHANICAL ENGINEERS CONFERENCE ON EMISSION CONTROLtalk clearly demonstrated that there is a vital needfor all types of aftertreatment, especially to complywith the very low U.S. limits. He concluded thateven with the best possible engines using EGR,aftertreatment will still be required to meet the 0.15g (kW h)–1 NOx limit proposed for the U.S. in2007.Another route to lowered NOx levels is offeredby the non-thermal plasma (NTP) technique.Hermann Breitbach (Delphi, Luxembourg)showed that a potential NTP system, coupled witha zeolite-based catalyst, can reduce emissions frompassenger cars. Currently, when running the NTPsystem on a car, ~ 300 W (~ 1 kW at peak condi-tion) is required to generate good dielectricbehaviour. This results in a fuel penalty of ~ 3 percent. However, with the future 42 V electrical sys-tems, coupled with integrated starter motors, NTPin cars will be much easier to integrate and to supply with power.Diesel ParticulateDiesel particulate and its measurement – downto aerodynamic particle diameters of ~ 7 nm –remains of strong interest to engine manufacturersand, indeed, to the public at large. The use ofCRTTM (Continuously Regenerating Trap) systems,containing a platinum-based catalyst and particu-late filter, is well established for particulatereductions.The characterisation of particles from heavy-duty diesel (HDD) and light-duty diesel (passengercars) was examined by Barbara Wedekind (RicardoConsulting Engineers, U.K.). She also discussedthe effects of a CRTTM on a Euro 2 HDD, as wellas the effects of diesel particulate filters on a selec-tion of passenger cars. Work on the Peugeot 607,VW Golf and Peugeot 406, all fitted with a varietyof oxidation catalysts and filters, showed that vehicles fitted with these devices were capable ofachieving very low particulate mass emissions.Under all conditions tested, the CRTTM consistent-ly reduces particulate mass. However, further workon the characterisation and measurement of par-ticulate is required both to establish the origin ofany particulate observed after filtration, and to finda standard set of measurement conditions onwhich all test houses can agree, for possible futurelegislation and correlation.The post-catalyst exhaust gases from gasoline-powered vehicles (aiming at SULEV (super ultralow emission vehicle) emissions) are so clean as tobe almost immeasurable with some of today’sdevices. Indeed, in some instances the exhaust gashas been cleaner than the intake ambient air. Thisillustrates the need for more advanced quantitativemethods for measuring evaporative hydrocarbons,particulates and other pollutants. Future Trends in EnginesCompressed natural gas (CNG) and controlledauto-ignition (CAI) were among other engine/fuelpowertrains described. Both promise potentiallylower NOx emissions. While gaseous fuels are cur-rently relatively inexpensive, the potential emissionof methane from such engines will need to beaddressed catalytically. CAI gives NOx values aslow as 10 ppm, but system control is extremely dif-ficult, and CAI has not yet been fully demonstratedin a running vehicle.Paul Kapus (AVL, Austria) reviewed work onthe ‘G90’ vehicle. The ‘G90’ is a modified GM/Vauxhall/Opel Corsa with a typical fuel consump-tion of 5.7 litres/100 km (as purchased). Aftermodifications to body shape (for superior aerody-namic drag) and transmission, and the addition ofvariable valve actuation, along with partial down-sizing, the fuel consumption was reduced to 3.9litres/100 km and CO2 emissions were loweredfrom 137 to 90 g km–1. This shows that the wayforward to enable engines to meet CO2 limits willbe a smart combination of technologies.The views of Toyota on hybrid powertrains,were presented by Tokuta Inoue (Toyota andGenesis Research Institute, Japan). He describedPlatinum Metals Rev., 2001, 45, (1) 32Source/Standard NOx, g (kW h)–1Lowest possible by engine design (SI) ~ 0.56Lowest for diesel ~ 1.12Europe 2008 (proposed EU 5) 2.0U.S.A. 2007 (proposed) 0.15the Prius, Toyota’s hybrid electric vehicle (HEV).Currently, the Prius (second generation coupled toa gasoline internal combustion engine) contains anew rectangular battery module (21 kW) coupledto a 33 kW gasoline engine. This delivers 3.4litres/100 km under the Japanese driving test.When compared to a pure electric vehicle, thisHEV has a longer driving range, good fuel econo-my and good drivability without the need forrecharging. The year 2001 Prius meets theJapanese and U.S. SULEV emissions, as well asthe Euro 4 regulations. The Prius is the firstToyota vehicle, and perhaps one of the first-everproduction vehicles, to use a catalyst support of900 cells inch–2, wall thickness 0.5 mm, carrying apalladium and rhodium catalyst. The increase inhighly active geometric surface area has been opti-mised together with an ~ 19 per cent lower totalcatalyst volume than prior systems. It contains ahydrocarbon absorbing component to assisthydrocarbon capture at low temperatures withsubsequent oxidation after light-off is complete.Future Vehicles and TechnologiesIt is expected that future vehicles will includemore models with direct injection (gasoline andCNG) with advanced variable valve timing.Powertrains will be based more on combinationsof technologies, such as turbo-charged CNG, CAIwith direct injection, and CNG with direct injec-tion. The market will become segmented withsome sectors finding unique solutions (HDD vehi-cles will remain for trucks/transport of goods). Inother areas multiple solutions are possible, withfuel cells and hydrogen-based fuels expected toeventually gain a large part of the market share.Hybridisation and hybrid vehicles will begin toplay a prominent part in powertrains, with elec-tric/fuel combinations being prominent. Clearly,the variety of powertrain combinations will havean effect on the catalyst systems they use. Futuredevelopments will need to take all component intoconsideration (filters, catalysts, monitors, sensors,fuels, etc.) and to maximise any synergistic effectsto achieve the lowest overall emissions, and thelowest possible CO2 levels for their class. Vehicledesigners and component suppliers will probablywork together closely to achieve cost-effectivesolutions. In general, consumers will increasinglydemand comfort, safety, cost reductions, good dri-ving performance, enhanced durability, reliabilityand low emissions. However, the catalytic con-verter will clearly remain the main pollution-control device for the next generation of vehicles,although, 15 years from now, it may not be recog-nisable in its present form.The papers presented at this conference will bepublished in Spring 2001 in the IMechE Seminarpublication series. Information can be found at:http://www.imeche.org.uk. J. P. WARRENJames Warren is a Staff Tutor/Lecturer in the Faculty ofTechnology at the Open University, based in Cambridge. Hisinterests are in automotive supply chain systems, sustainabletransport and vehicle exhaust gas purification.Platinum Metals Rev., 2001, 45, (1) 33Brain imaging via positron emission tomography(PET) using the short-lived 11C positron emitter(half-life ~ 20 minutes) requires a fast chemical reac-tion to incorporate the small amounts of 11C into acarrier (tracer) which delivers it to the tissue underexamination.Researchers in Japan and Sweden have nowdeveloped a new rapid, efficient Stille methylation ofarylstannanes which produces a structure systemthat can deliver sufficient quantities of 11C toprostaglandin receptors (IP2) in the brain (M. Suzuki,H. Doi, K. Kato, M. Björkman, B. Långström, Y.Watanabe and R. Noyori, Tetrahedron, 2000, 56, (42),8263–8273). The Stille methylation involves a palla-dium-promoted cross-coupling reaction of methyliodide and tributyltin derivatives of tolylisocarbacy-clins (TICs); the TIC binds to the IP2 receptors. Inone methylation, which is a novel stepwise opera-tion, an initial methylpalladium complex is producedand is then mixed with other materials for the cross-coupling. The Pd promoter is a Pd(0) complexgenerated from Pd2(dba)3 and P(o-CH3C6H4)3 in thepresence of CuCl and K2CO3. The synthesis is high-ly reproducible, and with 11C incorporated, results ina [11C]-labelled PET tracer with radioactivity of sev-eral GBq, which can be injected intravenously.Palladium Cross-Coupling Reaction for Brain Tracers

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