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For catalytic reactions in the aqueous phase the encapsulation in polyvinylalcohol hydrogel pearls is a new approach to technically advantageous catalysts, e.g. for the hydrogenation of nitrite to nitrogen (U. Preiss et al., Braunschweig). The total oxidation of organic materials, including chlorohydrocarbons, on perovskites (M. Haftendorn et al., Leuna) orthe catalytic hydrodechlorination of chlorohydrocarbons (P. Birke et al., Leuna) on supported transition metals are further examples of contributions of interest for the solution of environmental problems. BERNHARD LUCKE MATERIALS FOR ENVIRONMENTAL

CATALYSIS

The Materials Research Society Spring Meeting held in San Francisco from 17th to 21st April included a symposium on Materials for Environmental Protection - the Control of Air Quality. This day and a half session, organised by Michael Quick and Kenneth Voss, both of Engelhard Corporation, Stephen Lot of Sandia National Laboratories and Kenneth Poepelmeier of Northwestern University, contained papers on a variety of topics, ranging from deNOx and VOC control to a contribution on bio- derived lubricants. In addition to papers from US labs, there was one from Ireland and a series of related presentations from Japan, Several contributions due to be presented by scientists from Russia and the Ukraine unfortunately did not materialise. The meeting started with a paper by M. Shelef of the Ford Research Laboratory (coauthors M.J. Rokosz and C.P. Hubbard) on the subject of the stabilisation of ZSMd zeolite, for use in de-NOx catalysts, against dealumination and consequent loss of catalytic properties in the presence of steam; Dr. Shelef reported that both Ce and La ions virtually halted the loss of aluminium species from the zeolite structure. This paper was followed by one by James Jones and Julian Ross (University of Limerick, Ireland) which showed that a catalyst consisting of vanadia supported on an alumina-modified zirconia could be used for the simultaneous selective reduction of NO, and the oxidation of chlorinated hydrocarbons under flue gas conditions; other supported vanadia materials were unselective (giving N20 formation) under the conditions required to give the oxidation of the chlorinated molecules. The next paper described electron microscopic results obtained forthe ageing of Rh/alumina catalysts for NO, reduction in automobile applications; the authors (Zara Weng-Sieh, Ronald Gronsky and Alexis T. Bell, UC Berkeley) showed that air ageing of the catalyst at 500°C resulted in Rh particle sintering but that higher-temperature treatment gave densification of the support. An interesting paper by Randy Wright (Idahoe National Engineering Laboratory) then described the use of non-noble metal alloys for the oxidation of CO and hydrocarbons and the reduction of NO,; Dr Wright showed that these materials had activities comparable with or better than those of noble metal catalysts and that they were relatively unaffected by SOn or water in the gas mixture. The afternoon session of the first day started with a keynote applied catalysis 6: environmental

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lecture by Ronald Heck (with coauthor Robert Farrauto) of Engelhard Corporation which described the new materials likely to be used for automobile catalysts to meet the future needs for low hydrocarbon emissions. Particular attention was given to the use of different geometries to assure control of emissions from cold start conditions, including catalysts in a ‘close-coupled’ situation (close to the exhaust manifold instead of ‘under- floor’, i.e. nearer the exhaust exit) and the use of electrically heated catalysts; the current trends to use palladium instead of platinum plus rhodium were also discussed. This was followed by a paper by J.W. Koenitzer and K.R. Poeppelmeier of Northwestern University, in which the use of Ba-La-Bi mixed oxides as oxygen transfer membranes for the conversion of methane to synthesis gas was described, and another by U Balachandran, J.T. Dusek, P.S. Maija and R.L. Melville, of Argonne National Laboratory and MS. Kleefisch and CA. Udovich of Amoco Corporation on a similar topic. Several of the subsequent papers concerned the properties of carbon materials in air-pollution control. For example, a paper by Gwyn Jenkins and L.R. Holland (Alabama A&M University) discussed the production of refractory impermeable tubes of glassy polymeric carbon. G.M. Kimber (with coauthors F.J. Derbyshire, Y.Q. Fei and M. Jagtoyen, of the University of Kentucky) discussed the preparation of monolithic activated carbon fibres from isotropic pitch and phenolic resin binder and described the use of these materialsforthe separation of CH4 and COn mixtures. An interesting paper by Aurora Rubel and John Stencel from the same university then described the use of activated carbon for the adsorption of NO, and SO;! from power plant flue gas; both these gases could be adsorbed simultaneously and the amount of SOn adsorbed was greater in the presence of NO, than without it. Finally, the paper by R. Ghosal, D.J. Kaul and U. Boes (Cabot Corp.) and D.M. Smith, A. Mascara and G.P. Johnston (NanoPore) described the preparation of porous carbons by pyrolysis of fuel oil pyrolysis in a continuous process. The final paper of the afternoon session, by E.N. Balco and James Chen of Engelhard Corporation described the kinetics of the selective catalytic reduction of NO, at relatively high temperatures (350450°C) over an iron oxide on beta-zeolite catalyst; these interesting materials are already being used commercially for the control of stack-gas emissions in situations where the catalyst unit must be placed (in a retrofii of a unit) prior to heat exchangers in a position where the temperature is too high for a conventional vanadia-titania catalyst to be used. The second day of the meeting was taken up largely by a series of five papers from a group of scientists from Tokyo Institute of Technology (Megu Koyima, Takuyuki Togawa, Taizo Sano, Masamichi Tsuji, YutakaTamaura, Yuji Wada, MasahiroTabata, Takashi Yamamoto, Tatsuya Kodama, Hiroyasu Kato and Norito Hasegawa) which were concerned with a variety of reactions such as the methanation of Con, the decomposition of COn to give surface carbon, the release of surface oxygen and the decomposition of water to give hydrogen with nickel ferrite materials pre-treated in various ways, It was argued that the ferrite structure was maintained under all conditions and that oxygen could be removed (even by thermal desorption) or replaced in the lattice at will, the oxygen deficient material being capable of decomposing CO1 or water, especially if carbon was present on the surface. Personally, I had the sneaking feeling that many of the results presented could be obtained with a partially reduced nickel catalyst of any type and that the behaviour reported is not unique to the nickel ferrites described; although no metallic nickel was discernable by X-ray diffraction after hydrogen treatment of the metals at 309”C, this does not exclude the formation of some

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small nickel crystallites at this temperature, even if the material is not fully reduced. The final paper of the symposium, by Lou Honary and Kirk Manferedi of the University of Northern Iowa, did not concern catalysis. Instead, it discussed the testing of environmentally friendly bio-derived lubricants, particular attention being given to their thermal stability against oxidation during use. JULIAN ROSS 1st WORLD CONFERENCE 1995

ON ENVIRONMENTAL

CATALYSIS,

Pisa, l-5

May

The conference has been held in Pisa, Italy, on l-5 May 1995. It is the first of a triannual series of meetings “aiming at promoting the interdisciplinary approach to catalysis for a better environment and quality of life”. The conference was attended by 499 participants from 32 countries: 50% of the attendants were from companies and 50% from universities or other public institutions. The number of submitted papers was 278. The selection of the scientific committee ended with 51 oral and 118 poster presentations. The latter were divided into two sessions. Furthermore, a third poster session was devoted to 39 recent research reports. Accepted “concise reports” (4 pages) have been published in the Proceedings of the conference by the Italian Chemical Society. Full papers will be published by the end of the year in two special issues of Catalysis Today, after refereeing by an international scientific committee. One plenary and five extended lectures preceded the morning and afternoon sessions. The following areas were covered: control of emission from stationary or mobile sources, clean fuels, more environmentally friendly chemical production and catalysis, depollution of liquid effluents, catalytic combustion, reduction of the greenhouse effect and unsteady-state technologies. Both basic and applied chemical and engineering effects of environmental catalysis were considered, devoted to both post-process clean-up and to novel, intrinsically less polluting processes or safer catalysts. The policy of the Organising Committee to avoid parallel sessions was greatly appreciated. Indeed, keeping all the attendants in the same conference room and reducing the number of posters in every poster session strongly stimulated fruitful scientific discussions and helped in establishing or reinforcing warm and friendly personal relationships among the participants. L. FORNI

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