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Fifth international conference on zeolites Naples, Italy 2–6 June 1980
OrN LrrRLETM LrrRLErPOIRIS Fifth International Conference on Zeolites Naples, Italy 2-6 June 1980 The conference was held at the 'Mostra D'Oltremare' in Napoli, under the chairmanship of Professor R. Sersale of the University of Napoli. Some 300 participants attended the conference from many different countries, indicating the world-wide interest in zeolites. Sessions were devoted to Synthesis, Geology and Mineralogy, Structure, Ion Exchange and Modification, Adsorption and Diffusion, Catalysis, and Technology, each topic being introduced by a plenary lecture. These were entitled 'Zeolite Synthesis and Crystallization', by L. B. Sand; 'Geology of Natural Zeolites and Zeolite Rocks' by A. lijima; 'Review of New Crystal Structures and Mineralogy of Zeolites and Related Materials' by J. V. Smith; 'Zeolite Exchangers -- Some Equilibrium and Kinetic Aspects' by R. M. Barrer; 'Investigation of the Adsorption in Zeolites at Zero Filling' by A. V. Kiselev; 'Recent Developments in Catalysis by Zeolites" by C. Naccache; arid 'Molecular Sieve Zeolite Technology - The First Twenty-Five Years' by E. M. Flanigen. These seven lectures adequately covered the advances made in the field of zeolites since the Fourth Conference in Chicago in April 1977. Ninety other papers were accepted for the conference, and the Proceedings have been published by Heyden and Son Ltd., London (Ed. L. V. C. Rees) at a price of £33.60 (US $76.00). The papers published in the Proceedings emphasize the interesting applications of zeolites which have developed in the past three or four years. The use of zeolite ZSM-5 and related members of this family in the catalytic conversion of methyl alcohol to petroleum is, undoubtedly, the most significant. Sodium-A zeolite is now being widely used in the USA and in West Germany as a builder in detergents. Various ion-exchanged forms of zeolites are being more and more extensively used in the liquid chromatographic separation of mixtures. Large quantities of natural clinoptilolite are now being used or about to be used in sewage treatment plants, nuclear fuel reprocessing plants, and in animal feeds. Natural zeolites are also being used in solar energy conversion units. There are about 20 papers dealing with synthesis, geology and mineralogy and a paper on pillared interlayered clays describes an interesting discovery which is open to further development. Infrared and n.m.r, spectroscopy are the two most widely used spectroscopic techniques and the application of far infrared spectroscopy to study cation positions in zeolite frameworks is an interesting new development. The papers in the Diffusion section seem to resolve the problem of the large differences previously found in the diffusion coefficients of hydrocarbons when measured by sorption uptake and n.m.r, techniques respectively. Adsorption and catalysis are still, however, the two dominant areas of zeolite research.
To accommodate the large number of papers accepted for the conference without resorting to parallel sessions, Professor Sersale conducted the conference by means of a General Reporter system. The reporters -- Professor Lechert (synthesis and crystallization), Professor Hay (geology and mineralogy), Professor Meier (structure), Dr. Sherry (ion exchange and modification), Professor Ruthven (adsorption), Professor Rickert (diffusion), Professors Weiss and Barthomeuf (catalysis) and Professor Schirmer (technology) -tried manfully (or womanfully) to present the salient features of the papers to be covered in their report, but the fears of the majority of the members of the organizing committee were justified. This method of conducting the conference was disliked by most of the participants for several reasons. The reporters had insufficient time and, because of the varied nature of the papers included in some of the sessions, insufficient knowledge, to do the papers justice. Whatever the failings of the method whereby authors present their own material, and there are often problems when an author is speaking in a language foreign to his own, these inadequacies are minor compared with the drawbacks of the reporter system. One of the main reasons for having international conferences is to allow one to meet ones fellow scientists from other countries. Although it is a problem for scientists from the Eastern bloc to obtain~permission to attend conferences in the West the reporter system encourages the submission of papers by persons who are unlikely to be able to attend the conference. Every effort must be made to dissuade such practices and to encourage the free movement of all scientists across the world. Personally I dislike parallel sessions but I hope that in future zeolite conferences, if such a large number of papers have to be accepted, that parallel sessions with authors presenting their own papers will be employed. The reporter system was also used to allow sufficient time for lively discussions after each session. Because of the limited amount of material presented on each paper and, also, because of the problem of remembering the important features of each paper even when one had taken the trouble to read the proceedings before the meeting, discussion mainly centred on the material presented in the plenary lecture. Many authors were very disappointed by this lack of discussion of their papers. There were one or two discussion periods in which lively and even heated arguments developed -- the 'Structure' discussion was very critical of certain papers which had been published in the literature, and the discussion period which followed the 'Technology' session was also quite lively although it was mainly of a trivial nature on the effects of feeding zeolites to animals. Poster sessions were held during several lunch periods where interesting reports of current research were presented. The
ZEOLITE& 1981, Vol 1, April
55
Conference reports posters and the discussions are to be published in a separate volume which is being prepared by Professor Sersale. We await with enthusiasm the appearance of this volume. Apart from these criticisms, however, the conference was very enjoyable. The 'Mostra D'Oltremare' was an excellent conference centre and the food and wine at the conference and in the nearby restaurants were excellent. The reception in the Castel dell'Ovo was memorable and the banquet at the Hotel Excelsior will be remembered for the good food and the sincere speech by Professor Sersale. He covered the lifetime achievements of Professor Barrer, who was then presented with a leather-bound copy of the proceedings as a memento of the conference which was dedicated to him on his seventieth birthday.
At the General Assembly of the International Zeolite Association it was decided after a vote, to hold the Sixth International Conference on Zeolites at Lake Tahoe in Nevada, USA, in 1983. This meeting is to be organized by Dr. J. Ward of Union Oil Company of California and Dr. D. Vaughan of Exxon Research, Linden, New Jersey. Finally, it was with great sadness to all members of the IZA to learn that Dr. Donald W. Breck died only a few days after returning from Napoli. His contribution to zeolite research and the application of zeolites was immense and he will be greatly missed.
Lovat V. C. Rees
The Seventh International Congress on Catalysis Tokyo, Japan, 30 June-4 July 1980 Around 1000 participants from 40 countries attended this Congress, which was highly successful in all respects. The scientific proceedings, which concentrated on heterogeneous catalysis, commenced with a plenary lecture, 'Molecular Shape Selective Catalysis' by Dr. P. B. Weisz of Mobil Research and Development Corporation. The programme of each of the following four days opened with a further plenary lecture, in the tradition of the Congress. There were more than 100 contributed papers, six of which dealt specifically with aspects of catalysis by zeolites, while a further three, though mainly dealing with non-zeolitic topics, incorporated work on zeolites. Brief summaries of the zeolite papers, which attracted considerable interest and discussion in both formal sessions and informally, are given below. Additionally, some 70 short communications were presented, five of which dealt with zeolite catalysis. The proceedings of the Congress are expected to be published in Spring 1981. Several post-congress symposia on narrower areas of catalysis took place in Tokyo and elsewhere in Japan.
Zeolite Papers The plenary lecture by P. B. Weisz provided an excellent exposition of the current state of knowledge and development of shape-selective catalysis by zeolites, and highlighted some applications and potential applications of this field to industrial catalysis. Shape selectivity by mass-transport discrimination and by local configuration constraint were discussed and exemplified. Tri, Massadier, Gallezot and Imelik (CNRS, Villeurbanne) reported investigations into a series of Y zeolites containing small platinum crystallites (0.8 or 1.0 nm) located in the supercages, or somewhat larger platinum crystallites (2 nm) occluded in the bulk. The environments of the crystallites were modified by the presence of various levels of Na+, Ce3+ or both. Members of the series thus also possessed varying numbers of protons per unit cell. The electronic properties of the Pt crystallites (as revealed by X-ray absorption edge spectroscopy) indicated that the electron deficiency (or electrophilic character, EC) is greater for the smaller crystallites; particularly greater when
56 ZEOLITES, 1981, Vol 1, April
the crystallites are situated in zeolites of higher acidity or Ce3+ content, n-Butane/hydrogen reaction rates and orders were measured at 590 K for the series of catalysts, and a correlation between the hydrogenolysis rates and the EC was established. It was assumed that the correlation arises because the EC controls the adsorption equilibrium between t42 and n-butane on the crystallite surface. A PtMo-Y sample was also investigated: the EC was not enhanced, though the hydrogenolysis rate was found to be very high. A direct Pt-Mo association was proposed to be responsible, qualitatively distinct from the electronic perturbation brought about, for example, by Ce3+ associated with the zeolitic framework. Gelin, Ben Taarit and Naccache (also at Villeurbanne) described the vapour phase carbonylation of methanol at 403-433 K, in the presence of methyl iodide, to methyl acetate, using catalysts derived from rhodium- and iridiumexchanged Y zeolite. Carbonyl infrared spectra and kinetic measurements were used as a basis for suggesting mechanisms. In the case of the Rh system, the ratedetermining step was considered to be the oxidative addition of methyl iodide to a carbonyl species, while in the Ir case, the proposed slow step was methanol addition to the catalytic species followed by the migration of methyl coordinated to the metal. Verdonck, Schoonheydt and Jacobs (Leuven) presented work on the low temperature water gas shift reaction at 363-523 K (1). The catalysts used were derived from ruthenium-exchanged faujasites. H20 + CO ~ H2 + CO2
(1)
The objective was investigation of the active site and elucidation of the mechanism. Zeolites, Y, X, L and EZ and also mordenite were investigated, though only X and Y showed appreciable activity, X being somewhat more active than Y. The presence of supercages was thus postulated to be important, and lower acid strength apparently beneficial. Maximum activity was found to correspond to an exchange level equivalent to one Ru per supercage: the implication was that more than one Ru in a supercage sterically
To accommodate the large number of papers accepted for the conference without resorting to parallel sessions, Professor Sersale conducted the conference by means of a General Reporter system. The reporters -- Professor Lechert (synthesis and crystallization), Professor Hay (geology and mineralogy), Professor Meier (structure), Dr. Sherry (ion exchange and modification), Professor Ruthven (adsorption), Professor Rickert (diffusion), Professors Weiss and Barthomeuf (catalysis) and Professor Schirmer (technology) -tried manfully (or womanfully) to present the salient features of the papers to be covered in their report, but the fears of the majority of the members of the organizing committee were justified. This method of conducting the conference was disliked by most of the participants for several reasons. The reporters had insufficient time and, because of the varied nature of the papers included in some of the sessions, insufficient knowledge, to do the papers justice. Whatever the failings of the method whereby authors present their own material, and there are often problems when an author is speaking in a language foreign to his own, these inadequacies are minor compared with the drawbacks of the reporter system. One of the main reasons for having international conferences is to allow one to meet ones fellow scientists from other countries. Although it is a problem for scientists from the Eastern bloc to obtain~permission to attend conferences in the West the reporter system encourages the submission of papers by persons who are unlikely to be able to attend the conference. Every effort must be made to dissuade such practices and to encourage the free movement of all scientists across the world. Personally I dislike parallel sessions but I hope that in future zeolite conferences, if such a large number of papers have to be accepted, that parallel sessions with authors presenting their own papers will be employed. The reporter system was also used to allow sufficient time for lively discussions after each session. Because of the limited amount of material presented on each paper and, also, because of the problem of remembering the important features of each paper even when one had taken the trouble to read the proceedings before the meeting, discussion mainly centred on the material presented in the plenary lecture. Many authors were very disappointed by this lack of discussion of their papers. There were one or two discussion periods in which lively and even heated arguments developed -- the 'Structure' discussion was very critical of certain papers which had been published in the literature, and the discussion period which followed the 'Technology' session was also quite lively although it was mainly of a trivial nature on the effects of feeding zeolites to animals. Poster sessions were held during several lunch periods where interesting reports of current research were presented. The
ZEOLITE& 1981, Vol 1, April
55
Conference reports posters and the discussions are to be published in a separate volume which is being prepared by Professor Sersale. We await with enthusiasm the appearance of this volume. Apart from these criticisms, however, the conference was very enjoyable. The 'Mostra D'Oltremare' was an excellent conference centre and the food and wine at the conference and in the nearby restaurants were excellent. The reception in the Castel dell'Ovo was memorable and the banquet at the Hotel Excelsior will be remembered for the good food and the sincere speech by Professor Sersale. He covered the lifetime achievements of Professor Barrer, who was then presented with a leather-bound copy of the proceedings as a memento of the conference which was dedicated to him on his seventieth birthday.
At the General Assembly of the International Zeolite Association it was decided after a vote, to hold the Sixth International Conference on Zeolites at Lake Tahoe in Nevada, USA, in 1983. This meeting is to be organized by Dr. J. Ward of Union Oil Company of California and Dr. D. Vaughan of Exxon Research, Linden, New Jersey. Finally, it was with great sadness to all members of the IZA to learn that Dr. Donald W. Breck died only a few days after returning from Napoli. His contribution to zeolite research and the application of zeolites was immense and he will be greatly missed.
Lovat V. C. Rees
The Seventh International Congress on Catalysis Tokyo, Japan, 30 June-4 July 1980 Around 1000 participants from 40 countries attended this Congress, which was highly successful in all respects. The scientific proceedings, which concentrated on heterogeneous catalysis, commenced with a plenary lecture, 'Molecular Shape Selective Catalysis' by Dr. P. B. Weisz of Mobil Research and Development Corporation. The programme of each of the following four days opened with a further plenary lecture, in the tradition of the Congress. There were more than 100 contributed papers, six of which dealt specifically with aspects of catalysis by zeolites, while a further three, though mainly dealing with non-zeolitic topics, incorporated work on zeolites. Brief summaries of the zeolite papers, which attracted considerable interest and discussion in both formal sessions and informally, are given below. Additionally, some 70 short communications were presented, five of which dealt with zeolite catalysis. The proceedings of the Congress are expected to be published in Spring 1981. Several post-congress symposia on narrower areas of catalysis took place in Tokyo and elsewhere in Japan.
Zeolite Papers The plenary lecture by P. B. Weisz provided an excellent exposition of the current state of knowledge and development of shape-selective catalysis by zeolites, and highlighted some applications and potential applications of this field to industrial catalysis. Shape selectivity by mass-transport discrimination and by local configuration constraint were discussed and exemplified. Tri, Massadier, Gallezot and Imelik (CNRS, Villeurbanne) reported investigations into a series of Y zeolites containing small platinum crystallites (0.8 or 1.0 nm) located in the supercages, or somewhat larger platinum crystallites (2 nm) occluded in the bulk. The environments of the crystallites were modified by the presence of various levels of Na+, Ce3+ or both. Members of the series thus also possessed varying numbers of protons per unit cell. The electronic properties of the Pt crystallites (as revealed by X-ray absorption edge spectroscopy) indicated that the electron deficiency (or electrophilic character, EC) is greater for the smaller crystallites; particularly greater when
56 ZEOLITES, 1981, Vol 1, April
the crystallites are situated in zeolites of higher acidity or Ce3+ content, n-Butane/hydrogen reaction rates and orders were measured at 590 K for the series of catalysts, and a correlation between the hydrogenolysis rates and the EC was established. It was assumed that the correlation arises because the EC controls the adsorption equilibrium between t42 and n-butane on the crystallite surface. A PtMo-Y sample was also investigated: the EC was not enhanced, though the hydrogenolysis rate was found to be very high. A direct Pt-Mo association was proposed to be responsible, qualitatively distinct from the electronic perturbation brought about, for example, by Ce3+ associated with the zeolitic framework. Gelin, Ben Taarit and Naccache (also at Villeurbanne) described the vapour phase carbonylation of methanol at 403-433 K, in the presence of methyl iodide, to methyl acetate, using catalysts derived from rhodium- and iridiumexchanged Y zeolite. Carbonyl infrared spectra and kinetic measurements were used as a basis for suggesting mechanisms. In the case of the Rh system, the ratedetermining step was considered to be the oxidative addition of methyl iodide to a carbonyl species, while in the Ir case, the proposed slow step was methanol addition to the catalytic species followed by the migration of methyl coordinated to the metal. Verdonck, Schoonheydt and Jacobs (Leuven) presented work on the low temperature water gas shift reaction at 363-523 K (1). The catalysts used were derived from ruthenium-exchanged faujasites. H20 + CO ~ H2 + CO2
(1)
The objective was investigation of the active site and elucidation of the mechanism. Zeolites, Y, X, L and EZ and also mordenite were investigated, though only X and Y showed appreciable activity, X being somewhat more active than Y. The presence of supercages was thus postulated to be important, and lower acid strength apparently beneficial. Maximum activity was found to correspond to an exchange level equivalent to one Ru per supercage: the implication was that more than one Ru in a supercage sterically