NJC Accepted Manuscript This is an Accepted Manuscript, which has been through the Royal Society of Chemistry peer review process and has been accepted for publication. Accepted Manuscripts are published online shortly after acceptance, before technical editing, formatting and proof reading. Using this free service, authors can make their results available to the community, in citable form, before we publish the edited article. We will replace this Accepted Manuscript with the edited and formatted Advance Article as soon as it is available. You can find more information about Accepted Manuscripts in the Information for Authors. Please note that technical editing may introduce minor changes to the text and/or graphics, which may alter content. The journal’s standard Terms & Conditions and the Ethical guidelines still apply. In no event shall the Royal Society of Chemistry be held responsible for any errors or omissions in this Accepted Manuscript or any consequences arising from the use of any information it contains. www.rsc.org/njc Page 1 of 16 PleaseNew Journal do not adjustof Chemistry margins New Journal of Chemistry PERSPECTIVE REVIEW Zeolite science and technology at Eni Giuseppe Bellussi,a Roberto Millini,b Paolo Pollesela and Carlo Peregob* Received 00th January 20xx, In the last forty years Eni laboratories have contributed to the advancement of zeolite science and technology in both the Accepted 00th January 20xx materials synthesis and characterization and the application in catalysis. This work has led to several industrial applications for selective oxidations and acid-base catalysis as well as for gas separation and water remediation. A brief review of the DOI: 10.1039/x0xx00000x main results is reported with some comments of the future perspectives for these branches of technology. www.rsc.org/ Manuscript This paper is part of a special issue dedicated to Francois Fajula, Introduction a world-renowned scientist who has contributed in a decisive way to the advancement in the field of zeolites and related Zeolites constitute an important and fascinating class of materials. It is superfluous to say that the experience and crystalline microporous materials, whose technological teaching received from scientists as Francois Fajula is very relevance is demonstrated by the extensive application as valuable for our daily research work and, therefore, we want to heterogeneous catalysts in several petrochemical and oil give him a sign of gratitude and esteem. refining processes, as ion-exchangers for domestic and Here, we try to connect research on different chemical industrial uses, as molecular sieves for the separations of Accepted reactions and zeolite catalysis by a not so thin common thread. specific molecules from complex mixtures. As the major oil We will make a journey through the long research activity, with companies in the world, from the very beginning of the modern brief stops to describe the main achievements that, we do hope, era of the science and technology of zeolites, Eni has recognized demonstrate our contribution to the development of the the potential provided by these materials investing significant science and technology of zeolites and related microporous resources in the preparation of new materials and in their materials. applications, mainly (but not exclusively) in some of those fields which are traditionally its main businesses: petrochemistry and oil refining. Even within the limits imposed by being an Zeolite synthesis evolution at Eni industrial company, the research is conducted in a very open manner, giving due importance to the sharing of the results with The progress in the petrochemical and oil refining industries is Chemistry the international scientific community. In fact, there is a strong highly dependent on the technological innovation of the belief that innovation can only benefit from the exchange of transformation processes that, in turn, require innovative experiences and from the collaboration with leading research materials with characteristics and properties tailored to the of groups in the field. This allowed us to reach significant specific needs. Already at the dawn of the modern era of the achievements, many of which remain of purely scientific science and technology of zeolites, Eni has recognized the high interest and have been shared with the scientific community potential of the crystalline microporous materials, devoting through several publications on international peer-reviewed considerable efforts and resources in research aimed at the journals, contributions to national and international preparation of new materials with innovative properties. conferences, invited lectures in universities and public/private The guideline that has characterized research on zeolites at Eni research centres. On the other hand, some of them have been in the last 40 years was to consider as new materials not only the basis for in the development of new industrial processes still those characterized by a new structure, but also those resulting Journal used today in Eni’s industrial sites or licensed to other from the compositional and morphological modification of companies in the world. known phases. In this regard, considerable efforts have been devoted to the process known as "isomorphous substitution", consisting in the, at least partial, replacement of Al and/or Si New with other tri- or tetravalent elements, capable of imparting a. Eni SpA, Development, Operations and Technology, Downstream R&D, Via F. Maritano 26, I-20097 San Donato Milanese (Italy). new properties to the zeolite framework. In this way, the b. Eni SpA, Development, Operations and Technology, Renewable Energy & successful incorporation of Ti into the Silicalite-1 (MFI) Environmental R&D, Via G. Fauser 4, I-28100 Novara (Italy). framework, claimed by Taramasso et al., 1 c. * Corresponding author, e-mail: [email protected] led to the discovery of Titanium-Silicalite-1 (TS-1), the first crystalline microporous This journal is © The Royal Society of Chemistry 20xx New J. Chem., 2016, 00, 1-3 | 1 Please do not adjust margins PleaseNew Journal do not adjustof Chemistry margins Page 2 of 16 ARTICLE Journal Name oxidation catalyst particularly active and selective in oxidation reactions with H2O2 under mild conditions. The original recipe is 50 nm based on the controlled hydrolysis of aqueous solutions containing tetraethyl orthosilicate, tetraethyl orthotitanate and tetrapropylammonium hydroxide. This mixed alkoxide procedure allows a fine control of the synthesis, favouring the crystallization of high quality TS-1 samples. 1 Once recognized the excellent properties of this catalyst, several alternative synthesis methods have been reported, but many of them lead to the crystallization of TS-1 samples of lower quality respect to the original material. 2 More recently, an improved synthetic method, operating at a particularly low dilution, has been 3 developed. With suitable H2O/Ti molar ratios in the reaction mixture, TS-1 is prepared, in pure phase, with a high productivity. An extensive physico-chemical characterization of TS-1 allowed to assess that up to a maximum of 2.5 atom% of Ti are incorporated in the framework in tetrahedral coordination Fig. 2 Transmission electron micrograph of the zeolite beta catalyst (Fig. 1) 2,4-9 and from this originate the excellent catalytic employed in the cumene and ethylbenzene technologies. Manuscript properties of this material. Later on, the modification of the composition of the zeolite It is the case, for instance, of the zeolite beta catalyst employed framework was extended to other elements, including Ga, V in the liquid phase alkylation of benzene with propylene to and, most important, B. The latter is quite interesting in zeolite cumene and with ethylene to ethylbenzene, more extensively synthesis because, contrarily to Ti, it can be incorporated into a treated hereinafter. 13 The optimization of the synthesis 10 variety of different structures. Original synthesis procedures conditions led to the preparation of samples composed by sub- were developed for the preparation of crystalline microporous micronic berry-like aggregates of very small crystallites (15 nm borosilicates (“boralites”) with the RUT (BOR-A), ANA (B- average dimensions), ideal morphology for the heterogeneous analcime), EUO (B-EU-1), FER (B-ferrierite), LEV (B-levyne), Beta catalysts (Fig. 2). (BOR-B), MFI (BOR-C), MFI/MEL intergrowths (BOR-D, BOR-E), It is worth noting that these aggregates, formed by crystallites Accepted 10 MWW (ERB-1) and MTW (B-ZSM-12) framework structures. of very small dimensions and with large mesoporosity resulting Several structural and spectroscopic evidences unambiguously from their assembly, constitute a system with hierarchical assessed the real framework incorporation of this trivalent porosity. This anticipates by some years another fruitful element, leading to conclude that B is the most versatile research line, precisely dedicated to the generation of different element for the isomorphous substitution of Al in zeolite interconnected levels of porosity within the frameworks. Among boralites, ERB-1 (MWW) proved to be crystals/aggregates, necessary for eliminating the diffusional particularly interesting because it was demonstrated for the limitations normally affecting large zeolite crystals. Similar first time the layered nature of its precursor, the ordered 3D results were achieved in the case of the ZSM-12 catalyst a priori structure being obtained by simple