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- Elucidation of the zeolite role on the hydrogenating activity of Pt-catalystsPublication . Mendes, Pedro; Gregório, André F. C.; Daudin, Antoine; Bouchy, Christophe; Silva, João; Ribeiro, M FilipaToluene hydrogenation was studied over model catalysts with a fixed hydrogenating function (Pt/Al2O3) mechanically mixed with either HUSY or HBEA zeolites. Such mechanical mixtures showed improved platinum turnover frequencies compared to single Pt/Al2O3. Comparing to Pt-impregnated zeolite catalysts, the mechanical mixtures have lower activities per site showing that the contribution of acid sites decreases (and so the hydrogenating activity) with increased distance between Pt clusters and acid sites. Therefore, toluene hydrogenation can be used as a powerful tool to evaluate Pt-acid site intimacy in bifunctional catalysts.
- Synergies, cooperation and other effects: a review for hydroconversion catalystsPublication . Mendes, Pedro S. F.; Silva, João M; Ribeiro, M Filipa; Daudin, Antoine; Bouchy, ChristopheMixing different components is the basis of chemistry. In heterogeneous catalysis, combinations of different active phases are frequently used, but involved in a mysterious way similar to alchemy. The language employed to describe such systems is typically imprecise due to the lack of clear definitions and efforts to quantify the observed performances. In this review, focused in the particular case of bifunctional catalysis, a set of definitions is provided aiming at an analytical and coherent examination of the literature. The works on hybrid zeolite based catalysts for hydroconversion processes are reviewed, and an attempt to classify the various origin of potential cooperation effects is provided. By such means, we hope to provide not only a clear view on the current state-of-the-art on hydroconversion catalysts but also a common framework for a more rigorous investigation of possible synergies of hybrid catalysts over all catalysed reactions.
- Quantification of metal-acid balance in hydroisomerization catalysts: a step further toward catalyst designPublication . Mendes, Pedro S. F.; Silva, João; Ribeiro, M. Filipa; Duchene, Pascal; Daudin, Antoine; Bouchy, ChristopheA methodology was developed to interpret the results of n-.paraffins hydroisomerization over bifunctional catalysts based on two simple kinetic models used consecutively. First, a macrokinetic model was used to obtain the corresponding turnover frequency over the acid sites and the maximum of C-16 isomer yield. Second, a dual-function model was used to correlate these catalytic descriptors to the ratio of metal to acid sites of the catalyst. To illustrate the methodology, Pt/HBEA and Pt/HUSY catalysts with different Pt loadings were evaluated. The impact of metal-acid balance on the catalytic turnover frequency and the maximal C-16 isomer yield were adequately captured for the bifunctional HUSY and HBEA catalysts. Moreover, the parameters of the dual-function model revealed to be intrinsic to the catalytic properties of the zeolite under the scope. This methodology is believed to be of interest for information-driven catalyst design for the hydroisomerization of n-paraffins.
- Induction heating in nanoparticle impregnated zeolitePublication . Morales Casero, Irene; MUÑOZ, MARTA; Costa, Catia S.; Alonso, Jose Maria; Silva, João M.; Multigner, Marta; Quijorna, Mario; Ribeiro, M. Rosário; De La Presa, PatriciaThe ultra-stable Y (H-USY) zeolite is used as catalyst for the conversion of plastic feedstocks into high added value products through catalytic cracking technologies. However, the energy requirements associated with these processes are still high. On the other hand, induction heating by magnetic nanoparticles has been exploited for different applications such as cancer treatment by magnetic hyperthermia, improving of water electrolysis and many other heterogeneous catalytic processes. In this work, the heating efficiency of gamma-Fe2O3 nanoparticle impregnated zeolites is investigated in order to determine the potential application of this system in catalytic reactions promoted by acid catalyst centers under inductive heating. The gamma-Fe2O3 nanoparticle impregnated zeolite has been investigated by X-ray diffraction, electron microscopy, ammonia temperature program desorption (NH3-TPD), H-2 absorption, thermogravimetry and dc and ac-magnetometry. It is observed that the diffusion of the magnetic nanoparticles in the pores of the zeolite is possible due to a combined micro and mesoporous structure and, even when fixed in a solid matrix, they are capable of releasing heat as efficiently as in a colloidal suspension. This opens up the possibility of exploring the application at higher temperatures.