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Undoubtedly, hydrogen (H2) is a clean feedstock and energy carrier whose sustainable production should be anticipated. The pyrolysis of biomass or waste plastics and the subsequent reforming over base (transition) or noble metals supported catalysts allows reaching elevated H2 yields. However, the catalyst used in the reforming step undergoes a rapid and severe deactivation by means of a series of physicochemical phenomena, including metal sintering, metallic phase oxidation, thermal degradation of the support and, more notoriously, coke deposition. This review deals with the currently existing alternatives at the catalyst and reactor level to cope with catalyst deactivation and increase process stability, and then delves with the fundamental phenomena occurring during this catalyst deactivation. An emphasis is placed on coke deposition and its influence on deactivation, which depends on its location, chemical nature, morphology, precursors or formation mechanism, among others. We also discuss the challenges for increasing the value of the carbon materials formed and therefore, enhance process viability.

Here is the link for the free download over the next days: https://authors.elsevier.com/a/1aWoF4s9Hvxlyn

Polyolefin wastes are great feedstock for the fluid catalytic crackers (FCC). In our work in Fuel Processing Technology (Elsevier), we proved once more the benefits of this feedstock and step up into the best way to feed these wastes: a previous pyrolysis in delocalized units. In particular, in this work we demonstrate how polyolefins are beneficial in terms of conversion, product distribution, gasoline yield and above all, diminishing the catalyst deactivation. We have recurrently analyzed the deactivated FCC samples in order to propose a mechanism behind the mentioned positive outcomes of polyolefins. Thus, in light of our results polyolefins can be of interest as when co-fed with very heavy oil fractions, in order to cope the severe coke deposition of the latter.

In our recent work in Reaction Chemistry & Engineering (RSC) we have proved the great impact of solid arrangement in microreactors for developing a particular hydrodynamic flow. This issue is of primary importance in order to enhance mass and heat transfer in high-throughput screening systems using catalyst (solid and stationary) and a dynamic flow of gas and liquid passing trough. Examples of these systems are used every day for hydroprocessing, hydrotreating, selective hydrogenation, selective oxidation, liquid phase reforming… among many others. Besides, the mentioned mass and heat transfer limitations are pressingly important for very active catalyst testing, which is the case in the majority of the examples mentioned.

Our approach was designing, building and testing micro-machined reactors, with pillars of 150 µm arranged homogeneously or heterogeneously. The testing experiments were performed allowing flows of liquid and gas trough the systems; using different capillary numbers, contact angles and gas-liquid velocities; and quantifying the hydrodynamic behavior by image processing using a florescence microscope and Matlab. The results show that the interfacial area and the pulsing hydrodynamic behavior can be modified by changing the arrangement of the pillars, the capillary number or the contact angle in these systems.

Many catalytic reactions involve thousands of types of molecules with different nature, interacting one another and with the catalyst. In such cases, performing a catalyst screening is rather difficult because simple concepts such as “conversion” cannot be calculated straight forward. Based on a detailed product analysis, we propose in this work a methodology to account and quantify catalyst activity in complex multi-parallel chemistries with heavy fractions. This is a step forward into the rational reaction engineering of these processes.

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 Palos, R., Kekäläinen, T., Duodu, F., Gutiérrez, A., Arandes, J.M., Jänis, J., Castaño, P., Screening Hydrotreating Catalysts for the Valorization of a Light Cycle Oil/Scrap Tires Oil Blend Based on a Detailed Product Analysis,Appl. Catal. B: Environ. (0926-3373), 256 (2019) 117863. DOI: 10.1016/j.apcatb.2019.117863.