Research
My research focuses on engineering sustainable fuels and platform chemicals, converting pollutants and wastes, like carbon dioxide, waste plastics, used tires, biomass and lignin, into products of interest, like hydrogen, olefins, platform chemicals and fuels. My ambition is to contribute to the development of a chemical, petrochemical and fuel industry respectful to the environment. To that end and more specifically, my objectives are:

  1. 1. Improve the understanding and sustainability of processes for the valorization of carbon dioxide, waste plastics, used tires, biomass or lignin

  2. 2. Engineer and develop catalysts for fuel-chemical production and pollutant removal

  3. 3. Control the catalyst deactivation by coke in sustainable processes

  4. 4. Reaction systems (reactors) design, analysis and advanced models

1. Valorization. In my group, we have proposed original paths of valorization of different materials targeting high quality fuels or platform chemicals, making significant contributions to improve the viability and to understand the limitations of each of the valorization processes:

  1. 1.1. Carbon dioxide by electrocatalysis. In a publication in Green Chemistry and with the collaboration of the University of Cantabria, we have revised the route methanol production through the electrocatalytic conversion of carbon dioxide, which offers good prospects for redirect possible peaks of energy generation into chemical energy in the form of methanol.

  2. 1.2. Biomass like lignocellulose, lignin and thermal pyrolytic lignin (thermal and catalytic processing). In our work published in ChemSusChem we have synthesized interesting carbon materials from the thermal treatment of bio-oil (produced in the flash pyrolysis of biomass and that is very interesting from the point of view of the sustainable refinery). A thorough characterization of these materials obtained under different conditions allows us to optimize the composition for particular applications, such as fuel, activated carbons or other raw materials.

  3. 1.3. Waste plastics like polyolefins (using also a combination of thermal and catalytic processing). Waste polyolefins can be converted back to the raw materials from where they were synthesized; light olefins. We have been working on the pyrolysis+cracking in series or simultaneously in several works published in Applied Catalysis B with very attractive yields, or co-feeding the pyrolysis waxes to the refinery units as the fluid catalytic cracker or FCC (Energy & Fuels).

  4. 1.4. Used tires and refinery waste (pyrolysis gasoline and light cycle oil) for production, in all cases. Waste tires also shows good perspectives to be transformed in a oil like mixture with properties to be added as blending for gasoline or diesel. Nonetheless, the extremely high concentration of sulfur, aromatics and high boiling point molecules hinders this route. We have proposed a 2-stage hydroprocessing route for boosting the quality and amount of fuels consisting in hydrotreating (Fuel) and hydrocracking (Energy & Fuels)

2. Catalysis. We have designed and developed heterogeneous catalysts with improved properties based on innovative material synthesis, enhanced support interactions, elimination of diffusional limitations, alloying metallic sites, balancing active sites in multifunctional catalyst, among others:

  1. 2.1. Acidic catalyst. We have worked actively on synthesizing and modifying microporous-acidic silicas, aluminosilicates and aluminophosphate-silicates like HZSM-5 (ZSM-5 or MFI), HY (FAU), MCM-41, SBA-15, HMS, Hbeta (BEA), SAPO-34 (CHA) and SAPO-18 (AEI), among others for a variety of catalytic applications. Characterization acidity qualitatively, quantitatively and spatially of these solids deserves special efforts since it is still an interesting topic with great room for improvement. Acidic catalysts are used industrially with an inert matrix of filler and binder, that provides with mechanical strength and avoid thermal excursions among others. In our work in ChemCatChem (together with the University of Utrecht), we have discovered the importance of the spatial dispersion of the zeolite domains within the catalytic particles (with the matrix) to enhance the catalytic selectivity and overall performance.

  2. 2.2. Metal supported catalyst. Metallic nanoparticles show fascinating features to improve the performance of the supported catalysts applied to remove pollutants or to produce chemicals and fuels sustainably. In our work in Journal of Catalysis (together with the Institute of Catalysis and Petrochemistry), we pointed to the importance of Au+ exposure for the aromatic hydrogenation catalyst supported on mesoporous silica (HMS).

  3. 2.3. Bifunctional and multifunctional catalysts. Bifunctional catalyst typically consists in micro or mesoporous-acidic supports with metallic nanoparticles deposited on the surface of the former. There are several ways to add functionality to a particular catalyst, so we can expand its selectivity, lifetime or activity but particularly the number of reactions involved on its surface. In our work in Green Chemistry, we developed multifunctional catalysts to remove oxygen and aromatic renewable fossil feeds feeds, leading to guidelines for the design and operation of industrial units for this kind of multifunctional processes.

  4. 2.4. Activated carbons. In collaboration with the University of Malaga and the University of Calgary, we have developed stable and active catalysts based on activated carbons from wastes (petcoke or olive stone). These catalysts have shown outstanding performance several processes such as tire oil hydrocracking (Fuel Process Technology and Catalysis Communications) or bio-oil hydrodeoxygenaiton (Applied Catalysis B).

3. Deactivation. Inevitably, most of the heterogeneous catalysts deactivate, that is to say that their performance or selectivity degrade over the course of time. Among the several causes for deactivation, fouling is the most important one, and its importance is even bigger when treating wastes or heavier feedstock. Fouling is caused by the deposition of carbonaceous material (also known as coke, with a lower ratio of H/C than the feed) on the surface of the catalyst. As a result, the catalyst loses its sites and the activity diminishes (in general). Controlling, analyzing or minimizing coke deactivation is of a primordial importance to enhance the competitiveness of processes aiming a sustainable production of fuels or chemicals:

  1. 3.1. Analysis of coke and deactivation pathway. Understanding the nature of coke and the composition and correlate them with the process conditions like temperature, pressure and composition of the reactant media enable to set deactivation pathways of the catalyst. In our work in Catalysis Science and Technology we applied this approach to solve the deactivation mechanisms during the cracking of polyolefins.

  2. 3.2. Location of coke. Deactivations by fowling do not occur in the entire catalytic surface at once, but preferentially on the most active sites or in the pores where these molecules are trapped. In our work in ChemCatChem we analyzes this heterogeneous distribution of the coke along relevant catalytic particles.

  3. 3.3. Regeneration of coke. Fortunately, if the deactivated catalyst is stable enough, it can be regenerated by combustion with air. In some cases we can use the heat released by the combustion to other processes, enhancing the energy efficiency of the entire plant. The kinetics of coke combustion is therefore a key point from the process efficiency. We have developed models for predicting better the kinetics and thermodynamics of coke combustion in the regeneration step (Chemical Engineering Science).

4. Systems. I have been committed to develop systems for a sustainable production of chemicals, energy and fuels, and as a result I lead a volunteer project to implement this kind of systems in a School of Sao Tome (Africa, STPEnergy): heaters, furnaces, evaporators and solar fryers as well as a production unit and bio-gas.

  1. 4.1. Microreactors. Parallel microreactos offer a rapid catalyst testing with reduced volume and wastes. In the work I developed in TUDelft, with Shell and Albemarle as funding companies, we published in Applied Catalysis A guidelines for the conditions at which intrinsic kinetics can be obtained from these microreactors.

  2. 4.2. Periodic reactors. These are systems where conditions vary periodically in order to reveal some intrinsic kinetic mechanisms or avoid secondary reactions. In a new research proposal granted, my team will focus on these type of reactors, which has been used for extracting kinetically relevant information in single experiments (Chemical Engineering Science).

  3. 4.3. Modeling kinetics. I have several open research lines regarding modeling of heterogeneous catalyzed chemical reactions aiming the prediction of quality and yields of products, e.g. aromatic hydrogenation (Applied Catalysis B), cycloalkane ring opening (Chemical Engineering Journal), pyrolysis gasoline hydroporcessing (Chemical Engineering Journal), among others.

  4. 4.4. Modeling molecular dynamics in heterogeneous catalytic process and multi-physic phenomena. I am focusing some of my research on modeling complex chemical systems from different scale point of view and comparing the intrinsic molecular dynamics of coke formation during the transformation of methanol, dimethyl ether or chloromethane on zeolites.