Catalizadores para biorrefinería: obtención de furfural y su transformación a productos de condensación aldólica

Tesis doctoral inédita. Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Química Física Aplicada. Fecha de lectura: 20-01-201

Deactivation of solid catalysts in liquid media: the case of leaching of active sites in biomass conversion reactions

This review is aimed to be a brief tutorial covering the deactivation of solid catalysts in the liquid phase, with specific focus on leaching, which can be especially helpful to researchers not familiarized with catalytic processes in the liquid phase.</p

Overcoming catalyst deactivation during the continuous conversion of sugars to chemicals: maximising the performance of Sn-Beta with a little drop of water

Producing chemicals from renewable resources represents one of the key challenges in chemical science. Whilst catalytic methods for converting renewables to chemicals offer several advantages over biological approaches, the solid catalysts developed to date are typically plagued by rapid rates of deactivation, prohibiting their greater exploitation. Here, we demonstrate, for the first time, that a Sn-containing zeolite, Sn-Beta, is capable of continuously converting saccharide solutions to value added chemicals with high levels of activity, selectivity and stability. For both the isomerisation of glucose to fructose, and the conversion of fructose to alkyl lactates, we observe that the addition of up to 10% of water to the methanol/sugar reaction feed increases reactivity by a factor of 2.5, and catalyst stability by one order of magnitude. Continuous operation for up to 1366 h (57 days) is demonstrated, with only limited loss of activity being observed over this period of time. Post-reaction characterisation indicates that the addition of water influences several elements of the catalytic system, which cooperatively result in improved performance

Catalizadores para biorrefinería: obtención de furfural y su transformación a productos de condensación aldólica

279 páginas, 72 figuras.Como consecuencia de la disminución de reservas de petróleo, y de la creciente preocupación por el medioambiente, se está favoreciendo la aparición un concepto nuevo, el de biorrefinería, en la cual la biomasa se utiliza como materia prima para lograr los mismos objetivos que en las refinerías tradicionales: producción de productos químicos, combustibles, energía, e incluso comida. En el contexto de las biorrefinerías basadas en lignocelulosa, el furfural está adquiriendo una importancia creciente como uno de los productos químicos plataforma más destacados. Puede ser utilizado en la producción de biocombustibles o de otros productos químicos. Esta tesis doctoral explora dos reacciones implicadas en estos procesos: la deshidratación de xilosa para obtención de furfural y su posterior transformación mediante condensación aldólica a productos de mayor valor añadido y que pueden ser convertidos en biocarburantes.Peer reviewe

Deactivation of solid catalysts in liquid media: the case of leaching of active sites in biomass conversion reactions

This review is aimed to be a brief tutorial covering the deactivation of solid catalysts in the liquid phase, with specific focus on leaching, which can be especially helpful to researchers not familiarized with catalytic processes in the liquid phase. Leaching refers to the loss of active species from the solid that are transferred into the liquid medium, causing eventually a deactivation of the catalyst. Intriguingly, not many published studies have dealt with leaching, since this is a specific phenomenon in the liquid phase and heterogeneous catalysis is mainly carried out in gaseous phase. However, as a consequence of the development of new processes for biorefineries, an increasing number of reactions deal with liquid media, and thus, the stability and reusability of a solid catalyst in this situation represent a huge challenge that requires specific attention. Leaching of active phases is particularly problematic because of its irreversibility and it can be one of the main causes of catalyst deactivation in liquid media, threatening the sustainability of the process. This tutorial review presents a survey of the main aspects concerning the deactivation due to leaching of active species from the solid catalyst such as mechanisms, detection methods, impact of these factors on global activity and finally, some procedures to try and minimize the leaching or to cope with it. A decision flowchart is presented to help in the study of catalyst stability and reusability. Interesting biomass conversion reactions have been chosen as examples to illustrate the importance of these aspects.The authors would like to acknowledge funding and contributions from the Centre for Catalysis and Sustainable Chemistry, DTU Chemistry, the Institute of Catalysis and Petrochemistry, CSIC and Haldor Topsøe A/S to part of the reported work.Peer Reviewe