Polytechnic University of Valencia

About: Polytechnic University of Valencia is a education organization based out in Valencia, Spain. It is known for research contribution in the topics: Catalysis & Population. The organization has 16282 authors who have published 40162 publications receiving 850234 citations.

MOF catalysis in relation to their homogeneous counterparts and conventional solid catalysts

Abstract: Metal–organic frameworks have recently attracted attention as heterogeneous catalysts due to their high content of metal centres and large surface area and pore volume, along with their impressive topological richness. Therefore, many studies describing the use of MOFs as heterogeneous Lewis acid catalysts have been published. In this regard, these efforts have been directed towards probing the catalytic activity. Further information is required in terms of kinetic parameters and comparison of performance with their homogeneous counterparts, or other conventional heterogeneous catalysts. Here we have attempted to put MOFs into perspective with respect to their homogeneous counterparts and more conventional heterogeneous catalysts to show their advantages and limitations. We have exemplified a number of reactions reported in the literature wherein MOFs have been used as catalysts, and we have carried them out using homogeneous counterparts, i.e. benzoates and acetates, and other well defined conventional solid catalysts. The activities and selectivities of the catalysts are compared and then put into perspective on the basis of kinetic parameters, such as turnover numbers and turnover frequencies. Additionally, we illustrate using selected examples what the potential advantages of MOF catalysts could be, and how they may outperform the potential of other solid catalysts.

Innovation management techniques and tools: a review from theory and practice

Abstract: Knowledge is considered to be an economic driver in today's economy. It has become a commodity, a resource that can be packed and transferred. The objective of this paper is to provide a comprehensive review of the scope, trends and major actors (firms, organizations, government, consultants, academia, etc.) in the development and use of methods to manage innovation in a knowledge-driven economy. The paper identifies the main innovation management techniques (IMTs) aiming at the improvement of firm competitiveness by means of knowledge management. It will specifically focus on those IMTs for which knowledge is a relevant part of the innovation process. The research study, based on a survey at the European level, concludes that a knowledge-driven economy affects the innovation process and approach. The traditional idea that innovation is based on research (technology-push theory) and interaction between firms and other actors has been replaced by the current social network theory of innovation, where knowledge plays a crucial role in fostering innovation. Simultaneously, organizations in both public and private sectors have launched initiatives to develop methodologies and tools to support business innovation management. Higher education establishments, business schools and consulting companies are developing innovative and adequate methodologies and tools, while public authorities are designing and setting up education and training schemes aimed at disseminating best practices among all kinds of businesses.

New trends in tailoring active sites in zeolite-based catalysts.

Abstract: This review addresses the recent developments and trends in tailoring the nature and local properties of active sites in zeolite-based catalysts, with a special focus on novel extra-large pore, layered (2D), nanocrystalline, and hierarchical (mesoporous) zeolites with enhanced pore accessibility. In the first part of the review, we discuss the latest achievements in the bottom-up (direct synthesis) and top-down (post-synthesis) approaches for isomorphous substitution in zeolites enabling control over the type (Bronsted, Lewis, or both), amount, strength, and location of acid sites. The benefits in catalysis provided by such zeolites with tuned acidity and improved accessibility are shown for different acid-catalyzed reactions involving bulky molecules, as in the synthesis of fine chemicals and biomass transformations. The incorporation of metal species of different sizes (increasing from single atoms to clusters and to nanoparticles) in zeolites allows expanding the set of reactions catalyzed by these materials. The main preparation strategies for designing metal–zeolite catalysts, especially those offering control over the size of the metal species, and their catalytic behaviour in industrially relevant and emerging sustainable catalytic processes are dealt with in the second part of the review. Particular attention is paid to the stabilization of size-controlled small metal clusters and nanoparticles through their encapsulation in the voids of zeolite frameworks as well as to the dynamic behaviour of the metal species under reactive environments with important implications in catalysis. The need for using advanced operando spectroscopic and imaging tools to unveil the precise nature and functioning of the active sites in working zeolites is emphasized. The information gathered in this review is expected to provide guidance for developing more efficient zeolite-based catalysts for existing and new applications.

A New Simplified Multilevel Inverter Topology for DC–AC Conversion

Abstract: Multilevel converters offer high power capability, associated with lower output harmonics and lower commutation losses. Their main disadvantage is their complexity, requiring a great number of power devices and passive components, and a rather complex control circuitry. This work reports a new multilevel inverter topology using an H-bridge output stage with a bidirectional auxiliary switch. The new topology produces a significant reduction in the number of power devices and capacitors required to implement a multilevel output. The new topology is used in the design of a five-level inverter; only five controlled switches, eight diodes, and two capacitors are required to implement the five-level inverter using the proposed topology. The new topology achieves a 37.5% reduction in the number of main power switches required (five in the new against eight in any of the other three configurations) and uses no more diodes or capacitors that the second best topology in the literature, the Asymmetric Cascade configuration. Additionally, the dedicated modulator circuit required for multilevel inverter operation is implemented using a FPGA circuit, reducing overall system cost and complexity. Theoretical predictions are validated using simulation in SPICE, and satisfactory circuit operation is proved with experimental tests performed on a laboratory prototype