IV. Los retos tecnológicos de la pequeña y mediana empresa en México

INTRODUCCIÓN El ambiente de los negocios en la actualidad sufre el impacto de la tecnología a muchos niveles; el cambio es en particular evidente en las empresas, industrias, regiones y países. La rápida difusión de la tecnología en todo el mundo está permitiendo a los productores con bajos costos desafiar las posiciones establecidas en el mercado por empresas dominantes. La tecnología tiene un impacto competitivo en dos formas relevantes: proporciona una ventaja de mercado mediante diferenci..

Micro y pequeña empresa en México

Este libro presenta un grupo de reflexiones y de propuestas que enriquecen el abanico de opciones de política económica y social, en un entorno globalizado que requiere hacer compatible la modernización con mayores niveles de bienestar social

Role of Looping-Calcination Conditions on Self-Reactivation of Thermally Pretreated CO 2

The conversion of thermally pretreated CaO along successive carbonation/calcination cycles has been investigated, as affected by looping-calcination conditions, by means of Thermogravimetric Analysis (TGA). Sorbent samples have been subjected in situ to a thermal preheating program based on Constant Rate Thermal Analysis (CRTA) by virtue of which decarbonation is carried out at a low controlled rate, which is able to promote self-reactivation in the first carbonation/calcination cycles. Our observations support a pore-skeleton model according to which solid-state diffusion in the first carbonation stages, which is enhanced by thermal pretreatment, gives rise to a soft skeleton with increased surface area. Yet, the results show that self-reactivation is hindered as looping-calcination conditions are harshened. Increasing the looping-calcination temperature and/or the looping calcination time period favors sintering of the soft skeleton and eventually self-reactivation is precluded. A model is developed that retrieves the main features of multicyclic conversion of thermally pretreated sorbents in the first cycles based on the balance between surface area gain due to promoted solid-state diffusion carbonation and surface area loss due to sintering of the soft skeleton in the looping-calcination stage, which can be useful to investigate the critical looping-calcination conditions that nullify self-reactivation. The proposed model allows envisaging the behavior of the sorbent performance as a function of the pretreatment conditions.Junta de Andalucía FQM-5735Ministerio de Economía y Competitividad FIS2011-25161, CTQ2011-2762

New insights on the kinetic analysis of isothermal data: The independence of the activation energy from the assumed kinetic model

© 2014 American Chemical Society. Isothermal experiments are widely employed to study the kinetics of solid-state reactions or processes to extract essential kinetic information needed for modeling the processes at an industrial scale. The kinetic analysis of isothermal data requires finding or assuming a kinetic function that can properly fit the evolution of the reaction rate with time, so that the resulting parameters, i.e., the activation energy and pre-exponential factor, can be considered reliable. In the present work, we demonstrate using both simulated and experimental data that the kinetic analysis of a set of isothermal plots obtained at different temperatures, considering a single-step solid-state reaction, necessarily leads to the real activation energy, regardless the mathematical function selected for performing the kinetic analysis. This makes irrelevant the election of the kinetic function used to fit the experimental data and greatly facilitates the estimation of the activation energy for any single process.Peer Reviewe