Modeling and Optimization of Lactic Acid Synthesis by the Alkaline Degradation of Fructose in a Batch Reactor

The present work deals with the determination of the optimal operating conditions of lactic acid synthesis by the alkaline degradation of fructose. It is a complex transformation for which detailed knowledge is not available. It is carried out in a batch or semi-batch reactor. The ‘‘Tendency Modeling’’ approach, which consists of the development of an approximate stoichiometric and kinetic model, has been used. An experimental planning method has been utilized as the database for model development. The application of the experimental planning methodology allows comparison between the experimental and model response. The model is then used in an optimization procedure to compute the optimal process. The optimal control problem is converted into a nonlinear programming problem solved using the sequencial quadratic programming procedure coupled with the golden search method. The strategy developed allows simultaneously optimizing the different variables, which may be constrained. The validity of the methodology is illustrated by the determination of the optimal operating conditions of lactic acid production

Intensification of cellulose hydrolysis process by supercritical water: Obtaining of added value products

En la Presente tesis doctoral se ha estudiado el proceso de hidrólisis de celulosa V Uiomása vegetal en agua supercritica. Se ha estudiado la cinética de hidrólisis de celulosa y sus productos derivados, Un intensivo estudio sobre la dependencia de las cineticas con la presion y temperatura fue desarrollado. La produccion de compuestos de alto valor añadido como ácido láctico o glicolaldehido fue analizado utilizando agua supercritica como medio de reaccion e hidróxido de sodio como medio de reaccion. El reactor diseñado y construido para el estudio de la hidrólisis en agua supecritica fue probado con salvado le trigo, como ejemplo de biomasa natural. Además, se ha estudiado teoricamnete la integracion energetica del proceso de hidrólisis de celulosa en agua supercrita con los procesos comerciales de produccion combinada de calor y potencia.Departamento de Ingeniería Química y Tecnología del Medio Ambient

Heterogeneously catalyzed hydrothermal processing of C5-C6 sugars

Biomass has been long exploited as an anthropogenic energy source; however, the 21st century challenges of energy security and climate change are driving resurgence in its utilization both as a renewable alternative to fossil fuels and as a sustainable carbon feedstock for chemicals production. Deconstruction of cellulose and hemicellulose carbohydrate polymers into their constituent C5 and C6 sugars, and subsequent heterogeneously catalyzed transformations, offer the promise of unlocking diverse oxygenates such as furfural, 5-hydroxymethylfurfural, xylitol, sorbitol, mannitol, and gluconic acid as biorefinery platform chemicals. Here, we review recent advances in the design and development of catalysts and processes for C5-C6 sugar reforming into chemical intermediates and products, and highlight the challenges of aqueous phase operation and catalyst evaluation, in addition to process considerations such as solvent and reactor selection

Selective fructose dehydration to 5-hydroxymethylfurfural from a fructose-glucose mixture over a sulfuric acid catalyst in a biphasic system: Experimental study and kinetic modelling

A two-step process combining the (equilibrium) glucose isomerization to fructose with selective dehydration of fructose in the obtained sugar mixture to 5-hydroxymethylfurfural (HMF), where glucose is largely unconverted and recycled, represents an attractive concept to increase the overall efficiency for HMF synthesis. This work presents experimental and modelling studies on the conversion of such fructose-glucose mixture to HMF using the sulfuric acid catalyst in a water-methyl isobutyl ketone biphasic system under a wide range of conditions (e.g., temperature, catalyst and sugar concentrations). Through detailed product analyses and ESI-MS spectroscopy, the excess formation of formic acid (together with humins) by the direct sugar/HMF degradation was confirmed and included in the reaction network (neglected in most literatures). The kinetic modelling based on batch experiments in monophasic water well describes the measurements thereof, whereas distinct deviations were found in the prediction of typical literature kinetic models. The incorporation of HMF equilibrium extraction into the developed kinetic model, with consideration of phase volume change as a function of temperature and partial phase miscibility, enables to predict reaction results in the biphasic system in batch. This kinetic model allows to optimize conditions for HMF synthesis that are favored in continuous reactors with minimized back mixing. Based on the model implications, the biphasic system was optimized with slug flow microreactors to better address process intensification and scale-up aspects. Using a simulated fructose-glucose mixture feedstock to represent commercially available high fructose corn syrups, a maximum HMF yield of 81% was obtained at 155 °C over 0.05 M H2SO4 at a residence time of 16 min in the microreactor, with 96% fructose conversion and over 95% of glucose remaining unconverted

Porous metallosilicates for heterogeneous, liquid-phase catalysis: perspectives and pertaining challenges

Porous silicates containing dilute amounts of tri-, tetraand penta-valent metal sites, such as TS-1, Sn-β and Fe- ZSM-5, have recently emerged as state of the art catalysts for a variety of sustainable chemical transformations. In contrast with their aluminosilicate cousins, which are widely employed throughout the refinery industry for gas-phase catalytic transformations, such metallosilicates have exhibited unprecedented levels of performance for a variety of liquidphase catalytic processes, including the conversion of biomass to chemicals, and sustainable oxidation technologies with H2O2. However, despite their unique levels of performance for these new types of chemical transformations, increased utilization of these promising materials is complicated by several factors. For example, their utilization in a liquid, and often polar, medium hinders process intensification (scaleup,catalyst deactivation). Moreover, such materials do not generally exhibit the active-site homogeneity of conventional aluminosilicates, and they typically possess a wide variety of active-site ensembles, only some of which may be directly involved in the catalytic chemistry of interest. Consequently,mechanistic understanding of these catalysts remains relatively low, and competitive reactions are commonly observed. Accordingly, unified approaches towards developing more active, selective and stable porous metallosilicates have not yet been achieved. Drawing on some of the most recent literature in the field, the purpose of this mini review is both to highlight the breakthroughs made with regard to the use of porous metallosilicates as heterogeneous catalysts for liquidphase processing, and to highlight the pertaining challenges that we, and others, aim to overcome during the forthcoming years

Catalytic Methods in Flow Chemistry

The chemical industry is essential in the daily humn life of modern society; despite the misconception about the real need for chemical production, everyone enjoys the benefit of the chemical progress. However, the chemical industry generates a large variety of products, including (i) basic chemicals, e.g., polymers, petrochemicals, and basic inorganics; (ii) specialty chemicals for crop protection, paints, inks, colorants, textiles, paper, and engineering; and (iii) consumer chemicals, including detergents, soaps, etc. For these reasons, chemists in both acdemia and industry are challenged with developing green and sustainable chemical production towrad the full-recycling of feedstocks and waste. Aiming to improve the intensification of the process, chemists have established chemical reactions based on catalysis, as well as alternative technologies, such as continuous flow. The aim of this book is to cover promising recent research and novel trends in the field of novel catalytic reactions (homogeneous, heterogeneous, and enzymatic, as well as their combinations) in continuous flow conditions. A collection of recent contribution for conversion of starting material originated from petroleum resources or biomass into highly-added value chemicals are reported

Recent advances on the utilization of layered double hydroxides (LDHs) and related heterogeneous catalysts in a lignocellulosic-feedstock biorefinery scheme

Layered double hydroxides (LDHs) and derived materials have been widely used as heterogeneous catalysts for different types of reactions either in gas or in liquid phase. Among these processes, the valorization/upgrading of lignocellulosic biomass and derived molecules have attracted enormous attention because it constitutes a pivotal axis in the transition from an economic model based on fossil resources to one based on renewable biomass resources with preference for biomass waste streams. Proof of this is the increasing amount of literature reports regarding the rational design and implementation of LDHs and related materials in catalytic processes such as: depolymerization, hydrogenation, selective oxidations, and C-C coupling reactions, among others, where biomass-derived compounds are used. The major aim of this contribution is to situate the most recent advances on the implementation of these types of catalysts into a lignocellulosic-feedstock biorefinery scheme, highlighting the versatility of LDHs and derived materials as multifunctional, tunable, cheap and easy to produce heterogeneous catalysts

Development of porous solid acid catalysts for lignocellulose and plastic upcycling.

My goal is to develop chemical processes for transforming waste to solve environmental problems and enhance sustainability. Environmental problems such as pollution and massive amounts of waste are the main drivers that stimulate my research ideas. I focused on creating novel, efficient catalytic processes for converting polymeric waste feedstocks into high-value chemicals by integrating my expertise in catalysis, materials science, and synthetic chemistry to develop porous solid catalytic materials. During my Ph.D., I focused on two polymeric feedstocks, lignocellulose, and discarded plastic. Early in my Ph.D. journey, I focused on catalytic upcycling of lignocellulose. Lignocellulosic biomass is cost-effective, abundant, and renewable. Upcycling lignocellulose into renewable fuels and chemicals has the potential to reduce reliance on fossil fuels, mitigate global warming, and promote a sustainable bioeconomy. The major challenge in upcycling lignocellulose is the active, selective, and reusable catalysts. I developed porous solid acid catalysts by solvothermal techniques and tuned their catalytic performance through surface modifications to upcycle these lignocellulose samples. Later part of my Ph.D. tenure, I continued to use my understanding of lignocellulose polymer and catalysis to upcycle synthetic polymers (discarded plastic). Global plastic production creates more than 400 million metric tons of plastic per year. Polyolefins account for \u3e60% of global plastic consumption. Unfortunately, most plastics are discarded in landfills, and they pollute waterways and food chains, negatively affecting human health and the environment. In addition, most plastics are inert and designed to last a lifetime. As a result, discarded plastic ends up in landfills, pollutes waterways, and negatively affects the environment and health. The ability to upcycle plastic will mitigate plastic pollution and support a circular economy, thereby providing a financial incentive for industries to upcycle plastics instead of sending them to landfills. I divided this dissertation into nine chapters to provide a guide in designing catalytic systems for upcycling lignocellulose and discarded plastic. Chapter One gives the background on lignocellulose and plastic and catalysis. I briefly discussed the aim and scope of this dissertation. Chapter Two explores the surface modification techniques of zeolites by organic surfactants and applies them for efficient glycerol conversion to solketal. Chapters Three, Four, Five, and Six discuss how tuning properties and structural modification of MOFs enhanced the acidity and catalytic performance. Chapter Seven combines experimental results and computational study to elucidate how Hf- and Zr-containing MOFs activate biomass-derived carbonyl compounds during transfer hydrogenation reaction. Chapters Eight and Nine detail upcycling approaches for plastic Brønsted acid sites. Chapter Eight shows the development of the novel solid Brønsted acidic catalysts by sulfonating polypropylene for esterification of lignocellulose-derived levulinic acid. This work allowed me to translate my knowledge in lignocellulose conversion to plastic upcycling. Chapter Nine explores the use of plastic-derived Brønsted acidic catalysts for the conversion of different biomass-derived compounds and elucidates the reaction pathways for efficient conversion. Overall, the development of porous solid acid catalysts for lignocellulose and plastic upcycling will provide promising solutions to transition our society toward a circular economy