Supercritical water processes: future prospects

Producción CientíficaThis contribution examines the challenges faced by supercritical water processes for industrial development. As an alternative, the intensification of the supercritical water processes is presented in order to reduce the size of the equipment needed and to facilitate the scaling up of the process. The perspective of developing micro combustors using hydrothermal flames as the internal heat source could open up an alternative for the in-situ energy generation in biorefineries, for example. The fundamental studies about supercritical water hydrolysis using ultrafast reactors has enabled extremely high selectivity in the biomass fractionation processes, and in the production of C2 and C3 building blocks from key components. The high-energy consumption of this process is another issue that limit its commercialization. In the examples proposed, the energy, work recovery and energy integration allows the reduction of the total energy consumption and, in some processes, the availability of extra energy as heat and work.2018-12-30Ministerio de Economía, Industria y Competitividad - FEDER (Proyect CTQ2013-44143-R)Ministerio de Economía, Industria y Competitividad - FEDER (Proyect CTQ2016-79777-R)Junta de Castilla y León (programa de apoyo a proyectos de investigación – Ref. VA040U16

Ultrafast heating by high efficient biomass direct mixing with supercritical water

Producción CientíficaThis work analyzes the influence of the mixer configuration on the mixing efficiency in the process of biomass ultrafast hydrolysis by supercritical water. The results of the CFD simulations of a horizontal tee, a vertical tee and a mixing cross, selected as the optimum mixing configurations, together with the experimental results obtained in our hydrolysis plant, are the base to determine the configuration which provides the best mixing performance. Although slightly higher conversions are obtained in those experiments performed with a horizontal tee, the small differences between the results demand a theoretical analysis. Therefore, according to the CFD simulation results, since the mixing cross provides the best flow distribution and temperature homogenization at the outlet of the mixers and because of the great similarity between the residence time distribution curves of the mixers, the mixing cross is selected as the optimum geometry to perform the mixing.Ministerio de Economía, Industria y Competitividad - FEDER (Projects CTQ2013-44143-R and CTQ2016-79777-R

CFD-Aspen Plus interconnection method. Improving thermodynamic modelling in computational fluid dynamic simulations

Producción CientíficaThermodynamic modelling in CFD is basically limited to the models available in the simulators. The method presented in this paper connects CFD simulators with Aspen Plus which instantaneously calculates and returns the value of any physical property required. Therefore, all the thermodynamic models and compounds available in Aspen Plus can be implemented in CFD simulations. The connection, created via Matlab and Excel-VBA, has been validated solving two identical CFD simulations first selecting a thermodynamic model available in the simulator and then connecting the simulator with Aspen Plus and selecting the same model. The maximum absolute average deviation between the density and viscosity values obtained in both simulations, for the two case studies analyzed, is lower than 0.7% which demonstrates the proper interconnection. The accuracy of the results obtained modeling multicomponent mixtures and supercritical fluids proves the applicability of the method to any scenarios2018-12-31Ministerio de Economía, Industria y Competitividad - FEDER (Proyects CTQ2013-44143-R and CTQ2016-79777-R

Heterogeneous catalysis for the extraction of arabinoxylans from wheat bran

Introduction The conversion of biomass within biorefineries into chemicals and energy is seen as a real possibility for the substitution of fossil resources. Raw materials of high lignocellulosic content are an interesting option. Besides wood and non-food crops, agricultural residues like straw and corn stover as well as other by-products of various origins are of high interest as feedstocks. Wheat bran represents such a by-product, which accrues in enormous quantities during the production of white wheat flour. It is estimated that 150 million tons are produced per year worldwide [1]. Currently wheat bran is mainly used as a low value ingredient in animal feed. Arabinoxylans are the most abundant structural polysaccharides in wheat bran, and they can be suitable compounds for the production of sugar alcohols. In general terms, the conversion of these hemicellulosic components from biomass into sugar alcohols is a two‑step reaction: 1) extraction and hydrolysis of arabinoxylans and 2) hydrogenation of these hemicelluloses into polyols (Figure 1). Please click Additional Files below to see the full abstract

Barley and yeast β-glucans as new emulsifier agents for the development of aqueous natural antifungal formulations

Producción CientíficaBarley and yeast β-glucans were selected, together with lecithin, to encapsulate resveratrol by emulsification-evaporation method to develop new and safer antifungal formulations. Different emulsification techniques were used: high-shear, high pressure and high pressure and temperature emulsification. Morphology, crystallinity, encapsulation efficiency and in vitro antifungal activity against Botrytis cinerea of the different formulations were evaluated. No significant differences between each emulsification procedure in particle size (below 90 nm) and in encapsulation efficiency (70–100%) were observed; only barley β-glucan emulsions showed lower efficiency due to the formation of a gel that retained most of the active compound. A great influence of the emulsification method and the encapsulating material on the crystallinity of the particles was observed. The highest antifungal activity (up to 53% growth inhibition) was obtained by the formulations with yeast β-glucans, indicating an enhanced absorption of encapsulated resveratrol through the cell wall of the fungus at the presence of (1–3, 1–6)-β-glucans.Junta de Castilla y León (programa de apoyo a proyectos de investigación – Ref. VA040U16

Pretreatment Processes of Biomass for Biorefineries: Current Status and Prospects

Producción CientíficaThis article seeks to be a handy document for the academy and the industry to get quickly up to speed on the current status and prospects of biomass pretreatment for biorefineries. It is divided into two biomass sources: vegetal and animal. Vegetal biomass is the material produced by plants on land or in water (algae), consuming sunlight, CO2, water, and soil nutrients. This includes residues or main products from, for example, intensive grass crops, forestry, and industrial and agricultural activities. Animal biomass is the residual biomass generated from the production of food from animals (e.g., manure and whey). This review does not mean to include every technology in the area, but it does evaluate physical pretreatments, microwave-assisted extraction, and water treatments for vegetal biomass. A general review is given for animal biomass based in physical, chemical, and biological pretreatments

Selective production of sugars and glycolaldehyde from agricultural biomass using supercritical water as reaction medium

Introduction Biomass is a renewable and worldwide-distributed carbon resource which has the potential to produce energy, chemicals and fuels for the future sustainable industries [1]. Biobased industries, based on the use of renewable materials and energy, are still in development to success to promote a decentralized production that can be an alternative to the centralized petrochemical production plants. Taking into account the wide range of possibilities for biomass refineries, plant biomass is considered a promising source to replace fossil fuels as feedstock for the sustainable production of fuels, materials and fine chemicals as sugars and added-value compounds as glycolaldehyde [2, 3] that can be obtained via thermochemical processes such as hydrolysis [4]. Glucose would be obtained from cellulose hydrolysis, hemicellulose would release its component sugars and lignin would produce phenolic compounds [5]. Also, glycolaldehyde is the main retro-aldol condensation product from glucose and it is a promising raw material to produce two-carbon building block molecules. For example, ethylene glycol is a widely applied polymer in the plastic and polyester industries. Apart from petroleum, it can be obtained through the hydrogenation of glycolaldehyde by a transition metal catalyst [6, 7]. Therefore, selective hydrolysis of cellulose into glucose and glycolaldehyde is a key process for the effective use of biomass [8]. Please click Additional Files below to see the full abstract

Selective fractionation and depolymerization of lignocellulosic biomass using subcritical and supercritical water to produce hemicellulose, cellulose and lignin

Cellulose and hemicelluloses contained in woody biomass can be hydrolysed to monomeric sugars, which can be fermented to ethanol, or can be converted into higher value products [1]. Hemicelluloses, when isolated from biomass, have unique properties. They can be used to produce films for packaging applications in substitution to synthetic plastics, as polysaccharides works as barriers against oxygen permeation; another important application is the production of aerogels to insulate products. Xylose from hemicellulose, for instance, can be converted to furfural, which is a precursor used in different fields, such as oil refining, plastics, pharmaceutical, and agrochemical industries. L-Xylose can be also hydrogenated or enzymatically transformed to xylitol, which is a sweetening agent and is also used for preventing tooth decay [2]. The idea of transforming biomass to energy, materials, and chemicals, defines the concept of biorefinery, particularly interesting topic nowadays, considering the issues related to fossil combustibles and derivatives [3-5]. Please click Additional Files below to see the full abstract

Aromatics from Lignin through Ultrafast Reactions in Water

Producción CientíficaNowadays, the valorization of lignin, the major natural source of aromatics in earth, is being a challenge for the scientific community. In this study, kraft lignin is effectively converted into aromatic monomers by ultrafast depolymerization in hot and pressurized water. At reaction times below 500 ms, it is possible to avoid char formation originated from undesirable condensation reactions by controlling accurately the reaction time. Under alkaline medium, the reaction reaches an optimum point at 386ºC and 300 ms with a light oil yield of 60% with a concentration in key compounds such as guaiacol, creosol, vanillin and acetovanillone of around 20 %w/w. The char formation in this point was surprisingly low (4 %w/w). Analysis and quantification of the products allows to identify the evolution of the different reaction steps and propose plausible mechanism for the depolymerization and repolymerization stages. Furthermore, it is proven that the proposed technology is equally effective to treat directly industrial black liquors with a yield higher than 50% to light oil, containing as main monomers guaiacol (2.7%), syringol (3.0%) and syringaldehyde (7.3%).2020-02-152020-02-15Ministerio de Economía, Industria y Competitividad (Project CTQ2016-79777-R)Ministerio de Educación, Cultura y Deporte (Proyect FPU15/00409

Efficient production of soy-bean lecithin – pluronic L64® encapsulated quercetin particles in nanometric scale using sfee and pgss drying processes

Quercetin is an antioxidant compound, and it is a highly promising material against a wide variety of diseases, including cancer. A major limitation for the clinical application of quercetin is its low bioavailability, due to its low solubility in water. One way to increase the bioavailability of quercetin is to precipitate it in sub-micrometric scale, encapsulated by a surfactant material, using Supercritical Fluid Extraction of Emulsions (SFEE) and/or Particles from Gas Saturated Solutions (PGSS) drying technology. In this work the efficiency of SFEE- and PGSS drying processes, in producing of quercetin loaded soy-bean lecithin – Pluronic L64® particles in sub-micrometric scale is studied. Robustness study of a batch SFEE process is done, moreover a scaled-up, semi-continuous SFEE process is developed, in order to increase the efficiency of the process, and to decrease the energy consumption. SFEE produced aqueous suspensions are further treated by PGSS drying and by lyophilization, in order to produce solid encapsulated quercetin particles, which are available for long term storage. Encapsulation efficiency and antioxidant activity of with PGSS drying and with lyophilization prepared dried products are measured and compared with each other. Please click Additional Files below to see the full abstract