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

Production of saccharides from sugar beet pulp by ultrafast hydrolysis in supercritical water

Producción CientíficaSugar beet pulp (SBP) is the major by-product in sugar industry. To make profit out of this undervalued residue, the FASTSUGARS process was proposed as a solution, combining the advantages of supercritical water as hydrolysis medium with very short reaction times in the so-called ultrafast reactors. Operating at 390 °C, 25 MPa and reaction times between 0.11 and 1.15 s it was possible to convert SBP into sugars and to obtain a lignin-like solid fraction. The highest yields of C-6 and C-5 sugars (61 and 71% w/w, respectively) were obtained at 0.11 s with the lowest yield of degradation products. The solid product obtained at 0.14 s was thoroughly analyzed by acid hydrolysis, TGA and FTIR analysis to prove its enhanced thermal properties and aromaticity. The FASTSUGARS process demonstrated being a versatile and promising technology to be integrated in the future biorefineries.Ministerio de Economía, Industria y Competitividad (Project CTQ2013-44143-R and CTQ2016-79777-R

Energy integration of high pressure processes using gas turbines and internal combustion engines

High pressure processes (e.g. sustainable hydrothermal manufacturing of nanomaterials [1], supercritical water oxidation (SCWO) [2] and biomass hydrolysis [3]) require high operational conditions. Water at high pressure and temperature conditions improves kinetic, selectivity and efficiency of these processes but entail high-energy operational expenditure. Use of fluids at high operational conditions makes necessary to supply heat of high quality, as well as power. Because of this, it is necessary to study reasonable solutions for energy recovery and integration in order to achieve the energy self-sufficiency of the process and, if possible, the net power production and with a viable efficiency [4]. In this work, the energy integration of supercritical water oxidation process is being studied. One solution that has been recently proposed is the integration of supercritical processes with energy production in cogeneration or Combined Heat and Power (CHP) cycles. Cogeneration is defined as the simultaneous production of various forms of energy – being the most frequent heat and shaft work, i.e., power – from one power source. The implementation of CHP processes is often joined to the use of gas turbines (GT) [3, 5]. SCWO process produces a high pressure reactor outlet stream, being these mainly composed of water, nitrogen and carbon dioxide and can be thermally integrated if there is a necessity of heat in other parts of the process. At the same time, it is possible to use this effluent to implement a steam injection in the gas turbine, which will improve the efficiency of the global process. This mechanism links the process of SCWO with the cogeneration process (Fig. 1). Steam injection is a technique which can increase the ability of a plant to generate extra power without burning extra fuel and requiring moderate capital investment. In its most basic form, steam injection works by increasing the global mass flow rate through the gas turbine without increasing the mass of air compressed. Please click Additional Files below to see the full abstract

Preparation of β-glucan scaffolds by hydrogel foaming with supercritical CO2

New materials and processing techniques are being constantly developed for the production of scaffolds for tissue engineering applications. Traditionally, foaming of polymers with supercritical fluids is one of the procedures used to create porous matrices. However, this technique cannot be applied to hydrophilic polymers which suffer degradation below their melting temperature. Foaming of hydrogels is an alternative to conventional gas foaming for the processing of hydrophilic polymers by dissolution of supercritical CO2 in the water of the hydrogels [1]. Through a fast depressurization, a highly porous structure is obtained, which results in the foamed matrix of polymer after water removal. In this work, β-glucan aerogels are produced by hydrogel foaming with supercritical CO2. Among polysaccharides, β-glucans have not been widely explored yet for tissue engineering applications. Depending on their origin, they posses different structures and properties. In our study, hydrogels were created from barley and yeast β-glucans. The produced aerogels were characterized in terms of morphology, mechanical properties and degradation rate in physiological fluids.MINECO (CTQ2013-44143-R)MINECO and UVa for Cierva fellowship (JCI-2012-14992)

10th World Congress of Chemical Engineering

Wine lees are water-waste residues generated during maceration and fermentation steps of the vinification process and they constitute a source of high value compounds, such as polyphenols, mainly anthocyanins (AC). The exploitation of these dregs could contribute to the development of new wine-related products and could also lead to a sustainable growth of the wine industry due to the concentration of AC is 10 times higher in wine lees than in grape skins [1]. After the recovery of the polyphenols from wine lees, a wet solid waste remains with poor chemical potential. This residue can be recycled by a hydrolysis step. Supercritical water (SCW) has proved to be a suitable environment-friendly media for biomass hydrolysis due to its unique properties, such as a high diffusivities or low dielectric constant [2]. This hydrolysis produces a liquid product rich in sugars that can be used as feed in a fermentation step afterwards. However, the yield of this last step would be lower with wine lees than with conventional biomasses since its cellulosic fraction only constitutes 18%. The main objective of the hydrolysis of the wine lees residue is to obtain reduced sugars which are essential chemical building blocks in the so-called biorefinery cycle. A continuous pilot plant was used to carry out the hydrolysis of wine lees in SCW. This facility was based on a continuous reactor with instantaneous heating and cooling that allowed precise control of the reaction time and therefore, high recovery of sugars was achieved and avoiding sugar degradation reactions. A wine lees-water suspension (10% w/w) was continuously fed to the reactor using a pump at a flow rate of 1 kg/h and processed under 380-395ºC and 25MPa at different reaction times, between 0.056 and 0.076s. A brown liquid was obtained after the hydrolysis step, rich in hexoses (yield of 50%) such as cellobiose, glucose and fructose. It was also observed that increasing the reaction time and temperature favored the degradation of the recovered sugars into pyruvaldehyde and glycolaldehyde.Marie Curie Industry-Academia Partnerships and Pathways actions (FP7-PEOPLE-2013-IAPP-612208)Junta de Castilla y Leon and FEDER 2014-2020, proyecto VA040U16Ministerio de Economía y Competitividad Spain (CTQ2015-64892-R

Preparation of barley and yeast β-glucan scaffolds by hydrogel foaming: evaluation of dexamethasone release

Porous polymeric materials are studied in tissue engineering, because they can act as support for cell proliferation and as drug delivery vehicles for regeneration of tissues. Hydrogel foaming with supercritical CO2 is a suitable alternative for the creation of these structures, since it avoids the use of organic solvents and high temperature in the processing. In this work, β-glucans were used as raw materials to create hydrogels due to their easily gelation and biological properties. The enhancement of porosity was generated by a fast decompression after keeping the hydrogels in contact with CO2. The effect of the processing conditions and type of β-glucan in the final properties was assessed regarding morphological and mechanical properties. Finally, the ability of these materials to sustainably deliver dexamethasone was evaluated. The scaffolds had good morphology and provided a controlled release, thus being suitable to be used as scaffolds and drug delivery vehicles.Authors acknowledge Ministerio de Economía y Competitividad (MINECO) through project CTQ2013-44143-R and project PIP 063/ 147181 from Fundación General of the University of Valladolid for financial support. M. Salgado thanks to Ministerio de Educación, Ciencia y Deporte (MECD) for her FPU and mobility grants. S. Rodríguez-Rojo acknowledges to MINECO and UVa for her Juan de la Cierva fellowship (JCI-2012-14992). The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement number REGPOT-CT2012-316331-POLARIS and from the project “Novel smart and biomimetic materials for innovative regenerative medicine approaches” RL1 − ABMR − NORTE-01-0124-FEDER-000016) co- financed by North Portugal Regional Operational Programme (ON.2–O Novo Norte), under the National Strategic Reference Framework (NSRF), through the European Regional Development Fund (ERDF).info:eu-repo/semantics/publishedVersio

Scaling up the production of sugars from agricultural biomass by ultrafast hydrolysis in supercritical water

Producción CientíficaThe FASTSUGARS process for sugars’ recovery from agricultural biomass was scaled up from laboratory to pilot plant scale. System performance was evaluated by comparing the results obtained from sugar beet pulp and wheat bran in laboratory and pilot plants. Similar trends were found for each biomass in both plant: as reaction time increased, selectivity to sugars decreased and conversion and degradation rate increased. Then, to bring the FASTSUGARS process closer to industrial applications, the particle size of the biomass was increased in the pilot plant. It was found that the particle size acted as a mass transfer resistance, slowing down the hydrolysis of biomass, providing lower conversion and therefore reducing sugars’ degradation (degradation yield was lower than 15 % in the pilot plant). In that way, higher selectivity to sugars was obtained, reaching values around 90 % for both sugar beet pulp and wheat bran in the pilot plant.Ministerio de Economía, Industria y Competitividad (Project CTQ2013-44143-R, CTQ2016-79777-R)Junta de Castilla y León (programa de apoyo a proyectos de investigación - Ref. VA040U16