Hydrolytic enzyme activity enhanced by Barium supplementation

10 páginas.-- 2 figuras.-- 1 tabla.-- 26 referenciasHydrolysis of polymers is a first and often limiting step during the degradation of plant residues. Plant biomass is generally a major component of waste residues and a major renewable resource to obtain a variety of secondary products including biofuels. Improving the performance of enzymatic hydrolysis of plant material with minimum costs and limiting the use of additional microbial biomass or hydrolytic enzymes directly influences competitiveness of these green biotechnological processes. In this study, we cloned and expressed a cellulase and two esterases recovered from environmental thermophilic soil bacterial communities and characterize their optimum activity conditions including the effect of several metal ions. Results showed that supplementing these hydrolytic reactions with Barium increases the activity of these extracellular hydrolytic enzymes. This observation represents a simple but major improvement to enhance the efficiency and competitiveness of this process within an increasingly important biotechnological sector.Support from the Spanish Ministry of Economy and Competitiveness (CONSOLIDER CSD2009-00006, CGL2014-58762-P, CTM2014-55095), the Andalusian Government (BIO288 and RNM2529), both cofinanced by FEDER funds, intramural project OEP2011 (201570I020), the mobility programme 003-ABEL-CM-2013 (NILS Science and Sustainability programme, EEA grants), the mobility and coordination European project ALGAENET (Marie Curie Actions IRSES- 295165, FP7-PEOPLE-2011) and COST Action ES1302.Peer reviewe

Production of fuel-cell grade H2 by sorption enhanced steam reforming of acetic acid as a model compound of biomass-derived bio-oil

Fuel-cell grade H2 has been produced by the sorption enhanced steam reforming (SESR) of acetic acid, a model compound of the bio-oil obtained from the fast pyrolysis of biomass. A Pd/Ni–Co catalyst derived from a hydrotalcite-like material (HT) with dolomite as CO2 sorbent was used in the process. A fixed-bed reactor with three temperature zones was employed to favor the catalytic steam reforming reaction in the high-temperature segment, the SESR reaction in the intermediate-temperature part, as well as the water-gas shift (WGS) and CO2 capture reactions in the low-temperature segment. Different conditions of pressure, temperature, steam/C molar ratio and weight hourly space velocity (WHSV) in the feed were evaluated. Higher steam/C molar ratios and lower WHSV values facilitated the production of H2 and reduced the concentrations of CH4, CO and CO2 in the produced gas. A fuel-cell grade H2 stream with a H2 purity of 99.8 vol.% and H2 yield of 86.7% was produced at atmospheric pressure, with a steam/C ratio of 3, a WHSV of 0.893 h−1 and a temperature of 575 °C in the intermediate part of the reactor (675 °C in the upper segment and 425 °C in the bottom part). At high pressure conditions (15 atm) a maximum H2 concentration of 98.31 vol.% with a H2 yield of 79.81% was obtained at 725 °C in the intermediate segment of the reactor (825 °C in the upper segment and 575 °C in the bottom part). Under these conditions an effluent stream with a CO concentration below 10 ppm (detection limit) was obtained at both low and high pressure, making it suitable for direct use in fuel cell applications.This work was carried out with financial support from the Spanish MINECO (Project ENE2014-53515-P), co-financed by the European Regional Development Fund (ERDF) and the Principado de Asturias (PCTI 2013-2017, GRUPIN14-079)Peer reviewe

Kinetic models comparison for non-isothermal steam gasification of coal–biomass blend chars

The non-isothermal thermogravimetric method (TGA) was applied to a bituminous coal (PT), two types of biomass, chestnut residues (CH) and olive stones (OS), and coal–biomass blends in order to investigate their thermal reactivity under steam. Fuel chars were obtained by pyrolysis in a fixed-bed reactor at a final temperature of 1373 K for 30 min. The gasification tests were carried out by thermogravimetric analysis from room temperature to 1373 K at heating rates of 5, 10 and 15 K min−1. After blending, no significant interactions were detected between PT and CH during co-gasification, whereas deviations from the additive behaviour were observed in the PT–OS blend. However, for the two coal–biomass blends, the gasification behaviour resembled that of the individual coal, as this component constituted the larger proportion of the blend. The temperature-programmed reaction (TPR) technique was employed at three different heating rates to analyze noncatalytic gas–solid reactions. Three nth-order representative gas–solid models, the volumetric model (VM), the grain model (GM) and the random pore model (RPM) were applied in order to describe the reactive behaviour of the chars during steam gasification. From these models, the kinetic parameters were determined. The best model for describing the reactivity of the PT, PT–CH and PT–OS samples was the RPM model. VM was the model that best fitted the CH sample, whereas none of the models were suitable for the OS sample.This work was carried out with financial support from the Spanish MICINN (Project PS- 120000-2006-3, ECOCOMBOS), and co-financed by the European Regional Development Fund, ERDF.Peer reviewe

Environmental Assessment of Olive Mill Solid Waste Valorization via Anaerobic Digestion Versus Olive Pomace Oil Extraction

Anaerobic digestion is a promising alternative to valorize agrifood wastes, which is gaining interest under an environmental sustainability overview. The present research aimed to compare anaerobic digestion with olive pomace oil extraction, by using life cycle assessment, as alternatives for the valorization of the olive mill solid waste generated in the centrifugation process with a two-outlet decanter from oil mills. In the case of olive pomace oil extraction, two cases were defined depending on the type of fuel used for drying the wet pomace before the extraction: natural gas or a fraction of the generated extracted pomace. The anaerobic digestion alternative consisted of the production of biogas from the olive mill solid waste, heat and electricity cogeneration by the combustion of the generated biogas, and composting of the anaerobic digestate. The life cycle assessment showed that anaerobic digestion was the best alternative, with a global environmental impact reduction of 88.1 and 85.9% respect to crude olive pomace oil extraction using natural gas and extracted pomace, respectively, as fuel.Ministerio de Economía y Competitividad CTM2014-55095-

H2 production by sorption enhanced steam reforming of biomass-derived bio-oil in a fluidized bed reactor: An assessment of the effect of operation variables using response surface methodology

High-purity H2 was produced by the sorption enhanced steam reforming (SESR) of acetic acid, a model compound of bio-oil obtained from the fast pyrolysis of biomass, in a fluidized bed reactor. A Pd/Ni–Co hydrotalcite-like material (HT) and dolomite were used as reforming catalyst and CO2 sorbent, respectively. The hydrogen yield and purity were optimized by response surface methodology (RSM) and the combined effect of the reaction temperature (T), steam-to-carbon molar ratio in the feed (steam/C) and weight hourly space velocity (WHSV) upon the sorption enhanced steam reforming process was analyzed. T was studied between 475 and 675 °C, steam/C ratio between 1.5 and a 4.5 mol/mol and WHSV between 0.893 and 2.679 h−1. H2 yield, H2 selectivity and H2 purity, as well as the CH4, CO and CO2 concentrations in the effluent gas, were assessed. The operating temperature proved to be the variable that had the greatest effect on the response variables studied, followed by the WHSV and the steam/C ratio. The results show that the H2 yield, H2 selectivity and H2 purity increased, while the CH4, CO and CO2 concentrations decreased, concurrently with the temperature up to around 575–625 °C. Higher values of the steam/C ratio and lower WHSV values favored the H2 yield, H2 selectivity and H2 purity, and reduced the CH4 concentration. It was found that the SESR of acetic acid at atmospheric pressure and 560 °C, with a steam/C ratio of 4.50 and a WHSV of 0.893 h–1 gave the highest H2 yield of 92.00%, with H2 purity of 99.53% and H2 selectivity of 99.92%, while the CH4, CO and CO2 concentrations remained low throughout (0.04%, 0.06% and 0.4%, respectively). The results also suggested that a slow CO2 capture rate led to a poor level of hydrogen production when the SESR process was carried out at low temperatures, although this can be improved by increasing the sorbent/catalyst ratio in the fluidized bed.The financial support from the Research Council of Norway (RCN) is gratefully acknowledged. The authors thank Franefoss Miljøkalk A/S (Norway) for supplying Arctic dolomite. M.V. Gil acknowledges funding from the CSIC JAE-Doc program, Spain, co-financed by the European Social Fund, and support from the Research Council of Norway through the Yggdrasil program.Peer reviewe

Hydrogen production from the co-utilisation of coal and biomass

In this work, co-gasification and co-pyrolysis of binary blends of a bituminous coal (PT) and two types of biomass (olive stones, OS; chestnut, CH) were conducted at atmospheric pressure in a fixed bed reactor. Pyrolysis was performed under nitrogen, and gasification under steam/oxygen atmosphere. In the fixed bed reactor, the particles of the different fuels are in close contact, providing an optimum means for evaluating possible synergetic effects. Pyrolysis tests showed the lack of interaction between the components of the blend.Plan Regional de Investigación del Principado de AsturiasPeer reviewe

Surface modification of activated carbons for CO2 capture

8 pages, 6 figures, 4 tables.-- Printed version published on Sep 15, 2008.The reduction of anthropogenic CO2 emissions to address the consequences of climate change is a matter of concern for all developed countries. In the short term, one of the most viable options for reducing carbon emissions is to capture and store CO2 at large stationary sources. Adsorption with solid sorbents is one of the most promising options. In this work, two series of materials were prepared from two commercial activated carbons, C and R, by heat treatment with gaseous ammonia at temperatures in the 200–800°C range. The aim was to improve the selectivity and capacity of the sorbents to capture CO2, by introducing basic nitrogen-functionalities into the carbons. The sorbents were characterised in terms of texture and chemical composition. Their surface chemistry was studied through temperature-programmed desorption tests and X-ray photoelectron spectroscopy. The capture performance of the carbons was evaluated by using a thermogravimetric analyser to record mass uptakes by the samples when exposed to a CO2 atmosphere.This work was carried out with financial support from the Spanish MEC (Project CTM2005-03075/TECNO). CP and MGP acknowledge funding from the CSIC I3P Program co-financed by the European Social Fund. JF acknowledges funding from the Plan Regional de Investigación del Principado de Asturias.Peer reviewe

Kinetic models comparison for steam gasification of different nature fuel chars

The reactivity in steam of five different types of solid fuels (two coals, two types of biomass and a petcoke) has been studied. The fuel chars were obtained by pyrolysis in a fixed-bed reactor at a temperature of 1373 K for 30 min. The gasification tests were carried out by thermogravimetric analysis (TG) at different temperatures and steam concentrations. The reactivity study was conducted in the kinetically controlled regime and three representative gas-solid models, volumetric model (VM), grain model (GM) and random pore model (RPM), were applied in order to describe the reactive behaviour of the chars during steam gasification. The kinetic parameters of these models were derived and the ability of the models to predict conversion and char reactivity during gasification was assessed. The best model for describing the behaviour of the samples was the RPM. The effect of the partial pressure of steam in gasification was studied, and the reaction order with respect to steam was determined. The reactivity of the chars was compared by means of a reactivity index. Biomass exhibited a higher reactivity than coals and petcoke. However, significant differences in reactivity were observed between the two types of biomass used, which could be due to catalytic effects.Peer reviewe

A comparison of two methods for producing CO2 capture adsorbents

Proceedings of the 9th International Conference on Greenhouse Gas Control Technologies (GHGT-9), 16–20 November 2008, Washington DC, USAHigh capacity CO2 adsorbents were prepared from a biomass residue, almond shells. Two different methods for producing these adsorbents were compared: activation with carbon dioxide and heat treatment with ammonia gas (amination and ammoxidation). The prepared carbons were physically and chemically characterised. Amination and ammoxidation introduced nitrogen into the carbon structure, up to a 5 wt.%, turning the carbon surface more basic, without the need of carrying out a preoxidation treatment. On the other hand, activation with carbon dioxide led to a significantly higher development of the texture of the samples. The CO2 adsorption capacity of the adsorbents was meassured in a thermogravimetric analyser. Amination and activation showed to be suitable methods for the production of CO2 adsorbents. The prepared adsorbents presented a high CO2 capture capacity, comparable to that of commercial activated carbons, and showed fully reversible adsorption.This work was carried out with financial support from the Spanish MEC (Project CTM2005-03075/TECNO). MGP and JF acknowledge the support from the CSIC I3P Program co-financed by the European Social Fund and the PCTI-Asturias, respectively.Peer reviewe

Developing almond shell-derived activated carbons as CO2 adsorbents

Two series of carbon dioxide adsorbents were prepared from almond shells, by carbonisation followed either by activation with CO2 or by heat treatment in the presence of ammonia gas (amination). Both procedures gave carbons with high CO2 adsorption capacities in pure CO2 as well as in a binary mixture of 15% CO2 in N2. Activation with carbon dioxide significantly developed porosity in the samples, mostly in the micropore domain, while amination at 800 °C moderately developed narrow microporosity in the char and incorporated stable nitrogen functionalities, which enhanced CO2 selectivity. Amination showed two additional advantages over conventional activation with CO2: a greater carbon yield and a shorter soaking time.This work was carried out with financial support from the Spanish MICINN (Project ENE2008-05087). M.G.P., C.F.M.and J.F. acknowledge funding from the CSIC I3P and, JAE programs, co-financed by the European Social Fund, and PCTI Asturias, respectively.Peer reviewe