Kinetic study of steam gasification of lignocelullosic biomass char obtained from pyrolysis

Hydrogen plays a key role in the energy transition towards a more sustainable model based on renewable energies, as it has the capacity to solve two major problems: i) reducing dependence on fossil fuels and ii) reducing greenhouse gas emissions. Currently, approximately 85 % of the world hydrogen production comes from fossil fuel technologies without CO2 capture. In this sense, a promising alternative for the substitution of these fuels may be biomass gasification with water vapor, due to its high availability and low cost, where the gas produced can be used directly as fuel or raw material to produce high value-added chemicals. The aim of this work is to perform the steam gasification of the solid residue obtained from biomass pyrolysis to optimize the hydrogen production. Three types of lignocellulosic biomass (almond shell, olive stone and hemp) were evaluated as raw material for steam gasification. Biomass samples were obtained by conventional pyrolysis in a fixed-bed reactor at a temperature of 800 °C, a heating rate of 10 °C/min for 1 h, obtaining a char that was later gasified in a downdraft fixed-bed reactor, using steam as the reacting agent (30 % vol.), in a temperature range between 800 °C and 900 °C. A kinetic model that takes into account the gas product distribution and the weight loss during the gasification reaction was developed using representative gas-solid models such as the volumetric model (VM), the grain model (GM) and the random pore model (RPM).Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

A Kinetic Model Considering Catalyst Deactivation for Methanol-to-Dimethyl Ether on a Biomass-Derived Zr/P-Carbon Catalyst

A Zr-loaded P-containing biomass-derived activated carbon (ACPZr) has been tested for methanol dehydration between 450 and 550 °C. At earlier stages, methanol conversion was complete, and the reaction product was mainly dimethyl ether (DME), although coke, methane, hydrogen and CO were also observed to a lesser extent. The catalyst was slowly deactivated with time-on-stream (TOS), but maintained a high selectivity to DME (>80%), with a higher yield to this product than 20% for more than 24 h at 500 °C. A kinetic model was developed for methanol dehydration reaction, which included the effect of the inhibition of water and the deactivation of the catalyst by coke. The study of stoichiometric rates pointed out that coke could be produced through a formaldehyde intermediate, which might, alternatively, decompose into CO and H2. On the other hand, the presence of 10% water in the feed did not affect the rate of coke formation, but produced a reduction of 50% in the DME yield, suggesting a reversible competitive adsorption of water. A Langmuir–Hinshelwood reaction mechanism was used to develop a kinetic model that considered the deactivation of the catalyst. Activation energy values of 65 and 51 kJ/mol were obtained for DME and methane production in the temperature range from 450 °C to 550 °C. On the other hand, coke formation as a function of time on stream (TOS) was also modelled and used as the input for the deactivation function of the model, which allowed for the successful prediction of the DME, CH4 and CO yields in the whole evaluated TOS interval.This research was supported by the Spanish Ministry of Science, Innovation and Universities and Junta de Andalucia through RTI2018-097555-B-I00 and UMA18-FEDERJA-110 projects, respectively. J.T.-L. also acknowledges the assistance of the Spanish Ministry of Economy, Industry and Competitiveness for the award of a predoctoral contract to become a Ph.D. (BES-2016-079237). Partial funding for open access charge: Universidad de Málag

Catalytic fast pyrolysis of olive stone for bio-oil deoxygenation.

In this work, conventional, fast and catalytic fast pyrolysis of olive stone residues were studied with a commercial catalyst with mild acidity, γ-Al2O3, an activated carbon from olive stones (AC) prepared by chemical activation with phosphoric acid and the same activated carbon loaded with Zr as active phase (ACZr). The results showed that fast pyrolysis has a higher content of liquid fraction (64 %wt) than that obtained in conventional pyrolysis (52 %wt), due to cracking reactions occur at a lesser extent. In the catalytic fast pyrolysis, the acid character of the catalysts favors the cracking and deoxygenation reactions that reduce the production of the liquid fraction, mainly producing an increase in the phenols species and a decrease in the acid species. On the other hand,a clear increment in the content of CO can be observed (conventional and catalytic fast pyrolysis, respectively), due to decarbonylation reactions, which are favored in the presence of catalysts.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

MgO-containing porous carbon spheres derived from magnesium lignosulfonate as sustainable basic catalysts

The presence of alkalis in lignosulfonate allows an easy preparation of sustainable MgO-containing carbon catalysts with surface basicity by carbonization of magnesium lignosulfonate and/or further partial gasification of the produced char with CO2. Carbon spheres with different chemical and physical properties were obtained from lignosulfonate treated at temperatures ranging from 500 to 900 ºC. Carbonization at 900 °C generates hollow porous carbon spheres (pore volume of 0.20 cm3/g and apparent surface area of 465 m2/g) with magnesium content of 12%. A kinetic study of CO2 gasification of the carbon spheres obtained at 900 °C at temperatures in the range of 700 – 800 °C revealed that the gasification rate can be accurately described by the random pore model up to conversion values of 0.5. Based on this study, in order to develop additional porosity on the carbon spheres obtained at 900 °C, a partial gasification with CO2 at 750 °C for 30 min was carried out, reaching surface areas higher than 700 m2/g and 15.3% of Mg loading, with an overall preparation yield of 30%. All the obtained carbon materials were tested as catalyst for 2-propanol decomposition, showing a high selectivity to acetone, evidencing the basic character of these carbon catalysts. The highest activity and selectivity were shown by the CO2-activated carbon spheres (conversion and acetone selectivity higher than 90% at 420 °C), indicating that magnesium lignosulfonate is an attractive raw material for the preparation of sustainable carbon catalysts for biorefinery applicationsThe authors wish to thank MICINN (RTI2018-097555-B-100) and Junta de Andalucía (UMA18-FEDERJA-110 and P18-RT-4592) for financial support. M.G.R. acknowledges the assistance of MICINN through an FPU Grant (FPU 18/01402). // Funding for open access charge: Universidad de Málaga / CBU

Hidroformilacion de 1-octeno utilizando catalizadores de rodio soportados sobre materiales de carbono porosos con grupos superficiales de fósforo.

La reacción de hidroformilación es una de las reacciones homogéneas catalizadas más importante a nivel industrial, ya que produce 10 millones de toneladas de aldehídos al año [1]. La reacción utiliza olefinas insaturadas y gas de síntesis (una mezcla de CO y H2) como reactivos, para producir aldehídos funcionales, que tienen gran aplicabilidad en la industria farmacéutica y cosmética. Se utilizan como catalizadores tanto complejos de cobalto como de rodio en fase homogénea a nivel industrial, los cuales muestran una elevada actividad y selectividad [2]. Además, se ha demostrado que la presencia de ligandos orgánicos de fosfina y fósforo inorgánico son eficaces en los sistemas catalíticos para la hidroformilación en fase homogenea y heterogénea, respectivamente [2]. Sin embargo, los catalizadores homogéneos de hidroformilación se enfrentan a graves problemas de separación, como la lixiviación de los metales preciosos utilizados y el vertido de residuos que contienen fósforo [3]. Por lo tanto, el uso de catalizadores heterogéneos para la hidroformilación podría evitar estas dificultades de separación, haciendo que la reacción de hidroformilación en fase heterogénea sea más económica y respetuosa con el medio ambiente.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

CO2 hydrogenation to methanol on In2O3/ZrO2 fibrillar catalysts.

Hydrogenation of CO2 to produce methanol is regarded as one of the most promising processes for achieving full deployment of carbon capture, utilization and storage technologies, which are needed to decrease the emission of greenhouse gases. In this communication, In2O3-ZrO2 nanostructured fibrillar catalysts, prepared by electrospinning technique, has been proposed for CO2 hydrogenation. The effect of the calcination temperature as well as the indium loading on the CO2 conversion have been evaluated.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Carbon-based biomass-derived catalysts for deoxygenation of fast pyrolysis bio-oil

Producing energy and chemicals from biomass is an interesting alternative for replacing conventional fossil sources with a renewable feedstock while enabling zero net greenhouse gases emissions. Particularly, fast pyrolysis of biomass waste enables the production of bio-oil, which can be upgraded to biofuels or value-added chemicals. The sustainability of this process can be enhanced by preparing carbon-based catalysts from the same biomass waste used as raw material for the biooil production, decreasing the inputs of the process and allowing recovery and recycle of the active phase by combustion of the carbon substrate. In this work, catalytic fast pyrolysis of olive stone residues was studied using mesoporous carbon-based acid catalysts prepared by activation with H3PO4 of olive stones.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Procedimiento para la fabricación a temperatura ambiente de micro y nanofibras de lignina y otros compuestos resinosos

Procedimiento para la fabricación a temperatura ambiente de micro y nanofibras de lignina y otros compuestos resinosos. La presente invención describe un procedimiento que permite el hilado a temperatura ambiente de ligninas procedentes de procesos de extracción tipo Alcell y Organosolv. Se describe también el procedimiento y dispositivo para fabricar a temperatura ambiente, fibras de lignina, de diámetro micro y nanométrico, mediante electrospinning y co-electrospinning. Las fibras obtenidas pueden ser simples (electrospinning) y huecas o coaxiales (coelectrospinning). Las fibras de lignina se transforman en nanofibras de carbono después de un tratamiento térmico apropiadoEspañ

Porosidad de carbones preparados mediante activación de distintas ligninas técnicas con H3PO4.

Contribución en forma de póster a un congreso científicoUniversidad de Málaga. Campus de Excelencia Internacional Andalucía Tech