Ramón Murillo | CSIC (Consejo Superior de Investigaciones Científicas-Spanish National Research Council) (original) (raw)

Papers by Ramón Murillo

Chemical Engineering Journal, 2022

espanolNeumaticos usados fueron valorizados por medio del tratamiento termoquimico de pirolisis u... more espanolNeumaticos usados fueron valorizados por medio del tratamiento termoquimico de pirolisis usando una instalacion a escala piloto de 150 kWth de capacidad nominal. Mas de 500 kg de neumaticos fueron pirolizados en un reactor continuo de tipo tornillo a 550oC. La fraccion solida producida, llamada aqui negro de carbon pirolitico (NCP), fue caracterizado en terminos de analisis proximo y elemental, area BET y porosimetria de Hg. Asimismo, el NCP fue sometido a diferentes tratamientos de acidificacion/basificacion con el fin de obtener un solido carbonoso con propiedades similares a los negros de carbono (NC) comerciales. Se observo que estos tratamientos disminuyen la concentracion de compuestos inorganicos sin detrimento de las propiedades texturales. Asi, mediante el uso de reactivos comerciales y baratos, usuales en la industria quimica, el contenido de cenizas del NCP fue reducido en un 80%, pasando del 14.9 al 3% (en peso) y presento propiedades similares a los NC comerciale...

In this study, co-pyrolysis of wood biomass and waste tyres was carried out in a fixed-bed reacto... more In this study, co-pyrolysis of wood biomass and waste tyres was carried out in a fixed-bed reactor using different proportions in the feedstock. The aim of this study was to test if an improvement exists on the properties of the condensable liquid fraction (less oxygen and water contents and higher heating value) when co-pyrolysis of these two materials is conducted. The possible synergic effects which can lead to an improve in the properties of the liquid fraction were also investigated. Experiments were carried out in a thermobalance, in a fixed-bed reactor and in an auger reactor pilot plant to test the scalability of the process. Moreover, in order to evaluate the possible use of this fraction as a fuel, liquid properties such as heating value, elemental analysis, pH, Total Acid Number (TAN), density, viscosity and water content were also determined. As expected, the results obtained from fixed bed reactor showed an increase in the heating value of the liquid fraction as the proportion of tyre increases. Thus, Bio60 (containing 60% biomass and 40% tyre in weight basis) and Bio80 (containing 80% biomass and 20% tyre in weight basis) showed a higher heating value of 24.18 and 16.54 MJ/kg respectively, comparing to Bio100 (15.24 MJ/kg). On the other hand results obtained from auger reactor showed major effects in the liquid properties. Heating value was higher and other properties (pH, TAN, oxygen content) were also improved.

SSRN Electronic Journal, 2018

Energies, 2020

This paper reports the performance of a spark ignition engine using gasoline blended with an upgr... more This paper reports the performance of a spark ignition engine using gasoline blended with an upgraded bio-oil rich in aromatics and ethanol. This upgraded bio-oil was obtained using a two-step catalytic process. The first step comprised an in-situ catalytic pyrolysis process with CaO in order to obtain a more stable deoxygenated organic fraction, while the second consisted of a catalytic cracking of the vapours released using ZSM-5 zeolites to obtain an aromatics-rich fraction. To facilitate the mixture between bio-oil and gasoline, ethanol was added. The behaviour of a stationary spark ignition engine G12TFH (9600 W) was described in terms of fuel consumption and electrical efficiency. In addition, gaseous emissions and polycyclic aromatic hydrocarbon (PAH) concentrations were determined. Trial tests suggested that it is possible to work with a blend of gasoline, ethanol and bio-oil (90/8/2 vol%, herein named G90E8B2) showing similar fuel consumption than pure gasoline (G100) at th...

Powder Technology, 2019

In this work, the suitability of two raw meals from cement manufacture was evaluated for use as C... more In this work, the suitability of two raw meals from cement manufacture was evaluated for use as CO2 sorbents. The evolution of their CO2 carrying capacity for the initial cycles was determined as a function of calcination conditions, and the Random Pore Model was applied to determine the kinetic parameters of the materials for carbonation. It was observed that the CO2 carrying capacity of the materials was totally dependent on reaction surface, which varies significantly with the calcination conditions (in terms of temperature and partial pressure of CO2). The presence of species other than CaO affected material sorption capacity but had no bearing on reaction kinetics. The calcined raw meal was able to reach maximum conversion in the short reaction times typical of entrained flow reactors, and the dependence of the critical CaCO3 product layer formed on CaO with reaction temperature was estimated.

International Journal of Hydrogen Energy, 2019

The paper presents a detailed analysis of the effect of a high number of oxidationreduction cycle... more The paper presents a detailed analysis of the effect of a high number of oxidationreduction cycles on the steam-methane reforming process over a commercial Ni-based catalyst under conditions of intrinsic kinetics. These cycles take place within the sorption-enhanced steam-methane reforming process for hydrogen production including sorbent regeneration step. Experiments of steam-methane reforming and reverse watergas shift reactions were carried out to obtain a complete characterisation of the system kinetics. After 80 cycles, methane conversion increased, while carbon dioxide conversion remained fairly constant. After 125 cycles, methane showed no significant changes in conversion compared to the increase exhibited by carbon dioxide. The kinetic model of Xu and Froment fitted the experimental results to provide the activation energies of the main reactions, which presented an evolution with redox cycles in line with the trends observed for conversion. The reactions with methane initially reduced their activation energy, facilitating conversion, while the reactions with carbon dioxide initially kept the activation energy constant, subsequently reducing it.

International Journal of Greenhouse Gas Control, 2019

The exothermic reduction of the CuO present in a bed of solids (39 % wt. CuO, 20 % wt. CaCO3 and ... more The exothermic reduction of the CuO present in a bed of solids (39 % wt. CuO, 20 % wt. CaCO3 and 1.5 % wt. Ni, being the rest inert materials) with a fuel gas, generated a pure CO2 stream once steam was condensed (and free of N2). In this way, a Cu/Ca molar ratio of approximately 2 in the bed of solids allowed for CaCO3 calcination efficiencies of around 95 % molar basis at the reducing gases breakthrough. This allowed performing consecutive cycles of the main reaction steps involved in the Ca/Cu H2 production process. The mixture CaO-based sorbent, reforming catalyst and Cu-based material was able to produce a gas stream with a 94.0 % vol. H2 at 10 bar during the CH4 sorption enhanced reforming stage. The Cu-based material was oxidized with a highly diluted air stream at 10 bar, reacting in a well defined reaction front. A pure CO2 gas stream was obtained at reactor exit during the calcination/reduction stage with a fuel gas typical composition of a SMR stage at high temperature. The experimental results indicated that it was possible to cool the bed and to produce a syngas with a H2/CO molar ratio of about 3.5 suitable for its use in the calcination/reduction stage, in a SMR stage at high temperature. It was also possible to perform the calcination/reduction and SMR in one single stage.

Waste Management, 2019

Pyrolysis offers the possibility to convert waste tires into liquid and gaseous fractions as well... more Pyrolysis offers the possibility to convert waste tires into liquid and gaseous fractions as well as a carbon-rich solid (CBp), which contains the original carbon black (CB) and the inorganic compounds used in tire manufacture. Whilst both liquid and gaseous fractions can be valorized without further processing, there is a general consensus that CBp needs to be improved before it can be considered a commercial product, seriously penalizing the pyrolysis process profitability. In this work, the CBp produced in a continuous pyrolysis process was demineralized (chemical leaching) with the aim of recovering the CB trapped into the CBp and thus, producing a standardized CB product for commercial purposes. The demineralization process was conducted by using cheap and common reagents (HCl and NaOH). In this sense, the acid treatment removed most of the mineral matter contained in the CBp and concentration was the main parameter controlling the demineralization process. An ash content of 4.9 wt.% was obtained by using 60 min of soaking time, 60 °C of temperature, 10 mL/g of reagent/CBp ratio and HCl 4M. The demineralized CBp (dCBp) showed a carbon content of 92.9 wt.%, while the FRX analysis indicated that SiO 2 is the major component into the ash. The BET surface area was 76.3 m 2 /g, and textural characterizations (SEM/EDX and TEM) revealed that dCBp is composed by primary particles lower than 100 nm. Although dCBp showed a low structure, the surface chemistry was rich in surface acidic groups. Finally, dCBp was used in Styrene Butadiene Rubber (SBR) compounding, probing its technical feasibility as substitute of commercial CB N550.

Journal of Power Sources, 2017

The operational limits of a commercial nickel-based catalyst under the conditions of a sorption-e... more The operational limits of a commercial nickel-based catalyst under the conditions of a sorption-enhanced steam-methane reforming process coupled to a Ca/Cu chemical loop are investigated for high-purity H 2 production in a cyclic operation. The performance of the reforming catalyst is tested by means of a high number of oxidation-reductionreforming cycles. After 100 oxidation-reduction cycles, this catalyst retains its exceptional reforming activity. The methane conversion values are close to the thermodynamic equilibrium under very demanding conditions: temperature between 500 ºC-700 ºC and mass hourly space velocity of 8.8 kgCH 4 h-1 kgcat-1. After 200 cycles, the sample shows reduction in its reforming activity in line with a lower dispersion of the Ni species. Sintering of Ni nanocrystals is evidenced during the oxidation-reduction multi-cycles. The performance of the catalyst after 200 oxidationreduction cycles mixed with a CaO-based CO 2 sorbent is studied under optimal conditions calculated for the sorption-enhanced reforming process coupled to a Ca/Cu cycle (temperature of 650 ºC, steam/methane ratio of 4, sorbent/catalyst ratio of 4 and space velocity of 0.75 kgCH 4 h-1 kgcat-1). Remarkably, an equilibrium value over 92 vol.% H 2 concentration is achieved, highlighting this catalyst as a promising candidate for the next steps of the process development.

Fuel, 2015

h i g h l i g h t s Potential for using high concentration of TPL fuel in boilers. A slight incre... more h i g h l i g h t s Potential for using high concentration of TPL fuel in boilers. A slight increase of efficiency from 50/50 TPL fuel blended with diesel fuel was observed. 50/50 TPL blend produced similar CO and THC emissions to diesel fuel but higher particle number concentration. Trade off NOx-PM 50/50 TPL fuel was obtained.

Applied Energy, 2014

h i g h l i g h t s For first time, a 5TPL has been tested in a current diesel engine by using NE... more h i g h l i g h t s For first time, a 5TPL has been tested in a current diesel engine by using NEDC. 5TPL proved its ability to be used as fuel in current automotive diesel engines. The properties of TPL to improve both gaseous and PM emissions were identified. Unregulated gaseous emissions has been included as novel result.

International Journal of Greenhouse Gas Control, 2012

This work presents a conceptual design of a novel method to obtain hydrogen and/or electricity fr... more This work presents a conceptual design of a novel method to obtain hydrogen and/or electricity from natural gas and a concentrated stream of CO 2 suitable for permanent geological storage. The method is based on the well known Sorption Enhanced Reforming (SER) principles for H 2 production using a CaO/CaCO 3 chemical loop. A second chemical loop of Cu/CuO is employed to solve the problem of endothermic CaCO 3 calcination in order to regenerate the sorbent and release the concentrated CO 2. The reduction reaction of CuO with natural gas, CO or H 2 is shown to be feasible for providing the necessary heat for calcination. A preliminary design of the process has been carried out based on the principles of fixed bed operation and high temperature PSA, making use of the information offered by the literature to define the operating best conditions for the key gas-solid reaction steps and assuming ideal plug flow behaviour in all the reactors during the chemical reactions and gas-solid heat transfer. This makes it possible to define the precise operating windows for the process, so that the reactors can operate close to neutrally thermal conditions. Special material properties (particularly the Ca/inert and Cu/inert ratios) are required, but these are shown to be within the limits of what have been reported in the literature for other gas/solid reaction 2 processes using the same reactions. The conclusion is that there is a great potential for achieving a high degree of energy efficiency with the proposed process by means of a sequence of reactions under the conditions described in this work.

Fuel Processing Technology, 2012

The thermal behaviour of solid particles of plastic, tyre, coal and biomass as feedstock in pyrol... more The thermal behaviour of solid particles of plastic, tyre, coal and biomass as feedstock in pyrolysis processes was studied. The samples were pyrolyzed in a thermogravimetric analyzer in nitrogen atmosphere (surface flow rate 2.65•10 − 3 m/s) at two different heating rates (5 and 10°C/min) with temperatures ranging from 150 to 950°C. This paper shows the successful application of the distributed energy model to study the effects of dynamic experiments on the solid pyrolysis, in particular, to ABS plastic and tyre rubber for the first time. In addition, the reaction model algorithm used was successfully implemented together with a heat transfer model to predict temperature profiles in the particle and to explore the effects of both solid characteristics and process conditions on the pyrolysis. Within the process conditions studied (particle size, inlet feedstock temperature, reactor temperature and global heat transfer coefficient) the particle size was the most influencing one. From the solid characteristics, the main influence in the particle behaviour was attributed to the characteristic devolatilisation obtained in thermobalance showing the physicochemical properties a weak influence on it.

Fuel Processing Technology, 2014

Co-pyrolysis of forestry wastes and waste tyres is carried out using different facilities: a fixe... more Co-pyrolysis of forestry wastes and waste tyres is carried out using different facilities: a fixed bed reactor and a continuous auger reactor. Remarkably, only one phase is found in the liquid fraction, which is not achieved by mixture of the pure liquids. In addition, positive effects between waste tyre and biomass are evidenced, being more notable even synergetic in the auger reactor. It is found that whilst acidity, density and oxygen content decrease, pH and calorific value increase with respect to the merely biomass pyrolysis liquid, leading to upgraded bio-oil. Upgrading process is linked to the presence of radical interactions between waste tyres and biomass pyrolysis products. In addition, it is observed that the addition of waste tyres to the feedstock blend is significantly decreasing the amount of aldehydes and phenolic compounds, which is beneficial for improving the stability of the new bio-oils.

Energy Conversion and Management, 2014

ABSTRACT This paper shows the maximum limit on syngas composition obtained from volatiles release... more ABSTRACT This paper shows the maximum limit on syngas composition obtained from volatiles released in waste tire pyrolysis when they are submitted to an air–steam partial oxidation process. Thus, from mass and energy balances and a stoichiometric equilibrium model, syngas composition and reaction temperature as well as some process parameters were predicted by varying both the equivalence ratio (ER) and the steam to fuel ratio (SF). In addition, pyrolysis experiments were performed using a continuous auger reactor, and the influence of pyrolysis temperature on composition of both volatiles and char was studied. Consequently, the resulting syngas characteristics were correlated with the pyrolysis temperature. The stoichiometric equilibrium model showed that an ER down to 0.4 is a practical limit to perform the air–steam partial oxidation process. When the process is carried out only with air, volatiles obtained at high pyrolysis temperature lead to lower reaction temperature and higher LHV of syngas in comparison with those found at low pyrolysis temperature. The H2 production is favored between 0.20 and 0.40 of ER and seems to be more influenced by the H/C ratio than by the water gas-shift reaction. On the other hand, the steam addition shows a more notable effect on the H2 production for volatiles obtained at the highest pyrolysis temperature (600 ºC) in agreement with the lower reaction temperature under these experimental conditions. This thermodynamic analysis provides essential data on the optimization of syngas production from volatiles released in waste tire pyrolysis prior to run any test.

Chemical Communications, 2012

BE (eV) CeO 2 Cu 0.993 Ce 0.007 .7 Cu 0.975 Ce 0.025 Cu 0.984 Ce 0.016 Cu 0.964 Ce 0.036 Cu 0.86 ... more BE (eV) CeO 2 Cu 0.993 Ce 0.007 .7 Cu 0.975 Ce 0.025 Cu 0.984 Ce 0.016 Cu 0.964 Ce 0.036 Cu 0.86 Ce 0.14 Cu 0.988 Ce 0.012 O1s XPS spectra of mesoporous CeO 2 and the range of copper containing catalysts.

Bioresource Technology, 2014

h i g h l i g h t s Catalytic pyrolysis of wood biomass is studied in an auger reactor. Calcium-b... more h i g h l i g h t s Catalytic pyrolysis of wood biomass is studied in an auger reactor. Calcium-based catalysts were evaluated for bio-oil upgrading. Oxygen content and acidity of bio-oils were remarkably reduced. An energy self-sustained system was proposed.