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Papers by Suni (Asunción) Aranda

Cu-CeO 2 catalysts with low Cu-loadings present high catalytic activity and also clean combustion... more Cu-CeO 2 catalysts with low Cu-loadings present high catalytic activity and also clean combustion, as only CO 2 was detected as a reaction product, for the total oxidation of naphthalene (Np). The improved behaviour has been related to the presence of one specific Ospecies, which corresponds to defective oxides or to surface oxygen ions with low coordination.

Applied Catalysis B-environmental, Mar 1, 2013

Highlights  Cu-Mn oxides more active than single oxides whatever the preparation method  Very h... more Highlights  Cu-Mn oxides more active than single oxides whatever the preparation method  Very high surface specific area of Cu-Mn oxides using the redox method  High dispersion of copper in close interaction with manganese in redox sample  Superior catalytic activity of "redox" Cu-Mn oxides in toluene oxidation  Adding Pt or Pd as dopant allows to get a better resistance to deactivation

International Journal of Hydrogen Energy, May 1, 2019

H 2 production Envoy of mankind CO 2 capture Multifunctional materials High shear agglomeration a... more H 2 production Envoy of mankind CO 2 capture Multifunctional materials High shear agglomeration a b s t r a c t Combined CO 2 sorbents and O 2 carrier materials have been prepared, characterized and tested over 40 TGA cycles under relevant operating conditions for the CaeCu Looping process. Materials were prepared using two different loadings of calcium and copper with a CuO/CaO [wt/wt] of 2, and mayenite (Ca 12 Al 14 O 33) as support, to produce powders with composition 20/40/40 wt% and 25/50/25 wt% CaO/CuO/Ca 12 Al 14 O 33. Three different copper precursors, CuO, Cu(OH) 2 and Cu(NO 3) 2 3H2Owereused.MaterialswerecharacterizedbypowderX−raydiffraction(PXD),scanningelectronmicroscopy(SEM),BrunauereEmmetteTellersurfaceanalysis(BET).Mixedcalcium−copperphases,CaCu2O3andCa2CuO3,werefoundinthecalcinedmaterialswhenCu(OH)2andCu(NO3)23H 2 O were used. Materials were characterized by powder X-ray diffraction (PXD), scanning electron microscopy (SEM), BrunauereEmmett eTeller surface analysis (BET). Mixed calcium-copper phases, CaCu 2 O 3 and Ca 2 CuO 3 , were found in the calcined materials when Cu(OH) 2 and Cu(NO 3) 2 3H2Owereused.MaterialswerecharacterizedbypowderX−raydiffraction(PXD),scanningelectronmicroscopy(SEM),BrunauereEmmetteTellersurfaceanalysis(BET).Mixedcalcium−copperphases,CaCu2O3andCa2CuO3,werefoundinthecalcinedmaterialswhenCu(OH)2andCu(NO3)23H 2 O were used as precursors. The mixed phases were not observed after TGA testing and did not hinder the activity of the materials. CO 2 carrying capacity of the synthesized powders was found to be more stable than O 2 carrying capacity. The latter decreased during 40 TGA cycles for all materials with 50 wt% CuO, while it exhibited an enhanced cyclic stability for copper loading of 40 wt %. This behaviour has been assigned to severe copper migration and sintering in the 50 wt % CuO containing material.

SSRN Electronic Journal, 2019

SSRN Electronic Journal, 2018

International Journal of Greenhouse Gas Control, 2020

Combined calcium-copper materials based on calcium zirconate (CaO/CuO/CaZrO3) for Calcium-Copper ... more Combined calcium-copper materials based on calcium zirconate (CaO/CuO/CaZrO3) for Calcium-Copper Chemical Looping (Ca-Cu Looping) have been synthesized using a scalable wet chemical method and characterized by powder X-ray diffraction (PXRD) with Rietveld refinement, temperature-programmed reduction (H2-TPR) and oxidation (O2-TPO), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and 45-50 cycles in a thermogravimetric analyser (TGA) representing realistic Ca-Cu Looping conditions. A material at 50 wt% active CuO loading and a CuO/CaO weight ratio of 2 deactivated due to copper migration and agglomeration, while materials with 40 wt% active CuO loading were stable throughout TGA cycles at CuO/CaO ratios of 2 and 10. 40 wt% CuO loaded combined CaO/CuO/CaZrO3 materials are promising candidates for Ca-Cu Looping with a demonstrated tuneable and stable CuO/CaO ratio (≥ 2 [wt/wt]) that could lead to process intensification. The maximum CuO loading for the investigated materials is likely found in the range of [40, 50) wt%, subject to the constraints of Ca-Cu Looping relevant CuO/CaO ratios (≥ 2 [wt/wt]) and the performed TGA testing.

International Journal of Greenhouse Gas Control, 2019

Chemical Looping Combustion (CLC) is a promising CO 2 capture option since it inherently separate... more Chemical Looping Combustion (CLC) is a promising CO 2 capture option since it inherently separates CO 2 from other flue components, theoretically with low energy penalty. Here, a Life Cycle Assessment model was developed of a theoretical hybrid CLC (HCLC) power plant facility utilising experimental data for CuO based oxygen carrier (OC) production and oxygen capacity. Power plant models with and without post-combustion CO 2 capture, recognised as the most mature capture technology, acted as environmental performance targets. Results show that when OC is produced at lab-scale without optimisation, almost all (> 99.9%) lifecycle impacts per kWh electricity from an HCLC plant derive from the specific OC material used, giving a total of˜700 kg CO 2 eq/kWh. This is related to high electrical input required for OC processing, as well as high OC losses during production and from plant waste. Only when processing parameters are optimised and OC recycling from plant waste is implemented-reducing fresh OC needs-is the environmental impact lower than the conventional technologies studied (e.g. 0.2 kg CO 2 eq/kWh vs.˜0.3-1 kg CO 2 eq/kWh, respectively). Further research should thus focus on identifying OCs that do not require energy intensive processing and can endure repeated cycles, allowing for recycling. elevated. This results in a typical loss in power plant efficiency of between 9% and 15% (

Energy Procedia, 2017

New cost effective and high performance bi-functional composite materials consisting of CaO and C... more New cost effective and high performance bi-functional composite materials consisting of CaO and CuO supported on Ca 12 Al 14 O 33 have been developed for the calcium-copper (Ca-Cu) looping process. A hydrothermal method has been used to synthesize the materials from low cost precursors. Prepared composites are characterised by X-ray diffraction, scanning electron microscopy together with energy-dispersive spectroscopy mapping, and by crushing strength tests. Long term chemical performances of the materials are tested in a thermo-gravimetric analyser. The composite containing 53 wt% CuO, 22 wt% CaO and 25 wt% Ca 12 Al 14 O 33 shows stable CO 2 capture (~15 g-CO 2 /100g composite) and O 2 carrying capacity (~7 gO 2 /100g composite) in long term Ca-Cu multi-cycle, and shows satisfactory mechanical strength compared to reference materials used in the Ca-Cu process.

Fuel Processing Technology, 2017

An experimental investigation on chemical activity and stability of innovative CuO-based oxygen c... more An experimental investigation on chemical activity and stability of innovative CuO-based oxygen carriers (OC) supported on coal fly ash, towards Chemical Looping Combustion (CLC) and Chemical Looping Oxygen Uncoupling (CLOU) is presented. The materials were prepared by granulation of fine powders of CuO and fly ash (FA), with 40-60-80 wt% CuO loading (Cu40FA, Cu60FA and Cu80FA), using a high shear granulator. CLC and CLOU activities were investigated in a thermogravimetric analyzer (TGA) in the presence of a reactive fuel or an inert atmosphere, respectively. A rather stable CLOU capacity (R o-CLOU) in the range of 4-8 g O 2 /100 g OC was found over 42 redox cycles, in agreement with the stoichiometry of the prepared samples. CLC oxygen carrying capacity (R o-CLC) with gaseous fuel, on the other hand, has evidenced a quick decline for the material with higher copper loading (80 wt% CuO). Furthermore, both oxygen carriers with 40-60 wt% CuO were tested for combustion of coal in a macro-TGA rig using CO 2 as carrier gas and different OC:fuel ratios. First, a blank test in the absence of the OC was carried out to characterize the fast devolatilization and slow gasification reactions taking place due to the exposure of the fuel to high temperature and CO 2-rich atmosphere. The comparison of the weight loss curve evolution with and without oxygen carrier, and the measured residual carbon after test, enabled to extract the CLOU effect for each combination of material/solid fuel.

Energy Procedia, 2011

In this paper, a new synthesis method to obtain mixed CaO/Ca 12 Al 14 O 33 solids for high temper... more In this paper, a new synthesis method to obtain mixed CaO/Ca 12 Al 14 O 33 solids for high temperature CO 2 capture is presented. The modification of a pure phase Ca 3 Al 2 O 6 solid through a thermal treatment under controlled conditions leads to a high CO 2 absorption capacity material, with very promising long term stability during absorption/desorption cycles. The influence of the calcination temperature during the synthesis of the Ca 3 Al 2 O 6 powders, and the temperature and atmosphere applied during the thermal treatment was studied. Therefore, optimum conditions for high stabilization rate and high final CO 2 absorption capacity of the sorbent could be determined. Comparison with a natural sorbent (dolomite) over 150 carbonation/calcination cycles is also included, showing a substantial improvement of the synthetic solid CO 2-uptake at long term use, compared to that of natural sorbents.

Energy Procedia, 2014

Synthetic CO 2 sorbent materials of CaO/Ca 12 Al 14 O 33 of different compositions were prepared ... more Synthetic CO 2 sorbent materials of CaO/Ca 12 Al 14 O 33 of different compositions were prepared using a simple hydrothermal method and low-cost hydroxides starting precursors. The products were characterized by X-ray diffraction, scanning electron microscopy, BET analysis and crushing tests. Sorption kinetics and chemical stability during carbonation/ calcination multicycling in pre-and post-combustion conditions were investigated by thermo gravimetric analysis. Long-term stability of the hydrothermally prepared sorbents is attributed to the formation of a stable frame of mayenite (Ca 12 Al 14 O 33) which reduces the sintering of the active CaO phase. Among all sorbents, the one with composition 27/73 wt % CaO/Ca 12 Al 14 O 33 is considered a promising CO 2 sorbent with stable capture capacity (21g-CO 2 /100g sorbent) in severe calcination conditions and high mechanical strength.

Journal of Analytical and Applied Pyrolysis, 2007

This is the first time that the thermochemical recycling of rubber from old tyres by pyrolysis an... more This is the first time that the thermochemical recycling of rubber from old tyres by pyrolysis and the emissions from combustion of the gas obtained in the pyrolytic process have been studied. In tyre pyrolysis, compounds in three phases are obtained: solid, liquid and gas. The solid compounds, approximately 40% weight of the initial rubber, are mostly constituted of carbon

Industrial & Engineering Chemistry Research, 2006

In recent years, pyrolysis has proven to be an effective thermochemical process for the recycling... more In recent years, pyrolysis has proven to be an effective thermochemical process for the recycling of waste tires. After pyrolysis, three fractions are obtained: carbonaceous solids, liquid hydrocarbons, and the socalled noncondensable gases. In this paper, the starting point is the pyrolysis reactor outlet that provides a gas stream with a temperature of 600°C and a pressure of 2 bar, comprising both the condensable and the noncondensable fractions. Although the pyrolysis process is technically and environmentally feasible, its economic viability will clearly depend on the possible salability or use of the three main derived products. Focusing on liquid hydrocarbons, usually the most abundant and valuable fraction, they are a mixture of aliphatic, aromatic, and polar compounds with a boiling point ranging between approximately 70 and 400°C. Therefore, it is difficult to find possible applications different from their direct combustion without a purification or separation step for their commercialization. In this paper, a complete process for the separation of valuable gas and liquid fractions is described by using commercial process simulation software. After a condensation step, the liquid stream is derived to a conventional crude distillation column where it is fractionated and the gas stream is conducted to an absorption column where H 2 S and CO 2 are removed to obtain a clean gas. In addition to the complete flow sheet description, an energy balance is provided and the liquid fractions are compared to those obtained in crude distillation.

Industrial & Engineering Chemistry Research, 2007

Temperature swing adsorption (TSA) of polycyclic aromatic hydrocarbons (PAH) has been studied. Na... more Temperature swing adsorption (TSA) of polycyclic aromatic hydrocarbons (PAH) has been studied. Naphthalene (Np)stwo aromatic ringssand phenanthrene (Phe)sthree aromatic ringsshave been selected as model compounds for the PAH hot gas cleaning process. Five activated carbons (AC) were produced from pyrolytic carbon black obtained in waste tire recycling. Carbon dioxide was used as a gasifying agent during five different reaction times, bringing about adsorbents with different textural properties. The influence of these properties has been assessed in the loss of adsorption capacity with the number of cycles of both model compounds. The adsorption process was performed at 150°C in helium atmosphere with a gas hourly space velocity of 25 000 h-1. Under these conditions, the breakthrough curve of each model compound was obtained with an inlet concentration of ca. 250 ppbv. AC regeneration was carried out in air by thermal desorption under fixed conditions (300°C, 25 000 h-1 , and 100 min) during five cycles. It was observed that the AC performance depends mainly on the model compound nature, total micropore volume, and micropore size distribution. In this work, it is shown that although the Np adsorption capacity is fairly constant with the number of cycles, Phe removal drastically decreases after the first regeneration cycle, but it is maintained in the successive adsorption/desorption cycles. This fact is likely due to a pore-blocking effect by Phe molecules retained in the molecular size pores.

Fuel Processing Technology, 2006

Scrap tyres are a growing environmental problem because they are not biodegradable and their comp... more Scrap tyres are a growing environmental problem because they are not biodegradable and their components cannot readily be recovered. In this investigation, the thermochemical recycling of rubber from old tyres by pyrolysis and the value of the products obtained have been studied. First, thermobalance experiments were carried out, studying the influence of the following variables: heating rate, flow rate, particle size and temperature. These thermobalance results were extended by performing experiments in a fixed bed reactor, studying the effect of the main process variables on yields of derived products: oils, gases and solid residue. The oils have been characterized using a combination of analytical techniques (TLC–FID, GC–MS and simulated distillation). No relationship between functional group composition of the oils determined by TLC–FID and process variables was found. The carbonaceous material obtained was characterized by N2 and CO2 adsorption. The possible uses of this char have been analyzed taking into account and calculating the emissions that would be produced if the char were burnt.

Fuel Processing Technology, 2006

Chemical Engineering Journal, 2007

Kinetic parameters for the steam activation of tyre pyrolytic carbon black have been determined b... more Kinetic parameters for the steam activation of tyre pyrolytic carbon black have been determined by thermogravimetric analysis (TGA). Pyrolytic carbon black is a mainly macro and mesoporous material whose surface area can be improved via gasification to obtain microporous activated carbons. The pyrolytic carbon black sample was produced in an experimental-scale assembly where shredded tyre was pyrolysed under controlled conditions in a fixed bed reactor. Then, the activation of the resulting solid was studied by TGA using steam as activating agent. Kinetic regime was ensured fixing experimental conditions and therefore, avoiding internal and external mass transfer and heat transmission phenomena. Temperature (850-950 • C) and activating gas concentration (10-40 vol.%) were the influencing variables under study. This is the first time that the random pore model (RPM) has been used to fit experimental data of the activation of pyrolytic carbon black with steam. Excellent fittings have been obtained because of the special applicability of this model to predict the behaviour of solid-fluid reactive systems, in which the solid phase shows a porous structure. Reaction evolution has successfully been modelled, including the maximum reaction rate obtained in experimental results. Additionally, intrinsic kinetic parameters of the activation reaction-reaction order, activation energy and pre-exponential factor-were calculated.

Chemical Engineering Journal, 2012

In this work, technical solutions for two remarkable environmental problems are undertaken: waste... more In this work, technical solutions for two remarkable environmental problems are undertaken: waste tyres (WT) valorisation by producing steam activated carbons (AC), and gas-phase polycyclic aromatic hydrocarbons (PAH) abatement, by adsorption on those solids. Firstly, the AC production process in a fixed bed reactor was modelled. For this purpose, the random pore model (RPM) was successfully applied, to model the solid evolution throughout the steam activation of WT. The model showed the capability of predicting with a high degree of accuracy both the conversion and the solid properties evolution, depending on the operational variables (i.e. temperature, steam concentration and time). The experimental results obtained in a lab-scale activation system allowed the model validation. Afterwards, the performance of the AC on the cyclic adsorption of naphthalene on gas phase was evaluated and related to the physical properties of the AC. These experiments confirmed the optima AC characteristics for naphthalene abatement. Since the physical properties of the AC can be accurately predicted with the proposed model, the activation process was optimized to enhance the final PAH adsorption capacity of the sorbents. Therefore, in this work, a useful tool for simulation and optimization of the AC production process for the specific application of PAH abatement has been developed.

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.

Catalysis Letters, 2009

Ceria catalysts have been prepared by a nanocasting procedure using SBA-15, MCM-48 and KIT-6 sili... more Ceria catalysts have been prepared by a nanocasting procedure using SBA-15, MCM-48 and KIT-6 silica-based templates, and investigated for the total oxidation of naphthalene. In all cases cubic fluorite CeO 2 was prepared, and the structure of the template was replicated when SBA-15 and MCM-48 were used. The KIT-6 template was not replicated by the nanocasting synthesis, but in all cases mesoporous CeO2 was obtained with high surface areas (91-190 m 2 g-1). All of the catalysts demonstrated high activity for naphthalene oxidation to CO 2 , and the most active was the catalyst prepared from the KIT-6 template. The high activity was attributed to the small crystallite size of the CeO 2 , combined with high surface area and the highly accessible catalyst surface.

Cu-CeO 2 catalysts with low Cu-loadings present high catalytic activity and also clean combustion... more Cu-CeO 2 catalysts with low Cu-loadings present high catalytic activity and also clean combustion, as only CO 2 was detected as a reaction product, for the total oxidation of naphthalene (Np). The improved behaviour has been related to the presence of one specific Ospecies, which corresponds to defective oxides or to surface oxygen ions with low coordination.

Applied Catalysis B-environmental, Mar 1, 2013

Highlights  Cu-Mn oxides more active than single oxides whatever the preparation method  Very h... more Highlights  Cu-Mn oxides more active than single oxides whatever the preparation method  Very high surface specific area of Cu-Mn oxides using the redox method  High dispersion of copper in close interaction with manganese in redox sample  Superior catalytic activity of "redox" Cu-Mn oxides in toluene oxidation  Adding Pt or Pd as dopant allows to get a better resistance to deactivation

International Journal of Hydrogen Energy, May 1, 2019

H 2 production Envoy of mankind CO 2 capture Multifunctional materials High shear agglomeration a... more H 2 production Envoy of mankind CO 2 capture Multifunctional materials High shear agglomeration a b s t r a c t Combined CO 2 sorbents and O 2 carrier materials have been prepared, characterized and tested over 40 TGA cycles under relevant operating conditions for the CaeCu Looping process. Materials were prepared using two different loadings of calcium and copper with a CuO/CaO [wt/wt] of 2, and mayenite (Ca 12 Al 14 O 33) as support, to produce powders with composition 20/40/40 wt% and 25/50/25 wt% CaO/CuO/Ca 12 Al 14 O 33. Three different copper precursors, CuO, Cu(OH) 2 and Cu(NO 3) 2 3H2Owereused.MaterialswerecharacterizedbypowderX−raydiffraction(PXD),scanningelectronmicroscopy(SEM),BrunauereEmmetteTellersurfaceanalysis(BET).Mixedcalcium−copperphases,CaCu2O3andCa2CuO3,werefoundinthecalcinedmaterialswhenCu(OH)2andCu(NO3)23H 2 O were used. Materials were characterized by powder X-ray diffraction (PXD), scanning electron microscopy (SEM), BrunauereEmmett eTeller surface analysis (BET). Mixed calcium-copper phases, CaCu 2 O 3 and Ca 2 CuO 3 , were found in the calcined materials when Cu(OH) 2 and Cu(NO 3) 2 3H2Owereused.MaterialswerecharacterizedbypowderX−raydiffraction(PXD),scanningelectronmicroscopy(SEM),BrunauereEmmetteTellersurfaceanalysis(BET).Mixedcalcium−copperphases,CaCu2O3andCa2CuO3,werefoundinthecalcinedmaterialswhenCu(OH)2andCu(NO3)23H 2 O were used as precursors. The mixed phases were not observed after TGA testing and did not hinder the activity of the materials. CO 2 carrying capacity of the synthesized powders was found to be more stable than O 2 carrying capacity. The latter decreased during 40 TGA cycles for all materials with 50 wt% CuO, while it exhibited an enhanced cyclic stability for copper loading of 40 wt %. This behaviour has been assigned to severe copper migration and sintering in the 50 wt % CuO containing material.

SSRN Electronic Journal, 2019

SSRN Electronic Journal, 2018

International Journal of Greenhouse Gas Control, 2020

Combined calcium-copper materials based on calcium zirconate (CaO/CuO/CaZrO3) for Calcium-Copper ... more Combined calcium-copper materials based on calcium zirconate (CaO/CuO/CaZrO3) for Calcium-Copper Chemical Looping (Ca-Cu Looping) have been synthesized using a scalable wet chemical method and characterized by powder X-ray diffraction (PXRD) with Rietveld refinement, temperature-programmed reduction (H2-TPR) and oxidation (O2-TPO), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and 45-50 cycles in a thermogravimetric analyser (TGA) representing realistic Ca-Cu Looping conditions. A material at 50 wt% active CuO loading and a CuO/CaO weight ratio of 2 deactivated due to copper migration and agglomeration, while materials with 40 wt% active CuO loading were stable throughout TGA cycles at CuO/CaO ratios of 2 and 10. 40 wt% CuO loaded combined CaO/CuO/CaZrO3 materials are promising candidates for Ca-Cu Looping with a demonstrated tuneable and stable CuO/CaO ratio (≥ 2 [wt/wt]) that could lead to process intensification. The maximum CuO loading for the investigated materials is likely found in the range of [40, 50) wt%, subject to the constraints of Ca-Cu Looping relevant CuO/CaO ratios (≥ 2 [wt/wt]) and the performed TGA testing.

International Journal of Greenhouse Gas Control, 2019

Chemical Looping Combustion (CLC) is a promising CO 2 capture option since it inherently separate... more Chemical Looping Combustion (CLC) is a promising CO 2 capture option since it inherently separates CO 2 from other flue components, theoretically with low energy penalty. Here, a Life Cycle Assessment model was developed of a theoretical hybrid CLC (HCLC) power plant facility utilising experimental data for CuO based oxygen carrier (OC) production and oxygen capacity. Power plant models with and without post-combustion CO 2 capture, recognised as the most mature capture technology, acted as environmental performance targets. Results show that when OC is produced at lab-scale without optimisation, almost all (> 99.9%) lifecycle impacts per kWh electricity from an HCLC plant derive from the specific OC material used, giving a total of˜700 kg CO 2 eq/kWh. This is related to high electrical input required for OC processing, as well as high OC losses during production and from plant waste. Only when processing parameters are optimised and OC recycling from plant waste is implemented-reducing fresh OC needs-is the environmental impact lower than the conventional technologies studied (e.g. 0.2 kg CO 2 eq/kWh vs.˜0.3-1 kg CO 2 eq/kWh, respectively). Further research should thus focus on identifying OCs that do not require energy intensive processing and can endure repeated cycles, allowing for recycling. elevated. This results in a typical loss in power plant efficiency of between 9% and 15% (

Energy Procedia, 2017

New cost effective and high performance bi-functional composite materials consisting of CaO and C... more New cost effective and high performance bi-functional composite materials consisting of CaO and CuO supported on Ca 12 Al 14 O 33 have been developed for the calcium-copper (Ca-Cu) looping process. A hydrothermal method has been used to synthesize the materials from low cost precursors. Prepared composites are characterised by X-ray diffraction, scanning electron microscopy together with energy-dispersive spectroscopy mapping, and by crushing strength tests. Long term chemical performances of the materials are tested in a thermo-gravimetric analyser. The composite containing 53 wt% CuO, 22 wt% CaO and 25 wt% Ca 12 Al 14 O 33 shows stable CO 2 capture (~15 g-CO 2 /100g composite) and O 2 carrying capacity (~7 gO 2 /100g composite) in long term Ca-Cu multi-cycle, and shows satisfactory mechanical strength compared to reference materials used in the Ca-Cu process.

Fuel Processing Technology, 2017

An experimental investigation on chemical activity and stability of innovative CuO-based oxygen c... more An experimental investigation on chemical activity and stability of innovative CuO-based oxygen carriers (OC) supported on coal fly ash, towards Chemical Looping Combustion (CLC) and Chemical Looping Oxygen Uncoupling (CLOU) is presented. The materials were prepared by granulation of fine powders of CuO and fly ash (FA), with 40-60-80 wt% CuO loading (Cu40FA, Cu60FA and Cu80FA), using a high shear granulator. CLC and CLOU activities were investigated in a thermogravimetric analyzer (TGA) in the presence of a reactive fuel or an inert atmosphere, respectively. A rather stable CLOU capacity (R o-CLOU) in the range of 4-8 g O 2 /100 g OC was found over 42 redox cycles, in agreement with the stoichiometry of the prepared samples. CLC oxygen carrying capacity (R o-CLC) with gaseous fuel, on the other hand, has evidenced a quick decline for the material with higher copper loading (80 wt% CuO). Furthermore, both oxygen carriers with 40-60 wt% CuO were tested for combustion of coal in a macro-TGA rig using CO 2 as carrier gas and different OC:fuel ratios. First, a blank test in the absence of the OC was carried out to characterize the fast devolatilization and slow gasification reactions taking place due to the exposure of the fuel to high temperature and CO 2-rich atmosphere. The comparison of the weight loss curve evolution with and without oxygen carrier, and the measured residual carbon after test, enabled to extract the CLOU effect for each combination of material/solid fuel.

Energy Procedia, 2011

In this paper, a new synthesis method to obtain mixed CaO/Ca 12 Al 14 O 33 solids for high temper... more In this paper, a new synthesis method to obtain mixed CaO/Ca 12 Al 14 O 33 solids for high temperature CO 2 capture is presented. The modification of a pure phase Ca 3 Al 2 O 6 solid through a thermal treatment under controlled conditions leads to a high CO 2 absorption capacity material, with very promising long term stability during absorption/desorption cycles. The influence of the calcination temperature during the synthesis of the Ca 3 Al 2 O 6 powders, and the temperature and atmosphere applied during the thermal treatment was studied. Therefore, optimum conditions for high stabilization rate and high final CO 2 absorption capacity of the sorbent could be determined. Comparison with a natural sorbent (dolomite) over 150 carbonation/calcination cycles is also included, showing a substantial improvement of the synthetic solid CO 2-uptake at long term use, compared to that of natural sorbents.

Energy Procedia, 2014

Synthetic CO 2 sorbent materials of CaO/Ca 12 Al 14 O 33 of different compositions were prepared ... more Synthetic CO 2 sorbent materials of CaO/Ca 12 Al 14 O 33 of different compositions were prepared using a simple hydrothermal method and low-cost hydroxides starting precursors. The products were characterized by X-ray diffraction, scanning electron microscopy, BET analysis and crushing tests. Sorption kinetics and chemical stability during carbonation/ calcination multicycling in pre-and post-combustion conditions were investigated by thermo gravimetric analysis. Long-term stability of the hydrothermally prepared sorbents is attributed to the formation of a stable frame of mayenite (Ca 12 Al 14 O 33) which reduces the sintering of the active CaO phase. Among all sorbents, the one with composition 27/73 wt % CaO/Ca 12 Al 14 O 33 is considered a promising CO 2 sorbent with stable capture capacity (21g-CO 2 /100g sorbent) in severe calcination conditions and high mechanical strength.

Journal of Analytical and Applied Pyrolysis, 2007

This is the first time that the thermochemical recycling of rubber from old tyres by pyrolysis an... more This is the first time that the thermochemical recycling of rubber from old tyres by pyrolysis and the emissions from combustion of the gas obtained in the pyrolytic process have been studied. In tyre pyrolysis, compounds in three phases are obtained: solid, liquid and gas. The solid compounds, approximately 40% weight of the initial rubber, are mostly constituted of carbon

Industrial & Engineering Chemistry Research, 2006

In recent years, pyrolysis has proven to be an effective thermochemical process for the recycling... more In recent years, pyrolysis has proven to be an effective thermochemical process for the recycling of waste tires. After pyrolysis, three fractions are obtained: carbonaceous solids, liquid hydrocarbons, and the socalled noncondensable gases. In this paper, the starting point is the pyrolysis reactor outlet that provides a gas stream with a temperature of 600°C and a pressure of 2 bar, comprising both the condensable and the noncondensable fractions. Although the pyrolysis process is technically and environmentally feasible, its economic viability will clearly depend on the possible salability or use of the three main derived products. Focusing on liquid hydrocarbons, usually the most abundant and valuable fraction, they are a mixture of aliphatic, aromatic, and polar compounds with a boiling point ranging between approximately 70 and 400°C. Therefore, it is difficult to find possible applications different from their direct combustion without a purification or separation step for their commercialization. In this paper, a complete process for the separation of valuable gas and liquid fractions is described by using commercial process simulation software. After a condensation step, the liquid stream is derived to a conventional crude distillation column where it is fractionated and the gas stream is conducted to an absorption column where H 2 S and CO 2 are removed to obtain a clean gas. In addition to the complete flow sheet description, an energy balance is provided and the liquid fractions are compared to those obtained in crude distillation.

Industrial & Engineering Chemistry Research, 2007

Temperature swing adsorption (TSA) of polycyclic aromatic hydrocarbons (PAH) has been studied. Na... more Temperature swing adsorption (TSA) of polycyclic aromatic hydrocarbons (PAH) has been studied. Naphthalene (Np)stwo aromatic ringssand phenanthrene (Phe)sthree aromatic ringsshave been selected as model compounds for the PAH hot gas cleaning process. Five activated carbons (AC) were produced from pyrolytic carbon black obtained in waste tire recycling. Carbon dioxide was used as a gasifying agent during five different reaction times, bringing about adsorbents with different textural properties. The influence of these properties has been assessed in the loss of adsorption capacity with the number of cycles of both model compounds. The adsorption process was performed at 150°C in helium atmosphere with a gas hourly space velocity of 25 000 h-1. Under these conditions, the breakthrough curve of each model compound was obtained with an inlet concentration of ca. 250 ppbv. AC regeneration was carried out in air by thermal desorption under fixed conditions (300°C, 25 000 h-1 , and 100 min) during five cycles. It was observed that the AC performance depends mainly on the model compound nature, total micropore volume, and micropore size distribution. In this work, it is shown that although the Np adsorption capacity is fairly constant with the number of cycles, Phe removal drastically decreases after the first regeneration cycle, but it is maintained in the successive adsorption/desorption cycles. This fact is likely due to a pore-blocking effect by Phe molecules retained in the molecular size pores.

Fuel Processing Technology, 2006

Scrap tyres are a growing environmental problem because they are not biodegradable and their comp... more Scrap tyres are a growing environmental problem because they are not biodegradable and their components cannot readily be recovered. In this investigation, the thermochemical recycling of rubber from old tyres by pyrolysis and the value of the products obtained have been studied. First, thermobalance experiments were carried out, studying the influence of the following variables: heating rate, flow rate, particle size and temperature. These thermobalance results were extended by performing experiments in a fixed bed reactor, studying the effect of the main process variables on yields of derived products: oils, gases and solid residue. The oils have been characterized using a combination of analytical techniques (TLC–FID, GC–MS and simulated distillation). No relationship between functional group composition of the oils determined by TLC–FID and process variables was found. The carbonaceous material obtained was characterized by N2 and CO2 adsorption. The possible uses of this char have been analyzed taking into account and calculating the emissions that would be produced if the char were burnt.

Fuel Processing Technology, 2006

Chemical Engineering Journal, 2007

Kinetic parameters for the steam activation of tyre pyrolytic carbon black have been determined b... more Kinetic parameters for the steam activation of tyre pyrolytic carbon black have been determined by thermogravimetric analysis (TGA). Pyrolytic carbon black is a mainly macro and mesoporous material whose surface area can be improved via gasification to obtain microporous activated carbons. The pyrolytic carbon black sample was produced in an experimental-scale assembly where shredded tyre was pyrolysed under controlled conditions in a fixed bed reactor. Then, the activation of the resulting solid was studied by TGA using steam as activating agent. Kinetic regime was ensured fixing experimental conditions and therefore, avoiding internal and external mass transfer and heat transmission phenomena. Temperature (850-950 • C) and activating gas concentration (10-40 vol.%) were the influencing variables under study. This is the first time that the random pore model (RPM) has been used to fit experimental data of the activation of pyrolytic carbon black with steam. Excellent fittings have been obtained because of the special applicability of this model to predict the behaviour of solid-fluid reactive systems, in which the solid phase shows a porous structure. Reaction evolution has successfully been modelled, including the maximum reaction rate obtained in experimental results. Additionally, intrinsic kinetic parameters of the activation reaction-reaction order, activation energy and pre-exponential factor-were calculated.

Chemical Engineering Journal, 2012

In this work, technical solutions for two remarkable environmental problems are undertaken: waste... more In this work, technical solutions for two remarkable environmental problems are undertaken: waste tyres (WT) valorisation by producing steam activated carbons (AC), and gas-phase polycyclic aromatic hydrocarbons (PAH) abatement, by adsorption on those solids. Firstly, the AC production process in a fixed bed reactor was modelled. For this purpose, the random pore model (RPM) was successfully applied, to model the solid evolution throughout the steam activation of WT. The model showed the capability of predicting with a high degree of accuracy both the conversion and the solid properties evolution, depending on the operational variables (i.e. temperature, steam concentration and time). The experimental results obtained in a lab-scale activation system allowed the model validation. Afterwards, the performance of the AC on the cyclic adsorption of naphthalene on gas phase was evaluated and related to the physical properties of the AC. These experiments confirmed the optima AC characteristics for naphthalene abatement. Since the physical properties of the AC can be accurately predicted with the proposed model, the activation process was optimized to enhance the final PAH adsorption capacity of the sorbents. Therefore, in this work, a useful tool for simulation and optimization of the AC production process for the specific application of PAH abatement has been developed.

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.

Catalysis Letters, 2009

Ceria catalysts have been prepared by a nanocasting procedure using SBA-15, MCM-48 and KIT-6 sili... more Ceria catalysts have been prepared by a nanocasting procedure using SBA-15, MCM-48 and KIT-6 silica-based templates, and investigated for the total oxidation of naphthalene. In all cases cubic fluorite CeO 2 was prepared, and the structure of the template was replicated when SBA-15 and MCM-48 were used. The KIT-6 template was not replicated by the nanocasting synthesis, but in all cases mesoporous CeO2 was obtained with high surface areas (91-190 m 2 g-1). All of the catalysts demonstrated high activity for naphthalene oxidation to CO 2 , and the most active was the catalyst prepared from the KIT-6 template. The high activity was attributed to the small crystallite size of the CeO 2 , combined with high surface area and the highly accessible catalyst surface.