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343 p., Esta tesis doctoral se enmarca dentro de una extensa línea de investigación, que abarca el desarrollo de procesos térmicos y catalíticos para la valorización de biomasa y residuos plásticos para la obtención de combustibles líquidos, materias primas (olefinas y aromáticos) e hidrógeno. Los conocimientos adquiridos en la gasificación de biomasa y plásticos en reactores spouted bed convencionales han alentado la realización de esta tesis. Por tanto, el objetivo principal de esta tesis es avanzar en el proceso de gasificación de biomasa con vapor para la producción de gas de síntesis y la eliminación de alquitrán.El reactor de spouted bed convencional se caracteriza por tener cortos tiempo de residencia, lo cual es una excelente característica para minimizar las reacciones secundarias no deseadas en los procesos de pirolisis. Sin embargo, esto es un serio inconveniente para la gasificación, ya que los cortos tiempos de residencia dificultan las reacciones de craqueo del alquitrán. En esta tesis se propone un novedoso sistema de reacción basado en la tecnología de spouted bed, que plantea la incorporación de determinados dispositivos, como el confinador de la fuente y el tubo central, llamado spouted bed de fuente confinada. Esta combinación pretende resolver las limitaciones de los spouted bed convencionales en los procesos de gasificación. Además, se han propuesto varias estrategias primarias de eliminación de alquitrán para mejorar la eficiencia de la gasificación de biomasa con vapor. Se ha desarrollado un nuevo régimen de contacto gas-sólido basado en el reactor de spouted bed y se ha optimizado el proceso general desde el punto de vista del diseño del reactor, condiciones de operación (temperatura) y catalizadores primarios (arena, olivina, dolomita, catalizador gastado de FCC, alumina y catalizador Fe/olivina). Los resultados muestran que usando dolomita como catalizador primario se consigue disminuir el tar hasta 5.0 g Nm-3 a 850 ºC y un ratio S/B de 2.

The pyrolysis and in line steam reforming of different types of representative agroforestry biomass wastes (pine wood, citrus wastes and rice husk) was performed in a two-reactor system made up of a conical spouted bed and a fluidized bed. The pyrolysis step was carried out at 500 °C, and the steam reforming at 600 °C with a space time of 20 gcatalyst min gvolatiles−1 and a steam/biomass ratio (S/B) of 4. A study was conducted on the effect that the pyrolysis volatiles composition obtained with several biomasses has on the reforming conversion, product yields and H2 production. The different composition of the pyrolysis volatiles obtained with the three biomasses studied led to differences in the initial activity and, especially, in the catalyst deactivation rate. Initial conversions higher than 99% were obtained in all cases and the H2 production obtained varied in the 6.7–11.2 wt% range, depending on the feedstock used. The stability of the catalysts decreased depending on the feedstock as follows: pine wood ≫ citrus waste > rice husk. A detailed assessment of the mechanisms of catalyst deactivation revealed that coke deposition is the main cause of catalyst decay in all the runs. However, the volatile composition derived from the pyrolysis of citrus waste and rice husk involved the formation of an encapsulating coke, which severely blocked the catalyst pores, leading to catalyst deactivation during the first minutes of reaction.

The combination of delocalized units for the fast pyrolysis of biomass to produce bio-oil followed by centralized units for the gasification of bio-oil appears as an economically attractive option for the full-scale production of syngas because transportation of bio-oil is less costly than that of biomass. First goal of this study lies in the validation of a bio-oil feeding device made up of a line-thermostated at 60–80 °C and a non-atomizing injector cooled by water. This injector allows feeding the crude bio-oil in continuous mode into the conical spouted bed reactor without being clogged by the pyrolytic lignin in the bio-oil. The effect of gasification temperature on gas properties, tar composition, and carbon conversion efficiency were assessed in the 800–900 °C range. The results show that temperature promotes tar reduction (from 40.7 to 12.5 g/Nm3), carbon conversion efficiency (from 91.2 to 96.3 %) and gas yield (from 1.37 to 1.85 Nm3/kg on a dry basis) as temperature is increased from 800 to 900 °C. A novel aspect of this study is the detailed characterization of the tar evolution with temperature, which, to our knowledge, is an aspect that has not been approached in the literature related to raw bio-oil gasification.

In the current energy scenario, the production of heat, power and biofuels from biomass has become of major interest. Amongst diverse thermochemical routes, gasification has stood out as a key technology for the large-scale application of biomass. However, the development of biomass gasification is subjected to the efficient conversion of the biochar and the mitigation of troublesome by-products, such as tar. Syngas with high tar content can cause pipeline fouling, downstream corrosion, catalyst deactivation, as well as adverse impact on health and environment, which obstruct the commercialization of biomass gasification technologies. Since the reduction of tar formation is a key challenge in biomass gasification, a comprehensive overview is provided on the following aspects, which particularly include the definition and complementary classifications of tar, as well as possible tar formation and transformation mechanisms. Moreover, the adverse effects of tar on downstream applications, human health or environment, and tar analyzing techniques (online and off-line) are discussed. Finally, the primary tar removal strategies are summarized. In this respect, the effect of key operation parameters (temperature, ER and S/B), catalysts utilization (natural and supported metal catalysts) and the improvement of reactor design on tar formation and elimination was thoroughly analyzed.

[EN]This work pursues the validation of a new reactor for the evaluation of char gasification kinetics. This novel reactor allows continuous gas flow through the fixed bed sample and accurately monitoring the mass loss throughout the reaction. Accordingly, this thermogravimetric flow reactor has a great potential for the analysis of different thermochemical processes, such as pyrolysis and gasification of solid feedstocks. In this paper, the gasification of pine sawdust char was carried out and the effect carbon dioxide concentration (10 and 100 vol%) and temperature (800, 850 and 900 °C) have on char gasification kinetics was assessed. The experimental results were fitted to five different kinetic equations, i.e., homogeneous model (VM), shrinking core model (SCM), nth order model, random pore model (RPM) and modified random pore model (MRPM), and the best-fit parameters (frequency factor, activation energy, adjustable parameters and fitting error) were obtained for each model. The modified random pore model provides the best fit to the experimental data. The new thermogravimetric flow reactor allows obtaining rigorous kinetic results, which is clear evidence that the reactor is suitable for studying char gasification kinetics under CO2 atmosphere.

[EN] The environmental concern associated with waste tyre disposal and the necessity of sustainable waste management policies has promoted the development of waste tyre valorization processes in the last decades. Within this framework, this review analyzes the main advances in waste tyre valorization by catalytic pyrolysis. Waste tyre pyrolysis allows converting this solid waste into three product fractions of potential interest, as are gases, pyrolysis oil (TPO) and char, with their yield and features being conditioned by pyrolysis conditions. Catalytic pyrolysis is an interesting alternative to improve the quality of the products and the selectivity of the process. A wide range of catalysts have been proposed in the literature for waste tyre valorization, with zeolites being the most commonly used due to their capacity for the production of valuable chemicals, such as BTX and light olefins. This review approaches multidisciplinary aspects for the evaluation of the critical points in this process, such as those related to pyrolysis technologies, reaction mechanisms, catalyst design and products properties

[EN] The performance of fixed and fluidized bed reactors in the steam reforming of biomass fast pyrolysis volatiles was compared, with especial attention paying to the differences observed in catalysts deactivation. The experiments were carried out in continuous regime in a bench scale unit provided with a conical spouted bed for the pyrolysis step. They were carried out on a Ni-Ca/Al2O3 commercial catalyst and under optimum conditions determined in previous studies, i.e., pyrolysis temperature 500 ºC, reforming temperature 600 ºC and a steam/biomass ratio of 4. Moreover, the influence of space time was analysed in both reforming reactors. The fixed bed reactor showed higher initial conversion and H2 yield, as it allowed attaining a H2 yield higher than 90 % with a space time of 10 gcat min gvol-1. However, a space time of 15 gcat min gvol-1 was required in the fluidized bed to obtain a similar H2 yield. Moreover, the fixed bed also led to lower catalyst deactivation. Catalyst deactivation was mainly related to coke deposition, and higher coke contents were observed in the catalysts used in the fluidized bed reactor (1.2 mgCOKE gcat-1 gbiomass-1) than those in the fixed bed one (0.6 mgCOKE gcat-1 gbiomass-1). Therefore, the differences in the performance of the two reactors were analysed and their practical interest was discussed.

[EN] A 2D Euler-Euler multiphase computational fluid dynamics (CFD) model in conjunction with the kinetic theory of granular flow (KTGF) was applied to describe the biomass pyrolysis in a spouted bed reactor. The primary interest in this work was the development of a CFD hydrodynamic model of the reactor coupled with a pyrolysis kinetic model for the prediction of biomass pyrolysis product yields (gas, bio-oil, and char). The kinetic model is based on three parallel reactions for the formation of the pyrolysis products and a secondary reaction of gas formation from bio-oil. The CFD hydrodynamic model suitably predicts the behavior of the spouting regime, and its simultaneous resolution with the kinetic model leads to a satisfactory quantitative agreement between the predicted and experimental values for bio-oil and gas yields. This study is evidence of the great potential of CFD techniques for the design, optimization, and scale-up of conical spouted bed reactors.

[EN] The influence of the metal selected as catalytic active phase in the two-step biomass pyrolysis-catalytic reforming strategy has been analyzed. The pyrolysis step was carried out in a conical spouted bed reactor at 500 ºC, whereas steam reforming was performed in a fluidized bed reactor at 600 ºC. Ni/Al2O3, Co/Al2O3 and two bimetallic Ni-Co/Al2O3 catalysts with different metal loadings were synthesized by wet impregnation method, and fresh and deactivated catalysts were characterized by N2 adsorption/desorption, X-ray Fluorescence (XRF), Temperature Programmed Reduction (TPR), X-Ray powder Diffraction (XRD), Temperature Programmed Oxidation (TPO), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Although Ni/Al2O3 and both bimetallic catalysts had similar initial activity in terms of (oxygenate conversion, (higher than 98%), the poorer metal dispersion observed in both bimetallic catalysts led to a fast decrease in conversion due to the promotion of coke formation on large particles. This occurred even though Ni-Co alloy formation has a positive influence by hindering the oxidation of Co0 species. The main cause for the deactivation of these catalysts is the formation of a coke with amorphous structure. The poor initial performance of Co/Al2O3 catalyst is related to changes in the Co0 oxidation state induced by the presence of steam, which led to a fast deactivation of this catalyst.

[EN] The performance of both fluidized and spouted bed reactors in the pyrolysis of waste plastics is conditioned by particle agglomeration phenomena, which worsen the quality of the gas-solid contact and eventually lead to defluidization. The objective of this work is to determine the optimum conditions for stable operation (without defluidization) in a bench scale plant fitted with a fountain confined conical spouted bed reactor and equipped with a nonporous draft tube, which operates in continuous mode. The insertion of these devices enhances the gas-solid contact, especially in the fountain region, and leads to a highly stable hydrodynamic regime, with these features being of especial relevance for the in situ catalytic pyrolysis of waste plastics. This paper deals with the effect different variables have on the minimum temperature for stable operation by avoiding defluidization. The variables analyzed are as follows: plastic type (HDPE, LDPE, PP, PS, PET and PMMA), plastic feed rate, mass of inert material in the bed, spouting velocity and use of catalyst. The results show that polymers whose chains decompose at low temperatures or have high degrees of branching require low operating temperatures. Besides, as the ratio of bed mass to plastic feed rate (Wbed/Qplastic) and/or spouting velocity were increased, the temperature required to avoid defluidization was also reduced. The use of a catalyst also reduced the temperature required for stable operation, as the activation energy of cracking reactions is greatly reduced, and so reaction rate is increased.

[EN] The joint process of pyrolysis-steam reforming is a novel and promising strategy for hydrogen production from biomass; however, it is conditioned by the endothermicity of the reforming reaction and the fast catalyst deactivation. Oxygen addition may potentially overcome these limitations. A thermodynamic equilibrium approach using Gibbs free energy minimization method has been assumed for the evaluation of suitable conditions for the oxidative steam reforming (OSR) of biomass fast pyrolysis volatiles. The simulation has been carried out contemplating a wide range of reforming operating conditions, i.e., temperature (500–800 °C), steam/biomass (S/B) ratio (0–4) and equivalence ratio (ER) (0–0.2). It is to note that the simulation results under steam reforming (SR) conditions are consistent with those obtained by experiments. Temperatures between 600 and 700 °C, S/B ratios in the 2–3 range and ER values of around 0.12 are the optimum conditions for the OSR under autothermal reforming (ATR) conditions, as they allow attaining high hydrogen yields (10 wt% by mass unit of the biomass in the feed), which are only 12–15% lower than those obtained under SR conditions.

The aim of this work was to study fast pyrolysis of three microalgae species in a continuous bench-scale conical spouted bed reactor at 500 °C. Bio-gas, bio-oil and bio-char yields have been determined and characterized by using GC, GC/MS, elemental analyzer and SEM. Bio-oil was the main product obtained through pyrolysis of microalgae. The non-condensable gaseous stream is made up of mainly hydrogen, carbon monoxide and carbon dioxide, apart from other light hydrocarbons detected in lower concentration, as are methane, ethane, ethylene, propane and propylene. The compounds identified in the bio-oil have been categorized into hydrocarbons, nitrogen containing compounds, ketones, alcohols, acids, lactones, phenols and aldehydes. The nitrogen and carbon contents of the microalgae bio-chars are higher than those for bio-chars derived from other biomasses. Pyrolysis improved the morphology and porous structure of microalgae. Finally, the mechanism involving microalgae pyrolysis has been approached and the main reaction pathways have been proposed.

[EN] The steam pyrolysis of pinewood sawdust has been conducted in a bench scale plant provided with a conical spouted bed reactor (CSBR). This process is of uttermost relevance for the in-line valorisation of pyrolysis volatiles, specifically for their catalytic steam reforming for hydrogen production. The influence of temperature on the product yields has been analyzed in the 500-800 degrees C range. A detailed analysis of the volatile stream (condensable and non-condensable components) has been carried out by chromatographic techniques, and the char samples have been characterized by ultimate and proximate analyses, N-2 adsorption-desorption, and Scanning Electron Microscopy. A high bio-oil yield was obtained at 500 degrees C (75.4 wt%), which is evidence of the suitable features of the conical spouted bed reactor for this process. As temperature was increased, higher gas and lower liquid and char yields were obtained. Steam was fully inert at low pyrolysis temperatures (500-600 degrees C), and only had a little influence at 700 degrees C due to the low gas residence time in the conical spouted bed reactor. At 800 degrees C, the reaction mechanism was controlled by gasification reactions. The composition of the liquid fraction was considerably influenced by pyrolysis temperature, with a less oxygenated stream as temperature was increased. Thus, phenolic compounds accounted for the major fraction at low pyrolysis temperatures, whereas hydrocarbons prevailed at 800 degrees C. The char obtained in the whole temperature range can be further used as active carbon or energy source.

[EN] A study was carried out on the valorization of different waste plastics (HDPE, PP, PS and PE), their mixtures and biomass/HDPE mixtures by means of pyrolysis and in line oxidative steam reforming. A thermodynamic equilibrium simulation was used for determining steam reforming data, whereas previous experimental results were considered for setting the pyrolysis volatile stream composition. The adequacy of this simulation tool was validated using experimental results obtained in the pyrolysis and in line steam reforming of different plastics. The effect the most relevant process conditions, i.e., temperature, steam/plastic ratio and equivalence ratio, have on H-2 production and reaction enthalpy was evaluated. Moreover, the most suitable conditions for the oxidative steam reforming of plastics of different nature and their mixtures were determined. The results obtained are evidence of the potential interest of this novel valorization route, as H-2 productions of up to 25 wt% were obtained operating under autothermal conditions.

[EN] The performance of olivine, dolomite and gamma-alumina primary catalysts was evaluated in the continuous tar elimination process in which toluene was selected as the biomass gasification tar model compound. Iron was incorporated into these catalysts in order to improve their catalytic activity. All the experiments were performed in a continuous flow fluidized bed micro-reactor, with a steam/toluene ratio of 4 and a space velocity (GHSV) of 820 h(-1), which corresponds to a catalyst amount of 3.8 cm(3). The effect of temperature was studied using olivine in the 800-900 degrees C range, which allowed concluding that 850 degrees C was the best temperature for tar removal. The fresh and deactivated catalysts were characterized by N-2 adsorption-desorption, X-ray fluorescence (XRF), X-ray diffraction (XRD) and temperature-programmed oxidation (TPO). Tar conversion efficiency was assessed by means of carbon conversion, H-2 yield (based on the maximum allowed by stoichiometry), gas composition and product yields, with Fe/Al2O3 leading to the highest conversion (87.6 %) and H-2 yield (38 %). Likewise, Fe/Al2O3 also provided the highest stability, as it allowed operating for long periods with high conversion values (85.9 % after 35 min on stream), although it underwent severe deactivation. The analysis of the spent catalysts revealed that deactivation occurred mainly by coke deposition on the catalyst surface and iron phase oxidation, with Fe/olivine and Fe/dolomite leading to the faster deactivation due to their poorer metal dispersion related to their reduced surface area. The TPO profiles showed that the coke deposited on the three catalysts was amorphous with a very small contribution of highly structured carbon.

343 p., Esta tesis doctoral se enmarca dentro de una extensa línea de investigación, que abarca el desarrollo de procesos térmicos y catalíticos para la valorización de biomasa y residuos plásticos para la obtención de combustibles líquidos, materias primas (olefinas y aromáticos) e hidrógeno. Los conocimientos adquiridos en la gasificación de biomasa y plásticos en reactores spouted bed convencionales han alentado la realización de esta tesis. Por tanto, el objetivo principal de esta tesis es avanzar en el proceso de gasificación de biomasa con vapor para la producción de gas de síntesis y la eliminación de alquitrán.El reactor de spouted bed convencional se caracteriza por tener cortos tiempo de residencia, lo cual es una excelente característica para minimizar las reacciones secundarias no deseadas en los procesos de pirolisis. Sin embargo, esto es un serio inconveniente para la gasificación, ya que los cortos tiempos de residencia dificultan las reacciones de craqueo del alquitrán. En esta tesis se propone un novedoso sistema de reacción basado en la tecnología de spouted bed, que plantea la incorporación de determinados dispositivos, como el confinador de la fuente y el tubo central, llamado spouted bed de fuente confinada. Esta combinación pretende resolver las limitaciones de los spouted bed convencionales en los procesos de gasificación. Además, se han propuesto varias estrategias primarias de eliminación de alquitrán para mejorar la eficiencia de la gasificación de biomasa con vapor. Se ha desarrollado un nuevo régimen de contacto gas-sólido basado en el reactor de spouted bed y se ha optimizado el proceso general desde el punto de vista del diseño del reactor, condiciones de operación (temperatura) y catalizadores primarios (arena, olivina, dolomita, catalizador gastado de FCC, alumina y catalizador Fe/olivina). Los resultados muestran que usando dolomita como catalizador primario se consigue disminuir el tar hasta 5.0 g Nm-3 a 850 ºC y un ratio S/B de 2.

[EN] Biomass gasification is a promising and sustainable process to produce renewable and CO2-neutral syngas (H2 and CO). However, the contamination of syngas with tar is one of the major challenges to limit the deployment of biomass gasification on a commercial scale. Here, we propose a hybrid plasma-catalytic system for steam reforming of tar compounds over honeycombbased catalysts in a gliding arc discharge (GAD) reactor. The reaction performances were evaluated using the blank substrate and coated catalytic materials (gamma-Al2O3 and Ni/gamma-Al2O3). Compared with the plasma alone process, introducing the honeycomb materials in GAD prolonged the residence time of reactant molecules for collision with plasma reactive species to promote their conversions. The presence of Ni/gamma-Al2O3 gave the best performance with the high conversion of toluene (86.3%) and naphthalene (75.5%) and yield of H2 (35.0%) and CO (49.1%), while greatly inhibiting the formation of byproducts. The corresponding highest overall energy efficiency of 50.9 g/kWh was achieved, which was 35.4% higher than that in the plasma alone process. Characterization of the used catalyst and long-term running indicated that the honeycomb material coated with Ni/gamma-Al2O3 had strong carbon resistance and excellent stability. The superior catalytic performance of Ni/gamma-Al2O3 can be mainly ascribed to the large specific surface area and the in situ reduction of nickel oxide species in the reaction process, which promoted the interaction between plasma reactive species and catalysts and generated the plasma-catalysis synergy.

The oxidative fast pyrolysis of plastics was studied in a conical spouted bed reactor with a fountain confiner and draft tube. An inexpensive fluid catalytic cracking (FCC) spent catalyst was proposed for in situ catalytic cracking in order to narrow the product distribution obtained in thermal pyrolysis. Suitable equivalence ratio (ER) values required to attain autothermal operation were assessed in this study, i.e., 0.0, 0.1, and 0.2. The experiments were carried out in continuous regime at 550 degrees C and using a space-time of 15 gcatalyst min gHDPE -1. The influence of an oxygen presence in the pyrolysis reactor was analyzed in detail, with special focus on product yields and their compositions. Operation under oxidative pyrolysis conditions remarkably improved the FCC catalyst performance, as it enhanced the production of gaseous products, especially light olefins, whose yields increased from 18% under conventional pyrolysis (ER = 0) to 30% under oxidative conditions (ER = 0.1 and 0.2). Thus, conventional catalytic pyrolysis led mainly to the gasoline fraction, whereas light olefins were the prevailing products in oxidative pyrolysis. Moreover, the oxygen presence in the pyrolysis reactor contributed to reducing the heavy oil fraction yield by 46%. The proposed strategy is of great relevance for the development of this process, given that, on one hand, oxygen cofeeding allows solving the heat supply to the reactor, and on the other hand, product distribution and reactor throughput are improved.

This study analyzes the two-step process of biomass pyrolysis and in-line steam reforming for the production of H2. In order to evaluate the effect of the volatile composition on the commercial Ni/Al2O3 catalyst performance and stability, biomass pyrolysis step was conducted at different temperatures (500–800 °C). The analysis of the deactivated catalysts has also allowed identifying the main bio-oil compounds responsible for catalyst decay (coke precursors). Pyrolysis temperature allows modifying the composition of the volatile stream that is subsequently reformed at 600 °C. An increase in pyrolysis temperature to 800 °C improves considerably the production of both H2 and gaseous stream at the initial reaction stages, reaching values of 12.95 wt% and 2.23 Nm3 kg−1, respectively. Catalyst stability is also considerably improved when pyrolysis temperature is increased due to the lower bio-oil yield and its different composition at high temperatures. Coke was the main cause of catalyst deactivation. Besides, the nature of the coke deposited is influenced by the composition of the pyrolysis volatiles, with encapsulating coke being formed by the adsorption and subsequent condensation of all hydrocarbons (oxygenated and non-oxygenated ones) preferably at low temperatures, whereas filamentous coke is formed when the concentrations of CO and light hydrocarbons in the volatile stream are increased at 800 °C.

Waste tires are solid wastes with large annual output and with the potential for great harm to the environment. The pyrolysis of waste tires can recycle energy and produce reusable products. Although there are many reviews in the literature in regard to the pyrolysis characteristics of waste tires, no one paper focuses on reviewing and summarizing the tire char. This paper critically appraises the achievements of earlier reports and literature and assesses the current state-of-the-art for the production and application of tire char from waste tires. Initially, the thermal decomposition behavior of different tire rubbers is discussed and compared where it is shown that the different components of waste tire rubber have different thermal degradation characteristics. The influencing factors on the yield and quality of tire char are discussed and assessed in terms of different pyrolysis reactors and technologies, tire type and composition, and a range of pyrolysis process conditions. The composition of the waste tire and pyrolysis conditions are the main factors affecting the distribution of pyrolysis products. Pyrolysis technology and reactor equipment also have an effect on the distribution of pyrolysis products. The physical and chemical structural characteristics of tire char are critically reviewed in detail, including a comparison of the fundamental differences with commercial carbon black and modified tire char (physical activation and chemical activation). Finally, high-value application fields and developmental prospects of tire char are summarized. Through extensive literature review, a novel development was that tire char could be used as a source of gra-phene. The economic analysis of the various tire char applications should be one of the main research directions in the future. The keynote of this review is to promote intensification of waste tire recycling and treatment so that more tire char can be obtained from waste tire pyrolysis and thereby be reused

[EN]n recent decades, the production of H-2 from biomass, waste plastics, and their mixtures has attracted increasing attention in the literature in order to overcome the environmental problems associated with global warming and CO2 emissions caused by conventional H-2 production processes. In this regard, the strategy based on pyrolysis and in-line catalytic reforming allows for obtaining high H-2 production from a wide variety of feedstocks. In addition, it provides several advantages compared to other thermochemical routes such as steam gasification, making it suitable for its further industrial implementation. This review analyzes the fundamental aspects involving the process of pyrolysis-reforming of biomass and waste plastics. However, the optimum design of transition metal based reforming catalysts is the bottleneck in the development of the process and final H-2 production. Accordingly, this review focuses especially on the influence the catalytic materials (support, promoters, and active phase), synthesis methods, and pyrolysis-reforming conditions have on the process performance. The results reported in the literature for the steam reforming of the volatiles derived from biomass, plastic wastes, and biomass/plastics mixtures on different metal based catalysts have been compared and analyzed in terms of H-2 production.

The performance of Fe/olivine catalysts was tested in the continuous steam gasification of sawdust in a bench scale plant provided with a fountain confined conical spouted bed reactor at 850 degrees C. Olivine was used as catalyst support and loaded with 5 wt%Fe. The activity and stability of the catalyst was monitored by nitrogen adsorption-desorption, X-ray fluorescence spectroscopy, temperature programmed reduction, X-ray diffraction and X-ray photoelectron spectroscopy techniques, which were conducted before and after the runs. The fountain confined conical spouted bed performs well in the biomass steam gasification with primary catalysts. In fact, this reactor allows enhancing the gas-solid contact, and therefore the catalytic activity by avoiding the elutriation of fine catalyst particles. The uncatalysed efficiency of the gasification process, assessed based on the gas production and composition, H-2 production, tar concentration and composition, and carbon conversion efficiency, was consideraby improved on the Fe/olivine catalyst, with tar reduction being especially remarkable (to 10.4 g Nm(-3)). After 140 min on stream, catalyst deactivation was particularly evident, as tar concentration increased to 19.9 g Nm(-3) (90% of that without catalyst). However, Fe/olivine catalyst was still active for WGS and CH4 steam reforming reactions, with gas and H-2 productions being 1.35 Nm(3) kg(-1) and 5.44 wt%, respectively. Metal iron oxidation to Fe3O4 caused catalyst deactivation, as the reaction environment shifted from oxidizing to reducing conditions due to operational limitations.

Continuous catalytic cracking of polyethylene over a spent fluid catalytic cracking (FCC) catalyst was studied in a conical spouted bed reactor (CSBR) with fountain confiner and draft tube. The effect of temperature (475-600 degrees C) and space-time (7-45 g(cat) min g(HDPE)(-1)) on product distribution was analyzed. The CSBR allows operating with continuous plastic feed without defluidization problems and is especially suitable for catalytic pyrolysis with high catalyst efficiency. Thus, high catalyst activity was observed, with waxes yield being negligible above 550 degrees C. The main product fraction obtained in the catalytic cracking was made up of C-5-C-11 hydrocarbons, with olefins being the main components. However, its yield decreased as temperature and residence time were increased, which was due to reactions involving cracking, hydrogen transfer, cyclization, and aromatization, leading to light hydrocarbons, paraffins, and aromatics. The proposed strategy is of great environmental relevance, as plastics are recycled using an industrial waste (spent FCC catalyst).

[EN]The activity and stability of a 10 wt%NiO/CaO catalyst were tested in the sorption enhanced ethanol steam reforming (SEESR) in a fluidized bed reactor. The effect of temperature in the 600-750 degrees C range was analyzed and the performance of the catalyst at 700 degrees C was assessed by conducting cycles of SEESR reaction and CO2 desorption. At zero time on stream, an increase in temperature enhanced ethanol steam reforming reactions, and therefore H-2 production increased from a yield of 20.3 wt% at 600 degrees C to 22 wt% at 750 degrees C. However, high temperatures hindered the catalyst sorption performance, i.e., CO2 capture declined from 7.9 to 2.1 mmol(CO2) g(cat)(-1). In order to evaluate the catalyst performance throughout the cycles and relate it with its features, both fresh and deactivated catalysts were characterized in detail by N-2 adsorption-desorption, X-ray fluorescence (XRF), X-ray diffraction (XRD), temperature programmed reduction (TPR) and oxidation (TPO) and transmission electron microscopy (TEM). Subsequent to 12 cycles, the catalyst CO2 capture performance was slightly lower than that of the fresh one (approximately 7%) and hardly changed in the next cycles. Furthermore, the use of the same temperature for SEESR reaction and CO2 desorption led to the highest adsorption capacity of the catalyst over multiple cycles.

[EN] Based on the promising results of La2O3 and CeO2 promoted Ni/Al2O3 catalysts in the reforming of biomass pyrolysis volatiles, the performance of these catalysts and the non-promoted one was 2 evaluated in the pyrolysis and in-line steam reforming of polypropylene (PP). The experiments were carried out in a continuous bench scale pyrolysis-reforming plant using two space times of 4.1 and 16.7 gcat min gplastic−1 and a steam/PP ratio of 4. The prepared catalysts and the deposited coke were characterized by N2 adsorption-desorption, X-ray fluorescence (XRF), X-ray diffraction (XRD), temperature programmed oxidation (TPO) and transmission electron microscopy (TEM). The Ni/Al2O3 catalyst showed suitable performance regarding pyrolysis product conversion and hydrogen production, and led to moderate coke deposition. It is to note that La2O3 incorporation remarkably improved catalyst performance compared to the other two catalysts in terms of conversion (> 99 %), hydrogen production (34.9 %) and coke deposition (2.24 wt%).

[EUS] Gradu Amaierako Lan honetan plastikoaren pirolisitik sortutako hegazkorren oxigenozko lurrun erreformakuntzaren analisi termodinamikoa egin da, hidrogenoa ekoizteko helburuarekin. Hidrogenoa Lurreko elementu ugarienetarikoa den arren, ezin da zuzenean naturatik lortu eta bere produkzioa, gaur egun, erregai fosilen kontsumora eta CO2 -aren emisiora lotuta dago (gas naturaletik, naftatik… lortzen baita, gehienbat). Horregatik, hidrogenoaren produkzio garbiagoa lortzea da etorkizuneko erronka, eta baita lan honen abiapuntua ere. Hori lortzeko, plastiko desberdinak (HDPE, PP, PET eta PS) eta euren arteko nahasketa elikatu dira prozesuan eta duten eragina aztertu da. Gainera, HDPE-ren pirolisi hegazkorren erreformakuntza autotermikoa izateko beharrezko baldintzak kalkulatu dira eta horien artean, ahalik eta hidrogeno gehien lortzeko baldintza optimoak aukeratu dira., [ES] En este Trabajo de Fin de Grado se ha realizado un análisis termodinámico de la reforma del vapor de oxígeno de los aviones procedentes de la pirólisis del plástico, con el objetivo de producir hidrógeno. Aunque el hidrógeno es uno de los elementos más abundantes de la Tierra, no es posible obtenerlo directamente de la naturaleza y su producción está actualmente asociada al consumo de combustibles fósiles y a la emisión de CO2 (gas natural, nafta, etc., principalmente). Por ello, el reto de futuro es lograr una producción más limpia de hidrógeno y el punto de partida de este trabajo. Para ello se han alimentado los diferentes plásticos (HDPE, PP, PET y PS) y su mezcla en el proceso y se ha analizado su efecto.Además, se han calculado las condiciones necesarias para que se produzca un reformado autotérmico de las pirólisis volátiles del PEP, entre las que se han seleccionado las condiciones óptimas para obtener el mayor número posible de hidrógeno.

[EUS] Egun ingurugiroa jasaten ari den kalteen konponbiderako, premiazkoa bilakatu da ohiko energia iturrien aurrean energia berriztagarriak erabiltzea. Energia berriztagarriak baliabide naturaletatik eratorritako energia agorrezinak eta doakoak dira. Erregai fosilak ez bezala, ugariak dira eta munduko edozein lekutan ustiatu daitezke. Are gehiago, energia berriztagarriak energia garbiak dira; izan ere, ez dituzte klima aldaketaren eragileak diren berotegi-efektuko gasak produzitzen. Gainera, energia hauek sortzeko bideak anitzak dira, hala nola, energia hidraulikoa, haize- eta eguzki-energia. Haatik, horiek ezagunenak izan arren, badira oraindik hedatu gabe dauden energia berriztagarriak; esaterako, biomasa. Biomasa prozesu biologikoen bidez sortutako edozein materia organikori deritzo. Prozesu termokimikoen bidez, biomasa H2-a bezalako erabilpen handiko produktuetan bilakatu daiteke. Halaber, hidrogenoa existitzen den erregai garbiena da, konbustio produktu moduan ur-lurruna baino ez baitu sortzen. Azken urteotan zenbait ikerlariek biomasa erabiliz bi etapako pirolisi-erreformakuntza hidrogenoaren ekoizpenerako estrategia bideragarria dela egiaztatu dute. Prozesu honen lehenengo etapan biomasaren deskonposizio termikoa ematen da, eta jarraian, lortzen diren hegazkorrak bigarren etapa katalitikora elikatzen dira, azken honen erreformakuntzatik hidrogenoa ekoizten delarik. Ikerketa hauen xede nagusia prozesua industria eskalara eramatea da eta horretarako ezinbestekoa da biomasa mota desberdinetarako baliagarria den prozesu sendo bat garatzea. Horrenbestez, Gradu Amaierako Lan honek biomasaren pirolisiko produktuen erreformakuntzan elikadura desberdinek duten eraginaren ezagutzan sakontzea du helburu. Horretarako, baldintza optimo batzuetatik abiatuz lehengai gisa arroz-azala erabili da, ondoren, emaitzak aurreko ikerketetako beste biomasa batzuekin alderatuz.

[EUS] Hidrogenoa erregai fosilak ordezkatzeko aukera egokia da. Hau, biomasa bezalako iturri berriztagarri batetik ekoiztu daiteke, lerroan burutzen den biomasaren pirolisi azkarra eta lurrun erreformakuntza prozesuaren bidez. Prozesu honen endotermikotasunak eskala-handitzerako muga suposatzen duenez, lan honetan oxigenozko lurrun erreformakuntza proposatu da, operazio autotermikoa lortzeko asmoz. Beraz, PRO II programaren bidez, biomasaren pirolisi hegazkorren oxigenozko lurrun erreformakuntzaren ikerketa energetiko eta termodinamikoa burutu da, oxigenoa elikatzeak prozesuan duen eragina aztertuz. Tenperatura eta lurrun/biomasa erlazioa ere operazio baldintza bezala aztertu dira. Horrela, lurrun erreformakuntza eta oxigenozko lurrun erreformakuntzaren artean hidrogenoaren ekoizpenaren ezberdintasuna aztertu da, H2-ren ekoizpen hau maximizatzeko operazio baldintza optimoen bila.

[EN]This work pursues the validation of a new reactor for the evaluation of char gasification kinetics. This novel reactor allows continuous gas flow through the fixed bed sample and accurately monitoring the mass loss throughout the reaction. Accordingly, this thermogravimetric flow reactor has a great potential for the analysis of different thermochemical processes, such as pyrolysis and gasification of solid feedstocks. In this paper, the gasification of pine sawdust char was carried out and the effect carbon dioxide concentration (10 and 100 vol%) and temperature (800, 850 and 900 °C) have on char gasification kinetics was assessed. The experimental results were fitted to five different kinetic equations, i.e., homogeneous model (VM), shrinking core model (SCM), nth order model, random pore model (RPM) and modified random pore model (MRPM), and the best-fit parameters (frequency factor, activation energy, adjustable parameters and fitting error) were obtained for each model. The modified random pore model provides the best fit to the experimental data. The new thermogravimetric flow reactor allows obtaining rigorous kinetic results, which is clear evidence that the reactor is suitable for studying char gasification kinetics under CO2 atmosphere.

[EN] The joint process of pyrolysis-steam reforming is a novel and promising strategy for hydrogen production from biomass; however, it is conditioned by the endothermicity of the reforming reaction and the fast catalyst deactivation. Oxygen addition may potentially overcome these limitations. A thermodynamic equilibrium approach using Gibbs free energy minimization method has been assumed for the evaluation of suitable conditions for the oxidative steam reforming (OSR) of biomass fast pyrolysis volatiles. The simulation has been carried out contemplating a wide range of reforming operating conditions, i.e., temperature (500–800 °C), steam/biomass (S/B) ratio (0–4) and equivalence ratio (ER) (0–0.2). It is to note that the simulation results under steam reforming (SR) conditions are consistent with those obtained by experiments. Temperatures between 600 and 700 °C, S/B ratios in the 2–3 range and ER values of around 0.12 are the optimum conditions for the OSR under autothermal reforming (ATR) conditions, as they allow attaining high hydrogen yields (10 wt% by mass unit of the biomass in the feed), which are only 12–15% lower than those obtained under SR conditions.

[EN] The performance of both fluidized and spouted bed reactors in the pyrolysis of waste plastics is conditioned by particle agglomeration phenomena, which worsen the quality of the gas-solid contact and eventually lead to defluidization. The objective of this work is to determine the optimum conditions for stable operation (without defluidization) in a bench scale plant fitted with a fountain confined conical spouted bed reactor and equipped with a nonporous draft tube, which operates in continuous mode. The insertion of these devices enhances the gas-solid contact, especially in the fountain region, and leads to a highly stable hydrodynamic regime, with these features being of especial relevance for the in situ catalytic pyrolysis of waste plastics. This paper deals with the effect different variables have on the minimum temperature for stable operation by avoiding defluidization. The variables analyzed are as follows: plastic type (HDPE, LDPE, PP, PS, PET and PMMA), plastic feed rate, mass of inert material in the bed, spouting velocity and use of catalyst. The results show that polymers whose chains decompose at low temperatures or have high degrees of branching require low operating temperatures. Besides, as the ratio of bed mass to plastic feed rate (Wbed/Qplastic) and/or spouting velocity were increased, the temperature required to avoid defluidization was also reduced. The use of a catalyst also reduced the temperature required for stable operation, as the activation energy of cracking reactions is greatly reduced, and so reaction rate is increased.

[EN] A 2D Euler-Euler multiphase computational fluid dynamics (CFD) model in conjunction with the kinetic theory of granular flow (KTGF) was applied to describe the biomass pyrolysis in a spouted bed reactor. The primary interest in this work was the development of a CFD hydrodynamic model of the reactor coupled with a pyrolysis kinetic model for the prediction of biomass pyrolysis product yields (gas, bio-oil, and char). The kinetic model is based on three parallel reactions for the formation of the pyrolysis products and a secondary reaction of gas formation from bio-oil. The CFD hydrodynamic model suitably predicts the behavior of the spouting regime, and its simultaneous resolution with the kinetic model leads to a satisfactory quantitative agreement between the predicted and experimental values for bio-oil and gas yields. This study is evidence of the great potential of CFD techniques for the design, optimization, and scale-up of conical spouted bed reactors.

[EN] The influence of the metal selected as catalytic active phase in the two-step biomass pyrolysis-catalytic reforming strategy has been analyzed. The pyrolysis step was carried out in a conical spouted bed reactor at 500 ºC, whereas steam reforming was performed in a fluidized bed reactor at 600 ºC. Ni/Al2O3, Co/Al2O3 and two bimetallic Ni-Co/Al2O3 catalysts with different metal loadings were synthesized by wet impregnation method, and fresh and deactivated catalysts were characterized by N2 adsorption/desorption, X-ray Fluorescence (XRF), Temperature Programmed Reduction (TPR), X-Ray powder Diffraction (XRD), Temperature Programmed Oxidation (TPO), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Although Ni/Al2O3 and both bimetallic catalysts had similar initial activity in terms of (oxygenate conversion, (higher than 98%), the poorer metal dispersion observed in both bimetallic catalysts led to a fast decrease in conversion due to the promotion of coke formation on large particles. This occurred even though Ni-Co alloy formation has a positive influence by hindering the oxidation of Co0 species. The main cause for the deactivation of these catalysts is the formation of a coke with amorphous structure. The poor initial performance of Co/Al2O3 catalyst is related to changes in the Co0 oxidation state induced by the presence of steam, which led to a fast deactivation of this catalyst.

The aim of this work was to study fast pyrolysis of three microalgae species in a continuous bench-scale conical spouted bed reactor at 500 °C. Bio-gas, bio-oil and bio-char yields have been determined and characterized by using GC, GC/MS, elemental analyzer and SEM. Bio-oil was the main product obtained through pyrolysis of microalgae. The non-condensable gaseous stream is made up of mainly hydrogen, carbon monoxide and carbon dioxide, apart from other light hydrocarbons detected in lower concentration, as are methane, ethane, ethylene, propane and propylene. The compounds identified in the bio-oil have been categorized into hydrocarbons, nitrogen containing compounds, ketones, alcohols, acids, lactones, phenols and aldehydes. The nitrogen and carbon contents of the microalgae bio-chars are higher than those for bio-chars derived from other biomasses. Pyrolysis improved the morphology and porous structure of microalgae. Finally, the mechanism involving microalgae pyrolysis has been approached and the main reaction pathways have been proposed.

[EN] The environmental concern associated with waste tyre disposal and the necessity of sustainable waste management policies has promoted the development of waste tyre valorization processes in the last decades. Within this framework, this review analyzes the main advances in waste tyre valorization by catalytic pyrolysis. Waste tyre pyrolysis allows converting this solid waste into three product fractions of potential interest, as are gases, pyrolysis oil (TPO) and char, with their yield and features being conditioned by pyrolysis conditions. Catalytic pyrolysis is an interesting alternative to improve the quality of the products and the selectivity of the process. A wide range of catalysts have been proposed in the literature for waste tyre valorization, with zeolites being the most commonly used due to their capacity for the production of valuable chemicals, such as BTX and light olefins. This review approaches multidisciplinary aspects for the evaluation of the critical points in this process, such as those related to pyrolysis technologies, reaction mechanisms, catalyst design and products properties

[EN] The performance of fixed and fluidized bed reactors in the steam reforming of biomass fast pyrolysis volatiles was compared, with especial attention paying to the differences observed in catalysts deactivation. The experiments were carried out in continuous regime in a bench scale unit provided with a conical spouted bed for the pyrolysis step. They were carried out on a Ni-Ca/Al2O3 commercial catalyst and under optimum conditions determined in previous studies, i.e., pyrolysis temperature 500 ºC, reforming temperature 600 ºC and a steam/biomass ratio of 4. Moreover, the influence of space time was analysed in both reforming reactors. The fixed bed reactor showed higher initial conversion and H2 yield, as it allowed attaining a H2 yield higher than 90 % with a space time of 10 gcat min gvol-1. However, a space time of 15 gcat min gvol-1 was required in the fluidized bed to obtain a similar H2 yield. Moreover, the fixed bed also led to lower catalyst deactivation. Catalyst deactivation was mainly related to coke deposition, and higher coke contents were observed in the catalysts used in the fluidized bed reactor (1.2 mgCOKE gcat-1 gbiomass-1) than those in the fixed bed one (0.6 mgCOKE gcat-1 gbiomass-1). Therefore, the differences in the performance of the two reactors were analysed and their practical interest was discussed.

A Ni/Al2O3 catalyst has been modified incorporating CeO2 and MgO promoters in order to improve its performance in the steam reforming of biomass pyrolysis volatiles. Ni/Al2O3, Ni/CeO2-Al2O3 and Ni/MgO-Al2O3 catalysts have been prepared and fresh and deactivated catalysts have been characterized by N2 adsorption/ desorption, X-ray Fluorescence (XRF), Temperature Programmed Reduction (TPR), X-ray powder diffraction (XRD), Temperature Programmed Oxidation (TPO), Transmission Electron Microscopy (TEM) and a technique based on Fourier Transform Infrared Spectroscopy-Temperature Programmed Oxidation (FTIR-TPO). The results obtained revealed a similar initial activity for the three catalysts tested (conversion higher than 98%), whereas stability has been greatly improved by incorporating CeO2 as promoter, as it enhances the gasification of coke precursors. However, Ni/MgO-Al2O3 catalyst is slightly less stable than Ni/Al2O3, presumably as a result of its lower reducibility due to the formation of MgAl2O4 spinel phase. Catalysts deactivation has been associated with coke deposition, although sintering phenomenon became also evident when the Ni/CeO2-Al2O3 catalyst was tested. The coke deposited on the catalysts does not present any specific morphology, which is evidence of its amorphous structure in the three catalysts studied.

[EN] The effect of La2O3 addition on a Ni/Al2O3 catalyst has been studied in the biomass pyrolysis and in-line catalytic steam reforming process. The results obtained using homemade catalysts (Ni/Al2O3 and Ni/La2O3-Al2O3) have been compared with those obtained using a commercial Ni reforming catalyst (G90LDP). The pyrolysis step has been performed in a conical spouted bed reactor at 500 °C and the reforming one in a fluidized bed reactor placed in-line at 600 °C, using a space time of 20 gcatalyst min gvolatiles−1 and a steam/biomass ratio of 4. The Ni/La2O3-Al2O3 catalyst had a better performance and higher stability than G90LDP and Ni/Al2O3 catalysts, with conversion and H2 yield being higher than 97 and 90%, respectively, for more than 90 min on stream.Nevertheless, conversion and H2 yield decreased significantly with time on stream due to catalyst deactivation. Thus, the deactivated catalysts have been characterized by N2 adsorption-desorption, X-ray diffraction (XRD), temperature programmed oxidation (TPO), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Coke deposition has been determined to be the main cause of catalyst deactivation, with the structure of the coke being fully amorphous in the three catalysts studied.

[EN] This study pursues the valorization of waste tires by pyrolysis using a different approach for tire parts, specifically, the tire tread rubber and side wall rubber. Tire tread rubber was used to produce hot char with the purpose of using it as cracking catalyst. Side wall rubber was valorized by pyrolysis and online catalytic pyrolysis over tire tread rubber derived hot char in two fixed bed reactor. This work aims to improve the quality of pyrolysis products using tire tread rubber derived hot char as catalyst. The thermal decomposition behavior and products characteristics were tested by means of TG-FTIR, GC, GC-MS, nitrogen adsorption and SEM. Under catalytic pyrolysis temperature of 500−550 °C, a high yield of valuable single ring aromatics (concentration in the oil of 50 %) was obtained. The yield of gas can reach 10.5 wt.% after catalytic pyrolysis, which only 3.0 wt.% without catalytic pyrolysis. The yield of undesirable byproducts as PAHs and carbon deposits was also limited. This strategy represents a novel and feasible alternative to traditional waste tire catalytic pyrolysis processes using expensive catalysts as zeolite.

[ES] Se desarrollará un modelo cinético para la pirólisis rápida de la biomasa en reactor spoutedbed ajustando los parámetros del modelo a los resultados experimentales, obtenidos en el laboratorio trabajando a tres temperaturas diferentes (450ºC, 500ºC y 550ºC) y con tres caudales de gas diferentes ( 2, 6 y 11 L/min)

A study has been carried out of the regenerability of a commercial Ni catalyst used in the steam reforming of volatiles from biomass pyrolysis, determining the evolution of the reaction indices in successive reaction-regeneration cycles. The causes of catalyst deactivation (coke deposition and Ni sintering) have been ascertain characterizing the deactivated and regenerated catalysts by TPO, TEM, TPR and XRD. Catalyst activity is not fully recovered by coke combustion in the first cycles due to the irreversible deactivation by Ni sintering, but the catalyst reaches a pseudo-stable state beyond the fourth cycle, reproducing its behaviour in subsequent cycles.

The influence the support has on the performance of Ni catalysts used in the reforming of biomass fast pyrolysis volatiles has been assessed. Accordingly, five catalysts have been prepared by wet impregnation method, namely Ni/Al2O3, Ni/SiO2, Ni/MgO, Ni/TiO2 and Ni/ZrO2. These catalysts have been characterized by nitrogen adsorption/desorption, X-ray fluorescence spectroscopy, temperature programmed reduction and X-ray diffraction techniques. The pyrolysis-reforming runs have been performed in a bench scale unit operating in continuous regime. The biomass (pine wood sawdust) pyrolysis step has been carried out in a conical spouted bed reactor at 500 ºC, with the volatiles produced (a mixture of gases and bio-oil) being reformed in-line on the prepared catalysts in a fluidized bed reactor at 600 ºC. Remarkable differences have been observed amongst the catalyst prepared, with Ni/Al2O3, Ni/MgO and Ni/ZrO2 being those leading to the most encouraging results, whereas Ni/TiO2 and, especially Ni/SiO2, showed a limited reforming activity. The performance of each catalyst has been related to its properties determined in the characterization.

Lan honetan, poliolefinetatik abiatuta, olefinak ekoizteko bi estrategia ezberdin alderatzen dira. Bi kasuetan, lehen etapan, iturri-ohantze konikoko erreaktorean plastikoaren pirolisia egin da. Bigarren etapari dagokionez, bi aukera daude pirolisian sorturiko hegazkorren crackinga egiteko; alde batetik, ohantze finkoan, cracking katalitikoa HZSM-5 zeolita katalizatzaile modura erabiltzea, eta, bestetik, tutu anitzeko erreaktorean tenperatura altuko cracking termikoa erabiltzea; In this paper two strategies focused on the production of light olefins from polyolefins are compared. In both cases, the first stage consists in the plastics pyrolysis in a conical spouted bed reactor. With respect to the second stage, two different alternatives have been studied to perform the in-line cracking of the volatiles formed in pyrolysis.In the first alternative, a HZSM-5 catalyst is placed in a fixed bed reactor to perform the catalytic cracking, while in the second one a multitubular reactor is used for the high temperature thermal cracking

The continuous pyrolysis-reforming of pine sawdust and high density polyethylene mixtures (25, 50 and 75 wt% HDPE) has been performed in a two-stage reaction system provided with a conical spouted bed reactor (CSBR) and a fluidized bed reactor. The influence HDPE co-feeding has on the conversion, yields and composition of the reforming outlet stream and catalyst deactivation has been studied at a reforming temperature of 700 °C, with a space time of 16.7 gcat min gfeeding 1 and a steam/(biomass + HDPE) mass ratio of 4, and a comparison has been made between these results and those recorded by feeding pine sawdust and HDPE separately. Co-feeding plastics enhances the hydrogen production, which increases from 10.9 g of H2 per 100 g of feed (only pine sawdust in the feed) to 37.3 g of H2 per 100 g of feed (only HDPE in the feed). Catalyst deactivation by coke is attenuated when HDPE is co-fed due to the lower con- tent of oxygenated compounds in the reaction environment. The higher yield of hydrogen achieved with this two-step (pyrolysis-reforming) strategy, its ability to jointly valorise biomass and plastic mixtures and the lower temperatures required compared to gasification make this promising process for producing H 2 from renewable raw materials and wastes.

The effect of reforming conditions (temperature, space time and steam/biomass ratio (S/B)) has been studied in the continuous biomass pyrolysis and in-line catalytic steam reforming process in order to establish suitable conditions for attenuating the deactivation of a commercial Ni catalyst by coke deposition. The experiments have been performed in a conical spouted bed and a fluidized bed reactor for the pyrolysis and reforming steps, respectively. Biomass fast pyrolysis was performed at 500 ºC and the reforming operating conditions studied are as follows: 550-700 ºC; space-time, 10-30 gcatalyst min gvolatiles-1, and; S/B ratio, 2-5. The coke deposited on the catalyst has been analyzed by temperature programmed oxidation (TPO), and two types of coke have been identified, i.e., the coke deposited on the Ni active sites and the one separated from these sites, without filamentous coke being observed by transmission electron microscopy (TEM). Coke deposition has been related to the decomposition of the oxygenates derived from biomass pyrolysis and the re-polymerization of phenolic oxygenates. Suitable conditions to achieve almost full conversion with a H2 yield of up to 95 % and stability for 160 min on stream, the following have been established: 600 ºC, space time of 30 gcatalyst min gvolatiles-1 and S/B ratio of 3.

A continuous process has been developed consisting in the flash pyrolysis (500 ºC) of high density polyethylene (HDPE) in a conical spouted bed reactor (CSBR) followed by steam reforming in a fluidized bed reactor (Ni commercial catalyst). The effect reforming temperature in the 600-700 ºC range, space time from 2.8 to 20.8 gcat min gHDPE-1 and steam/plastic ratio between 3 and 5 have on product yields and gas composition has been studied. The continuous pyrolysis-reforming process performs well, with no operational problems and attaining complete HDPE conversion. Under the optimum conditions, i.e., 700 ºC, space time 16.7 gcat min gHDPE-1 and steam/plastic of ratio 5, the H2 yield was 92.5 % of that corresponding to stoichometry, which accounts for a H2 production of 38.1 g per 100g of HDPE in the feed.

El consumo acelerado de unos recursos energéticos finitos, el impacto ambiental asociado a la producción y uso de las energías tradicionales, la distribución de las reservas de energía , y los precios de las materias primas energéticas , confieren a las fuentes renovables de energía una importancia creciente en la política energética de la mayor í a de los países desarrollados. Además , la valorizació n energética de residuos representa un reto de la sociedad de consumo, por una parte para dar respuest a a los requerimientos de desarrollo sostenible y tamb ié n para fomentar el uso de fuentes de energí a renovables. Entre estos, una de las fuente s más importantes es la biomasa. Es evidente que, un desarrollo de las tecnologías y una planificación adecuada de los aprovechamientos de biomasa, permitiría contrarrestar los efectos perniciosos del excesivo uso de la energía , además de generar empleo, mejoras ambientales y el correspondiente desarrollo rural de zonas degradadas. Las previsiones establec en que antes de 2100 la cuota de participación de la biomasa en la producción mundial de energía debería estar entre el 25 y el 46 %. La producción de hidró geno a partir de biomasa es un proceso interesante y viable, teniendo en cuenta el aumento significa tivo del actual consumo de hidró geno. La producción actual se obtiene mayoritariamente a partir de fuentes fósiles , que emiten grandes cantidades de CO 2 y por lo tanto, surge la necesidad de reducir estas emisiones utilizando materias primas renovables. Por ello, en este sentido, el objetivo principal de este Proyecto Fin de Grado es avanzar en el aprovechamiento de la biomasa vegetal a través de la piró lisis flash y posterior reformado con vapor en línea para la obtención de hidró geno. Para ello, se ha p ropuesto una primera e tapa de piró lisis rápida a 500 º C en un reactor spouted bed cónico y una segunda etapa catal í tica de r eformado con vapor en lí nea en un lecho fluidizado, con el fin de optimizar la t

Egun pneumatiko erabilien kudeaketa interes handia berenganatzen ari da, alde batetik, euren isurketa eta pilaketak dakartzan ing urug iro arazoengatik eta, bestetik, pneumatiko erabi lia material baliotsua de lako ide ia gero eta indar gehiago hartzen ari delako . Balioztapen prozesu desberdinen artean, piro li sia da irtenbide erakarganienetarikoa. Izan ere, pneumatiko erabilia erregai gaseoso edo likido edota balio erantsia duten produktu kim.ikoen itu rri bilaka li teke. Iturri-ohantze konikoa erreaktore egokia da pneumatikoen pirolisia modu jarraituan eta eragozpenik gabe egiteko. Izan ere, prod uktu lik.idoaren %60 inguruko etekina lor daiteke. Lorturiko frakzio likidoa erregai gisa edo produktu kim.ikoen iturri gisa erabil daiteke. Honez gain, prozesu errentagatTia lortzeko, beharrezkoa da pirolisian lorturiko frakzio so lidoari berrerabi lpena aurkitzea. Lorturiko frakz io solidoa ikatz beltz edo ikatz aktibatu gisa erabi l daiteke, lehenengorako tratamendu egok.iaren bidez sufre kantitatea murriztuz eta bigarrenerako aktibazio prozesuaren bidez adsortziorako gaitasuna handituz .; Waste tyres are of special concern in developed countries due to the problems they may generate through inappropriate management. Besides, they are considered a valuable material. Pyrolysis of waste tyres is considered one of the most feasib le large-scale recycl ing methods, since waste tyres are a valuable source of liquid and gas fuels , as well as chemicals. The conical spouted bed reactor pe1forms well for continuous pyrolysis of waste tyres, in which the liquid fract ion is the main fraction obtained (%60). The liqu id fraction obtained could be used as fuel or source of chemical compounds.Given that a high sol id yie ld is obtained in tyre pyrolysis , a fact of great interest is to find a commercial applica tion for that product. This frac tion can be used as carbon black in tyre manufacturing oras active cm·bon, by reducing sulphur content or subjecting it toan activation p