Search

The catalytic cracking of 2-methoxy-4-methylphenol (MMP) and of a mixture of this compound (20 wt%) with n-hexadecane (C16) has been conducted in a CREC Riser Simulator Reactor at 400-550 °C using ...

[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. This work was carried out with the financial support from Spain's ministries of Science, Innovation and Universities (RTI2018-098283-JI00 (MCIU/AEI/FEDER, UE)) and Science and Innovation (PID2019-107357RB-I00 (MCI/AEI/FEDER, UE)), the European Union's Horizon 2020 research and innovation programme under the Marie SklodowskaCurie grant agreement No. 823745, and the Basque Government (IT1218-19 and KK-2020/00107).

[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. This work was carried out with the financial support from Spain's ministries of Science, Innovation and Universities (RTI2018-101678-B-I0 0 (MCIU/AEI/FEDER, UE) and RTI2018-098283-J-I0 0 (MCIU/AEI/FEDER, UE) ) and Science and Innovation (PID2019-107357RB-I0 0 (AEI/FEDER, UE) ) and the Basque Government (IT1218-19 and KK-2020/00107) . Moreover, this project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 823745.

The 3A zeolites are excellent adsorbents for industrial-scale gas dehydration because of the low energy required for regeneration and ease of operation. A computational study of the dehydration of an industrial feed stream containing ethane and water was performed using an in-house code that included an appropriate equilibrium adsorption isotherm. The validated computational model was used to examine the impact of particle size on the process dynamics and the corresponding pressure drop. The water concentration along the adsorption column was also investigated. To increase the process capacity, the packed adsorption bed was divided into two distinct layers, which were operated with different particle sizes. The length of each layer was determined by a parametric study. The best breakthrough time, i.e., 107,800 s, at the allowed pressure drop was obtained when the lengths of the first and second layers were 4.5 and 1 m, respectively. The results showed that the new two-layer adsorption bed could save around 33.8% in total energy requirement in comparison to that of a single bed.

Degradation behavior and kinetics of microalgae chlorella vulgaris, wood, scrap tire and binary and ternary mixtures were investigated by using thermogravimetry analysis method. Experiments were carried out at different heating rates of 10 − 20 and 40 ° C / min from ambient temperature to 600 °C. The results showed that decomposition of microalgae, wood and tire take place in three stages and the second stage is the main thermal decomposition step. Besides, heating rate enhancements shift the maximum peak temperature of microalgae, wood and scrap tire from 300 °C, 350 °C and 380 °C to 340 °C, 390 °C and 420 °C, respectively. In the case of the ternary mixture, the maximum peak temperature of the mixture was approximately equal to the maximum peak temperature of the tire. The interaction between materials was studied and the results showed that the interaction is inhibitive rather than synergistic. The results of kinetic investigation showed that the tire and the wood have the highest (273.64 kJ/mol) and the lowest (120.96 kJ/mol) activation energy, respectively. The presence of wood and microalgae increased the total weight loss of binary mixture of microalgae-tire and wood-tire, while tire presence did not improve the degradation of microalgae-wood mixture.

The performance and stability of different Ni supported catalysts have been studied in a continuous bench scale plant fitted with a conical spouted bed reactor for biomass pyrolysis at 500 °C and a fluidized bed reactor for the in line catalytic steam reforming of pyrolysis volatiles at 600 °C. The metal oxides selected as Ni supports have been Al2O3, SiO2, MgO, TiO2 and ZrO2, and all the catalysts have been prepared by the wet impregnation method. Significant differences have been observed in the performance and stability of the catalysts, with the most suitable ones concerning the evolution of bio-oil oxygenate conversion and H2 yield with time on stream being as follows: Ni/Al2O3 > Ni/ZrO2 > Ni/MgO > Ni/TiO2 > Ni/SiO2. The activity and stability are explained based on the properties of the catalysts, which have been measured prior and after their use, by means of different techniques: N2 adsorption/ desorption, X-ray fluorescence (XRF), X-ray powder diffraction (XRD), temperature programmed oxidation (TPO), in-line monitoring by Fourier-transform infrared spectroscopy-temperature programmed oxidation (FTIR-TPO), scanning electron microscopy (SEM), and transmission electron microscopy (TEM).

A study was carried out on the effect the evolution of the porous structure and metal content have on the gasification rate during char gasification in a conical spouted bed reactor. Partially gasified samples at different temperatures (800–900 °C range) were collected at various conversion levels and characterized by different techniques (N 2 adsorption-desorption, ultimate/proximate analysis and X-ray Fluorescence). At 900 °C there is a fast development of the porous structure, attaining the highest BET specific surface area (S BET ) (633 m 2 g −1 ) at low conversion. Char reactivity profiles revealed that the development of the porous structure influenced the reaction rate mainly at early stages, whereas the increase in the gasification rate for conversions higher than 60% (especially at 900 °C) was attributed to the catalytic effect of Ca, K and Fe (the main metals in the ashes).

A study was carried out to understand the influence of calcination conditions of a Ni/MgO–Al2O3 catalyst on its performance and stability in the reforming of biomass fast pyrolysis volatiles. Accordingly, the first calcination temperature subsequent to promoter impregnation on Al2O3 was modified from 900 to 700 °C. Subsequently, Ni was incorporated by impregnation and a second calcination was carried out at three temperatures (500, 600, and 700 °C). The performance of the different Ni/MgO–Al2O3 catalysts was evaluated in a bench-scale plant operating in the continuous regime, which comprised a conical spouted bed reactor for the pyrolysis step and a fluidized bed reactor for the in-line catalytic steam reforming step. The fresh catalyst was also characterized in order to establish the relationship between the catalyst properties and calcination temperatures at the synthesis step. Moreover, the deactivated catalysts were comprehensively characterized in order to ascertain the main causes of activity decay in the catalysts. Therefore, the catalyst calcined at the lowest temperature subsequent to both the impregnation steps (Ni500/MgO700Al2O3) exhibited the best performance at the reforming step, as the amount of spinel phase formed is lower, and therefore, the catalyst reducibility is increased, leading to higher reforming activity and stability with respect to time on stream.

A study has been carried out of the regenerability of a commercial Ni catalyst used in the steam reforming of the volatiles from biomass pyrolysis (gases and bio-oil), determining the evolution of the reaction indices (conversion, product yields and H2 production) in successive reaction–regeneration cycles. The causes of catalyst deactivation (coke deposition and Ni sintering) have been ascertained 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.

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 °C) and space‐time (7–45 gcat min gHDPE −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 °C. The main product fraction obtained in the catalytic cracking was made up of C5−C11 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)., One man's trash: The use of FCC spent catalyst in a fountain confined spouted bed reactor demonstrates great potential for plastics valorization. A complete polymer conversion towards valuable products as light olefins and gasoline‐range hydrocarbons is obtained. This strategy is of great environmental interest as plastics are recycled using a waste 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. This work was carried out with financial support from the Spain's Ministries of Science, Innovation and Universities (RTI2018-098283-J-I00 (MCIU/AEI/FEDER, UE) and (RTI2018-101678-BI00 MCIU/AEI/FEDER, UE) and Science and Innovation (PID2019-107357RB-I00 (MCI/AEI/FEDER, UE) , the Basque Government (IT1218-19 and KK-2020/00107) . This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 823745. Maria Cortazar also thanks the Basque Government for her research training grant.

The environmental problems related with the management of waste plastics require the development of efficient valorization routes. This chapter deals with three different strategies aimed at the selective conversion of plastics to chemicals and hydrogen following the two-step continuous processes. Flash pyrolysis performed in a conical spouted bed reactor is the first step in the three alternatives, whereas the options proposed for the second step are as follows: 1) non-catalytic cracking in a multitubular reactor for the production of light olefins, 2) catalytic cracking on a HZSM-5 zeolite in a fixed bed for light olefin production, and, 3) steam reforming in a fluidized bed reactor on a Ni-based catalyst for hydrogen production. The three strategies allow full conversion of wax (main pyrolysis product) with high selectivity to different products. Thus, the cracking processes lead to high olefin yields in the 62-77 wt% range, whereas reforming allows a hydrogen production of 38 wt%.

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. Kolsoom Azizi is grateful for the financial support from the Ministry of Science, Research and Technology, Tehran, Iran. Kolsoom Azizi and Mostafa Keshavarz Moraveji thank the Department of Chemical Engineering, University of Basque Country UPV/EHU, for the technical support. This work was carried out with financial support from the Spain’s Ministries of Economy and Competitiveness (CTQ2016-75535-R (AEI/FEDER, UE)) and Science, Innovation and Universities (RTI2018-098283-J-I00 (MINECO/FEDER, UE)), the Basque Government (IT1218-19), and the European Union’s Horizon 2020 research andinnovation programme under the Marie Skłodowska-Curie grant agreement No. 823745.

[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. This work was carried out with the financial support fromSpain’s ministries of Economy and Competitiveness (CTQ2016-75535-R (AEI/FEDER, UE) and Science, Innovation and Universities (RTI2018-101678-B-I00 (MCIU/AEI/FEDER, UE)), the EuropeanUnion’s Horizon 2020 research and innovation programme underthe Marie Skłodowska-Curie grant agreement No. 823745, and theBasque Government (IT1218-19 and KK-2020/00107).

[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. This work was carried out with the financial support from Spain’s ministries of Economy and Competitiveness (CTQ2016-75535-R (AEI/FEDER, UE) and Science, Innovation and Universities (RTI2018-101678-B-I00 (MCIU/AEI/FEDER, UE)), Science and Innovation (PID2019-107357RB-I00), the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 823745, and the Basque Government (IT1218-19 and KK-2020/00107).

The activity and stability of a Ni/ZrO2 catalyst have been studied in a continuous bench scale plant, in which biomass has been pyrolysed at 500 °C in a conical spouted bed reactor and the outlet volatile stream has been subjected to catalytic steam reforming at 600 °C in a fluidized bed reactor. The influence of space time has been analyzed, and both the fresh and the deactivated catalysts have been characterized by means of different techniques: N2 adsorption-desorption, X-ray fluorescence (XRF), X-ray powder diffraction (XRD), temperature programmed oxidation (TPO), and transmission electron microscopy (TEM). The aim of this characterization is to relate catalyst performance to the evolution of the properties from the fresh to the deactivated catalysts. Thus, an increase in space time leads to an improvement in the stability of the catalyst extending its operation period from 20 to 100 min on stream, with a maximum H2 yield of 92.4% (referred to the maximum allowed by stoichiometry) when a space time of 20 gcat min gvolatiles−1 has been used. Although the ZrO2 support has suitable properties, coke deposition is the main cause of catalyst deactivation.

The valorization of biomass (pine wood) for hydrogen production has been studied in a two-step process, comprising pyrolysis and subsequent steam reforming of the volatiles produced in the first step. This work focuses on the deactivation of the Ni commercial catalyst used in the second step. Pyrolysis of biomass has been performed in a conical spouted bed reactor at 500 °C, and the in-line catalytic steam reforming of the pyrolysis volatiles, in a fluidized bed reactor at 600 °C. Deactivated catalyst samples were recovered at different values of time on stream, and analyzed by means of XRD, N2 adsorption-desorption, SEM and TEM microscopies, TPO, Raman and FTIR spectroscopies. The results show that the deactivation is mainly due to the encapsulation of Ni particles by coke, together with Ni sintering, to a lesser extent (from a Ni particle size of 25 nm in the reduced fresh catalyst, to 39 nm at 100 min). The former is ascribed to the condensation of oxygenates (particularly phenols), and the latter is inevitable within the current conditions. As the fraction of uncovered Ni particles decreases with time on stream, the deposition of encapsulating coke is slowed down (from a formation rate of 0.30 mgcoke gcatalyst−1 min−1 to 0.20 mgcoke gcatalyst−1 min−1, at 0–50 min and 50–100 min on stream, respectively), promoting the deposition of coke on the catalyst support (with a formation rate of 1.04 mgcoke gcatalyst−1 min−1 at 50–100 min on stream), with a more carbonized structure and formed through the thermal decomposition of phenols in the reaction medium.

The steam gasification of sawdust was carried out in a bench scale plant fitted with a fountain confined conical spouted bed reactor and a nonporous draft tube, and using olivine as primary catalyst. The effect temperature (in the 800–900 °C range) had on product distribution (gas, tar and char) and composition was studied. Not only did temperature have a positive effect on the gas yield and carbon conversion, but it also played a crucial role in tar removal, as its concentration fell from 49.2 g Nm−3 (on a dry basis) at 800 °C to 6.7 g Nm−3 operating at 900 °C. Moreover, temperature also enhanced the hydrogen yield of the gas, recording a value of 7.28 wt% at 900 °C. Regarding tar formation and its evolution pathway, as gasification temperature was increased the tar composition (analyzed by GC/MS, FTIR and simulated distillation techniques) evolved to more stable aromatic compounds (of higher molecular weight), such as naphthalene or fluoranthene, with heterocyclic or light aromatic compounds being almost absent at 900 °C.

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 °C, 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 °C. 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, having a limited reforming activity. The performance of each catalyst has been related to its properties determined in the characterization.

An original kinetic model has been proposed for the reforming of the volatiles derived from biomass fast pyrolysis over a commercial Ni/Al2O3 catalyst. The pyrolysis-reforming strategy consists of two in-line steps. The pyrolysis step is performed in a conical spouted bed reactor (CSBR) at 500 °C, and the catalytic steam reforming of the volatiles has been carried out in-line in a fluidized bed reactor. The reforming conditions are as follows: 600, 650 and 700 °C; catalyst mass, 0, 1.6, 3.1, 6.3, 9.4 and 12.5 g; steam/biomass ratio, 4, and; time on stream, up to 120 min. The integration of the kinetic equations has been carried out using a code developed in Matlab. The reaction scheme takes into account the individual steps of steam reforming of bio-oil oxygenated compounds, CH4 and C2-C4 hydrocarbons, and the WGS reaction. Moreover, a kinetic equation for deactivation has been derived, in which the bio-oil oxygenated compounds have been considered as the main coke precursors. The kinetic model allows quantifying the effect reforming conditions (temperature, catalyst mass and time on stream) have on product distribution.

The fast pyrolysis of the juice squeezing derived orange waste has been carried out in a continuous pyrolysis bench-scale plant consisting of a conical spouted bed reactor (CSBR). A prior study performed in thermobalance and a kinetic model consisting of a multi-component mechanism allowed determining the contents of pectin (35 wt%), hemicellulose (16.6 wt%) and cellulose (17.1 wt%), but that of lignin could not be satisfactorily determined as its degradation curve overlapped with other compounds such as sugars, proteins and fats. In the bench scale experiments, the bio-oil yields were very high in the 425–500 °C range (close to 55 wt%) due to the suitable features of the CSBR (high heat and mass transfer rates and short residence time of the volatiles), but they are lower for higher temperatures due to the promotion of secondary cracking reactions. Compared to lignocellulosic biomasses, the orange waste produced a bio-oil with more methanol and furfural and less phenolic species, which is an encouraging fact for its stability and valorization by catalytic cracking or steam reforming. The high concentration of CO2 in the gas is a drawback for use for energy production. The char yield (33–27 wt%) was high in the whole range of temperatures studied and its high carbon content (71–73 wt%) and HHV (≈27 MJ kg−1) are suitable for use as fuel.

The hydrogen production by steam reforming (SR) of raw bio-oil (obtained by fast pyrolysis of pine sawdust) has been studied in a continuous two-step process, which consists of a thermal treatment at 500 °C, followed by SR in a fluidized bed reactor with Ni/La2O3-αAl2O3 catalyst. The effect of SR temperature on bio-oil conversion, product yields and catalyst deactivation was evaluated in the 550–700 °C range. The bio-oil conversion and H2 yield were significantly enhanced by increasing temperature. A H2 yield of around 88% and low catalyst deactivation were achieved at temperatures above 650 °C, for a S/C (steam/carbon) ratio of 6 and space-time of 0.10 gcatalysth/gbio-oil. The influence temperature has on product yields and catalyst deactivation was explained by the different nature of the coke deposited. The temperature-programmed oxidation (TPO) curves of coke combustion allow identifying two fractions: i) Coke I, which is the main responsible for deactivation (by encapsulating the Ni sites), whose formation depends on the concentration of bio-oil oxygenates; ii) Coke II, which has filamentous nature and CO and CH4 as main precursors. The effect of temperature on the formation of both types of coke depends on the space–time. Thus, for low values (0.04 gcatalysth/gbio-oil) there is significant formation of both types of coke, with their content increasing with temperature. For higher values (0.38 gcatalysth/gbio-oil), the increase in reaction temperature promotes the removal of coke I, and therefore this is the prevailing fraction at 550 °C and is negligible at 700 °C. This fact is of special relevance for attenuating the Ni/La2O3-αAl2O3 catalyst deactivation.

Pyrolysis of high density polyethylene (HDPE) has been carried out in a conical spouted bed reactor (500 °C) and the volatiles have been reformed in-line over a Ni commercial catalyst in a fluidized bed reactor. The evolution of reaction indices (conversion, H 2 yield and other gaseous product yields) with time on stream has been studied under the following operating conditions: temperature, 600–700 °C; space-time, 8.3–20.8 g cat min g HDPE − 1 , and steam/plastic ratio, 3–5. High initial conversion (> 94.5%) and H 2 yields (> 76.7%) are attained under all the operating conditions studied, with HDPE conversion and H 2 yield increasing when the three variables are increased, which is explained by the enhancement of the reforming reaction. However, a significant effect of operating conditions on catalyst stability has been observed. Thus, an increase in temperature, space-time and steam/plastic ratio decreases catalyst deactivation as a consequence of a lower rate of coke deposition on the catalyst due to both a lower C 5 + coke precursor amount in the reaction medium and a higher gasification rate of the coke deposited.

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 °C and the reforming operating conditions studied are as follows: 550–700 °C; space time, 10–30 gcat 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, are as follows: 600 °C, space time of 30 gcat min gvolatiles−1 and S/B ratio of 3.

The performance of an original two-step reaction system (pyrolysis and in-line reforming) was assessed in the hydrogen production from different plastics (polyethylene, polypropylene, polyethylene terephthalate and polystyrene) and their mixture. The pyrolysis step was performed in a conical spouted bed reactor at 500 °C, whereas the reforming of pyrolysis volatiles was carried out in a fluidized bed reactor at 700 °C. This two in-line reactor configuration was initially developed for the reforming of high density polyethylene pyrolysis volatiles, and this paper describes the influence composition of pyrolysis products derived from different plastics has on the reforming step, conversion, product yields and deactivation behavior. The products formed in both the pyrolysis and the reforming steps were analysed by on-line gas chromatography and micro-gas chromatography. Significant differences in the reforming behaviour of the plastics were observed, with hydrogen productions being higher in the case of polyolefins (from 34.8 to 37.3 wt% ) followed by polystyrene (29.1 wt%) and remarkably lower for polyethylene terephthalate (18.2 wt%). Furthermore, the evolution of conversion and product distribution with time on stream was assessed for the different plastics studied and the catalyst deactivation rate was related to the amount and morphology of the coke deposited on the reforming catalyst. It was proven that the features of the reactors used in the pyrolysis and reforming steps are suitable for minimizing operational problems, and therefore operating in continuous regime.

Biomass pyrolysis and the in-line catalytic cracking of the pyrolysis volatile stream has been approached in this study. The pyrolysis step was carried out in a conical spouted bed reactor at 500 °C, whereas the inert sand or the cracking catalysts (γ-Al2O3, spent FCC and olivine) were placed in a fixed bed reactor at 600 °C. Product analysis was carried out on-line by means of chromatographic methods, and the distribution and composition of the main products obtained have been related to the features characterizing each catalyst (physical properties, chemical composition and acidity). Decarbonylation reactions were favoured over decarboxylation ones when acid catalysts (spent FCC and γ-Al2O3) were used, whereas olivine promoted ketonization and aldol condensation reactions. The Fe species in the olivine structure enhanced reforming and WGS reactions. Bio-oil cracking was more severe as catalyst acidity was increased, leading to an increase in the hydrocarbon fraction. The Al2O3 derived bio-oil was substantially deoxygenated, with a considerable reduction in the phenolic fraction, which accounted mainly for alkyl-phenols. The three materials tested led to a significant decrease in acid and phenolic compounds in the volatile stream, making it suitable for further catalytic valorization for the production of H2, fuels and chemicals.

The kinetics of the steam reforming of HDPE pyrolysis volatiles is studied on a Ni commercial catalyst in a fluidized bed reactor in-line with the pyrolysis reactor (a conical spouted bed reactor at 500 oC). Steam reforming reactions have been carried out under the following conditions: 600-700 oC and space time 0-16.7 gcat min gHDPE-1. Based on the composition of HDPE pyrolysis volatiles, a kinetic scheme is assumed with four reactions (C5+ hydrocarbon reforming, C2-C4 hydrocarbon reforming, CH4 reforming and WGS reaction). Moreover, the kinetics of the deactivation has been quantified with an expression dependant on C5+ hydrocarbon concentration (coke precursors). Calculation of the kinetic parameters is conducted by nonlinear multiple regression, fitting the experimental data to those calculated by the mass conservation equations for each component in the reaction medium. The overall kinetic model proposed describes accurately the evolution of the main products (H2, CO2, CO) with time on stream in the ...

This study aims to synthesize a polyaniline nano-adsorbent and use it to adsorb methyl orange dye from the aqueous solution. The average particle size of nano-adsorbent was about 70 nm. The effects of various parameters have been analysed, as are pH, temperature, adsorption time, initial concentration and adsorbent dosage, and they were optimized by an artificial neural network model. The multilayer feed forward neural network with five inputs and one output has been trained with eight neurons in the hidden layer. A comparison of the experimental data with the dye adsorption efficiency predicted by the artificial neural network model showed that this model can estimate the behavior of the adsorption process of methyl orange dye on the polyaniline nano-adsorbent under different conditions. The study yielded the result that dye adsorption capacity of the nano-adsorbent increased from 3.34 to 32.04 mg/g and from 3.28 to 30.28 mg/g as the dye initial concentration was increased from 10 to 100 mg/L, at 65 °C and 25 °C, respectively. Also, dye adsorption equilibrium was achieved in 60 min for methyl orange dye. The adsorption kinetics was studied based on pseudo-first-order, pseudo-second-order, intraparticle diffusion and Elovich models. The results showed that the adsorption data at all levels of initial concentration have the best consistency with the pseudo-second order equation. Furthermore, two-parameter isotherm models (Langmuir, Freundlich and Temkin) and three-parameter isotherm models (Hill, Sips and R-P) were used to ascertain the nature of the adsorption isotherm. Based on this study, the maximum adsorption capacity was estimated to be 75.9 mg/g. Thermodynamic studies indicated that methyl orange dye adsorption was endothermic on the polyaniline nano-adsorbent.

The valorization of waste high density polyethylene (HDPE) for hydrogen production has been studied in a two-step process, comprising pyrolysis and subsequent steam reforming of the volatiles produced in the first step. Particularly, this work focuses on the deterioration mechanisms (sintering and coke deposition) of the Ni commercial catalyst used in the second step, as it conditions the overall process performance. Pyrolysis of HDPE has been performed in a conical spouted bed reactor at 500 °C, and the catalytic steam reforming of the pyrolysis volatiles, in a fluidized bed reactor at 700 °C. Deactivated catalyst samples were recovered at different values of time on stream, and characterized using XRD, N2 adsorption-desorption, SEM and TEM electronic microscopies, temperature programmed oxidation (TPO), Raman, FTIR and LDI-TOF MS spectroscopies. The results show that the deactivation is due to the sintering and encapsulation -by coke- of Ni. The former is inevitable within the current conditions, and the latter can be ascribed to the condensation of adsorbed precursors that evolve over time. Encapsulating coke is partially carbonized into filamentous coke with lower effect on catalytic deactivation and higher economic interest.

Waste truck tyre valorization by fast pyrolysis has been performed in a conical spouted bed reactor in the 425–575 °C range. The tyre pyrolysis oil (TPO) yield was found to decrease with increasing temperature whilst the yield of gas increased. The effect of temperature on TPO properties has been studied in order to establish the best possible valorization route. FTIR and chromatographic analysis revealed the presence of some undesired compounds with sulphur, nitrogen or oxygen functionalities (benzotiatholes, nitriles and carboxylic acids amongst others) and an increase of TPO aromaticity with increasing temperature. The carbon and sulphur content and the heating value of the TPO increased with temperature. The simulated distillation showed that approximately 70% of the TPOs produced at 425 and 475 °C correspond to diesel range, whereas that TPO obtained at 575 °C is between diesel and gasoline range. The properties of the TPOs evidenced their potential to substitute conventional fuels. However, some of them need to be improved, i.e., by reduction of the sulphur, nitrogen and aromatic content. Additionally, the TPO obtained at 425 and 475 °C could be an important source of limonene and that at 575 °C of xylenes, although current removal methods present some limitations.

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 g cat min g feeding −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 H 2 per 100 g of feed (only pine sawdust in the feed) to 37.3 g of H 2 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 content 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.

[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. This work was carried out with financial support from the Spain’s Ministry of Economy and Competitiveness (CTQ2016-75535-R (AEI/FEDER, UE) and CTQ-2015-69436-R (MINECO/FEDER, UE)), Ministry of Science, Innovation and Universities of Spanish Government (RTI2018-101678-B-I00 (MCIU/AEI/FEDER, UE)), the BasqueGovernment (IT1218-19), and from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 823745. Aitor Arregi thanks the University of the Basque Country for his postgraduate grant (UPV/EHU 2017).

This study investigates the effect the pyrolysis reactor and the condensing system type have on the tyre derived oil (TDO) and DL-limonene yield, as well as benzothiazole concentration in the TDO. All the experiments were performed at 475 °C and three technologies were investigated, fixed bed reactor (FBR), bubbling fluidised bed reactor (BFBR) and conical spouted bed reactor (CSBR), with the latter being the reactor that provided the highest TDO yield (58.2 wt.%). Furthermore, the CSBR enhances DL-limonene production due to its excellent features (low residence time of volatiles and high heat and mass transfer rates), which minimize secondary cracking reactions. Moreover, in order to maximize the TDO retention efficiency and selectively reduce the concentration of certain heteroaromatic species, two types of condensation systems were evaluated: tube-andshell condenser (indirect contact) and quenching condenser (direct contact). The quenching condenser not only promoted the condensation efficiency for DL-limonene, but also reduced the concentration of benzothiazole in the collected TDO. Indeed, the direct contact between water (fed into the quencher) and the hot volatile stream favours the dissolution of some polar heteroaromatic species, thus reducing the nitrogen and sulphur content in the TDO and increasing the applicability of TDO as fuel. This research was supported by the Recycling and Economic Development Initiative of South Africa (REDISA) and the National Research Foundation (NRF). It was also financed by the Ministry of Economy and Competitiveness (CTQ2016-75535-R) and the Ministry of Science, Innovation and Universities of the Spanish Government (RTI2018-101678-B-I00), the European Regional Development Fund (ERDF), the European Commission (HORIZON H2020-MSCA RISE- 2018. Contract No. 823745), the Basque Government (IT1218-19) and the University of the Basque Country (UFI 11/39). The authors acknowledge that any opinions, findings, conclusions or recommendations expressed in this material are the authors' own, and the sponsorscannot accept any liability whatsoever in this regard.

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. This work was carried out with financial support from the Ministry of Economy and Competitiveness of the Spanish Government (CTQ2016-75535-R (AEI/FEDER, UE) and CTQ-2015-69436-R (MINECO/FEDER, UE)), Ministry of Science, Innovation and Universities of the Spanish Government (RTI2018-101678-B-I00 (MCIU/AEI/FEDER, UE)), the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 823745, and the Basque Government (IT1218-19).

The fluidized bed fast pyrolysis of two different kinds of fuels, namely, wood pellets (WP) and solid recovered fuel (SRF) pellets made up of a municipal solid waste by ECONWARD TECH, S.L. (EP) has been carried out. Thus, the analysis of the influence of pyrolysis reactor temperature (600–800 °C) and fuel type in terms of product distribution, e.g. gases, char and tar has been performed. The conditions used in this work are of special interest for the gasification in fluidized beds, in which fast pyrolysis plays a relevant role as it is the first step of fuel conversion. The gas composition was continuously recorded and the tar samples collected during the experiments were analyzed by GC technique. The higher ash content in the EP enhanced charring and decarboxylation reactions, which greatly influenced the distribution of the gaseous products leading to a high CO2 yield. Tar composition was also affected by the constituents of the fuels used, with the content of phenolic compounds in the EP tar obtained at 650 °C being particularly low at the expense of a higher light aromatic content. The rise in temperature decreased the fraction of phenolic compounds and led to a gradual formation of light and heavy polycyclic aromatic hydrocarbons (PAHs), with naphthalene being the major compound in tars of both fuels, WP and EP, at high temperature. The results can be used to derive pyrolysis sub-models for fluidized bed gasification modeling.

Hydrogen production from polystyrene (PS) has been studied following continuous pyrolysis and in-line steam reforming. The first step was carried out at 500 °C in a conical spouted bed reactor and the subsequent reforming one was performed in a fluidized bed reactor on a commercial Ni catalyst at 700 °C. The effect space time and time on stream have on the reaction indexes (reforming conversion, yields of H2, CO2, CO, CH4 and hydrocarbons, and H2 production) has been determined. Furthermore, the process performance has been compared with the results obtained in a previous study conducted by feeding HDPE under the same conditions. Full reforming of PS derived volatiles and high H2 production of 29.1 wt% were attained at zero time on stream. However, a significantly poorer performance of the catalyst was observed after 100 min continuous operation, with the decrease in activity being more acute than that observed for HDPE in a previous study. This deactivating behaviour has been related to the aromatic nature of PS thermal degradation products. The cokes deposited in the degradation of PS and HDPE have been analysed by means of temperature programmed oxidation (TPO) and electron microscopy, and the higher deactivation rate observed in the case of PS has been related to the condensed and encapsulating nature of the coke formed from aromatic hydrocarbons.

Catalytic steam reforming of phenol over Ni/Al 2 O 3 catalyst with 10 wt% of Ni loading was carried out in a fixed bed reactor. The effect of temperature (650–800 °C), reaction time (20–80 min) and catalyst amount (0–2 g corresponding to 0–4.5 g cat h g phenol −1 ) on carbon conversion, H 2 potential and catalyst deactivation was studied. High efficiency of Ni/Al 2 O 3 catalyst in steam reforming of phenol is observed at 750 °C for a reaction time of 60 min when 1.5 g of catalyst (3.4 g cat h g phenol −1 ) is used, with carbon conversion and H 2 potential being 81 and 59%, respectively. An increase in temperature enhances phenol reforming reaction as well as coke gasification, minimizing its deposition over the catalyst. However, at high temperatures (800 °C) an increase in Ni crystal size is observed indicating catalyst irreversible deactivation by sintering. As catalyst time on stream is increased the coke amount deposited over the catalyst increases, but no differences in Ni crystal size are observed. An increase in catalyst amount from 0 to 1.5 g increases H 2 potential, but no further improvement is observed above 1.5 g. It is not observed significant catalyst deactivation by coke deposition, with the coke amount deposited over the catalyst being lower than 5% in all the runs.

Catalytic steam reforming of n -hexane, 1-hexene, tetradecane and toluene over a Ni commercial catalyst has been carried out in a fluidized bed reactor at 700 °C. These compounds have been selected as model compounds of the volatiles formed in the pyrolysis of waste plastics in order to study in detail the performance of the catalyst in the pyrolysis-reforming of different plastic wastes. High carbon conversions and hydrogen yields are obtained at zero time on stream, with peak values being 96.5% and 82.8%, respectively, when n -hexane is used as model compound. Similar reactivity has been observed for tetradecane and 1-hexene, whereas lower carbon conversion (82%) and hydrogen yields (65%) are obtained for toluene. Concerning catalyst stability, olefinic compounds (1-hexene) and aromatic compounds (toluene) cause faster catalyst deactivation than paraffinic compounds (tetradecane and n -hexane). These disparities are explained by the different nature of the coke deposited and the different potential of the compounds to block Ni active sites, with olefins and aromatics being encapsulating coke precursors (amorphous and structured, respectively) and paraffins being filamentous and inert coke precursors.

This work focuses the valorization by CO2 activation of the sewage sludge char obtained in the fast pyrolysis in a conical spouted bed reactor at 500 °C. In order to improve the quality of the activated material for use as adsorbent, the sewage sludge char was subjected to two sequential steps of washing by using first a solution of HCl (in order to remove part of the ashes) and then a solution of Na2CO3 (to extract most of the silica remaining), thereby comparing the properties of the char washed with only HCl with that treated with both HCl and Na2CO3. The materials treated with one or two steps of washing were activated with CO2 in a fixed bed reactor at 800 °C, which allowed proving that the step of Na2CO3 washing contributes significantly to increasing the gasification rate. Furthermore, the properties of interest for use as adsorbents were greatly improved, attaining a BET surface area of 440 m2 g−1 with a notorious presence of meso and macropores for an activation time of 15 min and a burn-off value of 42%.

A continuous process has been developed consisting in the flash pyrolysis (500 °C) 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 °C range, space time from 2.1 to 20.8 g cat min g HDPE −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 °C, space time 16.7 g cat min g HDPE −1 and steam/plastic of ratio 5, the H 2 yield was 92.5% of that corresponding to stoichometry, which accounts for a H 2 production of 38.1 g per 100 g of HDPE in the feed.

The steam gasification of pinewood sawdust derived char has been studied in a conical spouted bed reactor. The effect temperature (in the 800–900 °C range), steam partial pressure (from 0.2 to 1) and sawdust particle size (0.3–1, 1–2 and 2–4 mm ranges) have on the char gasification kinetics has been determined. The pyrolysis step was performed in situ prior to the gasification step, at the same temperature as that in gasification. Four models have been proposed for the fitting of experimental results, i.e., homogeneous, shrinking core, nth order and random pore models, with the latter providing the best results. The activation energy obtained from the fitting is 190 kJ mol−1 and the reaction order with respect to steam partial pressure (α) is 0.344.

A mathematical model and molecular dynamics simulation were applied to study the integrated process consisting of industrial methane steam reforming and pressure-swing adsorption (PSA) to produce pure hydrogen. The process was highly endothermic with an outlet temperature of 1190 K. It was found that the industrial plant suffers from high coke filament formation by the methane cracking reaction with the maximum affinity of 3. Moreover, the output H2/CO ratio of 3.27 was obtained for the industrial case under study. Relevant adsorption isotherms of the components and molecular dynamic simulations showed that hydrogen is not adsorbed on the zeolite 5A, while carbon dioxide and methane compete to adsorb on the zeolite. Results of a dual-bed PSA process showed that pure hydrogen (>99%) is produced during the process, and the results were compared to the available data reported in the literature for each step.

[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. This work was carried out with the financial support from Spain’s ministries of Economy and Competitiveness (CTQ2016-75535-R (AEI/FEDER, UE)) and Science, Innovation and Universities (RTI2018-101678-B-I00 (MCIU/AEI/FEDER, UE)), the Basque Government (IT1218-19), and the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No. 823745.

The upgrading of scrap tires pyrolysis oil (STPO) has been studied in order to produce high-quality alternative fuels, conceived as the second and third stage of an industrially orientated valorization pathway for tires: pyrolysis, hydrotreating, and hydrocracking. The experiments have been carried out in a fixed-bed reactor under the following experimental conditions: (i) for hydrotreating: NiMo/Al2O3 catalyst; time on stream (TOS), 0–8 h; 300–375 °C; 65 bar; H2:oil ratio, 1000 (v/v); space time, 0–0.5 gcat h gfeed–1; and (ii) for hydrocracking: PtPd/SiO2–Al2O3 catalyst; TOS, 0–6 h; 440–500 °C; 65 bar; space time, 0–0.28 gcat h gfeed–1; H2:oil ratio, 1000 (v/v). From the results, lump-based kinetic models have been established for both stages, considering the reactions of (i) hydrodesulfurization (HDS), (ii) hydrocracking (HC), and (iii) hydrodearomatization (HDA) in each one of them. Catalyst deactivation is insignificant in the hydrotreating stage but important for the hydrocracking stage. Therefore, d...

Continuous pyrolysis of polystyrene has been studied in a conical spouted bed reactor with the main aim of enhancing styrene monomer recovery. Thermal degradation in a thermogravimetric analyser was conducted as a preliminary study in order to apply this information in the pyrolysis in the conical spouted bed reactor. The effects of temperature and gas flow rate in the conical spouted bed reactor on product yield and composition have been determined in the 450–600 °C range by using a spouting velocity from 1.25 to 3.5 times the minimum one. Styrene yield is strongly influenced by both temperature and gas flow rate, with the maximum yield being 70.6 wt% at 500 °C and a gas velocity twice the minimum one.

Steam pyrolysis (500 °C) of high density polyethylene (HDPE) in a conical spouted bed reactor followed by a steam reforming (700 °C) in a fixed bed reactor (Ni commercial catalyst) has been carried out for obtaining a syngas stream rich in H 2 . The product yields obtained in the pyrolysis of HDPE using steam are very similar to the previous ones with N 2 as fluidizing agent. A comparison of the results obtained here with those for gasification-reforming strategy reveals that tar and C 2+ hydrocarbons are not fully reformed using the pyrolysis-reforming strategy. Besides, although a high H 2 yield is obtained (81.5% the stoichiometric value), it is slightly lower than the yield obtained in gasification-reforming. Coke yield is high (4.43 wt.%), which causes fixed bed blockage and hinders a correct flow of the volatiles through the bed. SEM, TEM and TPO results show that two types of coke are deposited on the catalyst, with amorphous coke prevailing in the pyrolysis-reforming strategy and filamentous coke in gasification-reforming.

Steam gasification (900 °C) of high density polyethylene (HDPE) in a conical spouted bed reactor (CSBR) followed by steam reforming in a fixed bed reactor (Ni commercial catalyst) has been carried out. The effect reforming temperature in the 600–700 °C range has on product yields and gas composition as well as on the amount and nature of the coke deposited on the catalyst has been studied. The reforming leads to a full transformation of C2+ hydrocarbons and tar. The maximum H2 yield is obtained at 700 °C (36 wt % by mass unit of HDPE in the feed, which accounts for 83 wt % of the maximum H2 yield according to stoichiometry), with CH4 conversion being 94% and the coke amount deposited on the Ni catalyst being minimum (3.3 wt % by mass unit of HDPE in the feed). The syngas obtained by reforming at 700 °C has a H2/CO volumetric ratio of 6 and is suitable for hydrogenation reactions and further valorization to produce H2.

The hydrocracking of hydrotreated scrap tires pyrolysis oil (HT-STPO) has been studied aiming at high-quality refinery blends for alternative automotive fuels. The hydrocracking runs have been carried out with a PtPd/SiO2-Al2O3 catalyst in a fixed-bed reactor at 440–500 °C, 65 bar and space time of 0.16 h. The catalyst has been characterized by inductively coupled plasma optical emission spectroscopy, N2 adsorption–desorption isotherms, and tert-butylamine adsorption–desorption (TPD), while coke has been studied both quantitatively and qualitatively by thermogravimetric-temperature-programmed oxidation (TG-TPO), Fourier transform infrared-TPO, and Raman spectroscopy. During the first two hours of reaction and at temperatures above 480 °C, we have been able to (1) reach ultra low sulfur levels lower than 15 ppm; (2) remove almost completely the less interesting fraction—boiling points higher than 350 °C, named as the gasoil fraction—with remaining amounts lower than 1 wt %; (3) obtain a paraffinic and isop...

A study has been performed on the production of high quality activated carbon from rice husk char obtained by flash pyrolysis in a conical spouted bed reactor. In order to enhance both the quality of the adsorbents obtained and the economy of the process, the amorphous silica contained in the char has been recovered with Na2CO3. Subsequently, the resulting carbonaceous material has been subjected to physical activation at 800 °C using steam and carbon dioxide as activating agents. Although the maximum BET surface areas obtained with carbon dioxide and steam are similar, 1514 and 1365 m2 g–1, respectively, significant differences are observed in the performance of the two oxidizers. Thus, steam gasification kinetics is faster than that of carbon dioxide. The carbons produced by activation using both steam and carbon dioxide have a wide pore size distribution, with microporous structure being more developed when the latter is used.

The rice husk char gasification kinetics with carbon dioxide has been studied in a thermogravimetric analyzer (TGA) under isothermal and dynamic regimes. The effect of the carbon dioxide concentration (50, 75, and 100 vol %) and heating rate (5, 10, and 20 °C min–1) was determined in the dynamic runs, and the effect of the temperature (750, 800, and 850 °C) was determined in the isothermal runs. Rice husk char gasification has a complex kinetic behavior, with reactivity being strongly dependent upon the temperature and char conversion. The experimental results have been fitted to four different kinetic models, namely, homogeneous, nth order, random pore model and modified random pore model. The random pore model is the model that provides the best fit to the experimental evolution.