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The co-feeding of scrap tires pyrolysis oil (STPO) on the catalytic cracking of vacuum gasoil (VGO) has been investigated with the aim of exploring the capacity of the refinery fluid catalytic cracking (FCC) unit to upgrade discarded tires at large-scale. The runs have been carried out in a CREC (Chemical Reactor Engineering Centre) riser simulator reactor that mimics the behavior of the industrial unit at the following conditions: 500-560 °C; catalyst/oil ratio, 3-7 g cat g oil -1 ; contact time, 6 s. Obtained results with the blend of 20 wt% STPO in VGO have been compared with those obtained in the cracking of the pure streams, i.e., STPO and VGO, to get a proper idea of the synergetic effects that could be involved in the co-feeding. This way, when the STPO is co-fed with the VGO the production of naphtha (C 5 -C 12 ) and light cycle oil (C 13 -C 20 ) lumps are maximized, as the over-cracking reactions that convert them into gaseous products (C 1 -C 4 ) are mitigated. Consequently, the co-feeding promotes the production of high-interest hydrocarbons for refineries. Additionally, the naphtha obtained in the cracking of the blend shows a lower content of paraffins and naphthenes than that obtained with the VGO, and higher of olefins and aromatics., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

The catalytic cracking of high-density polyethylene pyrolysis waxes under fluidized catalytic cracking conditions has been investigated with the aim of producing fuels at large-scale from waxes obtained in pyrolysis plants located nearby collection and segregation points. Additionally, preliminary information about the capacity of these units to valorize waste polyolefins has been obtained. The catalytic cracking runs have been performed in a riser simulator reactor under industrial conditions: 500-560 °C; catalyst to oil mass ratio, 3, 5 and 7 g cat  g oil ; and, contact time, 6 s. The product distribution has been quantified determining the yields of different fractions, which have been defined according to their boiling point range: dry gas, liquefied petroleum gas, naphtha, light cycle oil, heavy cycle oil and coke. The concentration of the families of compounds has been also determined, which are n-paraffins, iso-paraffins, olefins, naphthenes and aromatics. For the shake of comparison, the results of catalytic cracking of a common stream fed to the industrial units, i.e., vacuum gasoil, have been included. Globally, promising results have been obtained in the valorization of waste polyolefins by means of this combination of pyrolysis-cracking stages that expose, at the same time, the capacity of this unit to manage waste plastics.-1 ; and, contact time, 6 s. The product distribution has been quantified determining the yields of different fractions, which have been defined according to their boiling point range: dry gas, liquefied petroleum gas, naphtha, light cycle oil, heavy cycle oil and coke. The concentration of the families of compounds has been also determined, which are n-paraffins, iso-paraffins, olefins, naphthenes and aromatics. For the shake of comparison, the results of catalytic cracking of a common stream fed to the industrial units, i.e., vacuum gasoil, have been included. Globally, promising results have been obtained in the valorization of waste polyolefins by means of this combination of pyrolysis-cracking stages that expose, at the same time, the capacity of this unit to manage waste plastics., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Pinewood sawdust and the waste rubber from truck tyres have been co-pyrolysed in order to improve the properties of bio-oil for its integration in oil refineries. In addition, an analysis has been conducted of the effect the interactions between these two materials' pyrolysis reactions have on product yields and properties. Biomass/tyre mixing ratios of 100/0, 75/25, 50/50, 25/75 and 0/100 by weight percentage have been pyrolysed in continuous mode at 500 °C in a conical spouted bed reactor, obtaining oil yields in the 55.2-71.6 wt% range. Gaseous, oil and solid fractions have been characterised for the 50/50 biomass/tyre mixture, paying special attention to the oil fraction by determining its detailed composition, elemental analysis and calorific value. Co-processing enables the stabilization of the liquid, as the co-pyrolysis oil has a stable single phase, being composed mainly of water, aromatic hydrocarbons and phenols in concentrations of 14.5, 11.1 and 9.7 wt%, respectively. Adding tyre rubber to the biomass in the pyrolysis feed improves the oil's properties, as a liquid with higher carbon content and lower oxygen and water is obtained, even if sulphur content is also increased., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Abstract: Pinewood sawdust flash pyrolysis has been performed in continuous mode in a pilot plant provided with a conical spouted bed reactor, in the 400–600°C range. The influence of temperature on the pyrolysis yields and product properties has been studied. Product analysis has been carried out on-line by means of chromatographic methods. High liquid yields have been achieved, with the maximum bio-oil yield (75wt%) at 500°C. Gas yield is very low at low temperatures and this fraction is mainly composed of carbon dioxide, carbon monoxide and small amounts of methane, hydrogen and C2–C4 hydrocarbons. Bio-oil has been characterized and its major compounds are phenols, specifically guaiacols at low temperatures and catechols at high temperatures. At 600°C, there is an increase in light compounds due to the cracking reactions, but no aromatic compounds have been detected due to the low residence time of the volatiles in the reactor. The fuel properties of the bio-oil have been measured and the results indicate that it can be a potential substitute to conventional fuels, although its heating value should be improved by subjecting to further treatments. Char can be used as energy source or as active carbon. The char obtained at 600°C has a high surface area and is suitable for active carbon production. [Copyright &y& Elsevier]

The drying of sawdust was studied in a conical spouted bed pilot plant in order to adapt this feed for the pyrolysis process. Air at different temperatures was used and the effect of sawdust particle size and operating gas velocity was studied. Batch operation was performed with no internal device and with nonporous and open-sided draft tubes in order to ascertain the optimum configuration of the contactor. Although the nonporous draft tube required the lowest minimum spouting velocity, its performance was poor due to deficient gas–solid contact. Configurations with open-sided draft tubes and with no internal devices had higher efficiencies because of their better contacts. An increase in air temperature resulted in a reduction in drying time but the operating conditions need to be fine-tuned to ensure proper energy efficiency. [ABSTRACT FROM AUTHOR]

Highlights • Continuous pyrolysis reforming strategy allows for the H 2 production from biomass. • ZrO 2 is a suitable Ni support for the reforming of pyrolysis volatiles. • Ni/ZrO 2 showed limited coke deposition and low coke combustion temperatures. • A maximum H 2 production of 10.73 wt.% was obtained. Abstract The activity and stability of a Ni/ZrO 2 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: N 2 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 H 2 yield of 92.4% (referred to the maximum allowed by stoichiometry) when a space time of 20 g cat min g volatiles −1 has been used. Although the ZrO 2 support has suitable properties, coke deposition is the main cause of catalyst deactivation. [ABSTRACT FROM AUTHOR]

The composition of the carbonaceous deactivating species (coke) deposited on a Pt and Pd supported P-containing activated carbon catalyst has been studied. These deactivating species were deposited on the catalyst during the hydrocracking of scrap tire pyrolysis oil at 400–500 °C, and it has been selectively characterized by means of temperature-programmed oxidation (TPO), temperature-programmed desorption/gas chromatography (TPD/GC) and laser desorption-ionization/mass spectroscopy (LDI/MS). In addition, the evolution of the textural properties and the acidity of the deactivated catalysts have been evaluated. The high thermal and oxidation resistance of the catalytic support has allowed to combust the coke in the TPO and calculate its intrinsic activation energy as a function of the extent of the combustion. Combined TPO and LDI/MS results have shown that an increase in the hydrocracking temperature attenuates the catalyst deactivation due to the hydrocracking of coke precursors. Coke aging, by evolving towards a more condensed structure, is also favored at higher hydrocracking temperatures. The combustion of the most condensed coke requires of higher temperatures than 375 °C, which hinders the complete regeneration of the activated carbon-based catalyst. [ABSTRACT FROM AUTHOR]

The flash pyrolysis of waste truck-tyres was studied in a conical spouted bed reactor (CSBR) operating in continuous regime. The influence of temperature on product distribution was analysed in the 425–575 °C range. A detailed characterization of the pyrolysis products was carried out in order to assess their most feasible application. Moreover, special attention was paid to the sulphur distribution among the products. The analysis of gaseous products was carried out using a micro-GC and the tyre pyrolysis oil (TPO) by means of GC-FID using peak areas for quantification, with GC/MS for identification and elemental analysis. Finally, the char was subjected to elemental analysis and surface characterization. According to the results, 475 °C is an appropriate temperature for the pyrolysis of waste tyres, given that it ensures total devolatilisation of tyre rubber and a high TPO yield, 58.2 wt.%. Moreover, the quality of the oil is optimum at this temperature, especially in terms of high concentrations of valuable chemicals, such as limonene. An increase in temperature to 575 °C reduced the TPO yield to 53.9 wt.% and substantially changed its chemical composition by increasing the aromatic content. However, the quality of the recovered char was improved at high temperatures. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Sewage sludge fast pyrolysis bio-oil, produced in a conical spouted bed reactor (CSBR) in the 450–600 °C range, has been characterized. On the one hand, the effect of temperature on bio-oil composition has been analyzed by means of online chromatography and, furthermore, the ultimate analysis and the higher heating value of each liquid have been determined. On the other hand, the bio-oil collected at 500 °C, at which the liquid yield is maximized (77 wt.% on dry ash free), has been characterized in detail by determining its density, viscosity, water content and pH. The major organic compounds in the bio-oil were oxygenated and nitrogenated ones (phenols, ketones, alcohols, amides and nitriles among others). It is noteworthy that the bio-oil obtained in this work contains a lower amount of O than those derived from lignocellulosic materials; therefore, the concentrations of C and H in this bio-oil, as well as the lower heating value (LHV), are higher. In addition, the simulated distillation reveals that > 70% of the sewage sludge pyrolysis oil corresponds to the gasoil range. The fuel properties of sewage sludge bio-oil evidence that it has the potential to substitute conventional fuels; however, some properties need to be improved, i.e., the heating value should be increased and the nitrogen content reduced by subjecting this bio-oil to further treatments. [ABSTRACT FROM AUTHOR]

Continuous catalytic pyrolysis of high density polyethylene has been carried out for obtaining light olefins in a two step reaction system: (i) thermal pyrolysis in a conical spouted bed at 500°C; (ii) cracking of the volatiles (mainly waxes, C21+) formed in the first step, in a fixed bed reactor using a catalyst based on HZSM-5 zeolite. A kinetic model based on lumps including catalyst deactivation by coke deposition has been established to quantify the product distribution obtained in the second step and its evolution with time on stream. Experimental data have been obtained at 400, 450 and 500°C, with space-times of 0, 1, 2, 4, 6 and 8gcatmingHDPE−1 and for 5h time on stream. The discrimination of kinetic models has been carried out based on statistics calculated for Fischer distribution (stepwise procedure), and the best fits have been obtained for a model considering six steps: cracking of waxes to produce non-aromatic C5-C11 compounds, single-ring aromatics, light alkanes and light olefins; cracking of non-aromatic C5-C11 compounds to yield light olefins and light olefin condensation reactions to produce single-ring aromatic compounds. The deactivation kinetic equation considers waxes as main coke precursors, whose deposition rate decreases with time on stream. [ABSTRACT FROM AUTHOR]

Highlights: [•] Sequenced pyrolysis–cracking of HDPE using HZSM-5 zeolite yields 60wt% of olefins. [•] Catalyst is deactivated by coke; we report on pathways, equations and precursors. [•] Waxes deposit on the mesopores of the catalyst and evolve towards condensed coke. [•] Olefins form coke on the acid sites of the catalyst that plug the micropores. [ABSTRACT FROM AUTHOR]

Abstract: The continuous catalytic pyrolysis of high density polyethylene (HDPE) has been carried out in a two-step reaction system involving a pyrolysis conical spouted bed reactor followed by a catalytic fixed bed reactor. The good performance of the conical spouted bed reactor has allowed using a low temperature in thermal cracking (500°C) without defluidization problems, obtaining a volatile stream with a 90wt.% overall yield of C12–C20 and waxes in the first step. The effect of the second-step operating conditions on product yields and composition has been studied using a catalyst based on a HZSM-5 (SiO2/Al2O3 =30) zeolite. The influence of temperature in the 350–550°C range and space–time in the 0–8gcat min gHDPE −1 range has been studied. An increase in temperature or space–time gives way to an increase in the yield of light olefins, reaching a value of 62.9wt.% at 550°C and 8 gcat min gHDPE −1, with the individual yields of ethylene, propylene and butenes being 10.6, 35.6 and 16.7wt.%, respectively. Although the yield of single-ring aromatics increases when both variables studied are increased, the maximum yield obtained was lower than 13wt.%. The yield of waxes (the main product in the first step) is negligible even at low temperatures or spaces-times, which evidences the efficiency of the catalytic step. [Copyright &y& Elsevier]

Abstract: The thermal pyrolysis of three different polyolefin plastics (HDPE, LDPE and PP) has been carried out in a conical spouted bed reactor. This technology is especially interesting because of the high selectivity to waxes due to the low residence times and high heating rates that reduce secondary reactions and increase the yield of primary pyrolysis products (waxes). These have been obtained operating at 450, 500 and 600°C and a complete characterization has been carried out using different techniques, such as gel permeation chromatography (GPC), Fourier transform infrared (FTIR) spectrophotometry, simulated distillation and the measurement of heating value and melting point. Operating conditions and feed type have been observed to have a significant effect on the properties of the different waxes. The characterization has been carried out bearing in mind the potential use of waste plastic-derived waxes as a feedstock for cracking units. [Copyright &y& Elsevier]

Abstract: The hydrocracking of pyrolysis gasoline (70wt% of aromatics) has been studied using an integral fixed bed reactor with a Pt–Pd/HZSM-5 (0.2wt% Pt, 0.48wt% Pd; SiO2/Al2O3 =19) catalyst over a wide range of experimental conditions: 350–450°C; 20–50bar; P PyGas =1bar, H2:PyGas molar ratio (), 20–49; WHSV, 2.7–32h−1; Under these experimental conditions the deactivation is negligible and therefore data in the stationary state have been reported. Based on previous models for the hydrocracking of model compounds (methylcyclohexane and toluene), we have proposed a kinetic diagram and kinetic equations that satisfactorily describe the product distribution under the experimental conditions studied. The experimental data have been fitted to the proposed model and its parameters have been estimated. The kinetic model is used for reactor simulation and optimization. [Copyright &y& Elsevier]

Abstract: The deactivation of three different catalysts used in the cracking of high density polyethylene (HDPE) has been compared. The catalysts used are HZSM-5, Hβ and HY zeolites agglomerated with bentonite and alumina. The reactions have been carried out in a conical spouted bed reactor at 500°C, and plastic (high density polyethylene) has been fed in continuous mode (1gmin−1) for up to 15h of reaction. The HZSM-5 zeolite catalyst gives way to high yields of C2–C4 olefins (57wt%) and, moreover, it is the one least influenced by deactivation throughout the run, which is explained by the lower deterioration of its physical properties and acidity. The results of temperature program combustion and transmission electron microscopy show that coke growth is hindered in the HZSM-5 zeolite pore structure. The high N2 flow rate used in the conical spouted bed reactor enhances coke precursor circulation towards the outside of the zeolite crystal channels. [ABSTRACT FROM AUTHOR]

Abstract: Activation of tyre char has been carried out using steam as activation agent, and the effect of temperature and activation time has been studied. The char samples used in the activation have been obtained by continuous flash pyrolysis carried out in a conical spouted bed reactor at 500°C. The activation has been carried out at 850 and 900°C in a fixed bed reactor. During the process, a mesoporous structure is developed, with a predominant pore diameter of around 500Å and BET surface areas above 500m2/g for both the temperatures studied. Moreover, sulphur content significantly decreases during activation and activated carbons with low sulphur content are obtained. This reduction in content may be the key for the industrial application of tyre-derived-carbons, either as active carbons or as carbon blacks for tyre manufacturing. [Copyright &y& Elsevier]

Abstract: A commercial FCC catalyst based on a zeolite active phase has been used in the catalytic pyrolysis of HDPE. The experimental runs have been carried out in a conical spouted bed reactor provided with a feeding system for continuous operation. Different treatments have been applied to the catalyst to improve its behaviour. This paper deals with the optimization of catalyst steaming and pyrolysis temperature in order to maximize the production of diesel-oil fraction. The performance of the fresh catalyst has been firstly studied at 500°C. This catalyst gives way to 52wt% gas yield, 35wt% light liquid fraction and a low yield of C10 + fraction (13wt%). After mild steaming (5h at 760°C) the results show a significant improvement in product distribution. Thus, gas yield decreases to 22wt%, the yield of light liquid is similar to that of the fresh one (38wt%), whereas the yield of the desired C10 + fraction increases to 38wt%. Nevertheless, the best results have been obtained when a severe steaming is applied to the catalyst (8h at 816°C) and pyrolysis temperature is reduced to 475°C. There is a significant reduction in the gaseous fraction (8wt%). The light liquid fraction has also been reduced to 22wt%, but the yield of diesel fraction increases to 69wt%. Moreover, the deactivation of the catalyst has also been studied under the optimum conditions. [Copyright &y& Elsevier]

Scrap car tyres have been pyrolysed in a conical spouted bed reactor at 425, 500, 550 and in batch operation. The pyrolysis products have been analysed on-line in a gas chromatograph. Temperature has a great influence on the product distribution of gas, liquid, aromatics and tar fraction. The gas and aromatic fractions increase with temperature, whereas liquid and tar fractions decrease. A detailed identification of the composition of the fractions has been carried out. [Copyright &y& Elsevier]

The thermal fast pyrolysis of high density polyethylene (HDPE) has been carried out in a conical spouted bed reactor in the 450–715°C range, and individual products have been monitored with the aim of obtaining kinetic data for the design and simulation of this process at large scale. Kinetic schemes have been proposed in order to explain both the results obtained in the laboratory plant and those obtained in the literature by other authors operating at laboratory and larger scale. Discrimination has been carried out based on the contribution of the variance of model parameters (stepwise regression) to the total variance explained by the model. The models based on that of Westerhout et al. [R.W.J. Westerhout, J. Waanders, W.P.M. Van Swaaij, Recycling of polyethene and polypropene in a novel bench-scale rotating cone reactor by high-temperature pyrolysis. Ind. Eng. Chem. Res. 37 (6) (1998) 2293–2300] do not adequately predict the experimental results, especially those corresponding to aromatics and char, which is probably due to the very short residence times attained in the conical spouted bed and, consequently, to the lower yields of aromatics and char. The model of best fit is the one where polyethylene degrades to give gas, liquid (oil) and wax fractions. Furthermore, the latter undergoes secondary reactions to give liquid and aromatics, which in turn produce more char. [Copyright &y& Elsevier]

Abstract: The catalytic pyrolysis of high density polyethylene (HDPE) on a HY zeolite catalyst has been carried out in a conical spouted bed reactor (CSBR) at 500°C, and individual products have been monitored with the aim of obtaining product distribution data. The CSBR does not have defluidization problems in the pyrolysis of plastics. The 69wt% of the product stream corresponds to the gasoline fraction (C5–C10). It is noteworthy that this fraction fulfils European Union requirements for commercial gasoline and its RON index, 96.5, is of the same order as standard automotive fuel. The remaining products are mainly gases, especially propylene and butenes, although there is also a heavy fraction consisting of aromatics with more than one ring and unreacted waxes. [Copyright &y& Elsevier]