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Abstract: The purpose of this study was to investigate the influence of the method of adsorption of N2 at −196 °C on the isotherm obtained for, and hence derived textural parameters of, a wide series of carbonaceous materials (CM). Two pyrolyzed products, six activated carbons and two carbon blacks were used. The carbonized products were prepared by pyrolysis of cherry stones at 600 or 900 °C in nitrogen atmosphere (P-600, P-900). Three activated carbons were made by activation of P-600 at 275 °C in air and of P-900 at 850 °C in carbon dioxide or steam, whereas the remaining CM were commercial products. The adsorption isotherms for N2 at −196 °C were determined by static and dynamic methods in Quantachrome equipments. The CM were further characterized texturally by means of mercury porosimetry and helium and mercury density measurements. Because of the presence of helium in the adsorptive gas stream, the adsorption of nitrogen noticeably decreases for the CM containing micropores obstructed with tarry products (i.e. P-600 and the activated carbon prepared from it by air activation). For the rest of the activated carbons the adsorption increases, as they must possess narrow micropores having easier access to N2 at −196 °C. Helium causes a decrease in the degree of interaction between the nitrogen molecules in the gas stream and as a result the diffusion of nitrogen in pores of the adsorbent increases. For the carbon blacks, however, helium hardly affects the adsorption of nitrogen, except for at high relative pressures of this gas. Helium also influences the capillary condensation phenomenon occurring in mesopores. The variation percentages in the micro- and mesopore volumes are as high as 20 and 50, respectively. Such percentages as a rule are higher for the activated carbons. [Copyright &y& Elsevier]

Abstract: The pyrolysis process of Jerusalem artichoke (Heliantuhus tuberosus L.) waste was carried out. The objective of this work was to characterize the solid, liquid and gaseous phases, studying the influence of the operating variables and determining the optimal conditions. Thus, the influence of temperature (400–800°C), particle size (0.63–2.00mm), N2 flow rate (75–300mLmin−1) and initial sample mass (2.5–10g) were investigated. In these series, the yields of the three phases, their higher heating value and the proximate analysis of the solid phase were determined. Under the conditions of this study, an increase in reaction temperature leads to a decrease in the solid and liquid yields and to an increase in the gas phase yield. However, the variation of the initial sample mass and the particle size do not exert a defined influence in the yield of the three phases. On the other hand, increasing the N2 flow causes a decrease in the liquid and an increase in the gas yields. According to the energetic characterization of the phases generated, different uses were proposed. Finally, as previous step to the design of the industrial equipments, a kinetic study of the process, based on the generation of the principal gases, was accomplished. With this purpose, it was considered that the gases are formed through parallel independent first-order reactions, with different activation energies. From this model, rate constants for the formation of each gas and their corresponding activation energies were determined. [Copyright &y& Elsevier]

Abstract: The interest on energy recovery from renewable sources is increasing due to the global warming and fossil fuels limitation. Biomass thermochemical conversion methods present some significant advantages such as zero net emissions and the use of agricultural by-products. In this work, a study of the catalytic and non-catalytic pyrolysis of an exhausted olive waste was carried out. The objective was to characterize the solid, liquid and gaseous phases in terms of their energy content. Two experimental series were conducted: uncatalyzed processes, studying the influence of temperature in the range 400–900°C; and catalyzed ones, investigating the influence of temperature (500–800°C) and quantity of catalyst (0–100g). Also, the dolomite effectiveness as catalyst was evaluated. For this motive, consecutive experiments, without reactivating dolomite, were carried out (0–6 runs), and the yields of solids, liquids and gases were determined. It was found that increasing temperature leads in both series to a decrease in the solid and liquid yields and to an increase in the gas yield. The presence and amount of catalyst caused a significant decrease in the liquid phase yield and a high increase in the gas phase yield giving rise to a vast rise in hydrogen production. On the other hand, the catalyst proved to be stable and did not lose activity during at least six pyrolysis cycles. Finally, as a previous step to the design of industrial installations, a kinetic study of the process was performed, based on the generation of the principal gases, considering that these are formed through parallel independent first-order reactions, with different activation energy. [Copyright &y& Elsevier]

Abstract: Biomass samples (almond shell, walnut shell, almond tree pruning and olive stone) were subjected to thermoanalytical investigation to evaluate their thermal behaviour and its correlation with their lignocellulosic composition. Then, the pyrolysis process of these materials was studied in terms of the energy content of the phases generated (gas and liquid). Finally, the feasibility of obtaining effective adsorbents from the char generated was studied. With this aim, the char was used to prepare activated carbons (ACs) by steam gasification at fixed activation temperature and time, identical for the four chars. The differences found in the porosity development of the activated carbons were related to the lignocellulosic composition of the raw material. It is shown that the four biomass residues used are versatile precursors that allow the preparation of adsorbent materials with different textural characteristics. [Copyright &y& Elsevier]

Abstract: A study of the pyrolysis of a waste from the extraction of olive oil has been carried out. The work objective was to characterize the char, tar and gaseous phases generated in the process for their possible utilization in energy generation. On the other hand, the influence of a set of variables has been studied, including the efficacy of the dolomite as catalyst. Finally, as previous step to the design of industrial installations, a kinetic study of the process (catalyzed and uncatalyzed), based in the generation of the principal gases, has been carried out. In the uncatalyzed process only the influence of temperature (400–900 °C) was studied. In the catalytic process, the influence of temperature (500–800 °C) and mass of catalyst (0–100 g) was studied. Also, the dolomite effectiveness as catalyst was evaluated. For this motive, consecutive experiments, without reactivating dolomite, were carried out (0–6 runs), and the yields of solids, liquids and gases were determined. An increase in reaction temperature leads to a decrease in char and tar yield and to an increase in the gas phase yield. When the catalyst is present and when the mass of the same is increased, an important decrease in the tar yield and a high increase in the gas phase yield are produced. This increment in the yield of gases is very significant in the case of hydrogen. In addition, the catalyst is very stable. Your activity remains constant during six consecutive pyrolysis experiments, without need to carry out the reactivation of the same. In the kinetic study carried out, it has been considered that the gases are formed through parallel independent first-order reactions, with different activation energy. For uncatalyzed experiments, the experimental data, once adjusted to the model, provided activation energies of 77.8, 38.6, 70.5 and 16.9 kJ mol−1 and the Arrhenius pre-exponential factors of 210.1, 9.9, 775.3 and 0.43 min−1 for H2, CO, CH4, and CO2, respectively. For catalyzed experiments (following the same sequence) the activation energies were 15.6, 16.5, 12.7 and 23.3 kJ mol−1 and the Arrhenius pre-exponential factors 3.8, 1.4, 4.3 and 3.5 min−1. [Copyright &y& Elsevier]

Abstract: Thermal decomposition of natural polystyrene, recycled plastics, low density polyethylene, acrylonitrile butadiene styrene, polyenterophthalate of ethylene, and polypropylene has been carried out. Both isothermal and dynamic experiments at different heating rates have been performed in a thermobalance with the objective of determining the kinetic parameters. Also, a first set of experiments, performed in a cylindrical stainless-steel atmospheric pressure reactor, was designed to evaluate the products of the pyrolysis process. The effects of N2 flow rate (200–300 cm3 min−1), initial mass fed to the reactor (15–75 mg), temperature (415–490 °C), and heating rate (5–30 K min−1) were studied. By application of a first order kinetic model, the activation energy for every plastic has been determined. The values of activation energy in isothermic and dynamic regimen are the following: natural polystyrene: 136, and 168 to 286 kJ/mol. Recycled plastic: 250, and 150 to 290 kJ/mol. Low density polyethylene: 285, and 220 to 259 kJ/mol. Acrylonitrile butadiene styrene: 118, and 104 to 251 kJ/mol. Polyenterophthalate of ethylene: 161, and 117 to 255 kJ/mol. Polypropylene: 169, and 153 to 265 kJ/mol. [Copyright &y& Elsevier]

Abstract: Activated carbons were prepared from almond tree pruning by non-catalytic and catalytic gasification with carbon dioxide and their surface characteristics were investigated. In both series a two-stage activation procedure (pyrolysis at 800°C in nitrogen atmosphere, followed by carbon dioxide activation) was used for the production of activated samples. In non-catalytic gasification, the effect of the temperature (650–800°C for 1h) and the reaction time (1–12h at 650°C) on the surface characteristics of the prepared samples was investigated. Carbons were characterized by means of nitrogen adsorption isotherms at 77K. The textural parameters of the carbons present a linear relation with the conversion degree until a value of approximately 40%, when they come independent from both parameters studied. The highest surface area obtained for this series was 840m2 g−1. In the catalytic gasification the effect of the addition of one catalyst (K and Co) and the gasification time (2–4h) on the surface and porosity development of the carbons was also studied. At the same conditions, Co leads to higher conversion values than K but this last gives a better porosity development. [Copyright &y& Elsevier]

Abstract: In this work, a pyrolysis plant located in Valverde de Leganes, Badajoz (SW Spain) was studied. At present, only the solid phase obtained by pyrolysis finds an application as domestic fuel. In order to analyze the feasibility of a further energetic exploitation of the plant under study, the gases flowing through the chimneys were collected at different times throughout the pyrolysis process. Next, they were characterized and quantified by gas chromatography, the energy potential of each of the gases being determined. According to the results obtained in this study, a total energy potential of 5.6×107 MJ (i.e., 1.78MWt) might be generated yearly. Hence, considering an overall process yield equal to 20%, up to 358KWe would be produced. This power would supply enough electric energy to the industry, the remaining being added to the common electric network. [Copyright &y& Elsevier]

Water contamination by organic compounds is an important environmental problem. Activated carbon filters are widely used to eliminate these contaminants. After exhaustion, activated carbon must be regenerated or replaced by fresh carbon. In this study thermal regeneration of saturated carbon with p-nitrophenol has been analysed. Three thermal regeneration methods have been tested: (1) pyrolysis, (2) pyrolyis-gasification and (3) direct gasification, the gasifying agents being air and CO2. The results show that the pyrolysis treatment does not completely eliminate the contaminant from the carbon and the recovery of the initial adsorption properties is rather limited. The effect of gasification depends on both the gasifying agent and the sample (pyrolysed or saturated with PNP). CO2-gasification yields to a complete regeneration of the adsorption characteristics in both pyrolysis-gasification and direct gasification samples. In general, air-gasification produces lower regeneration properties, although direct air-gasification sample has 87% recovery of the PNP maximum adsorption capacity. These results suggest that thermal regeneration could be carried out in a single step, simplifying the process and reducing the operation cost. Moreover, although CO2 seems to give better recovery of the initial carbon characteristics than air, it should be noted that air is cheaper and the regeneration time is shorter. [Copyright &y& Elsevier]

The present work reports on the study of biofuel production from biooil obtained by cardoon pyrolysis ( Cynara cardunculus L.). The main process was carried out at 700 °C and at 50 cm 3 min −1 nitrogen flow rate for 1 h. The liquid yield in such pyrolysis process was 38.91% (wt/wt). Two solvents were used for biofuel extraction, namely ethyl ether and ethyl acetate, to achieve a 34.72% yield in biofuel. Subsequently, a distillation process in the range of kerosene (200–275 °C) was performed to finally obtain “biokerosene”, which was used to feed both a self-manufactured jet engine and an internal combustion engine (ICE). In the jet engine, experimental tests were run for four kerosene/biofuel mixtures in the range 0–20% biofuel, in atmospheric conditions (20 °C and 1015 mbar) and setting the engine in a slightly sloped arrangement in order to prevent excessive displacements. Fuel pressure at maximum power was recorded as 6 bar, which yielded 0.00252 kg s −1 fuel flow rate. Results –even for the mixture with 20% biofuel content– were found to be similar to those for pure kerosene. The turbocharger yield was 74% with 200,000 rpm and 0.091 kg s −1 air flow rate for all conditions, which equates to an approximate power of 100 hp for the use of the turbocharger in self-propulsion. On another note, the ICE was operated using a 80–20% diesel-biokerosene mix and was observed to show a satisfactory behaviour in terms of torque and power yields. The use of such biofuels to feed jet and ICE engines represents an excellent alternative to fossil fuels, and therefore quality improvement is a key topic for further research in the area. [ABSTRACT FROM AUTHOR]

Highlights: [•] Cyclic thermal regeneration of paranitrophenol spent adsorbents was studied. [•] The adsorbent showed increasing resistance towards regeneration. [•] Porosity became more and more difficult to recover. [•] A general pore widening was found as the number of cycles increased. [•] The permanence of cracking products was consistent with the surface chemistry changes. [Copyright &y& Elsevier]