Diverse biomass sources from the Canary Islands (vineyard, tomato plant residues, Canary pine needles and Pennisetum setaceum) ) were assessed due to their local abundance, availability, and low supply cost. Based on their physico-chemical properties, various thermochemical processes were conducted to assess their thermal degradation behaviour, using simultaneous thermal analysis, and their potential for energy production. The results indicate that while tomato plant biomass is unsuitable for thermochemical processes because of its elevated ash content and limited volatile matter, the other biomass sources show promising potential for pyrolysis and gasification, characterized by high fixed carbon content and reactivity. The yearly production of residual biomass in the Canary Islands was quantified at 87,253 tonnes. This biomass could generate an estimated 88.5 GWh of electricity annually. Considering that electricity consumption in the Canary Islands reached 8750 GWh in 2023, biomass-derived electricity could contribute approximately 1.0 % to the archipelago's energy needs. These findings highlight the significant role of local biomass resources in advancing renewable energy goals and reduce dependence on non-renewable sources, promoting a greener energy landscape for the Canary Islands.

A selection of some biomass sources from the Canary Islands, such as agricultural biomass (vineyard, VB; tomato plant, TPB), forestry biomass (Canary pine needles, CPB) and invasive species (Pennisetum setaceum, PSB) were evaluated to determine their potential as solid biofuels due to their abundant level, availability and low supply cost. In this work, the main physico-chemical properties (moisture content, ash content, volatile matter, fixed carbon, CHNOS content, mineral content, heating value, density, etc.) of the four biomasses were evaluated. From the results of this study it can be concluded that the TPB is not considered suitable due to its very high ash content and its relatively low content of volatile matter. However, VB, CPB and PSB proved to be potential candidates for energy generation through thermochemical conversion.

A packed-bed catalytic configuration reactor using pumice granules loaded with lithium (Li/Pumice) as a heterogeneous catalyst was developed for biodiesel production in continuous. For this purpose, Jatropha curcas oil was used as an alternative feedstock to edible oils and diethyl ether was used as a cosolvent to eliminate the limitations of mass transfer between the phases. In this work, the response surface methodology was applied to optimize the fatty acid methyl esters (FAME) yield in biodiesel production. The flow rate (0.7-1.4 mL min-1), the methanol/oil molar ratio (6:1-20:1) and the cosolvent/methanol molar ratio (0.5:1-1.5:1) were the independent variables studied. The effects of these factors over the FAME yield using Li/Pumice as catalyst were evaluated according to a Box-Behnken design. The optimum conditions for the maximum FAME yield (100%) were 1.4 mL min(-1), 20.0 methanol/oil molar ratio and 0.57:1 cosolvent/methanol molar ratio.

Tenerife is one of the main islands of the Canary Islands, which, due to its characteristics as outermost region, has a high energy dependence as well as a limitation on available territory; in addition, as it has been designated as a Remote Area, the elimination of Animal By-Products (ABPs) in landfills is permitted. This treatment does not contribute to the current trend of a circular economy and negatively harms the environment. The energy recovery of this waste through anaerobic digestion to produce biogas would enhance the use of renewable energies, contributing to the meat industry's energy independence and better management of the waste generated by this industry in Tenerife, promoting an energy transition towards cleaner energies. The study of the potential for biomethanization has been carried out both separately and in co-digestion in search of the best biogas production. Of the samples studied, only biogas was obtained in the anaerobic digestion of the rumen content, sewage sludge and for the co-digestion of viscera (cattle, pigs, goats, sheep, and rabbits) with raw blood and sewage sludge. The latter produces 128 mL of biogas per gram of volatile solids (VS) of the mixture, resulting in a total of 4,800 kWhe of electrical energy for Tenerife's estimated waste in 2019.

Due to the success of the use of energy crop oils in the production of biodiesel, the heavy cultivation of these plants in many countries is being promoted. However, it may lead to the problem with its associated waste shells, which contain low nutrient; consequently, they are not suitable for use as an agricultural fertilizer, and they are abundant in hemicellulose, cellulose, and lignin resulting in difficult to digest or degrade. Thus, a possible solution for this waste is to convert it into carbon-based adsorbents. Specifically, activated carbon is a product with a high added value, widely used material due to its adsorbent properties. These adsorbents could be used for reducing the free fatty acids content presents in oils intended for the biodiesel production. The presence of free fatty acids in the oils is undesirable for biodiesel production due to a performance reduction in the transesterification reaction. The aim of this work is to use biomass waste such as Jatropha curcas and Pongamia pinnata shells for the preparation of carbon-based materials (activated carbons, Ca(OH)2 supported on activated carbons and charcoals) and to study the possibility of using them as adsorbents for reducing the free fatty acids content of Jatropha curcas and Pongamia pinnata oils.

The increasing importance of sustainability in energy production has led to a global commitment to the use of fuels derived from renewable biological sources, such as biodiesel produced from plant crops or biomass residues, that do not compete with human food for their production. For a biofuel to be considered biodiesel, it must satisfy the specifications described in the UNE 14214, with the UNE-EN 14103 referring to the determination of fatty acid methyl ester content. This standard applies gas chromatography as an analytical technique. Gas chromatography is a widely used technique in the analysis of methyl ester although it has a number of drawbacks such as: long analysis times, a high consumption of high-quality gases and internal standards, does not allow the analysis of different compounds with the same column, etc. From an industrial production point of view, is necessary to know the fatty acid methyl ester content in biodiesel samples quickly. This paper studies the development of an analytical method using Fourier transform infrared spectroscopy (FTIR) as alternative to gas chromatography (GC), since it is a simple, rapid, and precise analytical technique to quantify fatty acid methyl ester content in biofuel samples.

An experimental study of the effect of temperature and pressure on zeta potential of typical reservoir minerals, including quartz, kaolinite, and calcite, is presented. Experiments included the design and construction of an electrophoretic cell for zeta potential measurements at variable pressure and temperature. Electrolyte concentration was varied in the range from 0.0001 to 0.1 M in the pH range from 2 to 9. For all the minerals it is found that the zeta potential decreases with temperature at a rate characteristic of each mineral; values are around −2.3 mV/°C for quartz, −0.96 mV/°C for kaolinite, and −2.1 mV/°C for calcite for pressure values less than 45 psi. The effect of pressure is found to depend on the mineral nature and pH of the electrolytic solution. In the case of quartz, a systematic increase in the value of the zeta potential with pressure is observed, whereas a decreasing trend is measured for the kaolinite. In the case of calcite, a decreasing trend is observed for pressures up to 45 psi, whereas the experimental data suggest an increasing trend for higher pressure values.

Activated carbon was modified with different sodium carbonate solutions (0.5 to 3.0 M) to produce a series of possible antacids. The modified carbon was characterized by means of XRD and BET surface area measurements. XRD confirmed the presence of bicarbonate species on the surface of the modified carbons, while the surface areas indicated that microporous of the solids were partially blocked. These solids were tested as antacids in a synthetic gastric juice. Results showed that these new antacids are effective to control the stomach hyperacidity. Furthermore, they are expected to be less expensive due to their low production costs.

A series of carbonated–nitrated cancrinite-type zeolites were synthesized using X zeolite as silicon and aluminum source and metallic cations such as magnesium, aluminum and their mixture as templates. The synthesized solids were characterized by means of techniques such as XRD, FT-IR, UV–visible, DTGA, BET surface area and chemical analysis. The XRD analysis confirmed the presence of cancrinite-type zeolite without the presence of other phases. The solids were tested in a synthetic gastric juice simulating condition of hyperacidity. Small doses of solids were enough to adjust the pH of the system. These results were compared to those obtained with a commercial hydrotalcite based drug. Both solids showed comparable results. Additionally, the solid–pepsin interaction was also evaluated among the synthesized cancrinite-type zeolites.

Se sintetizaron una serie de zeolitas carbonatadas tipo cancrinitas usando zeolitas FAUX como fuente de Si y Al, y como agentes direccionadores, se emplearon los cationes metalicos: Mg, Al y la mezcla de ambos. Adicionalmente, se sintetizaron hidrotalcitas con relacion Al/(Al+Mg) igual a 0,20, 0,25 y 0,33. Estos solidos sintetizados fueron caracterizados por diversas tecnicas fisicoquimicas, tales como: analisis quimico, difraccion de rayos X (DRX), analisis termogravimetrico (TGA), espectroscopia de infrarrojo (IR), espectroscopia UV-visible y medidas de area superficial. Los analisis de DRX de los solidos sintetizados confirmaron la presencia de cancrinita e hidrotalcita sin otras fases colaterales. Los solidos fueron evaluados frente a un jugo gastrico sintetico simulando la hiperacidez estomacal. Pequenas dosis de los mismos fueron suficientes para normalizar el pH del sistema. Estos resultados fueron comparados con los obtenidos usando un medicamento comercial a base de hidrotalcita, el cual presento un comportamiento muy similar a la mejor de las cancrinitas sintetizadas. Adicionalmente, la interaccion solido-pepsina fue bastante baja, confirmado la posibilidad de utilizarlos como agentes terapeuticos contra la acidez estomacal.

A series of carbonated cancrinite-type zeolites were synthesized using FAUX-type zeolites as the sources of silicon and aluminum. Metallic cations such as magnesium, aluminum and their mixture were used as templates. Additionally, hydrotalcites with an Al/(Al+Mg) ratio of 0.20, 0.25 and 0.33 were also synthesized. The solids were characterized by means of techniques such as XRD, FT-IR, UV-visible, TGA, BET surface area and chemical analysis. The XRD analyses confirm the presence of cancrinite-type zeolite and hydrotalcites, without occurrence of other phases. The solids were tested with a synthetic gastric fluid, simulating conditions of hyperacidity. Small doses of the solids were sufficient to adjust the pH of the system. These results were compared to those obtained with a commercial hydrotalcites-based formula. Both solids showed comparable results. Additionally, the solid-pepsin interaction was also evaluated in the synthesized solids, stressing the possible use of these solids as therapeutic antacids. Key Words: Cancrinite, hydrotalcite, antacid, carbonates, Al, Mg.

A series of molecular-sieves comprising dealuminated Y and mordenite zeolites (DY and DMOR) and unmodified SAPO-5, were tested as catalysts for the transformation of α-pinene in both gas and liquid phase. Selectivity to camphene was higher in liquid phase. Deactivation in gas phase was very pronounced. Based on the gas-phase specific rate of transformation, the following site-strength series was obtained: DMOR>SAPO-5>DY. The catalyst DMOR also showed the highest M/B ratio (monocyclic-to-bicyclic terpene products).

A series of highly crystalline silicoaluminophosphates having the AFI topology (SAPO-5) were synthesized with silicon content varying from 0 (AlPO4-5) to 0.11 molar fraction. As the silicon content increases, the total acidity per gram of solid, as determined by temperature programmed desorption of ammonia (NH3-TPD), also increases. However, the number of total acid sites per Si atom decreases by about 20% when passing from the lowest to the highest Si-containing SAPO. The previous finding is in line with the higher SM2+SM3 Si-substitution character of the latter, as determined by the 29Si MAS NMR technique. Brönsted sites retaining pyridine above 623K (medium+strong acidity) increase progressively with the Si content; however, only the solid with the lowest Si-loading showed Lewis sites of high acid strength. The highest specific activity observed for the latter sample during both the m-xylene and the α-pinene transformation can then be explained by the occurrence of a Lewis–Brönsted synergism. The specific rate of α-pinene transformation over SAPO-5 lay between that for dealuminated mordenite and that for dealuminated Y-zeolite. Camphene and limonene were the main products of the α-pinene transformation amounting up to 80% of the α-pinene converted, with a camphene/(camphene+limonene) ratio of 0.50, at conversion levels between 48 and 55%. Undesirable heavy compounds (HRTP) were less than 1%.

The transformation of α-pinene was studied in both gas and liquid phase over a series of faujasite‐like zeolites having different framework composition. A comparison with an amorphous silicoaluminate having 13 wt% of Al 2 O 3 (SA) was made. Camphene + limonene were the major products observed in liquid phase at 393 K at conversion levels lower than 90%. At 473 K, where the reaction in gas phase took place, limonene suffered an ulterior transformation mainly into terpinenes and terpinolenes and a faster deactivation of the zeolite catalysts as compared to the one in liquid phase was observed. This behaviour contrasts with the high stability shown by SA in gas phase. Over the wider pore system of SA undesired heavy products were formed in liquid phase at the expenses of the terpene isomers. However, in gas phase this ulterior transformation of monoterpenes was minimised. A maximum activity for the zeolite catalysts was observed when the number of Al IV per unit cell reached about 17, a value where the population of Si(0Al) sites has been shown to reach the maximum.

Dealuminated mordenite (MOR) and faujasite (FAU) zeolites, and a 13% alumina amorphous aluminosilicate were tested as catalysts for the liquid-phase transformation of cr-pinene at 120 degrees C in a batch reactor. Limonene and camphene were the main products observed over zeolites. Mordenites gave the maximum yield (68%) of limonene and camphene with a selectivity of camphene/(limonene+camphene) greater than 0.54. Wider pore diameters and larger pore volumes gave higher yields of undesired products, probably sesquiterpenes and other heavy compounds. The amorphous aluminosilicate selectivity to camphene+limonene was the poorest (18%) and gave the highest yield of undesired products (48%). The specific transformation rate of cl-pinene passes through a maximum at 0.4 Al-IV per 1000 Angstrom(3) Of unit cell, corresponding to 1 Al-IV/MOR unit cell or 6 Al-IV/FAU unit cell. (C) 1998 Elsevier Science B.V. All rights reserved.

XRD-pure SAPO-31 and SAPO-11 molecular sieves were obtained from the same synthesis gel, free of seeding, with a relatively low DPA/P2O5 ratio (0.3) after 40 and 120 h of crystallization, respectively, at 353 K. The phase transformation sequence was closely followed by XRD. The initial formation of the dense phases berlinite (B) and cristobalite (C) in the starting gel at a defined proportion seems to play an important role in directing the synthesis toward the desired molecular sieves. Structural factors were invoked to explain differences in the selectivity toward isobutene, observed for samples of SAPO-31 and SAPO-11 with similar acidity characteristics, during the transformation of 1-butene at 743 K and WHSV of 1.8 h(-1). (C) Elsevier Science Inc. 1997.

Fecha de recepción: 30 de octubre de 2007 Fecha de revisión: 25 de agosto de 2008 Fecha de aceptación: 2 de septiembre de 2008