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- Preliminary study on the use of biodiesel obtained from waste vegetable oils for blending with hydrotreated kerosene fossil fuel using Calcium Oxide (CaO) from natural waste materials as heterogeneous catalystPublication . Ozkan, Sila; Puna, Jaime; Gomes, João; Cabrita, T.; Palmeira, José; Santos, Maria TeresaIn this experimental work, calcium from natural seafood wastes was used as a heterogeneous catalyst separately or in a blend of "shell mix" for producing biodiesel. Several chemical reaction runs were conducted at varied reaction times ranging from 30 min to 8 h, at 60 degrees C, with a mass content of 5% (W-cat./W-oil) and a methanol/oil molar ratio of 12. After the purification process, the biodiesel with fatty acid methyl ester (FAME) weight content measured was higher than 99%, which indicated that it was a pure biodiesel. This work also showed that the inorganic solid waste shell mixture used as the heterogeneous catalyst can be reused three times and the reused mixture still resulted in a FAME content higher than 99%. After 40 different transesterification reactions were performed using liquid (waste cooking oils) and solid (calcium seafood shells) wastes for producing biodiesel, under the specific conditions stated above, we found a successful, innovative, and promising way to produce biodiesel. In addition, blends prepared with jet fuel A1 and biodiesel were recorded with no invalid results after certain tests, at 25 degrees C. In this case, except for the 10% blend, the added biodiesel had no significant effect on the viscosity (fluidity) of the biojet fuel.
- Synthesis gas production from water electrolysis, using the Electrocracking conceptPublication . Guerra, Luís; Moura, K.; Rodrigues, J.; Gomes, João; Puna, Jaime; Bordado, João; Santos, Maria TeresaThe present research work is focused on the production of synthesis gas by water electrolysis, using renewable electric energy and, further on, liquefied biomass as a carbon source necessary for obtaining carbon monoxide and carbon dioxide. In order to demonstrate and also optimize this process, this study comprised the influence of the electrolyte concentration, liquefied cork concentration, temperature and pressure and the main process outputs, such as: the flow rate of the produced gas, carbon monoxide, carbon dioxide and oxygen composition, as well as the energy consumed in the process. This gas can further on, be used for producing renewable synthetic fuels, such as: methane, methanol, dimethyl ether (DME), diesel, etc. The optimum operational conditions thus determined for this process, at laboratory scale, comprised the use of NaOH 1.2 M mixed with 20% (v/v) liquefied cork, as electrolyte. Applying these operating conditions a synthesis gas composed of 66.67% H2, 25.32% CO, 0.00% CO2 and 8.01% O2 was obtained at a flow rate of 8.31 L/h, consuming a power of 7.75 Wh/L. Also, the analysis of the residual biomass deposited in the electrodes showed some changes in the initial structure, as expected.
- Methane production by a combined Sabatier reaction/water electrolysis processPublication . Guerra, Luís; Rossi, S.; Rodrigues, J.; Gomes, João; Puna, Jaime; Santos, Maria TeresaThis paper describes production of synthesis gas (syngas) and its optimization through a one-step innovative 1 kW prototype of alkaline water electrolysis (patented), using graphite electrodes and without gas separation (containing CO, CO2, H2 and small amounts of O2). The behavior of the syngas composition and flow rate has been studied and optimized, changing operational parameters such as temperature, pressure and current intensity, and testing two different kinds of electrodes. Afterwards, the best syngas composition has been sent into a catalytic reactor (filled with a bed of Ni/CaO-Al2O3 catalyst) in order to achieve methane production, at 1 bar and different temperatures. The main competitive advantage of this process lies in the built-in of an innovative technology product, from renewable energy (RE) power in remote locations, such as islands, villages in mountains as an alternative for energy storage for mobility constraints. In the catalytic reactor it was possible to achieve a CH4 yield of 25.5 %, a CO2 conversion into CH4 of 44.2% and a CH4 selectivity of 96.5%.
- Towards the development of syngas/biomethane electrolytic production, using liquefied biomass and heterogeneous catalystPublication . Gonçalves, Ana; Puna, Jaime; Guerra, Luís; Rodrigues, José Campos; Gomes, João; Santos, Maria Teresa; Alves, DiogoThis paper presents results on the research currently being carried out with the objective of developing new electrochemistry-based processes to produce renewable synthetic fuels from liquefied biomass. In the current research line, the gas mixtures obtained from the typical electrolysis are not separated into their components but rather are introduced into a reactor together with liquefied biomass, at atmospheric pressure and different temperatures, under acidified zeolite Y catalyst, to obtain synthesis gas. This gaseous mixture has several applications, like the production of synthetic 2nd generation biofuel (e. g., biomethane, biomethanol, bio-dimethyl ether, formic acid, etc.). The behaviour of operational parameters such as biomass content, temperature and the use of different amounts of acidified zeolite HY catalyst were investigated. In the performed tests, it was found that, in addition to the synthesis gas (hydrogen, oxygen, carbon monoxide and carbon dioxide), methane was also obtained. Therefore, this research is quite promising, and the most favourable results were obtained by carrying out the biomass test at 300 degrees C, together with 4% of acidified zeolite Y catalyst, which gives a methane volumetric concentration equal to 35%.
- Production of synthesis gas obtained via alkaline water electrolysis and added biomassPublication . Gomes, João; Puna, Jaime; Santos, Maria TeresaThis paper presents the results of the research currently being carried out at ISEL with the objective of developing new electrochemistry-based processes to obtain renewable synthetic fuels from alkaline water electrolysis using a carbon source. In the developed process, the gas mixture obtained from alkaline water electrolysis and a carbon source is not separated into their components but rather is introduced into a catalyzed reactor, in order to achieve conversion to synthetic 2nd generation biofuels, such as biomethane, biomethanol, bio-dimethyl ether, etc. Tests have been previously executed in a pilot electrolyzer and reactor of 1 kW, and are now being scaled up to a pilot electrolyzer and reactor of 5 kW, producing 250 l/h CH4, as an intermediate step to a pilot of 100 kW.
- Calcium rich food wastes based catalysts for biodiesel productionPublication . Catarino, Maria Alice; Ramos, M.; Soares Dias, A. P.; Santos, Maria Teresa; Puna, Jaime; Gomes, JoãoBiodiesel produced from food wastes can help to solve several environmental issues: anthropogenic carbon emissions due to fossil fuels combustion and waste management. Biodiesel was produced using waste frying oils (WFO) and calcium rich food wastes such as mollusk, shrimp, eggs shells and cuttlebone to produce calcium based heterogeneous catalysts by calcination. The characterization of chalky white calcined powders by XRD showed diffraction lines typical of lime but some samples were slightly contaminated with calcite. The powders with low crystallinity showed high hydration rate presenting XRD features ascribable to nanocrystals of calcium hydroxide. The post reaction samples presented mainly lines due to calcium diglyceroxide and methoxide. Thermograms of used catalysts showed some weight loss of these calcium compounds, confirming the presence of such phases. All prepared catalysts were effective in catalyzing the methanolysis of soybean oil. A FAME yield around 96% was obtained after 2.5 h of reaction. When using WFO, the FAME yield was only 65% with simultaneous production of soap. The use of WFO and soybean oil mixtures attenuates the loss of catalytic performances. The obtained glycerin's presented a light color characteristic of heterogeneous catalyzed processes. FTIR spectra of glycerin's showed some features belonging to matter organic non glycerin and methanol. The catalyst reutilization without intermediate reactivation indicated that catalysts are somewhat stable. When WFO was used, the reused catalysts showed improved performance probably due to the formation of calcium diglyceroxide. Nevertheless, calcium diglyceroxide is bound to promote homogeneous catalysis and consequent deactivation.
- Conversão de dióxido de carbono em combustíveis sintéticos renováveis, através de um processo eletroquímicoPublication . Guerra, Luís Filipe; Rodrigues, J.; Puna, Jaime; Gomes, João; Santos, Maria TeresaProjeto que contempla um processo eletroquímico inovador de produção de combustíveis sintéticos renováveis a partir da conversão de CO2; Tecnologia emergente alternativa aos processos termoquímicos de oxidação de carbono (steam reforming e gaseificação do carvão); Os principais combustíveis a ser produzidos por esta via são: metanol, metano, DME, entre outros.