| 1. |
- Caetano de Souza, Antonio Carlos, et al.
(författare)
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A low cost & safe system of hydrogen production utilizing NaBH4 and CoO catalysis
- 2007
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Ingår i: 2nd International Congress University-Industry Cooperation (UNIDU07).
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Konferensbidrag (refereegranskat)abstract
- The objective of this study was to evaluate the hydrogen production through hydrolysisof sodium borohydride (NaBH4) utilizing catalysts containing CoO. The reactant is safe and stable(when dry) at room temperature. Few works and studies have presented results of investigationsutilizing catalysts containing cobalt; however utilizing catalysts containing CoO were not found yet.In this work simple and cheap hydrogen generation system was developed having reactions atnormal conditions of temperature and pressure. A solution containing a gravimetric composition of10% wt. NaOH, 10% wt. NaBH4 and 80% wt. H2O was utilized. The reaction was carried out atvarious times using the same catalyst to evaluate its performance. This catalyst presented highrates of hydrogen production, especially at its start-up (about 99% of the theoretical hydrogenvolume was produced) at room temperature. After start-up, e.g., when more solution was put, rateof hydrogen production decreased having its production performance also decreased. Probablythis fact occurred due to the formation of the solid phase products such as NaBO2 which might fillthe porous catalyst structure; decreasing the catalytic area. This catalyst is suggested in situationswhere high production rates are necessary such as start-up of fuel cells.
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| 2. |
- Caetano de Souza, Antonio Carlos, et al.
(författare)
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Hydrogen production through hydrolysis of NaBH4: The use of catalysts containing Pt and Pt-Ru
- 2007
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Ingår i: 2nd International Congress University-Industry Cooperation (UNIDU07).
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Konferensbidrag (refereegranskat)abstract
- Several works about hydrolysis of NaBH4 utilizing various catalysts (such as catalysts containing Pt or Ru) are available in the literature. Investigations involving NaBH4 has increased due to the possibility to produce hydrogen using simple and safe systems, even at room temperatures with very high efficiencies. A solution containing a gravimetric composition of 10%wt. NaOH, 10%wt. NaBH4 and 80%wt. H2O was utilized and the reaction was initiated immediately as soon as this solution was put in the chosen catalysts, in this case, catalysts containing Pt and mixtures of Pt-Ru. Catalysts containing Pt and Pt-Ru presented high yields of hydrogen after the solution being inserted in the reaction vessel several times. In this study it was found out that the rates of hydrogen production were increased with catalysts containing Pt and Pt-Ru (99 and 96% of theoretical hydrogen production respectively). The catalysts containing Pt presented higher production rate, while the catalysts containing the mixed Pt-Ru presented a quasi-linear production, e.g., stable production rate.
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| 3. |
- Coronado, Christian Rodriguez, et al.
(författare)
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Development of a thermoeconomic methodology for optimizing biodiesel production. Part II : Manufacture exergetic cost and biodiesel production cost incorporating carbon credits, a Brazilian case study
- 2014
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Ingår i: Renewable & sustainable energy reviews. - : Elsevier BV. - 1364-0321 .- 1879-0690. ; 29, s. 565-572
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Forskningsöversikt (refereegranskat)abstract
- The purpose of this study is to carry on a thermoeconomic analysis at a biodiesel production plant considering the irreversibilities in each step (part I: biodiesel plant under study and functional thermoeconomic diagram [1]), making it possible to calculate the thermoeconomic cost in US$/kWh and US$/1 of the biodiesel production, and the main byproduct generated, glycerin, incorporating the credits for the CO2 that is not emitted into the atmosphere (carbon credits). Assuming a sale price for both the biodiesel and the byproduct (glycerin), the annual revenue of the total investment in a plant with a capacity of 8000 t/year of biodiesel operating at 8000 h/year was calculated. The variables that directly or indirectly influence the final thermoeconomic cost include total annual biodiesel production, hours of operation, manufacturing exergy cost, molar ratio in the transesterification reaction, reaction temperature and pressure in the process. Depending on the increase or decrease in sale prices for both biodiesel and glycerin, the payback is going to significantly increase or decrease. It is evident that, in exergy terms, the sale of glycerin is of vital importance in order to reduce the biodiesel price, getting a shorter payback period for the plant under study.
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| 4. |
- Coronado, Christian Rodriguez, et al.
(författare)
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Development of a thermoeconomic methodology for the optimization of biodiesel production-Part I : Biodiesel plant and thermoeconomic functional diagram
- 2013
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Ingår i: Renewable & sustainable energy reviews. - : Elsevier BV. - 1364-0321 .- 1879-0690. ; 23, s. 138-146
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Tidskriftsartikel (refereegranskat)abstract
- This work developed a methodology that uses the thermoeconomic functional diagram applied for allocating the cost of products produced by a biodiesel plant. The first part of this work discusses some definitions of exergy and thermoeconomy, with a detailed description of the biodiesel plant studied, identification of the system functions through Physical Diagram, calculation of the irreversibilities of the plant, construction of the Thermoeconomic Functional Diagram and determination of the expressions for the plant's exergetic functions. In order to calculate the exergetic increments and the physical exergy of certain flows in each step, the Chemical Engineering Simulation Software "HYSYS 3.2" was used. The equipments that have the highest irreversibilities in the plant were identified after the exergy calculation. It was also found that the lowest irreversibility in the system refers to the process with a molar ratio of 6:1 and a reaction temperature of 60 degrees C in the transesterification process. In the second part of this. work (Part II), it was calculated the thermoeconomic cost of producing biodiesel and related products, including the costs of carbon credits for the CO2 that is not released into the atmosphere, when a percentage of biodiesel is added to the petroleum diesel used by Brazil's internal diesel fleet (case study).
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| 5. |
- Endalew, Abebe K., et al.
(författare)
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Heterogeneous catalysis for biodiesel production from Jatropha curcas oil (JCO)
- 2011
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Ingår i: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 36:5, s. 2693-2700
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Tidskriftsartikel (refereegranskat)abstract
- This work focuses on the development of heterogeneous catalysts for biodiesel production from high free fatty acid (FFA) containing Jatropha curcas oil (KO). Solid base and acid catalysts were prepared and tested for transesterification in a batch reactor under mild reaction conditions. Mixtures of solid base and acid catalysts were also tested for single-step simultaneous esterification and transesterification. More soap formation was found to be the main problem for calcium oxide (CaO) and lithium doped calcium oxide (Li-CaO) catalysts during the reaction of jatropha oil and methanol than for the rapeseed oil (RSO). CaO with Li doping showed increased conversion to biodiesel than bare CaO as a catalyst. La(2)O(3)/ZnO, La(2)O(3)/Al(2)O(3) and La(0.1)Ca(0.9)MnO(3) catalysts were also tested and among them La(2)O(3)-ZnO showed higher activity. Mixture of solid base catalysts (CaO and Li-CaO)and solid acid catalyst (Fe(2)(SO(4))(3)) were found to give complete conversion to biodiesel in a single-step simultaneous esterification and transesterification process. (C) 2011 Elsevier Ltd. All rights reserved.
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| 6. |
- Endalew, Abebe K., et al.
(författare)
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Inorganic heterogeneous catalysts for biodiesel production from vegetable oils
- 2011
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 35:9, s. 3787-3809
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Forskningsöversikt (refereegranskat)abstract
- Biofuels are renewable solutions to replace the ever dwindling energy reserves and environmentally pollutant fossil liquid fuels when they are produced from low cost sustainable feedstocks. Biodiesel is mainly produced from vegetable oils or animal fats by the method of transesterification reaction using catalysts. Homogeneous catalysts are conventionally used for biodiesel production. Unfortunately, homogeneous catalysts are associated with problems which might increase the cost of production due to separation steps and emission of waste water. Inorganic heterogeneous catalysts are potentially low cost and can solve many of the problems encountered in homogeneous catalysts. Many solid acid and base inorganic catalysts have been studied for the transesterification of various vegetables oils. The work of many researchers on the development of active, tolerant to water and free fatty acids (FFA), as well as stable inorganic catalysts for biodiesel production from vegetable oils are reviewed and discussed.
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| 7. |
- Garcia-Rojas, L. M., et al.
(författare)
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Rendimiento de los productos de la descomposición térmica De la madera de eucalyptus saligna smith a diferentes alturas del fuste comercial
- 2009
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Ingår i: Revista Chapingo, Serie Ciencias Forestales y del Ambiente. - 0186-3231. ; 15:2, s. 147-154
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Tidskriftsartikel (refereegranskat)abstract
- In this work the qualitative and quantitative results of the thermal pyrolysis of Eucalyptus Saligna Smith is presented, to different heights of the commercial wooden log. The wood was collected from Pinar del Rio, Cuba. The need to use this wood like energy source in the region led to the research at laboratory scale. The used trees were 20 and 22 years old, from which 20 cm disks were cut at 25; 55 and 85 % height of the log, milled to chips and air dried. The chemical composition was determined and was carried out the previous analysis of the samples, as well as the thermal decomposition in micro scale. The study of products from the pyrolysis (coal and tar), it was made in a reactor of fixed channel. The caloric value of the biomass and its charcoal was determined. The influence of the height of the log in the product yields from the pyrolysis was studied.As significant differences was observed as for the chemical composition of the studied wood: cellulose, hemicelulose and lignine, being observed an apparent increase of the lignine percentage with the height of the tree. The previous analysis belongs together with the chemical composition of the studied biomass. A small decrease was observed in the yield of the coal and of the percentage of tars with the height of the tree, this belongs together with the variation of the chemical composition according to the height of the tree. The biggest yield of coal and caloric value was achieved at the lowest height of the tree. The contribution to gas goes increasing with the height.
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| 8. |
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| 9. |
- Grimm, Alejandro, et al.
(författare)
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Comparison of different types of biomasses for copper biosorption
- 2007
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Ingår i: Bioresource Technology. - : Elsevier BV. - 0960-8524 .- 1873-2976. ; 99:7, s. 25559-2565
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Tidskriftsartikel (refereegranskat)abstract
- Three biomass, birch wood Betula sp., marine brown alga Fucus vesiculosus, and terrestrial moss Pleurozium schreberi, have been compared as raw materials for preparation of biosorbents for removal of copper ions from diluted water solutions. Small sample doses (0.5 g/100 ml) of the biosorbents prepared from alga and moss enabled more than 90% removal of Cu(II) ions from diluted water solutions (5-20 mg/l). The sample from sawdust was less effective.A pseudo-second-order rate model properly described the experimental kinetic data for the biosorbents. The maximum sorption capacities (X,) determined from the experimental equilibrium isotherms by applying the Langmuir model showed that the alga had the best copper-binding ability (X-m = 23.4 mg/g), followed by the moss (X-m = 11.1 mg/g), and the sawdust (X-m = 4.9 mg/g). No visible damages or performance losses were detected for the alga and moss after five sorption-desorption cycles using diluted HCl as eluent.
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| 10. |
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