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The influence of the physicochemical properties of a series of CaO catalysts activated at different temperatures on the biodiesel production was investigated.
These catalysts show dissimilar yields in the transesterification of triglycerides with methanol. We have found significant relationships between structural properties the type of the pore system, the typical CaO crystal phase and the sizes of crystallites up to 25 nmthe minimal weight percentage of CaO phase, the total surface basicity and potential existence of two types of basic active sites of CaO prepared and activated by means of thermal treatment at highest temperature and catalytic efficiency.
Benefits of this catalyst are short contact time, standard operating temperature and atmospheric conditions, relatively low molar ratios and small catalyst loading. These all together resulted in a very high biodiesel yield of high purity. The properties of effekat biodiesel obtained with the use of the prepared CaO catalyst blends with different diesel and biodiesel ratios indicate that the higher the fraction of biodiesel fuel the better the achieved fuel properties according to the EU standards.
A significant reduction of C[O. The use of biodiesel derived blends, and the eventual complete replacement of fossil fuels with biodiesel as a renewable, alternative fuel for diesel engines, would greatly contribute to the reduction of greenhouse gas emissions.
U ovom radu je ispitivan uticaj fizicko-hemijskih svojstava serije CaO katalizatora aktiviranih na razlicitim temperaturama za proizvodnju biodizela. Pomenuti katalizatori daju razlicite prinose u reakciji transesterifikacije triglicerida sa metanolom. Utvrdili smo bitnu povezanost izmedu strukturalnih svojstava tip poroznog sistema, tipicna CaO kristalna faza i velicina kristalita do 25 nm, minimalni procenat kristalne faze CaO, ukupna baznost i potencijalno postojanje dve vrste baznih centara CaO katalizatora pripremljenog i aktiviranog termijskim tretmanom na najvisoj temperaturi i kataliticke efikasnosti.
Prednosti koriscenja ovog katalizatora su: Sve navedeno rezultiralo je veoma visokim prinosom biodizela visokog stepena cistoce. Svojstva razlicitih namesanih biodizel dobijenog koriscenjem sintetisanog CaO katalizatora goriva sa drugacijim udelima dizel i biodizel goriva ukazuju da sto je veci udeo biodizela, bolja su ostvarena svojstva goriva imajuci u vidu referentne EU standarde.
Znacajno smanjenje emisija C[O. Koriscenje namesanih goriva sa biodizel gorivom, kao i potencijalna totalna zamena fosilnih goriva sa biodizelom kao obnovljivim, alternativnim, ekoloski prihvatljivim gorivom za dizel motore, moglo bi u velikoj meri da utice na smanjenje emisije gasova koji izazivaju efekat “staklene baste”.
Buduca istrazivanja na ovu temu i slicno orijentisane mogla bi dati odgovor na savremene energetske zahteve i potrebe transporta u Srbiji, koriscenjem novog, alternativnog, obnovljivog izvora.
Koriscenje biodizela obezbeduje nezavisnost u pogledu uvoza sirove nafte, kao i brojne energetske, ekoloske, geo-politicke i ekonomske benefite.
The great attention has been given lately to biodiesel production from renewable energy resources e. The production and use of biodiesel provided the means to a net reduction of C[O. Other advantages of biodiesel use are its lubricant properties, acceptable cetane number, flash point and low temperature properties, making it an alternative, environmental friendly, biodegradable, renewable fuel [2,3], and a direction to sustainable development and economy.
Disadvantages of homogeneous catalysis are the recovery of the catalyst used in the transesterification reaction and considerable volume of wastewater discharged from the process bste to refine the staklwne alkali hydroxide from the produced biodiesel.
Despite the long history of application of homogeneous catalysis in biodiesel production, a great number of benefits of heterogeneous catalysts are recognized.
Basge utilization of heterogeneous catalysts would be a solution for most of environmental and economic drawbacks of homogeneously catalyzed process.
A heterogeneous catalyst can be easily and quickly separated and reused and the produced biodiesel and glycerin could be rapidly purified and collected after separation. This easier and cheaper separation process would enable the elimination of consumption of large volumes of wastewaters .
In addition, the use of heterogeneous catalyst in biodiesel production makes it possible to simplify the production process by omitting sections from the complete process technology. However, at present there is only one commercially accepted transesterification process technology. Also, heterogeneous catalysts are not consumed in the production process, whereas homogeneous processes require a fresh batch of catalyst for each new production cycle.
Basic heterogeneous catalysts give higher reaction rate than acidic ones and are predominantly prepared and tested. Despite the fact that several basic catalysts have exhibited promising activities, such as alkali and alkali earth oxides [8,9], alkali and alkali earth carbonates , basic zeolites , hydrotalcites [12,13] under the atmospheric pressure, no real replacement was found for the homogeneous process.
The basic properties of the catalysts were established as the major determinant for the catalytic activity among the catalysts employed in the cited work . The basic properties i. The calcination temperature of [degrees]C yielded the highest amount of basic sgaklene of CaO .
The increase of the calcination temperature to a certain value caused the increase of the CaO activity; the optimal CaO calcination temperature of [degrees]C was recognized. This result was explained by dehydration of Ca[ OH. The catalytic activity of CaO was improved by activation treatment at [degrees]C after transformation of the CaC[O. The precursors were calcined for 2 h at a calcination temperature that was varied from to [degrees]C at an interval of [degrees]C. The activity of efskat catalysts increased in the following order: The basicity of efekaat prepared calcium oxide catalysts also differed according to efe,at precursors, and the relationship between the conversion level and the basicity of the CH catalysts was established .
The basicity of catalysts seemed to be determinant for the catalytic activity among all staklwne samples . In their other work, Kouzu et al.
The staolene was prepared as it was previously mentioned stakleje. Calcium oxide combined with the by-produced glycerol gave calcium diglyceroxide that was a major constituent of the collected catalyst. Calcium diglyceroxide would be the active evekat in the catalytic reaction with usage of calcium oxide for biodiesel production. Staklenr catalyst had the advantage of tolerance to air-exposure .
They have claimed that the best catalytic performance was achieved for calcination temperature above [degrees]C when XRD patterns showed a crystalline CaO phase. CaO was the active phase of the eggshell derived catalysts .
One the other side, the experimental results showed that a 9: To the best of our knowledge, there is no complete consensus on different activation procedures applied in the preparation of CaO-based catalysts published and on the relevance of the physicochemical properties of catalysts for beneficial catalytic performances.
Especially, such data concerning investigations in Serbia are missing in the scientific literature. Thus, in this work we decided to rectify edekat situation and investigate an impact of structural characteristics of CaO catalyst on the efficiency in the transesterification reaction, and a potential effect of biodiesel usage on the diesel engine performances and greenhouse gases emission.
Calcium oxide of technical grade was used as the catalyst precursor. It was further calcined at selected temperaturesand [degrees]C for 2. After calcination, the CaO-based catalyst powder was pressed into pellets. The pellets were sieved to obtain a fraction 1. These fraction dimensions were optimal efdkat avoid potential external diffusion restrictions within the reactor basket. Catalyst samples were labeled CaO-T, where T represented the calcination temperature.
Afterwards, the characterization of the catalysts was performed. Methanol of HPLC grade was used in the test reactions. Sunflower oil from a domestic producer was employed in the transesterification reactions.
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It was selected because sunflower represents a typical oilseed plant in Serbia and the region. The particular properties of the feedstock and the obtained biodiesel density, kinematic viscosity, cetane index, low temperature properties, flash point, sulfur content, water content, heating value were determined by standardized methods: Textural features of CaO catalytic samples were studied by low temperature [N.
Crystallite sizes were calculated from the Scherer equation. Before the recordings, the catalyst samples were exposed to phenol vapors to investigate the basic nature of surface sites, and afterwards exposed to vacuum to remove any physically adsorbed vapors.
Transesterification of sunflower oil was conducted over the prepared CaO catalysts in a stirred, commercial reactor, Parr The catalyst loading was 1 wt. Constant reaction temperature 64[degrees]C was maintained during 5 h of the stallene run at atmospheric pressure.
Reaction products samples were taken after each 1 h of a single reaction shaklene. The following conditions of the GC analyses were employed: Catalyst activity was ranked as FAME yield calculated as we have reported in our previous work .
Engine performances were investigated on a Tractor type Mahindra This type of tractor is common in Serbia, and can be used for various purposes in agriculture. The conventional stakldne conditions of the tractor engine with four cylinders Tier of the second generation were reached during the investigation: Fuel consumption was determined by the volume-method applying a flow-meter of type Pireburg Exhaust gas emissions were resolved according to the standard ISO and tracked with the use of Testo portable analyzer.
The textural properties of the prepared catalysts BET surface area, average pore diameter, BJH cumulative desorption pore volume and maxima in pore size distribution PSD are shown in Table 1. These properties are important characteristics of the solid state CaO-based catalysts because they readily influence the catalytic efficiency in the transesterification of sunflower oil.
These catalytic properties are also in correlation with the precursor of the CaO catalyst and thermal history of the activated CaO-based catalyst samples.
EFEKAT STAKLENE BAŠTE by Mirjana Jevtic on Prezi
Accordingly, the mean pore diameter became greater with the increase of the calcination temperature from to [degrees]C. Therefore, the sintering process went on to a smaller extent and this probably resulted in a consolidation of the catalyst samples . In this study, the measured specific surface areas of the CaO catalysts had somewhat lower values of BET surface areas when compared to the results of other authors [18,25].
These results may be explained by the fact that the exact origin of the CaO catalysts was unknown, thus, the catalyst features could be completely different despite the comparable gross chemical composition. In addition, we believe that the BET surface area of the CaO catalyst should be correlated with the precursor type and the relevant thermal treatment applied. To the best of our knowledge, there are no reported data on an identical CaO precursor used; hence, no analogous results on the textural properties of CaO catalysts could be expected.
The results indicate that the CaO catalyst samples calcined at the lowest temperature possess a surface area of 5.
The corresponding properties of the catalyst tsaklene calcined at staklrne temperatures and [degrees]C changed but not to a substantial extent. It seems that the textural characteristics of the CaO catalyst samples used in this experiment from CaO to CaO are favorable for a liquid-solid heterogeneous phase reaction, and provide sufficient reaction surface area for the conversion of large triglyceride molecules.
Nitrogen isotherms and pore size distribution curves for the CaO catalyst sample are shown in Fig. The pore system is in the mesopores range between 10 and nm with an average pore diameter around 28 nm according to the BJH desorption isotherms. Based on the PSD curve, a smaller fraction of the surface area is occupied by pores of around 10 nm in size followed with a larger volume fraction of pores of relatively large size between 60 and nm. Such mesopores and near-edge mesopores-macropores are generated as a result of residual areas among particles formed during the catalyst preparation.
The IV-type of isotherms is recognized for catalytic materials with porous system in the mesopore range  that additionally coincided with a rather spongy-like morphology of CaO particles proved by SEM. The etaklene two maxima in the PSD curve may be staklenr during the catalytic run due to an effective mass transfer process in the conversion of relatively large triglyceride reactants. Taking into account that the efekag dimensions of triglycerides along the fatty acid chain around 2.
Efekat Staklene Baste
Therefore, the increase of calcination temperature caused a shift of pore diameters to somewhat higher values for the CaO-based catalysts. Based on these and reported CaO textural properties, the authors believe that the reactivity of the catalyst is indirectly proportional to the specific surface area, whereas it is in a direct relation with the average pore staklens .
We strongly believe that these catalytic properties are vital in expressing the catalytic activity, but not the key ones.