Comparative Studies On The Production Of Biodiesel Using Various Heterogeneous Catalysts

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dc.contributor.authorEzebor, Francis
dc.date.accessioned2017-02-27T06:53:53Z
dc.date.available2017-02-27T06:53:53Z
dc.date.issued2015-05
dc.description.abstractHeterogeneous acid catalysts were prepared by incomplete carbonisation and sulphonation of oil palm trunk (OPT) and sugarcane bagasse (SCB) and characterised. The catalysts consisted of high densities of strong acid sites (-SO3H) and weak acid sites (COOH and phenolic OH groups). The performance of the catalysts was influenced by incomplete carbonisation and the grafting time for the Brønsted acid sites. The catalysts exhibited similarities in process behaviour to the basic reaction parameters (acid:methanol molar ratio, catalyst loading, reaction time and temperature). The activity of the catalysts was independent of total acidity and textural properties (surface area, pore volume and pore width). However, activity of the catalysts strongly correlated with the strong Brønsted acid sites density. The catalysts exhibited longer reaction time and selectivity towards esterification reaction under reflux at 65 to 130 oC. The catalysts are active in many cycles of usage with gradual decrease in activity during successive cycles. Elemental analysis of used catalysts showed a decrease in sulphur content from 2.89 to 2.65 % for the SCB catalyst and from 2.66 to 2.37 % for the OPT catalyst after the seventh cycle in esterification under the pseudo-infinite methanol. The decreased in activity was due to the leaching of small -SO3H bearing polycyclic compounds. Catalysts prepared by one-step synthesis showed very significant homogeneous contribution due to the leaching of the active sites. Remarkable improvement in catalytic activity and decrease in selectivity towards esterification is dependent on the control of the adsorption-desorption equilibria of predominant adsorbates. Under the pseudoxxvi infinite methanol, catalysts deactivation and dissolution effect of methanol over kinetic effect were minimised. The catalysts demonstrated rapid activity, reducing the time for optimum conversion of fatty acids to FAME from 5 h to 45 mins. In esterification, it gave 6.53 to 6.97 fold increase over conventional method. In transesterification of waste oil containing 42% FFA, the catalysts gave FFA conversion of 98.6 to 99.1% after 30 mins and FAME yield of 80.6 to 83.0% after 4 h. In contrast, the conventional method gave FAME yield of 43.7 to 45.0% after 6 h at the same temperature. The CaO-La2O3 mixed oxide catalysts showed basicity of 1.310 to 1.400 mmol/g and basic strength of 15.0<H_<18.4. Coupling of the pseudoinfinite methanol esterification with transesterification by the mixed oxide catalysts gave FAME yield of 97 to 98.2% within 60 to 100 mins of the transesterification step, thereby simplified the processing of high FFA oils. The reaction rate constants of the catalysts showed strong dependency on the temperature and were proportional to the concentration of the unconverted substrate but the equilibrium constant was weakly dependent on the temperature. The catalysed reactions of the OPT and SCB heterogeneous acid catalysts are strongly endothermic but surface effects predominate over kinetic reaction as the concentration of the products increases.en_US
dc.identifier.urihttp://hdl.handle.net/123456789/3783
dc.language.isoenen_US
dc.publisherUniversiti Sains Malaysiaen_US
dc.subjectThe Production of biodiesel usingen_US
dc.subjectVarious heterogeneous Catalysts.en_US
dc.titleComparative Studies On The Production Of Biodiesel Using Various Heterogeneous Catalystsen_US
dc.typeThesisen_US
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