<p>The production of biodiesel (methyl esters) from vegetable oils represents analternative means of producing liquid fuels from biomass, and one which is growing rapidly in commercial importance and relevance due to increase in petroleum prices and the environmental advantages the process offers. Commercially, biodiesel is produced from vegetable oils, as well as from waste cooking oils and animal fats. These oils are typically composed of C14-C20 fatty acid triglycerides. In order to produce a fuel that is suitable for use in diesel engines, these triglycerides are usually converted into the respective mono alkyl esters by base-catalyzed transesterification with short chain alcohol, usually methanol. In the first part of this study, the transesterification reactions of three different vegetable oils / sunflower (SFO), soybean (SBO) and waste cooking oil (WCO) with methanol was studied using potassium hydroxide as catalyst in a conventional batch process. The production of biodiesel from waste cooking oil was also studied via continuous operation systems (employing the use of low frequency ultrasonic technology and the jet loop reactor). The characterisation of the feedstock used and the methyl ester products were determined by different analytical techniques such as gas chromatography (GC), high performance liquid chromatography (HPLC) and thin layer chromatography (TLC). The effects of different reaction parameters (catalyst amount, methanol to oil ratio, reaction temperature, reaction time) on methyl ester/FAME yield were studied and the optimum reaction conditions of the different process systems were determined. The optimum reaction conditions for production of methyl esters via the batch process with the fresh oil samples (SFO and SBO) were established as follows: a reaction time of 60 min at 60 &ordm / C with a methanol: oil ratio of 6:1 and 1.0 KOH % wt/wt of oil / while the optimum reaction conditions for the used oil (WCO) was observed at a reaction time of 90 min at 60 &ordm / C, methanol: oil ratio of 6:1 and 1.5% KOH wt/wt of oil. The optimum reaction conditions for the transesterification of the WCO via ultrasound technology applied in a continuous system in this study were: a reaction time of 30 min, 30 &ordm / C, 6:1 methanol/oil ratio and a 0.75 wt% (KOH) catalyst concentration. The ultrasound assisted transesterification reactions performed at optimum conditions on the different oil samples led to higher yields of methyl esters (96.8, 98.32 and 97.65 % for WCO, SFO and SBO respectively) compared to methyl esters yields (90, 95 and 96 % for WCO, SFO and SBO respectively) obtained when using conventional batch procedures. A considerable increase in yields of the methyl esters in the ultrasound assisted reaction process were obtained at room temperature, in a remarkably short time span (completed in 30 min) and with a lower amount of catalyst (0.75 wt % KOH) while the results from the continuous jet loop process system showed even better results, at an optimum reaction condition of 25 min of reaction, a methanol: oil ratio of 4:1 and a catalyst amount of 0.5 wt%. This new jet loop process allowed an added advantage of intense agitation for an efficient separation and adequate purification of the methyl esters phase at a reduced time of 30 min. The use of homogeneous catalysts in conventional processes poses many disadvantages / heterogeneous catalysts on the other hand are attractive on the basis that their use could enable the biodiesel production to be more readily performed as a continuous process resulting in low production costs. Consequently, a solid base catalyst (KNO3/FA) prepared from fly ash (obtained from Arnot coal power station, South Africa) and a new zeolite, FA/Na-X synthesized from the same fly ash were used as solid base catalysts in the transesterification reactions in the conversion of a variety of oil feedstock with methanol to methyl esters. Since fly ash is a waste product generated from the combustion of coal for power generation, its utilization in this manner would allow for its beneficiation (as a catalytic support material and raw material for zeolite synthesis) in an environmentally friendly way aimed at making the transesterification process reasonably viable. Arnot fly ash (AFA) was loaded with potassium (using potassium nitrate as precursor) via a wet impregnation method while the synthesized zeolite FA/Na-X was ion exchanged with potassium (using potassium acetate as precursor) to obtain the KNO3/FA and FA/K-X catalysts respectively. Several analytical techniques were applied for characterization purposes. The results of the XRD and XRF showed that the AFA predominantly contained some mineral phases such as quartz, mullite, calcite and lime. The high concentration of CaO in AFA was apparent to be beneficial for the use of fresh fly ash as a support material in the heterogeneous catalysed transesterification reactions. XRD characterisation of KNO3/FA results indicated that the structure of KNO3/FA gradually changed with the increase in KNO3 loading. The catalyst function was retained until the loading of KNO3 was over 10 %. IR spectra showed that the KNO3 was decomposed to K2O on the fly ash support during preparation at a calcination temperature of 500 &ordm / C. The CO2-TPD of the KNO3/FA catalysts showed that two basic catalytic sites were generated which were responsible for high catalytic abilities observed in the transesterification reactions of sunflower oil to methyl esters. On the other hand, XRD results for the as- received zeolite synthesized from AFA showed typical diffraction peaks of zeolite NaX. SEM images of the FA /NaX showed nano platelets unique morphology different from well known pyramidal octahedral shaped crystal formation of faujasite zeolites and the morphology of the FA /KX zeolite did not show any significant difference after ion exchange. The fly ash derived zeolite NaX (FA /NaX) exhibited a high surface area of 320 m2/g. The application of the KNO3/FA catalysts in the conversion reactions to produce methyl esters (biodiesel) via transesterification reactions revealed methyl ester yield of 87.5 % with 10 wt% KNO3 at optimum reaction conditions of methanol: oil ratio of 15:1, 5 h reaction time, catalyst amount of 15 g and reaction temperature 160 &deg / C, while with the use of the zeolite FA/K-X catalyst, a FAME yield of 83.53 % was obtained for 8 h using the ion exchanged Arnot fly ash zeolite NaX catalyst (FA/KX) at reaction conditions of methanol: oil ratio of 6:1, catalyst amount of 3 % wt/wt of oil and reaction temperature of 65 &ordm / C. Several studies have been carried out on the production of biodiesel using different heterogeneous catalysts but this study has been able to uniquely demonstrate the utilization of South African Class F AFA both as a catalyst support and as a raw material for zeolite synthesis / these catalyst materials subsequently applied sucessfully as solid base catalysts in the production of biodiesel.</p>

<p>The production of biodiesel (methyl esters) from vegetable oils represents analternative means of producing liquid fuels from biomass, and one which is growing rapidly in commercial importance and relevance due to increase in petroleum prices and the environmental advantages the process offers. Commercially, biodiesel is produced from vegetable oils, as well as from waste cooking oils and animal fats. These oils are typically composed of C14-C20 fatty acid triglycerides. In order to produce a fuel that is suitable for use in diesel engines, these triglycerides are usually converted into the respective mono alkyl esters by base-catalyzed transesterification with short chain alcohol, usually methanol. In the first part of this study, the transesterification reactions of three different vegetable oils / sunflower (SFO), soybean (SBO) and waste cooking oil (WCO) with methanol was studied using potassium hydroxide as catalyst in a conventional batch process. The production of biodiesel from waste cooking oil was also studied via continuous operation systems (employing the use of low frequency ultrasonic technology and the jet loop reactor). The characterisation of the feedstock used and the methyl ester products were determined by different analytical techniques such as gas chromatography (GC), high performance liquid chromatography (HPLC) and thin layer chromatography (TLC). The effects of different reaction parameters (catalyst amount, methanol to oil ratio, reaction temperature, reaction time) on methyl ester/FAME yield were studied and the optimum reaction conditions of the different process systems were determined. The optimum reaction conditions for production of methyl esters via the batch process with the fresh oil samples (SFO and SBO) were established as follows: a reaction time of 60 min at 60 &ordm / C with a methanol: oil ratio of 6:1 and 1.0 KOH % wt/wt of oil / while the optimum reaction conditions for the used oil (WCO) was observed at a reaction time of 90 min at 60 &ordm / C, methanol: oil ratio of 6:1 and 1.5% KOH wt/wt of oil. The optimum reaction conditions for the transesterification of the WCO via ultrasound technology applied in a continuous system in this study were: a reaction time of 30 min, 30 &ordm / C, 6:1 methanol/oil ratio and a 0.75 wt% (KOH) catalyst concentration. The ultrasound assisted transesterification reactions performed at optimum conditions on the different oil samples led to higher yields of methyl esters (96.8, 98.32 and 97.65 % for WCO, SFO and SBO respectively) compared to methyl esters yields (90, 95 and 96 % for WCO, SFO and SBO respectively) obtained when using conventional batch procedures. A considerable increase in yields of the methyl esters in the ultrasound assisted reaction process were obtained at room temperature, in a remarkably short time span (completed in 30 min) and with a lower amount of catalyst (0.75 wt % KOH) while the results from the continuous jet loop process system showed even better results, at an optimum reaction condition of 25 min of reaction, a methanol: oil ratio of 4:1 and a catalyst amount of 0.5 wt%. This new jet loop process allowed an added advantage of intense agitation for an efficient separation and adequate purification of the methyl esters phase at a reduced time of 30 min. The use of homogeneous catalysts in conventional processes poses many disadvantages / heterogeneous catalysts on the other hand are attractive on the basis that their use could enable the biodiesel production to be more readily performed as a continuous process resulting in low production costs. Consequently, a solid base catalyst (KNO3/FA) prepared from fly ash (obtained from Arnot coal power station, South Africa) and a new zeolite, FA/Na-X synthesized from the same fly ash were used as solid base catalysts in the transesterification reactions in the conversion of a variety of oil feedstock with methanol to methyl esters. Since fly ash is a waste product generated from the combustion of coal for power generation, its utilization in this manner would allow for its beneficiation (as a catalytic support material and raw material for zeolite synthesis) in an environmentally friendly way aimed at making the transesterification process reasonably viable. Arnot fly ash (AFA) was loaded with potassium (using potassium nitrate as precursor) via a wet impregnation method while the synthesized zeolite FA/Na-X was ion exchanged with potassium (using potassium acetate as precursor) to obtain the KNO3/FA and FA/K-X catalysts respectively. Several analytical techniques were applied for characterization purposes. The results of the XRD and XRF showed that the AFA predominantly contained some mineral phases such as quartz, mullite, calcite and lime. The high concentration of CaO in AFA was apparent to be beneficial for the use of fresh fly ash as a support material in the heterogeneous catalysed transesterification reactions. XRD characterisation of KNO3/FA results indicated that the structure of KNO3/FA gradually changed with the increase in KNO3 loading. The catalyst function was retained until the loading of KNO3 was over 10 %. IR spectra showed that the KNO3 was decomposed to K2O on the fly ash support during preparation at a calcination temperature of 500 &ordm / C. The CO2-TPD of the KNO3/FA catalysts showed that two basic catalytic sites were generated which were responsible for high catalytic abilities observed in the transesterification reactions of sunflower oil to methyl esters. On the other hand, XRD results for the as- received zeolite synthesized from AFA showed typical diffraction peaks of zeolite NaX. SEM images of the FA /NaX showed nano platelets unique morphology different from well known pyramidal octahedral shaped crystal formation of faujasite zeolites and the morphology of the FA /KX zeolite did not show any significant difference after ion exchange. The fly ash derived zeolite NaX (FA /NaX) exhibited a high surface area of 320 m2/g. The application of the KNO3/FA catalysts in the conversion reactions to produce methyl esters (biodiesel) via transesterification reactions revealed methyl ester yield of 87.5 % with 10 wt% KNO3 at optimum reaction conditions of methanol: oil ratio of 15:1, 5 h reaction time, catalyst amount of 15 g and reaction temperature 160 &deg / C, while with the use of the zeolite FA/K-X catalyst, a FAME yield of 83.53 % was obtained for 8 h using the ion exchanged Arnot fly ash zeolite NaX catalyst (FA/KX) at reaction conditions of methanol: oil ratio of 6:1, catalyst amount of 3 % wt/wt of oil and reaction temperature of 65 &ordm / C. Several studies have been carried out on the production of biodiesel using different heterogeneous catalysts but this study has been able to uniquely demonstrate the utilization of South African Class F AFA both as a catalyst support and as a raw material for zeolite synthesis / these catalyst materials subsequently applied sucessfully as solid base catalysts in the production of biodiesel.</p>

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / Uma unidade de produÃÃo contÃnua de biodiesel com carga de 8000 kg.h-1 de Ãleo de dendà e metanol, com o uso da rota de transesterificaÃÃo heterogÃnea foi simulada, projetada e analisada economicamente com o uso do software Aspen HYSYS 7.3 e de planilhas de cÃlculo. O pacote termodinÃmico NRTL foi empregado para representar as propriedades de todos os fluidos na simulaÃÃo. Reatores de leito fixo foram dimensionados utilizando simulaÃÃes numÃricas para atingirem 97,3% de conversÃo do Ãleo no processo. Os reatores foram operados isotermicamente a 64,8ÂC e com razÃo Ãlcool/Ãleo de 17,5. Uma coluna de destilaÃÃo foi projetada para recuperar 99% do metanol em excesso. Um decantador para separar as fases biodiesel e glicerina foi dimensionado atravÃs do cÃlculo do tempo de residÃncia t. Uma segunda coluna de destilaÃÃo a vÃcuo foi projetada para purificar a fase biodiesel atà atingir 99,97% m/m, de acordo com as especificaÃÃes da ANP. A fase glicerina foi purificada em uma coluna de destilaÃÃo flash a vÃcuo atà 99,53% m/m. O Investimento Total ITOTAL da unidade foi estimado pelo MÃtodo Fatorial Detalhado, resultando em um valor de US$ 5,798,469. Os Custos VariÃveis de ProduÃÃo (VCOP) foram estimados utilizando a precificaÃÃo de matÃrias primas, de catalisador e utilidades, enquanto que as receitas anuais foram calculadas com uso das precificaÃÃes do biodiesel e da glicerina. Os Custos Fixos de ProduÃÃo (FCOP) foram orÃados considerando os custos com mÃo de obra operacional, custos de supervisÃo, custos de manutenÃÃo e reparos, despesas corporativas e seguro. Para o cÃlculo do fluxo de caixa do projeto foi considerado o regime tributÃrio vigente no Brasil, com a inclusÃo do PIS/COFINS a uma taxa segundo a regra geral e a reduÃÃo de 69% deste para empresas que adquiram o selo social, uma taxa de 12% para o ICMS incididos sobre as receitas, 25% de IRPJ e 9% de CSLL incididos sobre o Lucro LÃquido antes do Imposto de Renda (LAIR). Foi obtido um Lucro LÃquido apÃs Impostos (LL) de US$ 2,340,889, valor este positivo em comparaÃÃo com processos convencionais que utilizam Ãleo de soja virgem. A viabilidade econÃmica do projeto foi analisada pelo cÃlculo do Valor Presente LÃquido (VPL) e pela Taxa Interna de Retorno (TIR). Foram obtidos um VPL de US$ 21.36 milhÃes de dÃlares e TIR de 39,0%, valores que demonstraram a viabilidade econÃmica do projeto. A anÃlise de sensibilidade de preÃos de matÃrias primas demonstrou tambÃm que o processo à viÃvel desde que os preÃos do Ãleo dendà nÃo aumentem ou os do biodiesel nÃo diminuam, ambos em 3%. / A continuous biodiesel production plant with an 8000 kg.h-1 inlet of palm oil and methanol, using the heterogeneous transesterification route was simulated, designed and economically assessed with the software Aspen HYSYS 7.3 and spreadsheets. The thermodynamic fluid package NRTL was selected in order to represent all properties of the fluids through the simulation. Packed-bed reactors were designed using numerical simulation to achieve an oil conversion of 97.3% in the process. The reactors were operated isothermally at 64.8ÂC and with an alcohol/oil ratio of 17.5. A vacuum distillation column was designed to recovery 99% of the methanol in excess. A decanter to separate the biodiesel and glycerin phases was designed through the calculation of residence time t. A second vacuum distillation column was designed to purify the biodiesel phase until a 99.97 wt%, in accordance with the ANP specifications. The glycerin phase was purified in a vacuum flash distillation column until a 99.53 wt%. The Total Capital Invested ITOTAL on the plant was estimated using the Detailed Factorial Method presenting the amount of US$ 5,798,469 was found. The Variable Costs of Production (VCOP) were estimated using the prices of raw materials, catalysts and utilities, whereas the annual revenues were calculated using the prices of biodiesel and glycerin. The Fixed Costs of Production (FCOP) were calculated using the operating labor costs, supervision, maintenance, corporate overheads and insurance. In order to calculate the cash flow of the project, the current tax regime in Brazil was used, including PIS/COFINS with a rate following the general rule and the reduction of 69% on it to companies with the social stamp, 25% of IRPJ and 9% of CSLL on the Net Profit before Income Taxes (NPIT). A Net Profit after Taxes (NP) of US$ 2,340,889 was obtained, a positive figure if compared to conventional processes using virgin soybean oil. The economic viability of the project was analyzed by calculating the Net Present Value (NVP) and Internal Rate of Return (IRR). A NVP of US $ 21.36 million and IRR of 39.0% were obtained, showing the economic viability of the project. The raw material price sensitivity analysis also showed that the process is feasible as long as palm oil prices do not increase or biodiesel do not decrease more than 3%.