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Abstract As a result of the enormous demand for energy and the shortage of the fossil fuels, searchingfor alternative sources of energy is an urgent necessity. Biodiesel is a suitable substitute ofpetrodiesel. Biodiesel liquid fuel is sustainable, biodegradable, non-toxic, environmentalfriendly, has lower emissions and can be blended with petrodiesel. Biodiesel is mainlyproduced by a homogeneous base-catalyzed transesterification of vegetable oils and methanol(or ethanol) by using NaOH or KOH as a catalyst. However, production of biodiesel in Egyptfaces many problems. The first problem is the high production cost due to the high price ofthe refined oil. This research overcomes this problem by using waste frying oil (Chipsy wastefrying oil) to lower the production cost and avoid blockages of sewer pipes as well as waterpollution due to disposal of waste oil in sinks, rivers and seas. However, the major technicalproblem of using waste frying oil is its high content of free fatty acids . These acidsdeplete the basic catalyst (NaOH, KOH) through a saponification reaction. The resulting soapcomplicates biodiesel production due to separation difficulties.The use of homogeneous acid-catalyzed (H2SO4) esterification converts free fatty acids tobiodiesel. Reducing the free fatty acid to prevents the saponification reaction and theundesirable effect of soap. This research investigated the use of CaSO4–SiO2–CaO/SO42-,heterogeneous crystalline composite with various SiO2 to CaO weight ratios to overcome theprocessing difficulties of using CaO and keep the catalyst price low. It was found that thecomposite with 1:1 SiO2 to CaO weight ratios has the highest biodiesel production yield. Theoptimum conditions for transesterification process are found to be 3:1 methanol to oil molarratio, 3 wt. % (w Catalyst /w Oil) catalysts loading at 55 ºC, 300 rpm stirring speed for 30 minreaction time.The second problem is the corrosion and pollution generated as a result of usinghomogeneous catalysts. They also form water during esterification which slows the process.Water removal leads to additional costs. This research addresses this problem by using thelowest amounts of H2SO4 for the esterification process and by using effective and low costheterogeneous catalysts in transesterification process, which can be separated easily. Inaddition, utilizing heterogeneous catalysts result in a higher biodiesel production yield.To reduce petrodiesel consumption, the produced biodiesel was mixed with petrodiesel toproduce B10 and B20 biodiesel- petrodiesel blends. The physical and chemical properties ofbiodiesel, B10 and B20 were analyzed and the results confirmed the compatibility of thesefuel blends for use in diesel engines. Moreover, biodiesel blends in most tests have improvedthe petrodiesel properties. |