الفهرس 
AbstractOnly 14 pages are availabe for public view
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Abstract
Energy and environment are the most significant concerns of the contemporary world and the greatest obsession of modern civilizations. The conventional fossil fuels and their derivatives are the main sources of energy for most of the industrial institutes and all the transportation techniques. The enormous consumption of such fuel resources may cause enormous economic and environmental problems in the coming decades. Economically, the estimated reserves for the common fossil fuel resources will be exhausted within less than ten decades, and the gradual increase in the fossil fuels demands continuously facing the depletion of the related resources. Environmentally, combustion of the traditional fuels resulted in excessive emission of injurious gases (COx, SOx, and NOx) and other air pollutants which resulted in several problems for the environment, ecosystem and human health in addition to their major role in greenhouse. Therefore, introducing renewable and environmental fuels as an alternative source of energy is a critical demand for energy and environmental agencies.
Biodiesel was introduced as one of the best alternative energy sources for the traditional diesel fuel. Chemically, it is of alkyl methyl esters with long chains of fatty acids that can be produced through esterification of fatty acids or transesterification of vegetable oils, animal fats and cooking. The reaction occurs in the existence of alcohol with a short chain and suitable homogenous or heterogeneous catalyst. The biodiesel is clean, eco-friendly, non-toxic and biodegradable fuel. Also, it is characterized by its high flash point, low viscosity, high octane number, and high lubricant properties. Moreover, it can be used in the present engines without modifications. In the later period, transesterification production of biodiesel utilizing suitable solid heterogeneous catalysts attracted the attention of numerous researchers in this field. This ascribed to several an advantages; low production cost, low corrosion properties, non-toxicity, high purity of yielded biodiesel, easy separation and recovering of it from the reaction system, high stability of such catalysts even at high temperatures and their suitability to be used for several transformation cycles. Several natural and synthetic materials have been investigated as a heterogenous catalyst for efficient conversion of fatty acid and vegetable oils into biodiesel. Supporting of the heterogeneous catalysts on suitable materials was studied to minimize the disadvantages of heterogeneous catalysts. However, little work focuses on introducing cheap, efficient and available natural porous silica as an alternative catalyst supports in biodiesel production. The use of available porous natural materials will give a more realistic view of the applicability of using the final product on the industrial scale.
A novel K+ trapped geopolymer heterogeneous catalyst based on nanoporous MCM-48 and Mg/Al LDH as a precursor was synthesized and characterized as a novel basic heterogeneous catalyst for transesterification of waste sunflower oil into biodiesel. The conducted tests were accomplished based on the suggestion of central composite rotatable statistical design and the detected best experimental conditions 4 h time, 4 wt., % catalyst loading, 15:1 methanol-to-oil ratio and 120 oC temperature with biodiesel yield of 94.6 %. The predicted optimum conditions by the statistical design are 5h as reaction time, 5.4 wt., % as catalyst loading, 117.5 oC as temperature, and 16.4:1 as methanol-to-oil molar ratio achieving biodiesel yield of 96.12 %. The obtained biodiesel showed properties close to that of the international standards of biodiesel.