Abstract-Applying metal-organic frameworks (MOFs) as a solid catalyst in esterification of oleic acid and methanol for model of biodiesel production were investigated. Taking an advantage on high surface area, chemical/thermal stability and surface chemistry (acid/basicity) properties on MOF materials (MOF-808, ZIF-8, MIL-125) applied for catalyzed reaction of carboxylic acid to ester compound. Those MOF materials showed the catalytic properties higher than the reported alumina compound at same reaction condition. Their recyclability properties in heterogeneous catalyst were investigated. The characteristic properties of MOF materials such as crystal structure, porosity, surface area and functional group (chemical bonding) on spend catalyst after reaction were studied on this work.Index Terms-Metal-organic frameworks, biodiesel, esterification, heterogeneous catalyst.
I. INTRODUCTIONEsterification plays an important with numerous application for industrial e.g. polymer, paints, varnishes, lacquers, medicines, dyes and synthetic rubber, including energy relative such as the production of biodiesel [1]. This reaction was also used to produce the bio-fuel or biodiesel from vegetable oil and/or animal fats. The product of biodiesel can utilized as fuel which their represent a safe, non-toxic and renewable energy source [2]. The catalyst is requirement to transformation the triglyceride (TGs) into fatty acid methyl esters (FAMEs) with ethanol. The source of biodiesel production are usually low cost feed stock such as waste cooking oils, by products of the vegetable oil refining, some non-edible oils, and animal fats etc., however, these source should contained free fatty acids (FFAs) less than 1% since an excess of FFAs causes side reaction (saponification) and problem in process of product purification (reduced the production yield and emulsion formation) [3], [4]. Whereas, the acid catalyst is very important for the industrial production since can convert FFAs to eater product and non-side reaction generated.Generally, the most common catalyst widely used in biodiesel production are base catalyst such as NaOH or KOH etc. and acid catalyst such as H 2 SO 4 or HCl etc., which those homogeneous catalyst have been proven as the most affective for acceleration reaction [5]. However, the homogeneous catalyst was several drawback for using in commercial scale in view of economic and environmental view point e.g. critical step to wash biodiesel product, waste of water and water treatment, corrosive in metal devices of reactor and also increasing the cost of production, non-reusable catalyst and so on. Therefore, the developing in heterogeneous catalyst comes to replace with reducing the biodiesel production cost and more environmental friendly since the catalyst easy removable, non-corrosive, the recovery reused possible. During the last decades, several diverse heterogeneous catalyzed esterification have already been investigated. Some of the examples are ion-exchange resins having sulfonic acid groups [6], sulfated or mi...