Available free online at www.medjchem.com Mediterranean Journal of Chemistry 2021, 11(1), 75-83 *Corresponding author: Karna Wijaya Received November 20, 2020 Email address: karnawijaya@ugm.ac.id Accepted December 18, 2020 DOI: http://dx.doi.org/10.13171/mjc02101141493kw Published January 14, 2021 Dealuminated and Desilicated Natural Zeolite as a Catalyst for Hydrocracking of Used Cooking Oil into Biogasoline Susi Efrina Purba, Karna Wijaya * , Wega Trisunaryanti and Remi Ayu Pratika Physical Chemistry Laboratory, Chemistry Department, Universitas Gadjah Mada, Yogyakarta-55281, Indonesia Abstract: The modification of natural zeolite has been conducted by dealumination and desilication using HCl and NaOH treatments as a catalyst for hydrocracking of used cooking oil into biogasoline. This research aimed to study the effect of dealumination and desilication on the natural zeolite activity and selectivity of a hydrocracking process. A variety of catalysts was prepared by applying 3, 6, and 9 M HCl in the dealumination of natural zeolite to produce DNZ(3-1), DNZ(3-2) DNZ(3-3), DNZ(6-1), DNZ(6-2), DNZ(6-3), DNZ(9-1), DNZ(9-2), and DNZ(9-3) catalysts and NaOH in the desilication of natural zeolite to obtain NZB catalyst. The results showed that the dealumination and the desilication treatments affected the liquid product conversion of used cooking oil from catalytic hydrocracking. The hydrocracking of used cooking oil with NZB catalyst produced the highest gasoline fuel conversion of 94.87%. Keywords: natural zeolite; dealumination; desilication; hydrocracking; used cooking oil. 1. Introduction Hydrocracking is a process that combines catalytic cracking and hydrogenation to convert larger hydrocarbon molecules into smaller molecules. One of the fuel fractions produced from the hydrocracking process is the gasoline fraction with C5-C12 hydrocarbons 1 . Used cooking oil can be employed to produce biogasoline through the hydrocracking process. Structurally, used cooking oils are composed of glycerides, formed out of long hydrocarbon chains that can be cracked into shorter hydrocarbon chained compounds and fuels 2-3 . Zeolites are a type of acid catalyst that possess several advantages; strong acidity, high surface area, non- corrosive, environmentally safe or friendly, and easy to separate from a mixture as they make up heterogeneous catalysts. Zeolites are commonly found as a natural zeolite. Natural zeolite can be used for cracking, hydrocracking, and isomerization reactions 4,5 . The illumination process is used to remove aluminum from the zeolite framework to obtain the Si/Al mole ratio in the desired amount. The increase of Si/Al mole ratio can produce hydrophobic (lipophilic) zeolite with good chemical stability and strong acidity. An increase in acidity strength accompanies the increase in the amount of Si/Al mole ratio. Dealumination process that employs strong acid can also change the properties of natural zeolite, i.e., increased Si/Al mole ratio, reduced crystallinity, removed impurities, and increased specific surface area 6-7 . Anggoro et al. 8 reported that the zeolite Y dealuminated with H2SO4 solution of 3-8.5 M at temperatures of 40-67.6°C and reaction time of 2-6 hours showed greater acidity and surface area than zeolite Y without the dealumination treatment. A larger zeolite pore diameter allows molecules to pass easier and reach the active sites 9 . Zeolites are materials that have a micropores structure. The small pore size can inhibit the zeolite's active site in a cracking process, causing an increased coke mass of the final product 10 . One technique that can be done to increase the pore diameter of a zeolite is desilication, which removes Si atoms from a zeolite framework by leaching with alkaline solutions. Desilication can obtain zeolite with the mesoporous structure without destroying the microporous structure of the zeolite 11,12 . While still being in control of a zeolite’s Si/Al mole ratio, acid treatment can be implemented to increase the mesoporous of a catalyst to generate better catalyst performance 13,14 . Peron et al. 10 reported that the combined dealumination dan desilication treatments on the ZSM-5 catalyst generated new pore sizes, namely within the mesoporous range with large surface area dan pore size. The types of zeolites that are often used in research related to zeolites are zeolite Y and ZMS-5, which require higher cost and energy. In this study, the zeolite used is natural zeolite from Klaten, Central Java, Indonesia. The utilization of this zeolite type has yet been developed widely, especially within the