Esterification of Acetin Production from By-Products of Biodiesel Industry Using Heterogeneous Catalysts Based on Wetland Commodities

Abstract

The peculiarities of wetland commodities are unique and can produce new materials which function as catalysts. The objective was to determine the best catalyst components, crystalline properties, pore size, catalyst morphology, and selectivity in producing acetin. The research started with sampling, sorting, purification, extraction, catalyst synthesis, characterization, and determining the molar ratio between glycerol sourced from biodiesel industry by-products and CH3COOH. Determination of catalyst components by XRF spectrometry, crystallinity by XRD, pore size by Brunauer-Emmett-Teller, and morphology of the resulting catalyst used SEM/EDS. Selectivity of the target compound in the form of acetin, either monoacetin, diacetin, or triacetin, used GC-MS. The catalyst of orange peels obtained silica 29.201% and alumina 4.115%, pineapple leaves obtained silica 34.072% and alumina 0.074%, and sugar palm peels obtained silica 40.017% and alumina 0.953%. The diffractogram results showed that all heterogeneous catalysts had sharp-narrow peaks, meaning the crystallinity of the sample was high according to the typical peak of SiO2. The pore size of the orange peel catalyst was 4.328 nm with a surface area of 263.475 m2 g-1, the pineapple leaf catalyst was 4.850 nm and 35.983 m2 g-1, and the sugar palm peel catalyst was 5.658 nm and 10.884 m2 g-1. The results of the morphological test of orange peels were composed of a very heterogeneous dense porous structure; pineapple leaves were amorphous, while sugar palm peels were composed of small, irregular pores. All the resulting heterogeneous catalysts met the characteristics of standard SiO2 silica catalysts. The best acetin selectivity result is a 1:9 molar ratio.