TEXTURAL PROPERTIES OF WASTE-DERIVED SOLID HYDROXY SODALITE CATALYST FOR BIODIESEL PRODUCTION

Abstract

Hydroxy sodalite catalyst is an emerging heterogeneous catalyst developed from waste material sources within coal mining fields and coal powered combustion sites in South Africa. It is capable of high reactivity, selectivity and, it is a metal-base stable catalyst that can be industrially applied in biodiesel production and ion exchanged/chemical adsorption. This novel catalyst from wastes is demonstrated to possess high catalytic performance compared with the non-waste chemically synthesized hydroxy sodalite catalyst during biodiesel production. Hydroxy sodalite was synthesized from coal fly ash (CFA) and waste industrial brine (WIB) via hydrothermal technique. A mixing ratio of range 1:1 to 1:11 of CFA and WIB formed was treated with different molar concentrations of NaOH solutions for optimal hydrothermal synthesis of hydroxy sodalite catalyst. The resulting waste-derived catalyst was characterized for purity, crystallinity, enhanced morphology and textural properties using XRD, SEM-EDS, FT-IR and BET-N₂ adsorption-desorption, respectively. The catalyst produced using 3.5 M concentration of NaOH and CFA+WIB, and of 1:7 mixing ratio gave the desired purity, crystallinity, morphology and enhanced textural properties for increased catalytic performance. A catalyst performance test was also carried out, and it revealed that its activity is effective in the transesterification of animal fat oil (AFO) with a high free fatty acid content (12.42 %) to biodiesel. The FT-IR and GC-MS results confirmed production of fatty acid methyl esters (FAMEs). The BET results also displayed an enhanced surface area, pore volume and pore size of solid waste-derived HSOD of 19.05 m²/g, 0.15 cm³/g and 30.82 nm, respectively and are comparable with the results found in the literature.