SYNTHESIS AND CHARACTERISATION OF GREEN AND SUSTAINABLE CLAY-BASED SOLID ACID CATALYSTS

ABSTRACT

Catalysis plays a crucial role in achieving sustainable chemical production, especially carefully designed green catalysts. One of the many abundant, affordable, and renewable materials that can easily be modified to generate potential green heterogeneous catalysts is clay minerals. In order to improve acid (H+ ) function and create a green solid acid catalyst that could replace mineral acid in different acid-catalyzed organic synthesis, clay from a study site in Omialafara, Ifon Ose Local Government Area, Ondo State, Nigeria, was modified in this study. 5 grams of pre-treated clay samples underwent 10% and 15% HCl treatments, respectively. X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), and Brunauer-Emmett-Teller (BET) surface area analysis were used to characterize the modified clay (15% HCl) and the untreated clay after treatment. Both clay samples had Si-O and Si-O-Al functional groups, according to the results of the FT-IR spectra, while the clay that had undergone the hydrochloric acid treatment had none. Si, Al, and O are the principal elements found in both clay samples as determined by the SEMEDX analysis. Carbon (30.2%) was also noticeably present in the untreated clay sample but significantly less so in the clay sample modified with 15% Hydrochloric acid , where a value of 3.2% was achieved. The SEM micrographs showed large lumpy particles for the untreated clay and there was noticeable disaggregation of the particles upon treatment with hydrochloric acid. The surface area (345.364 m2 /g) and pore volume (0.198cm3 /g ) of untreated clay appeared to increase upon treatment with 15% hydrochloric acid to 358.571m2 /g for surface area and 0.181cm3 /g for pore volume which is a de sired feature for effective heterogeneous catalyst. The pore size (2.132 nm) was reduced for the treated clay which could mean that the concentration of the hydrochloric acid was not enough to provide the desired increase in surface area necessary for an effective heterogeneous catalyst . However, it remains to be seen the effect of the 15% hydrochloric acid modification on the clay catalytic performance relative to the untreated. Thus, the modified clay based catalyst may likely be an efficient catalyst for acid catalyzed reactions.