AMMONIUM CHLORIDE MODIFIED NATURAL CLAY AS A POTENTIAL SOLID ACID GREEN CATALYST.

ABSTRACT

In the wake of environmental pollutions, the demand for sustainable and environmentally friendly chemical processes is at the core of both industrial and academic research for sustainable chemical production. Catalysis is a playing pivotal role in achieving sustainable chemical especially carefully designed green catalysts. Clay minerals is one of such abundant, low-cost, and renewable materials that can easily be modified to generate potential green heterogeneous catalysts for various organic synthesis, yet it has received less attention relative to the expensive zeolites and other metal-based catalysts. In this study, clay obtained from a study site in Omialafara, Ifon Ose Local Government Area, Ondo State, Nigeria, was modified with ammonium chloride solution to enhance acid (H+ ) function with a view of producing a green solid acid catalyst capable of replacing mineral acid in various acid catalyzed organic synthesis. Pre-treated clay samples (5 g) were treated with 1% and 5% NH4Cl respectively. After treatment the modified clay (5% NH4Cl) as well as the untreated clay were characterized using 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. The FT-IR spectra results showed the presence of Si-O and Si-O-Al functional groups on both clay samples, however, there was not OH group present in the modified clay upon the ammonium chloride treatment. The major elements present for both clay samples which was obtained from the SEM-EDX aanalyis are Si, Al and O. Also notably present for the untreated clay sample was carbon (30.2%), which was greatly reduced for the 5% ammonium chloride modified clay sample with a value 6.0% obtained. The SEM micrographs showed large lumpy particles for the untreated clay and there was noticable disaggregation of the particles upon treatment with ammonium chloride. The surface area (345.364 m2 /g) and pore volume (0.198 cm3 /g) of untreated clay appeared to decrease upon treatment with 5% ammonium chloride to 281.992 m2 /g for surface area and 0.173 cm3 /g for pore volume. The pore size (2.132 nm) remained the same for both clay materials which could mean that the concentration of the ammonium chloride was not enough to provide the desired increase in surface area necessary for effective hetereogeneous catalyst . However, it remains to be seen the effect of the 5% ammonium chloride modification on the clay catalytic performance relative to the untreated.