SYNTHESIS AND CHARACTERISTION OF ACID-MODIFIED CLAY-BASED GREEN HETEROGENEOUS CATALYST

ABSTRACT

Clay catalysts are considered environmentally friendly, and hold promise for positively influencing the sustainability of the chemical industry. This research work was aimed at modifying clay by treating it with 30% and 35% conc. HCl respectively to improve its acid function. This approach has the potential to bring about a substantial transformation in the production and utilization of chemicals. The clay was obtained from Omilafara in the Ose Local Government Area of Ondo State, Nigeria. A quantity of 5 grams of clay was carefully measured and placed into a beaker. Subsequently, a 35% hydrochloric acid (HCl) solution from stock was added to the clay, and the mixture was stirred continuously for a duration of 24 hours. Afterward, the mixture underwent a filtration process to eliminate any residual chlorine present. Following filtration, the sample was left to air dry for a period of 24 hours. Finally, the dried sample was subjected to a calcination process and subsequently underwent a characterization analysis. The 35% hydrochloric acid (HCl) treated clay underwent characterization using various techniques, including FTIR, SEM-EDX, XRD, and BET. In the FTIR analysis, specific results were obtained at 1047cm^-1, 775cm^-1, and 663cm^-1. This analysis revealed the disappearance of an organic compound and dehydroxylation processes. When examining the clay using SEM-EDX, a highly porous structure was observed in the acid-treated clay. The composition detected by EDX corresponded with the findings from FTIR, confirming the absence of an organic compound. Treated clay with 35% caused a reduction in the carbon content from 35% to 5.4%, and other elements also showed a decrease in their percentages, while oxygen content significantly increased to 35%. XRD analysis revealed a distinct alteration in the crystalline structure of the treated clay compared to the untreated clay. The BET results indicated an increase in pore volume from 0.197 cm³g^-1to 0.264 cm³g^-1 and surface area from 345.4 m²g^-1 to 527.6 m²g^-1 as the acid concentration increased. Notably, there was a significant presence of both macropores and mesopores in the treated clay. The pore size 2.132nm decrease to 2.125nm for both clay materials which could mean that the concentration of HCl was enough to provide the desired increase in surface area necessary for effective heterogeneous catalyst.