Free fatty acid esterification (FFA) in palm oil mill waste (POME) was carried out using a sulfonated carbon-zeolite composite catalyst. The catalyst is synthesized with carbon precursor obtained from molasses, which is adsorbed on the surface of the zeolite and then carbonized and sulfonated with concentrated H2SO4 to form a sulfonated carbon-zeolite catalyst composite, which will be used for the esterification catalyst and the optimization process for the esterification reaction is carried out using the response surface methodology (RSM) and experimental central composite design (CCD). Importantly, the observed independent variables were temperature, catalyst weight, and reaction time to produce fatty acid methyl ester (FAME) products. The catalyst was successfully synthesized, which was shown from the SEM characterization strengthened by the presence of a sulfate group in the FTIR results and the calculation results of high acidity properties. Optimization of FFA esterification with SCZ catalyst obtained optimal conditions with a temperature of 79oC, a catalyst weight of 3.00 g, and a reaction time of 134 minutes with a FAME product of 93.75%, considering that the viscosity of biodiesel is below that required by the API.

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The reaction of levulinic acid production from glucose has a reaction stage that requires a high temperature and high activation energy so that in this levulinic acid production reaction a catalyst is needed. The required catalyst must have a lewis acid site and a bronsted acid site so that the acidity of the catalyst is very influential for the successful production of levulonic acid. Silica nickel phosphate catalysts have lewis acid sites from Ni metal and bronsted acid sites from phosphoric and silica groups. The acidity of the catalyst was measured using the pyridine and ammonia adsorption method and the acidity center strength method using the TGA-DTA base adsorption-desorption. The adsorption of ammonia and pyridine uses the gravimetric method so that it can easily obtain the amount of total acidity of the catalyst and the acidity of the catalyst surface while the TGA-DTA method shows the acid strength of the actual catalyst, which is the real state of the catalyst when catalyzing a reaction and shows the catalyst's resistance to high temperatures. These two methods of measuring acidity have the same disadvantage that they cannot show and know the number of lewis acid sites and bronsted acid sites.

The influence of montmorillonite and cane sugar mixture with composition of 1:3, 1:2, 1:1, 2:1, and 3:1 to the characteristics of the synthesized montmorillonite-carbon sulfonate composite catalyst had been investigated. The mixture of montmorillonite and cane sugar was carbonized at 400 oC for 15 hours and then sulfonated using sulfuric acid at 175 oC for 15 hours. The presence of sulfonate group was detected using FT-IR and the surface topology of the catalyst was characterized using SEM-EDX. FT-IR spectra showed the existence of sulfonate group at wave number of 1095 cm-1. SEM-EDX analysis showed that the catalyst with the montmorillonite and cane sugar ratio of 1:2 consisted of 1.06% sulfur. The catalyst activity was examined using an esterification reaction between acetic acid and ethanol, and the reaction products were characterized using GC-MS. The chromatogram peak at m/z = 88 confirmed that the product was ethyl acetate. Catalyst with the montmorillonite and cane sugar ratio of 1:2 was shown to have the highest acidity and gave the highest esterification product with 76.97% conversion.

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