Characterization and Performance Test of Sulfonated Activated Carbon as a Catalyst in the Levulinic Acid Production Process from Cellulose

Abstract

The production levulinic acid from cellulose was investigated using active carbon
as catalyst. This research conducted the characterize of activated carbon, sulfonated activated
carbon, and nickel impregnation into sulfonated active carbon. The results showed that the
acidity of the active carbon catalyst is 1233.046 μmol/g, while the Ni/sulfonated activated
carbon had the highest catalyst acidity of 6106.512 μmol/g. In addition, the highest acidity of
the sulfonated activated carbon catalyst was obtained at a sulfonation temperature variable of
150℃ and a H2SO4 concentration of 10 N is 5108.332 μmol/g. At a sulfonation temperature
that is too high, degradation of the -OH functional group occurs and can damage the pore
structure of the active carbon. The results of FTIR analysis show that in the sulfonated activated
carbon catalyst, the S-O, S=O, and C-S groups appear at wavelengths of 748-883 cm-1, 1148
cm-1, and around 600 cm-1 respectively, which proves that the sulfonic acid group successfully
attached to the surface of the sulfonated carbon catalyst. Meanwhile in Ni/sulfonated active
carbon, the Ni2+ peak appears at a wavelength of 473 cm-1. XRD patterns of the three variables,
indicating that sulfonation does not affect the carbon microstructure. The appearance of a new
peak at 43° indicates the presence of NiO species in Ni/sulfonated active carbon and the sharper
peaks in Ni/sulfonated active carbon indicate that there has been a change in the amorphous
area to crystalline, which proves that Ni metal is not only attached to the surface but has entered
the active carbon structure. Catalyst performance test show that hydrothermal cellulose without
catalyst produces a cellulose conversion of 12% while active carbon catalyst produces a
cellulose conversion of 20%. The results of the catalyst performance test also show that
hydrothermal cellulose using sulfonated activated carbon produces a conversion of 30% due to
the presence of -COOH, -OH, and -SO3H functional groups which have the power to adsorb
cellulose so that it is efficient for the cellulose hydrolysis reaction. The highest cellulose
conversion of 42% was achieved when using Ni/ sulfonated active carbon due to the presence
of Ni which bound to the sulfonate groups enhanced the acidity and catalytic activity.