Catalyst
waste from the residue fluid catalytic cracking (RFCC)
plant process can still be utilized to catalyze the catalytic cracking
of palm oil to fuels. However, we should regenerate the active sites
of the catalyst waste. This paper focuses on enhancement of Brønsted
and Lewis acid sites on the spent RFCC catalyst waste through various
acid treatments in order to regenerate its catalyst active sites.
In order to regenerate the Brønsted and the Lewis acid sites
as active sites in the palm oil catalytic cracking, the spent RFCC
catalyst was treated by citric acid, sulfuric acid, and mixture of
both acids. The catalysts were characterized by X-ray fluorescence,
X-ray diffraction, Brunauer–Emmett–Teller-Barrett–Joyner–Halenda,
and pyridine-FTIR analysis. The modified catalyst performance was
tested over a fixed bed reactor for the catalytic cracking process
of palm oil to liquid fuels. It was found that the acid treatment
on the spent RFCC catalyst can increase surface area, pore volume,
and Brønsted to Lewis acid site ratio of catalysts. The Brønsted
acid sites of the spent RFCC catalyst strongly increase by the treatment
using sulfuric acid, which is because of the proton transfer from
acid to catalyst and because of the formation of sulfate groups (HOSO3−) in the catalysts. It was found that the Brønsted
acid site leads to the formation of long-chain hydrocarbon, while
the Lewis acid site pronounces the formation of short-chain hydrocarbon
and coke. Moreover, the total acidity and the Lewis acid site amount
on the catalyst have roles in the formation of hydrocarbon fraction
in the liquid product.