A new process that used the coupling of the reaction and separation was employed, which greatly improved the conversion
of cottonseed oil (triglyceride) and free fatty acids (FFA) when a model waste oil feedstock was used. The
vegetable oil asphalt-based catalyst showed the highest catalytic activity. This was due to the high density
and stability of its acid sites, its loose irregular network, its hydrophobicity that prevented the hydration
of –OH species, and large pores that provided more acid sites for the reactants.