Beside the title reaction the aldol condensation is observed as a side-reaction. A mechanism is proposed in which the aromatic ring is involved in the rearrangement process. Factors governing the activities and product selectivities are presented. Over these new catalysts the dimerization rate is independent of the choice of solvent, which highlights the increased accessibility of the acid sites. Depending upon the reaction conditions different dimerization products are obtained.
Complete conversion is achieved even at very high space velocities.
The catalyst can be recycled at least five times with little decrease in its activity. Sulfur content before and after reaction and the amount of coke at the end of the reaction were measured. The coke deposited on the catalysts blocks the pores of small size and decreases the surface area of the used catalysts. After regeneration, surface area is not completely restored. The loss of sulfur during reaction, probably associated to the reaction medium, also produces a decrease in surface area by the collapse of the smallest pores which generates larger ones.