The solid phosphoric acid (SPA) catalyzed alkylation of benzene with 1-pentene was studied in the range
160−220 °C, 3.8 MPa, and with aromatic to olefin ratios in the range 6:1−1:6. It could be shown that SPA
has the potential to be a selective alkylation catalyst for the production of linear alkyl benzenes (LABs) even
at low aromatic to olefin ratios, provided that reaction pathways leading to skeletal isomerization can be
suppressed. It was also found that steric effects were more important than electronic effects in governing the
alkylation selectivity of SPA and that a protonated cyclopropane structure was the most likely transition-state
for alkylation that followed an Eley−Rideal mechanism. Laboratory and pilot plant studies indicated that the
carbon chain length of the product was limited to C15, with less than 5% di-alkylation of benzene taking
place, even for reactions at 1:6 aromatic to olefin ratio.