Benzylation of benzene with benzyl alcohol on zeolite catalysts

[Display omitted] ▶ Diphenylmethane (DPM) is mostly used in the fragrance industry and agrochemicals. ▶ Benzylation is carried out in “green” advantageous conditions with S DPM of 88.9%. ▶ Used catalysts are cheap and the experimental set-up is simple and practical. ▶ The purification of the final product is easily done. The catalytic liquid phase benzylation of benzene to diphenylmethane (DPM) with benzyl alcohol (BnOH) was investigated over various zeolite catalysts (HSZ 600 mordenite, CBV 20A mordenite, H-beta zeolites with Si/Al of 10.8 and 35.8, respectively) at 353–423 K and under atmospheric pressure, using three reaction methodologies: (A) by adding all benzyl alcohol at the beginning of the reaction, (B) by dropwise addition of benzyl alcohol (1–2 drops/min for 4 h) and (C) under continuous flow conditions. Nafion-embedded silica and AlCl 3/MCM-41 were also tested for comparison. The conversion and product distribution largely depended on the experimental conditions and the zeolite nature. Under optimal conditions using the Beta zeolite (Si/Al molar ratio of 10.8) and the (C) methodology, selectivity to DPM of 88.9% for a conversion of BnOH of 99.2% were achieved. Recycling tests showed that the catalyst preserved its activity and selectivity to DPM after several cycles.