t-Butylation of 1,2-dihydroxybenzene over acidic zeolites

t-Butylation of 1,2-dihydroxybenzene (DHB) with isobutene as alkylating age nt was carried out over various acidic zeolites such as USH-Y, H-beta, and H-ZSM-5. USH-Y zeolite exhibits the highest catalytic activity and consider able selectivity of 4-t-butylcatechol (4-TBC). The selectivity of 4-TBC is increased in the order of H-ZSM-5>USH-Y congruent to H-beta. 3-t-Butylcatec hol (3-TBC) is well produced over catalyst with high SiO2/Al2O3 ratio and l arge pore aperture. 3,5-Di-t-butylcatechol (3,5-DTBC) selectivity is maximu m in zeolite which contains strong acidity and large pore channel. The infl uences of various reaction parameters such as reaction temperature, space v elocity reactant molar ratio are discussed. In order to improve 4-TBC forma tion and decrease in 3,5-DTBC selectivity simultaneously, USH-Y zeolite was silylated by tetraethylorthosilicate (TEOS) resulting in the decrease of 3 ,5-DTBC selectivity over modified catalysts by about 25%. USH-Y zeolite sho ws high stability in the t-butylation for at least 350 h. The coke formed d uring the reaction was identified by FT-IR and the USH-Y zeolite could be r egenerated through oxidative thermal treatment. (C) 2000 Elsevier Science B .V. All rights reserved.