Journal of Molecular Catalysis, 71 (1992) 373-381 373 M2799 Hydroxylation of phenol over TS-2, a titanium silicate molecular sieve J. Sudhakar Reddy, S. Sivasanker and P. Ratnasamy Catalysis Division, National Chemical Laboratory, Pune 8 (India) (Received July 7, 1991; accepted October 4, 1991) Abstract The influence of different process parameters on the hydroxylation of phenol with H202 over the titanium silicate molecular sieve TS-2 has been investigated. Apart from the primary products v/s., p- and o-dihydroxybenzenes, the corresponding quinones are also formed. Higher Ti contents in the catalyst (TS-2) and higher catalyst concentrations lower the formation of the secondary oxidation products. Solvents have an influence on the relative amounts of the two dihydroxybenzenes in the product. H202 efficiency of up to 74% is obtainable at ~ 2896 phenol conversion to dihydroxybenzenes. Introduction The titanium silicate molecular sieve, TS-1, [1, 2] with an MFI structure has been reported to catalyze a number of reactions, such as hydroxylation of aromatics [3, 4], selective oxidation of alkanes [5], ammoximation of cyclohexanone [6[ and rearrangement of cyclohexanone oxime [7]. A more recent discovery is the titanium silicate molecular sieve, TS-2 [8, 9], which has an MEL structure. This material has also been reported to catalyze the ammoximation of cyclohexanone [ 10] and the selective oxidation of n-hexane [11]. The first commercial process utilizing titanium silicate (TS-1) as a catalyst was the hydroxylation of phenol to hydroquinone and catechol, introduced by Enichem, Italy [2, 12]. Some aspects of the TS-l-catalyzed hydroxylation reaction have been revealed recently [2, 12 ]. We have investigated the reaction using TS-2 as the catalyst, and present the results in this paper. Experimental The titanittm silicate molecular sieve with MEL structure (TS-2) was synthesized by mixing tetrabutylammonium hydroxide, tetraethylorthosilicate and titanium butoxide and autoclaving the mixture at 443 K for 48 h. The details of the synthesis and characterization of this new titanium silicate have already been reported elsewhere [8, 9]. The as-synthesized TS-2 was filtered, washed, dried and calcined in dry air for 16 h at 823 K. 0304-5102/92/$5.00 © 1992- Elsevier Sequoia. All rights reserved