The adsorption of methanol on the (110) surface of g -alumina was investigated using both ab initio and density functional theory quantum chemical methods. A [Al 3 O 9 H 10 ] ϩ cluster model comprising one tetrahedral and two octahedral aluminum cations were used to describe the surface and the mechanism of adsorption of methanol. This has allowed us to rationalize the stable structures of adsorbate and the mode of bonding. The IR frequency shifts between the gas phase and the adsorbed species were also calculated and they exhibit good agreement with experiment. ᭧

It has been shown that, after a partial deactivation, y-alumina ( y-A1203) is a good catalyst for selective methylation of 1,2-benzenediol in the temperature range of 260 -310 "C. The main products are the desired 3-methyl-I ,2-benzenediol and 2-methoxyphenol, which may be converted in another step into 3-methyl-I ,2-benzenediol, giving an overall selectivity for the desired products of 80 to 90%. The catechol forms a strongly chemisorbed surface species on y-alumina and its steric adsorption model correlates with the kinetic data.

No abstract

-Gas-phase alkylation of catechol with methanol on T-alumina and modified "t-alumina catalysts is studied experimentally. By limiting the conversion to X < 0.3, the formation of polymethylated species can be avoided and only the three isomers guaiacol, 3-methylcatechol and 4-methylcatechol are observed. Optimising the catalyst composition and the reaction conditions, a selectivity of 0.75 for the industrially most valuable product 3-methylcatechol can be obtained.

No abstract