CoAl-MCM-41 (X) catalysts with X = n(si)/(n(Co) + n(Al)) various ratios were synthesized and ethylation of phenol with ethanol was studied in vapor-phase at temperatures between 250 and 450 degrees C. The products obtained were O-alkylated product (ethyl phenyl ether), C-alkylated products (2-ethylphenol and 4-ethylphenol), and C-IO-alkylated products (ethyl ethylphenyl ether). The phenol conversion increased significantly with reaction temperature over all the catalysts. The activity of the catalysts followed the order CoAl-MCM-41 (20) > CoAl-MCM-41 (50) > CoAl-MCM-41 (80). Selectivity between the C-alkylation and the O-alkylation depended on the factors such as acidity of the catalyst and the reaction temperature. CoAl-MCM-41 (20) catalyst displayed a phenol conversion of 40% and a selectivity of more than 80% for 2-ethylphenol under the optimized reaction condition. The ethanol to phenol ratios and the reactant flow rate are also influential for both activity and selectivity of CoAl-MCM-41 catalysts. (c) 2004 Elsevier B.V. All rights reserved.