A method of modifying a zeolite catalyst to increase selectivity of the
catalyst is achieved by dissolving alumina in a phosphorus-containing
acid solution, and treating the zeolite catalyst with the dissolved
alumina solution. A method of preparing an aromatic product, such as a
xylene product, is also achieved by contacting the modified zeolite
catalyst with an aromatic hydrocarbon, such as toluene, and an alkylating
agent, such as methanol, under reaction conditions suitable for aromatic
alkylation. For xylene products the aromatic hydrocarbon may be toluene
and the reaction conditions may be suitable for at least one of toluene
methylation and transalkylation.