TOLUENE METHYLATION METHOD UTILIZING SPECIFIC START-UP CONDITIONS, WHICH PRODUCE P-SYLENE AND TO ACHIEVE STABLE CATALYTIC ACTIVITY

摘要

PURPOSE: A toluene methylation method is provided to produce p-xylene with high selectivity and to achieve stable catalytic activity over extended periods by utilizing specific start-up conditions. CONSTITUTION: The method of preparing a xylene product comprises the steps of: providing a reactor containing a phosphorus-treated ZSM-5-type zeolite catalyst; initiating start-up of a toluene methylation reaction by contacting the catalyst with a toluene/methanol feed and a hydrogen cofeed introduced into the reactor at start-up conditions, wherein the toluene/methanol feed is introduced into the reactor at a liquid hourly space velocity(LHSV) of about 2hr¬-1 or more and the hydrogen cofeed is introduced into the reactor at a hydrogen/hydrocarbon(H2/HC) mole ratio of about 8 or less, the temperature is about 500 to 700deg.C; operating the reactor at the start-up conditions for about 30 minutes to about 20 hours; and then operating the reactor at run conditions, wherein the LHSV is 10 hr-1 or less and H2/HC mole ratio is at least 1.0 and the temperature is about 500 to 700deg.C.