Patent ID: 7902414

Claim:
A process for the selective production of para-xylene comprising the steps of reacting an aromatic hydrocarbon selected from toluene, benzene and mixtures thereof with a gas stream comprising carbon monoxide and hydrogen in the presence of a catalyst, said catalyst comprising: (i) a zeolite having a constraint index of from 1 to 12; (ii) and at least one metal selected from zinc, copper, chromium, cadmium, palladium, ruthenium, and magnesium; said catalyst further characterized by said at least one metal present in the amount of 0.1wt % to 50wt %, based on the weight of the total catalyst; wherein said process includes a catalyst selectivation phase and a para-xylene production phase and wherein: (a) said catalyst selectivation phase includes the step of contacting said aromatic hydrocarbon and said gas stream with said catalyst under a first set of conditions effective to decrease the diffusivity of said catalyst and increase the para-selectivity of said catalyst, and (b) said para-xylene production phase includes the step of contacting said aromatic hydrocarbon and said gas stream with said catalyst under a second set of conditions different from said first set of conditions and effective to selectively produce para-xylene; with the proviso that said first set of conditions and said second set of conditions differ at least in one of temperature, molar concentration and/or feed rate of at least one of said aromatic hydrocarbon, carbon monoxide and hydrogen, and wherein step (a) does not involve the addition of a selectivating agent different from said aromatic hydrocarbon and said gas stream.