Abstract: In a process for producing p-xylene which comprises catalytically methylating toluene with a methylating agent in the gaseous phase, the improvement wherein(a) said methylation is carried out continuously in a multi-stage reaction system consisting of a plurality of separate series-connected fixed catalyst layers without separating the resulting xylenes in an intermediate stage,(b) said toluene is fed together with hydrogen gas into only the first-stage fixed catalyst layer and passed successively through the subsequent fixed catalyst layers, the amount of toluene fed being such that the total weight hourly space velocity of toluene is from 1 to 300 hr.sup.-1,(c) said methylating agent is fed into each of said fixed catalyst layers, if desired together with hydrogen gas, the amount of the methylating agent fed into each catalyst layer being 0.

Abstract: In a process for isomerization of xylenes which comprises contactng an aromatic hydrocarbon stock mainly containing xylene isomers not attaining a thermodynamic equilibrium composition with a catalyst composition containing a crystalline aluminosilicate at an elevated temperature in the vapor phase in the presence of hydrogen, the improvement wherein said catalyst composition comprises a crystalline aluminosilicate having a silica/alumina mole ratio of at least 10 and contains at least two metals which are (a) platinum and (b) at least one metal selected from the group consisting of titanium, chromium, zinc, gallium, germanium, strontium, yttrium, zirconium, molybdenum, palladium, tin, barium, cesium, cerium, tungsten, osmium, lead, cadmium, mercury, indium, lanthanum, beryllium, lithium and rubidium.

Abstract: In a process for dealkylating a hydrocarbon material containing at least one alkyl-substituted aromatic hydrocarbon having bonded to the aromatic ring at least one alkyl group with at least 2 carbon atoms in the gaseous phase in the presence of hydrogen using a hydro-dealkylation catalyst, the improvement wherein (a) said hydro-dealkylation catalyst is composed of a crystalline aluminosilicate having a silica/alumina mole ratio of from 20 to 200 and containing a noble metal selected from platinum, palladium, rhodium and iridium, and (b) said dealkylation is carried out at a temperature of 250.degree. C. to 420.degree. C. and a pressure of not more than 100 psig, thereby selectively removing said alkyl group containing at least 2 carbon atoms from said alkyl-substituted aromatic hydrocarbon.

Abstract: A process for isomerizing xylenes, which comprisescontacting an aromatic hydrocarbon feedstock containing mainly a xylene isomeric mixture containing ethylbenzene with a catalyst of a palladium-containing crystalline aluminosilicate in the vapor phase in the presence of hydrogen to continuously isomerize xylenes and simultaneously de-ethylate the ethylbenzene selectively;interrupting the isomerization reaction;introducing an oxygen-containing gas into a bed of the catalyst in which coke has been deposited during the isomerization reaction, to contact the catalyst with the oxygen-containing gas;burning off the coke deposits on the catalyst with the oxygen-containing gas by gradually increasing the temperature of introduction of the oxygen-containing gas from not more than 200.degree. C. to a temperature in the range of 330.degree. to 390.degree. C. with no part of the catalyst bed exceeding a maximum temperature of 400.degree. C. while controlling the hot spot temperature of the catalyst bed not to exceed 50.