Abstract: A method of distilling a liquid containing dimethyl sulfoxide using a distillation system, including mixing sodium carbonate with a liquid containing dimethyl sulfoxide at a bottom of the distillation system such that sodium carbonate accounts for 0.005% to 25% by weight relative to 100% by weight of the liquid containing dimethyl sulfoxide and sodium carbonate in total at the bottom of the distillation system and heating the bottom; and obtaining a distillate containing dimethyl sulfoxide at a position lower than a position at which the liquid containing dimethyl sulfoxide is introduced and higher than a position of the heating portion.

Abstract: A method of distilling a liquid containing dimethyl sulfoxide using a distillation system, including mixing sodium carbonate with a liquid containing dimethyl sulfoxide at a bottom of the distillation system such that sodium carbonate accounts for 0.005% to 25% by weight relative to 100% by weight of the liquid containing dimethyl sulfoxide and sodium carbonate in total at the bottom of the distillation system and heating the bottom; and obtaining a distillate containing dimethyl sulfoxide at a position lower than a position at which the liquid containing dimethyl sulfoxide is introduced and higher than a position of the heating portion.

Abstract: A process converts ethylbenzene in a C8 aromatic hydrocarbon mixture containing a large amount of non-aromatic hydrocarbons, mainly to benzene, by which the xylene loss is small, the deactivation rate of the catalyst can be reduced, and a high conversion rate to p-xylene can be attained. The process for converting ethylbenzene includes bringing a feedstock containing an alicyclic hydrocarbon(s) in an amount of not less than 1.0% by weight, ethylbenzene and xylene into contact with hydrogen in the presence of a catalyst to convert ethylbenzene mainly to benzene, wherein the catalyst is mainly composed of MFI zeolite and an inorganic oxide(s) and rhenium-supported, and wherein the conversion is carried out at a reaction pressure of not less than 1.0 MPa-G.

Abstract: A process converts ethylbenzene in a C8 aromatic hydrocarbon mixture containing a large amount of non-aromatic hydrocarbons, mainly to benzene, by which the xylene loss is small, the deactivation rate of the catalyst can be reduced, and a high conversion rate to p-xylene can be attained. The process for converting ethylbenzene includes bringing a feedstock containing an alicyclic hydrocarbon(s) in an amount of not less than 1.0% by weight, ethylbenzene and xylene into contact with hydrogen in the presence of a catalyst to convert ethylbenzene mainly to benzene, wherein the catalyst is mainly composed of MFI zeolite and an inorganic oxide(s) and rhenium-supported, and wherein the conversion is carried out at a reaction pressure of not less than 1.0 MPa-G.

Abstract: A process for converting ethylbenzene, by which ethylbenzene in a feedstock containing C8 aromatic hydrocarbon is converted to benzene at a high degree of conversion is disclosed. The process for converting ethylbenzene includes bringing a C8 aromatic hydrocarbon mixed feedstocks containing ethylbenzene into contact with an acid type catalyst containing at least one metal selected from the group consisting of the metals belonging to Group VII and Group VIII in the presence of H2 to convert ethylbenzene to benzene. The feedstock contains C9-C10 aromatic hydrocarbons including ethyltoluene, and the ethyltoluene is converted to toluene together with the conversion of ethylbenzene.

Abstract: A method for converting aromatic hydrocarbons by contacting an aromatic hydrocarbon starting material including benzene and having a non-aromatic compound content of 1% by weight or less, with a catalystto generate useful C7 and C8 aromatic hydrocarbons while reducing the catalyst deactivation.

Abstract: Disclosed herein is a catalyst composition for transalkylation of alkylaromatic hydrocarbons which exhibits the percent conversion of ethyltoluene higher than 50 wt %, is composed of mordenite (100 pbw), inorganic oxide and/or clay (25-150 pbw), and at least one metal component of rhenium, platinum, and nickel, and contains mordenite such that the maximum diameter of secondary particles of mordenite is smaller than 10 &mgr;m. Disclosed also herein is a process for producing xylene by the aid of said catalyst from alkylaromatic hydrocarbons containing C9 alkylaromatic hydrocarbons containing more than 5 wt % ethyltoluene and less than 0.5 wt % naphthalene, in the presence of hydrogen.

Abstract: Disclosed herein is a catalyst composition for transalkylation of alkylaromatic hydrocarbons which exhibits the percent conversion of ethyltoluene higher than 50 wt %, is composed of mordenite (100 pbw), inorganic oxide and/or clay (25-150 pbw), and at least one metal component of rhenium, platinum, and nickel, and contains mordenite such that the maximum diameter of secondary particles of mordenite is smaller than 10 .mu.m. Disclosed also herein is a process for producing xylene by the aid of said catalyst from alkylaromatic hydrocarbons containing C.sub.9 alkylaromatic hydrocarbons containing more than 5 wt % ethyltoluene and less than 0.5 wt % naphthalene, in the presence of hydrogen.

Abstract: Aromatic hydrocarbons are efficiently converted by bringing feedstock containing from 5 to 50% by weight of an aromatic hydrocarbon having an ethyl group and a C.sub.9 alkyl aromatic hydrocarbon into contact with a catalyst capable of disproportionation, trans-alkylation and dealkylation, a secondary particle diameter of a zeolite in the catalyst being 10 .mu.m or less.

Abstract: An improved process for producing xylene from feedstock containing C.sub.9 alkyl aromatic hydrocarbons with the aid of a catalyst capable of disproportionation, rearrangement, and dealkylation, wherein said improvement comprises performing the reaction in the presence of an aromatic hydrocarbon having one or more ethyl groups in an amount of 5 to 50 wt %.