Process for improving purity of para-xylene product

A reactive purification process for producing at least 99.5 wt. % para-xylene from a mixture of isomers of xylene which contains more than about 90 wt. % para-xylene and which has been produced by a process exclusive of a selective alkylation process consisting essentially of the steps of:

• (a) alkylating substantially all of the isomers of xylene other than para-xylene in the mixture of xylene isomers, wherein the mixture of xylene isomers contains between about 90 and 99.8 wt. % para-xylene, with an alkylating agent having at least one tertiary butyl moiety in the presence of an acidic catalyst and with molecular contact between the catalyst and the xylene isomers, while alkylating substantially none of the para-xylene;
• and
• (b) separating the para-xylene in at least 99.5 wt. % purity and at least greater than the concentration of para-xylene in the mixture of xylene isomers, from the alkylated xylene isomers to give the final product stream.

A purification process for producing at least 99.5 wt. % para-xylene from a mixture of isomers of xylene having between 90 and 99.8 wt. % para-xylene and which has been produced by a process exclusive of a selective alkylation process consisting essentially of the steps of:

• (a) alkylating substantially all of the isomers of xylene other than para-xylene in the mixture of xylene isomers, wherein the mixture of xylene isomers contains between about 90 and 99.8 wt. % para-xylene, with an alkylating agent having at least one tertiary butyl moiety at a temperature in the range of about 1 to about 300° C. in the presence of an acidic, heterogeneous catalyst with a high surface area of at least 200 m2/g and with molecular contact between the catalyst and the xylene isomers, while alkylating substantially none of the para-xylene;
• and
• (b) separating the para-xylene in at least 99.5 wt. % purity and at least greater than the concentration of para-xylene in the mixture of xylene isomers, from the alkylated xylene isomers to give the final product stream.