Xylene isomerization

A process for isomerizing a feed which contains ethylbenzene and xylene, which process comprises the steps of:

• (a) contacting the feed under ethylbenzene conversion conditions with a particulate first catalyst component which comprises a molecular sieve having a Constraint Index of 1-12, the contacting step converting ethylbenzene in the feed to form an ethylbenzene-depleted product, and the particles of said first catalyst component having a surface to volume ratio within the range of 128 to 150 inch.sup.-1 such that the xylene losses during the contacting step are less than that those which would be obtained with a first catalyst component having a surface to volume ratio outside said range;
• and then
• (b) contacting the ethylbenzene-depleted product under xylene isomerization conditions with a second catalyst component.