Startup method for a moving-bed hydrogenation zone

A startup method for a hydrogenation process in which a feed stream comprising hydrogen and olefinic materials is contacted with a bed of solid catalyst located in a substantially cylindrical catalyst retention volume which comprises the steps of:

• (a) passing the feed stream downward through a moving-bed reactor while less than 99 vol.% of the catalyst retention volume of the moving-bed reactor is filled by the bed of solid catalyst and effecting the hydrogenation of olefinic materials in the feed stream at on-stream non-cracking hydrogenation conditions including a pressure of from about 100 psig. to about 1200 psig. and a temperature of from about 250.degree. F. to about 500.degree. F. and a hydrogen feed rate of about 500 scf/bbl to 2000 scf/bbl;
• (b) intermittently charging a quantity of catalyst greater than 0.1 vol.% of the catalyst retention volume and less than 5.0 vol.% of the catalyst retention volume per intermittent charge of catalyst to the reactor at a first rate of catalyst transfer and distributing each quantity of catalyst on top of the bed of solid catalyst;
• (c) intermittently removing a quantity of used catalyst from the bottom of the reactor at a second rate of catalyst transfer less than the first rate of catalyst transfer;
• and,
• (d) equalizing the first and the second rates of catalyst transfer when the catalyst retention volume of the moving-bed reactor becomes filled.