Cri International, Inc.

J Gary Welch

Robert E Ellingham

A mixture of shaped catalysts, catalyst supports or sorbents comprising generally cylindrical, free flowing particles of regular geometric shape having substantially the same diameter and of varying length are length graded into a first group of particles having a length below a predetermined length, L.sub.1, in the range of fromn 0.8 to about 24 millimeters and an L/D greater than one, and a second group of particles having a length greater than L.sub.1, by feeding the mixture into a rotating cylindrical drum having inwardly opening indentations in its cylindrical wall having a transverse diameter of substantially L.sub.1. The drum is rotated about its longitudinal axis at speeds sufficient to entrap in the indentations and convey particles having a length below L.sub.1 comprising the first group upwardly to a height permitting the particles to fall into a fixed, upwardly opening trough, while retaining the second group of particles having a length above L.sub.1 in a bottom portion of the drum for separate recovery of the two groups of particles.

Hydrotreating with catalyst particles using length and density grading

A spent hydrotreating catalyst having carbonaceous and metallic deposits comprising generally cylindrical, free flowing particles of regular geometric shape having substantially the same diameter but of varying length is stripped, length graded, density graded using an upward flow of gas through an inclined, vibrating surface, and regenerated to achieve catalyst activity very near that of a fresh catalyst.

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Baltimore, MD, United States of America

J Gary Welch