Composition and hydrotreating process for the operation of a magnetically stabilized fluidized bed

A process for conducting hydrotreating reactions via fluids-solids contacting wherein a catalytically active particulate material is formed into a magnetically stabilized fluidized bed to provide high magnetization at a low applied field which comprises contacting a bed comprising particles of average size ranging from about 10 .mu.m to about 4000 .mu.m containing a non-ferromagnetic refractory, porous inorganic oxide component composited with a plurality of elongate ferromagnetic components, a ferromagnetic component being multidomain, having dimensions of at least 1 .mu.m in all directions, elongated in one or two directions, and having a length:diameter (L/D) ratio of at least 2 but not more than 19.5 where the ferromagnetic inclusions are elongated in one direction, or an L/D ratio of not more than 313 where ferromagnetic components are elongated in two directions, said ferromagnetic component being present in the composite particles as inclusions within a nonferromagnetic matrix, and randomly oriented and constituting at least 0.5%, but for particles elongated in one direction not more than 2.pi./3(L/D+1).sup.2, and for particles elongated in two directions not more than .pi./2(L/D+1), of the total volume of each particle, where L/D is the average ratio of the longest dimension of a ferromagnetic inclusion relative to the shortest dimension, and wherein from about 2 percent to about 25 percent of a metal selected from the group consisting of nickel, cobalt, molybdenum, tungsten, platinum, palladium, ruthenium, rhenium, iridium, and the like, based on the weight of the catalyst composition, is dispersed on the surface of the composite particle, sufficient that the composite particles are catalytically active for conducting the hydroxitating reactions.