432.    CAPELL, R. G., AMERO, R. C., AND WOOD, W. H.  Fuller’s Earth as a Binder for Catalysts and Adsorbents.  Petrol. Refiner, vol. 25, No. 2, 1946, p. 69-71.

                  Florigel is a grade of Florida-Georgia fuller’s earth that develops its maximum adsorptive or decolorizing capacity when heated to 1,200° F. and its maximum dehydrating capacity at 600° F.  Plastic properties are destroyed at 700° F., and a hard granule is formed resistant to the action of H₂O or steam.  Above 1,200° F. its adsorptive and catalytic properties decline.  In investigating the use of Florigel as a binding agent in catalyst manufacture, experimental samples were prepared by mixing a finely ground catalytic base material and a binding agent, kneading in the desired amount of H₂O and extruding the mixture, drying at 1,200° F., cooling, and testing for crushing strength.  A pellet strength of 20 lb., the minimum usually considered acceptable, was obtained with about 8.5% of Florigel, whereas approximately 19% of ball clay was needed for good extrusion.  Fine grinding and thorough mixing are essential in increasing pellet strength and use of enough H₂O to give it the consistency of a stiff mud.  Florigel requires 150% more H₂O than does ball clay to obtain the same consistency.  Additives, such as tannic acid, Na₂CO₃, and NaOH, dissolved in the H₂O improve extrusion characteristics.  Florigel was tested as a bonding agent for a synthetic Mg silicate, an excellent decolorizing agent; at about 35% of Florigel, a maximum decoloring capacity was attained and a hardness for commercial use.  The following characteristics make Florigel suitable as a binder:  Mixed with H₂O and catalytic or adsorptive materials it is readily pelleted, pressed or extruded; it increases mechanical strength of soft nonplastic materials; it is irreversible with respect to H₂O; it is porous and insoluble, hence does not detract from the surface area of the material being bound; it is an adsorbent and a catalyst in its own right; it is stable at high temperature.

                  CAPP, J. P.  See abs. 740.

                  CARLILE, J. H. G.  See abs. 450.