Houdry pelletted catalyst

In 1940, Houdry Process Corporation initiated commercial manufacture of a synthetic silica-alumina catalyst at Paulsboro, New Jersey (133). The synthetic catalyst is produced in pellet form (51,265) and contains 12 to 13% alumina (221,276). It has the advantages of controlled chemical composition, higher purity, and greater heat stability, but is more expensive than the activated-clay catalyst. 

In 1944, Socony-Vacuum Oil Company started manufacture of synthetic silica-alumina catalyst in the form of beads (262). This catalyst was reported to contain about 10% alumina. The bead catalyst gives about the same product distribution as the pelleted synthetic catalyst and was developed primarily to achieve greater physical strength for use in the TCC process. The bead catalyst has also been used in Houdry fixed-bed units (51,171). Subsequently, a harder bead catalyst was developed for use in the air-lift units. The improved bead catalyst consists of approximately 15% alumina and 85% silica and contains 0.003% chromium to minimize afterburning by suppressing formation of carbon monoxide during regeneration (333). 

Mills, Ashwill, and Gresham (39) compared pelleted Houdry kaolin and sieve catalysts for cracking heavy sweet gas oil. Table I shows their results obtained at constant conversion of 70 vol %. Results correspond to those for fluid catalyst 9.4 vol % additional gasoline results, and propylene yield is reduced from 3.7 to 2.6 wt %. 

The catalyst particles in the Houdry-type cracking processes, both fixed and moving bed, were initially granules, then pellets or beads of about 3 mm diameter. Later, fluid catalytic cracking used beds of catalyst in the form of fine powder, initially made by grinding and later by spray drying of microspheres, with 50 to 80 wt% of the particles in the size range of about 50 to 150 microns, with the remainder down to 20 or even 10 microns (That part was quickly lost from the unit, as fines.) ( 7),... 

The Houdry Catalytic Cracking (HCC) process was a precursor to FCC. Houdry catalyst particles are pellets, which are carried to a storage hopper by a conveyor belt or pneumatic lift tubes. The pellets flow down from the hopper through the reactor, and from the reactor to a regenerator. The HCC product slate is similar to that for FCC, but FCC conversions and gasoline yields are significantly higher. 

Regular Houdry clay pellets have lasted more than 18 months. Newer catalysts contain some high-thermal-conductivity material to assist in heat flow, and T.C.C. beads are being used because of their mechanical stability. Catalyst costs are less than 2 cents per barrel processed. New catalyst is very active, and hence process steam is introduced and then rieduced in amount as the run proceeds. Increase in pressure from tbe usual 10 psig to 70 psig increases the gasoline yield, but the yields of gas and coke increase even more rapidly. 

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