Silica-alumina catalyst Houdry

Pig. 12. Nitrogen adsorption-desorption isotherms for Houdry silica-alumina catalysts. 

The inherent variability of the raw mineral, particularly with respect to minor constituents which in certain cases were known to have major effects on the cracking reaction, led to the development by the Houdry Process Corp. of a synthetic silica-alumina catalyst of controlled chemical composition and more stable catalytic properties. Full scale manufacture of synthetic catalyst was started in 1939. 

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). 

A choice remained between Mechanisms A-l and A-2 which requires that the active centers be either Lewis or Bronsted acid, respectively. Since A-2 would lead to the formation of molecular hydrogen, an attempt was made to detect and measure any hydrogen evolution concomittant with the chemisorption of triphenylmethane. Triphenyl-methane was chemisorbed on 28 gm of Houdry S-65 synthetic silica-alumina catalyst in a sealed, evacuated apparatus. When the chemisorption was completed the gas phase, collected using a Sprengle pump,... 

To study the properties of silica-alumina catalysts Houdry M-46 silica-alumina was used mainly although the results were also compared with those obtained with a mixed gel silica-alumina catalyst. The latter was prepared by grinding together the wet gels of alumina and silica, obtained, respectively, by the hydrolysis of purified aluminum isopropoxide and ethylorthosilicate dissolved in isopropyl alcohol. All catalysts were treated with air for 3 hours at 600° and evacuated in the reactor at the same temperature for more than 30 hours until no more water was evolved. 

As a matter of fact, Houdry was the first one to use acid-treated bentonites as cracking catalysts back in 1936. In the 1940s, silica-alumina catalysts were synthesized, and they... 

Acid-treated clay minerals were employed as cracking catalysts in the first commercial process, the Houdry process, widely used in the early petroleum industries to produce high-octane gasoline. The Houdry process catalysts had been discussed extensively by many investigators (2) but were eventually completely replaced by synthetic silica-alumina or zeolite catalysts. Recently, the need for new catalytic materials has revived special interest in the layer lattice silicates because of their ion-exchange properties and their expandable layer structures. 

Houdry cracking process. Decomposition of petroleum or heavy petroleum fractions into more useful lower-boiling materials by heating at 500C and 30 psi over a silica-alumina-manganese oxide catalyst. 

Silica-alumina cracking catalysts France Houdry... 

Polymerization of ethylene on silica-alumina was investigated in a manner similar to that used with alumina. The catalyst was mainly Houdry M-46 silica-alumina, although mixed gel catalysts were also used for comparison. Catalyst pretreatment has been described in Section III. 

Another important polymer catalyst development was triethylene diamine (TEDA), trademarked Dabco by the Houdry Process Corp. in 1959 as a one-step catalyst for poljuirethanes. In 1956, Houdry had made this unusual compound as a by-product of research directed toward synthesis of heterocyclic nitrogen compounds using silica-alumina cracking catalysts. The use of TEDA as a urethane catalyst was suggested by Professor Milton Orchin of the University of Cincinnati it was developed by Houdry researchers led by Adalbert Farkas. Dabco soon became the major urethane catalyst (85). 

The common catalysts lose most of their activity at the following temperatures Super Filtrol natural, 1400°F silica-alumina synthetic, 2000 F silica-magnesia, 1400°F and silica-boria, 1400°F. However, in practice, regeneration temperatures are kept below 1000 to 1100 or 1150°F except bauxite which may be regenerated at even 1300°F without appreciable loss in activity. All catalysts lose some activity upon long use. The decline is. particularly noticeable with natural catalyst processing sour stocks and even the excellent catalyst cases of the Houdry process allow some decline in activity over a period of a... 

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