For fluid cracking catalysts

FCC. (1) Abbreviation for Food Chemicals Codex, a publication giving specifications and test methods for chemicals used in foods. (2) Abbreviation for fluid-cracking catalyst as used in the petroleum refining industry. Examples are powdered silica alumina, in which alumina is impregnated with dry synthetic silica gel, and various natural clays impregnated with alumina. 

Both devices described above were developed in order to test the friability of fluid-cracking catalysts. Nowadays the application of these or similar tests is a common procedure in the development of fluidized bed catalysts. Contractor et al. (1989), for example, used a submerged-jet test to compare the attrition resistance of newly developed VPO catalysts. In fact, such tests can be applied to any type of fluidized bed processes. Sometimes they have to be slightly modified to adapt them to the process under consideration. The drilled plate may, for example, be substituted by... 

Prior to 1938, gasoline was obtained from thermal-cracking plants then the Houdry fixed-bed catalytic cracking process led to the development of a fluidized-bed process by Standard Oil for the catalytic production of motor fuels (4-8). Acid-treated clays of the montmorilIonite type were the first fluid-cracking catalysts widely employed by the industry. However, the ever greater demand for aviation fuels during the 1939-1945 period prompted the search for more active and selective catalysts. Research on novel catalyst... 

Steam pre-treatment of fluid cracking catalysts has been conventionally employed to represent the deactivation occurring in a commercial FCC unit. Appropriate steam pre-treatment methods have been developed so that the activity and selectivity of the steam pre-treated catalyst is equivalent to a commercially deactivated catalyst (12). However, a unique steaming method may not be suitable for catalysts of varying compositions (12). Two steaming methods designed to simulate deactivation in a commercial unit of the two types of catalysts used in this work were employed. Super-D was treated for 8 hours at 732 C with a steam pressure of 2 atmospheres. The catalysts containing ZSM-5 were treated for 12 hours at 827°C with a steam partial pressure of 0.2 atmosphere. 

DFCr systems appear to have the necessary metals tolerance to process residual oils and the abundant, cheaper, but heavily vanadium-contaminated, Venezuelan and Mexican crudes (1-4). Therefore, the dual function fluid cracking catalyst (DFCC) concept could lead to the generation of important catalysts for U.S. refineries should Middle East politics cause another sudden escalation in crude oil prices and availability. The concept is... 

This paper reviews literature data on model fluid cracking catalysts (FCC) and reports results of spectroscopic studies performed in our laboratories for catalysts in which vanadium has been passivated by tin. Mossbauer spectroscopy, luminescence, x-ray powder diffraction and electron paramagnetic methods have been used to monitor vanadium-tin interactions in all the catalysts studied. 

The test requires the use of a standard batch of gas oil as a feedstock and a set of equilibrium fluid cracking catalysts with consensus mean conversion values assigned in a reactor of specified design. The gas oil and the set of equilibrium cracking catalysts are useful reference materials. Conversion for any equilibrium or laboratory-deactivated fluid cracking catalyst can be measured and compared to a conversion calibration curve. Conversion is measured by the difference between the amount of feed used and the amount of unconverted material. The unconverted material is defined as all liquid product with a boiling point above 216°C. 

A further report of the oxidation ability of manganese nodules is that of Nitta.53 Several reactions were carried out with natural manganese oxide nodules including oxidative dehydrogenations of alkanes and cycloalkanes, reduction of NO, total oxidation of CO, and use in the gettering of metal and mixed metal ions. For example, nodules were found to have a tremendous capacity for adsorption of heavy metals and toxic metals like Pb2+, and Hg2+. in addition, nodules have been used to sequester metals that are present in petroleum fractions that can contain metals like V and Ni. These metals can cause degradation of the fluid cracking catalysts even at levels as low as 1 ppm. 

The weight of catalyst in a vessel is determined by measuring the pressure differential between taps installed at the top and bottom. Density of the fluidized catalyst is determined in a similar manner from the differential pressure between taps located a measured distance apart in the dense phase. Location of the catalyst level can be determined from the combination of the density and the total weight of catalyst, or by the use of a series of pressure taps placed at intervals along the height of the vessel. A hot-wire probe has been used to locate the level in laboratory fluidized beds (250), but this technique has not been adopted for fluid cracking units. The method depends upon the fact that heat-transfer rate from the heated wire is much higher when immersed in the dense phase of fluidized solids than when in the dilute phase. 

Lanthanum-exchanged zeolite-Y is an important catalyst used for fluid cracking in... 

Olefins crack more readily than paraffins since double C=C bonds are more friable under reaction conditions. Iso-paraffins and naphthenes are cracked more readily than normal paraffins, which in turn are cracked more readily than aromatics. In fact, aromatic ring compounds are very resistant to cracking, since they readily deactivate fluid cracking catalysts by blocking the active sites of the catalyst (see the next part). The reactions postulated for olefin compounds apply principally to intermediate products within the reactor system, since the olefin content of catalytic cracking feedstock is usually very low. 

Figure 84 Greldhart classification of particles for fluidization by air at ambient temperature. Region A corresponds to the properties of well-behaved fluid cracking catalysts. [After D. Kunii and O. Levenspiel, Fluidization Engineering, with permission of Butterworth-Heinemann, Boston, MA, (1991).]...

The decomposition of ozone was studied in a fluidized bed 0.1 m in diameter using different samples of fluid cracking catalyst [16,19]. Some data for catalyst with a broad size distribution and a mean particle size of 60 txm are given in Table 9.1. Use Model II to calculate the values of K. 

Pillared rectorites are expanded clay minerals with a surface area in the 150-220 mVg range, and thermal and hydrothermal stability similar to that of zeolites with the faujasite structure (1-4). After steaming at 760°C/5h (100% steam, 1 atm), these materials retain their pillared structure, and at microactivity test conditions (MAT) they are as active as commercial fluid cracking catalysts (FCC) for gas oil conversion... 

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