Cracking activity test

Polyethylene and polystyrene are examples of plastics subject to environmental stress cracking. Crack resistance tests have shown that surfactants, alcohols, organic acids, vegetable and mineral oils, and ethers provide an active environment for stress cracking of polyethylene. Table 6 lists typical sterile devices and plastic materials used to fabricate them, while Tables 7-9 list the potential effects of sterilization processes on polymeric materials. The effect of gamma irradiation on elastomeric closures has been studied by the Parenteral Drug Association [15]. 

This paper gives an example of the response of one equilibrium catalyst to the three basic Demet procedures and to modified versions of these procedures. The catalysts are evaluated by elemental analysis and by their cracking performance, as determined by the micro activity test (MAT). 

Cracking performance. Micro activity test results for the different preparations are given in Table II. Variants of all three basic Demet procedures (see Fig. 1-3) can be used to improve the performance of this equilibrium catalyst. 

Kaolin had little or no cracking activity, and catalyst activity as tested in the laboratory was directly related to silica-alumina gel content. However, the catalyst performed much better in commercial tests than anticipated from laboratory testing. Undoubtedly, this open structure encountered much less severe conditions at the outer surface of the microsphere during regenerations and made internal catalytic surfaces more readily available. This first of the so-called "semisynthetics" was called Nalco 783, and the matrix is still used in many forms some 28 years later.(7,13) Today it is estimated that some 200,000 tons/yr. of kaolin clay is used for cracking catalyst manufacture as reported by Georgia Kaolin Corporation.(24) Figure 10 shows the pore volume distribution for Nalco 783 and two other commercial semisynthetics from that period. 

This type of coke depends exclnsively on the FCC cracking activity. In order to have samples with different activity and little inflnence of contaminant coke, the fresh catalyst was deactivated hydrothermally at different severity conditions withont metals. MAT test for these deactivated samples was performed with VGO as a feedstock to diminish coke yields. 

An earlier report from this laboratory (7) noted that in a series of mildly extracted mordenites, the hexane cracking activity in a continuous-flow test went through a marked maximum with increasing severity of extraction, while the f-butane to n-butane ratio continuously increased. The activity and product distribution were measured after 10 min on stream. Since catalyst deactivation was rapid, it was not possible to... 

The purpose of the present work is to incorporate aluminum into the framework of SBA-15 during the synthesis in order to create acid sites on the surface of the material directly and to enhance its activity in acid-catalyzed reactions and to study the stability of SBA and AlSBA molecular sieves under various treatments. The influence of these treatments on the pore size, wall thickness and the environment of Al in these materials are investigated in detail. X-ray diffraction (XRD), Electron Microscopy (TEM) and N2 adsorption were used to characterize the structure, the porosity and the stability of these materials. 27Al MAS NMR was used to ascertain the nature and environment of Al, cumene cracking to test the catalytic activity of parent materials and ammonia chemisorption to probe their surface acidity. 

The catalytic activity of SBA and AISBA samples toward cumene cracking were tested in a continuous flow fixed-bed microreactor system with helium (25 mL min 1) as carrier gas. The catalyst load for the tests was 100 mg and the catalyst was preheated at 573 K under helium flow for 3 h. For the reaction, a stream of cumene vapor in helium was generated using a saturator at room temperature. The reaction products were analyzed by gas chromatography. 

The low iso/normal C6-C7 paraffin ratios observed in the MAT testing with fresh additive is then the result of iso-C6 and -C7 carbenium ion cracking, reducing the amount of these species available for conversion to isoparaffins by H-transfer. C4 and C5 carbenium ions are too small to crack, requiring the formation of a primary ion, so that C4 and C5 isoparaffins increase due to cracking of C7-plus ions. For deactivated additive, the C6-C7 iso/normal ratios are higher than for the base catalyst, since the cracking activity of the additive is reduced, and since H-transfer activity... 

Dealuminated Y zeolites which have been prepared by hydrothermal and chemical treatments show differences in catalytic performance when tested fresh however, these differences disappear after the zeolites have been steamed. The catalytic behavior of fresh and steamed zeolites is directly related to zeolite structural and chemical characteristics. Such characteristics determine the strength and density of acid sites for catalytic cracking. Dealuminated zeolites were characterized using X-ray diffraction, porosimetry, solid-state NMR and elemental analysis. Hexadecane cracking was used as a probe reaction to determine catalytic properties. Cracking activity was found to be proportional to total aluminum content in the zeolite. Product selectivity was dependent on unit cell size, presence of extraframework alumina and spatial distribution of active sites. The results from this study elucidate the role that zeolite structure plays in determining catalytic performance. 

If water was added to the 15% Si02 co-gel to fill the pore voids a partially recrystallized boehmite was formed with a surface area of 464 m /g and with a pore volume of 1.8 oc/g. If water was added to the 15% Si02 co-gel to form a slurry and then dried and calcined at 500 a partially recrystallized bodunite was formed with a surface area of 334 m /g. steam treatment at 760 of this second, small pore, bodunite-like silica-alumina resulted in no change in the surface area. The gas oil cracking activity of the steamed sample was definitely hi er than that for the amorphoias co-gel, i.e., a Micro Activity Test (MAT) Activity Number of 38 (see Table 1.). 

Catalytic cracking. A modified micro activity test (MAT) was used for testing cracking performance. The feed oils used in this study were a... 

Micro activity test (MAT). This test was developed and standardized by ASTM (ASTM-D-3907). In the MAT test, a sample of cracking catalyst is contacted with gas oil in a fixed-bed reactor. Gas chromatographic analysis on gas and liquid products is used to determine the yield structure. Recently, the MAT conditions have been adapted to simulate commercial units more accurately in terms of contact times. A higher catalyst activity results in improved conversion and higher regenerator temperature. 

The various rare earth faujasites were calcined at 538°C and then tested for cumene cracking activity. Conversion levels are plotted in Figure 6. HY is superior to the rare earth forms. With the exception of La, Eu, and Yb, the rare earths generally give conversions in the 15-25% range. 

Addition of flourine to H-mordenite enhanced considerably the acid strength of this catalyst but decreased the ratio of Brpnsted to Lewis acidity (167). Using IR spectroscopy of adsorbed pyridine, X-Ray diffraction, catalytic activity tests for cumene cracking, and microcalorimetric measurements of ammonia adsorption, it was shown that some of the acidic hydroxyl groups were substituted with fluorine and that the inductive effect of fluorine increased the acid strength of the remaining hydroxyl groups. 

Numerous laboratory cracking tests have been developed for determination of activity. The test methods can be classified into two categories methods in which the reported activity rating is some primary result of the cracking test, such as yield or quality of one of the cracked products and methods in which the activity is reported in terms of the ratio of the amounts of reference and test catalyst required to achieve the same degree of cracking at otherwise identical conditions. The first classification includes the Jersey D - - L test (101) and the Houdry Cat A test (1,3). The second classification includes the Indiana relative-activity test (290) and the U.O.P. relative-activity test (55,300). Other methods have also been published (69,178,183,212,267,326). 

Cracking properties of a Si-VPl-5 (Si/Al=0.4 in the gel) and the reference catalyst were also investigated by Micro Activity Tests (MAT), using a short contact time MAT (SCT-MAT) which is a modified version of the ASTM MAT with better correlation to a commercial unit 1 g of atmospheric residue was fed to the reactor during 30 seconds at 524°C. Liquid products were collected at 0°C and analyzed on a HP 5880 Sim Dist GC, while gas products were collected over a saturated KCl-solution and injected on a HP 5880 Refinery Gas Analyzer. 

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