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In cumene cracking

Figure 3. Extent of conversion and composition of liquid products in cumene cracking over NiCaY catalyst (2.4 wt % nickel), depending on temperature (volume rate 1.10 h l, ratio of hydrogen. cumene 10) 1, total conversion extent 2, benzene 3,... Figure 3. Extent of conversion and composition of liquid products in cumene cracking over NiCaY catalyst (2.4 wt % nickel), depending on temperature (volume rate 1.10 h l, ratio of hydrogen. cumene 10) 1, total conversion extent 2, benzene 3,...
Figure 1. Gravimetric reactor used in cumene cracking studies. Figure 1. Gravimetric reactor used in cumene cracking studies.
Fig. 2. Arrhenius plot for Imh REY seolite used in cumene cracking... Fig. 2. Arrhenius plot for Imh REY seolite used in cumene cracking...
Ri and R2 could be alkyl groups. The electron-deficient carbon atom of a C—H bond so polarized could then serve as the active center for reactions of the carbonium ion type complete cleavage of the C—H bond is not required. The Linde workers were unable to correlate zeolite hydrogen content with hexane isomerization activity (40) nor did they attribute the great rise in cumene cracking activity (48) obtained by replacing univalent cations with bivalent cations in zeolite Y as arising... [Pg.280]

She, L. Q., Liu, X. Y., and Li, X. W. 1985. Relationship between catalytic activity and add strength ofLaHY zeolites in cumene cracking and o>xylene isomoi-zation. In Catalysis by Acids and Bases, B. Imelik et al., eds. pp. 335-342. Amsterdam Elsevier Science Publishers B. V. [Pg.56]

A Study of coke formation in cumene cracking over silica-alumina has been made by Plank and Nace (1955). They found that the coke is due to an impurity in cumene feed. They proposed the following for the inhibition of the reaction by the impurity ... [Pg.372]

Fig. 7 Cumene cracking over H-ZSM5 and the physical mixture of Pt/Si02 and H-ZSM-5 at 423K in a pulse reactor. Fig. 7 Cumene cracking over H-ZSM5 and the physical mixture of Pt/Si02 and H-ZSM-5 at 423K in a pulse reactor.
ILLUSTRATION 12.1 ESTIMATION OF COMBINED DIFFUSIVITY FOR CUMENE IN A CRACKING CATALYST... [Pg.436]

ILLUSTRATION 12.3 DETERMINATION OF CATALYST EFFECTIVENESS FACTOR FOR THE CUMENE CRACKING REACTION USING THE EFFECTIVE DIFFUSIVITY APPROACH Use the effective diffusivity approach to evaluate the effectiveness factor for the silica-alumina catalyst pellets considered in Illustration 12.2. [Pg.449]

It is noted that the microporous effect was greater in the disproportionation of 1,2,4-TrMB than in the cracking of cumene. As shown in the previous paper [14], the disproportionation of 1,2,4-TrMB at 200°C proceeds via a bimolecular transition state and obeys the second order kinetics. In contrast, the cracking of cumene is the first order kinetics with respect to cumene concentration. Thus, it seems that the microporous effect is exerted more significantly in the second order reaction (disproportionation) than in the first order reaction (cracking) if pore structure plays an important role in localizing concentration of reactant molecules. [Pg.382]

Kerr, Plank, and Rosinski reported the preparation and catalytic properties of aluminum-deficient zeolite Y materials 35). Topchieva and co-workers studied the catalytic properties of cationic forms of aluminum-deficient Y zeolites, the aluminum deficiency being effected by the H4EDTA method 36-40). They found that up to 50% aluminum removal increased both stability and cumene cracking activity maximum activity was observed at the 50% removal level. Increased catalytic cracking activity was observed by Eberly and Kimberlin for mordenites from which about 80% aluminum had been removed (. 1). Weiss et al. removed over 99% of the aluminum from a hydrogen mordenite and found the zeolite retained catalytic activity of the type induced by Bronsted acids 42). Although the initial activity of this material was lower than that of more aluminum-rich mordenites, the aging rate was markedly reduced, and in a relatively short time the aluminum-deficient catalyst was the most active. [Pg.229]

Few authors considered the reactivity of hydroxyl groups at catalyti-cally interesting temperatures. In situ infrared spectroscopy showed that in the cumene cracking reaction the 3550 cm-1 hydroxyls in a HY sample are only affected above 325° C. The 3650 cm-1 hydroxyl decreased in intensity at 250° C (6). During the cracking of hexane on a similar sample the gradual deactivation of the catalyst is accompanied by the progressive... [Pg.487]

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. [Pg.210]

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. [Pg.211]

Si4(Al5/3Mgi/2)(OH)20io]1/3 -Nauj. By calcination, microporous solid catalysts with pore sizes of about 8 A have been prepared (383). This catalyst is active for cumene cracking (384), conversion of methanol (385), and alkylation (386) and it can be used as a support for metal catalysts (387, 388). Ru supported on Al203 intercalating montmorillonite is a catalyst for the production of C6-Ci2 hydrocarbons in CO hydrogenation (388). [Pg.232]

The second drawback—that acid colors can be produced by processes other than simple proton addition—is more serious. The case of alumina is an example. Several of the indicators listed in Table I give faint acid colors with samples of pure, activated aluminas that have previously been shown to be inactive for an acid-catalyzed reaction such as cumene cracking (22). However, closer visual examination indicates that the acid... [Pg.102]

The work by Mills et al. (32) includes an early example of catalytic titration behavior. Figure 10 taken from their study shows that cumene cracking at 425°C drops sharply as nitrogen bases are chemisorbed in increasing amounts on silica-alumina catalyst. Base effectiveness decreases in the order quinaldine > quinoline > pyrrole > piperidine > decylamine > aniline. [Pg.114]

Despite the presence of sites that strongly chemisorb a variety of molecules, pure silica gel is catalytically inactive for skeletal transformations of hydrocarbons. However, as has recently been emphasized by West et al. (79), only trace amounts of acid-producing impurities such as aluminum need be present in pure silica gel to provide catalytic activity— especially when a facile reaction such as olefin isomerization is used as a test reaction. They found that addition of 0.012% Al to silica gel resulted in a 10,000-fold increase in the rate of hexene-1 isomerization at 100°C over the pure gel. An earlier study by Tamele et al. (22) showed that introduction of 0.01% wt Al in silica gel produces a 40-fold increase in cumene conversion when this hydrocarbon is cracked at 500°C. The more highly acidic solids that are formed when substantial concentrations of metal oxides are incorporated with silica are discussed in following sections. [Pg.122]


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See also in sourсe #XX -- [ Pg.158 ]




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