Isopropyl benzene cracking

The cumene (isopropyl benzene) cracking reaction is often used as a model reaction for determining the relative activities of cracking catalysts. 

Dependence of isopropyl benzene cracking activity at 600 C. on acidity for a series of SiOj-AljOs catalysts. (Tamele, 9b.)... 

The deactivation of a lanthanum exchanged zeolite Y catalyst for isopropyl benzene (cumene) cracking was studied using a thermobalance. The kinetics of the main reaction and the coking reaction were determined. The effects of catalyst coke content and poisoning by nitrogen compounds, quinoline, pyridine, and aniline, were evaluated. The Froment-Bischoff approach to modeling catalyst deactivation was used. 

The catalyst used is a commercial catalyst known as the super-D manufactured by Crosfield Chemicals Ltd., UK. It is in the form of particulate spheroid with an average diameter of 81 microns and consists of 15-18% ion exchanged Re sodium Y-zeolites on a support silica-alumina matrix. Heat treatment of catalyst particles at 150°C for 48 hours is undertaken before cracking reaction commenced. The isopropyl benzene (cumene) has the purity higher than 99.5% which was supplied by Fissons Scientific Apparatus. 

Another correlation is shown in Fig. 11 where activity of a number of silica-alumina catalysts for cracking isopropyl benzene is plotted against acidity by titration by anhydrous n-butylamine in nonaqueous medium (Tamele, 9b). Cracking was conducted at 500° at various space velocities. Since the conversion is not a linear function of activity, and the reaction constants could not be calculated from conversions without knowledge of the kinetics of the reaction, values of fc were calculated... 

Like ethylene, propylene is produced by the cracking of hydrocarbons. The major use of propylene is to make polypropylene but it is also a feedstock to manufacture other industrial chemicals, including propylene glycol, acrylic acid, propylene oxide, cumene, and isopropyl alcohol. Propylene oxide is made by the oxidation of propylene, and hydrolysis of propylene oxide gives propylene glycol. The alkylation of benzene with propylene gives isopropyl benzene, more commonly called cumene. Note that the product is not n-propyl benzene. This is because the intermediate is the more stable secondary carbocation which results in isopropyl benzene. 

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