Catalytic cumene synthesis

Fig. 1. UOP catalytic condensation process for cumene synthesis. R = reactor RECT = rectifier DP = depropanizer RC = recycle column ...

Figure 6.14 Catalytic distillation column for cumene synthesis.

Figure 6.15 Flowsheet for cumene synthesis making use of catalytic distillation.

Transalkylation of DIPB isomers with benzene is an effective way for utilizing this byproduct and increasing the cumene yield again. Therefore, it was of some interest to investigate the efficiency and catalytic behaviour of triflic acid as catalyst for cumene synthesis with a higher yield from DIPB isomers (p-, and m-) by isomerization and transalkylation reactions at room temperature. 

Phenol is the starting material for numerous intermediates and finished products. About 90% of the worldwide production of phenol is by Hock process (cumene oxidation process) and the rest by toluene oxidation process. Both the commercial processes for phenol production are multi step processes and thereby inherently unclean [1]. Therefore, there is need for a cleaner production method for phenol, which is economically and environmentally viable. There is great interest amongst researchers to develop a new method for the synthesis of phenol in a one step process [2]. Activated carbon materials, which have large surface areas, have been used as adsorbents, catalysts and catalyst supports [3,4], Activated carbons also have favorable hydrophobicity/ hydrophilicity, which make them suitable for the benzene hydroxylation. Transition metals have been widely used as catalytically active materials for the oxidation/hydroxylation of various aromatic compounds. 

Many organics also undergo oxidation of a noncombustion nature to form various commercial products. Such reactions are mostly catalytic and include production of synthesis gas, a mixture of CO and H2, conversion of ethylene to ethylene oxide, and cumene to phenol and acetone. 

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 most important autoxidation used industrially is the synthesis of cumene hydroperoxide from cumene and air (i.e., diluted oxygen) (Figure 1.37). It is initiated by catalytic amounts of dibenzoyl peroxide as the radical initiator (cf. Figure 1.11). The cumyl radical is produced... 

Oxidation of organic molecules with O2 (flameless) is referred to as autoxidation. The synthesis of cumene hydroperoxide from cumene is initiated by catalytic amounts of 2.36 as the radical initiator, which generates the cumyl radical A. The cumyl radical A reacts with O2 to give the radical B in the first propagation step and regenerated in the second propagation step, in which cumene hydroperoxide (2.62) is also formed (Scheme 2.48). 

The catalytic work on the zeolites has been carried out using the pulse microreactor technique (4) on the following reactions cracking of cumene, isomerization of 1-butene to 2-butene, polymerization of ethylene, equilibration of hydrogen-deuterium gas, and the ortho-para hydrogen conversion. These reactions were studied as a function of replacement of sodium by ammonium ion and subsequent heat treatment of the material (3). Furthermore, in some cases a surface titration of the catalytic sites was used to determine not only the number of sites but also the activity per site. Measurements at different temperatures permitted the determination of the absolute rate at each temperature with subsequent calculation of the activation energy and the entropy factor. For cumene cracking, the number of active sites was found to be equal to the number of sodium ions replaced in the catalyst synthesis by ammonium ions up to about 50% replacement. This proved that the active sites were either Bronsted or Lewis acid sites or both. Physical defects such as strains in the crystals were thus eliminated and the... 

Among the reactions catalyzed by titanium complexes, the asymmetric epoxidation of allylic alcohols developed by Sharpless and coworkers [752, 807-810] has found numerous synthetic applications. Epoxidation of allylic alcohols 3.16 by ferf-BuOOH under anhydrous conditions takes place with an excellent enantioselectivity (ee > 95%) when promoted by titanium complexes generated in situ from Ti(0/ -Pr)4 and a slight excess of diethyl or diisopropyl (R,R)- or (iS, 5)-tartrates 2.69. The chiral complex formed in this way can be used in stoichiometric or in catalytic amounts. For catalytic use, molecular sieves must be added. Because both (RJ )- and (5,5)-tartrates are available, it is posable to obtain either enantiomeric epoxide from a single allylic alcohol. Cumene hydroperoxide (PhCMe20OH) can also be used in place of ferf-BuOOH. This method has been applied to industrial synthesis of enantiomeric glycidols [811, 812]. 

Other Processes. Borosilicates have been used to catalyze a number of other reactions. Among these are dealkylation of cumene by faujasite-type sieves (11). The sieves used for this reaction were prepared by hydrothermal synthesis and contained some aluminum. The catalytic activity increased as the boron content increased. 

A method is described for the preparation of zinc-containing zeolite by direct synthesis from hydrogels. The synthesis of Zn-MFI type zeolite materials and the post synthesis introduction of Cu are discussed. The samples are characterized by XRD, AAS, thermal analysis, SEM and Si-NMR spectroscopy. The catalytic results on the cumene conversion are discussed. 

In conclusion, the epoxidation of propylene with bulky oxidants (such as cumene or TBHP) can be successfully achieved using titanium-containing mesoporous materials as catalysts. The catalytic chemistry of the active sites can be controlled via the synthesis conditions and postsynthesis modifications. The hydrophobicity of the catalyst is of great importance to achieve a highly selective catalyst. The Ti-MCM-41-based heterogeneous catalyst has demonstrated excellent performance in the commercial process for PO manufacture. 

Shirakawa [35] and co-workers suggested a method of solvent-free PA synthesis. For this purpose, the catalytic system was treated in hexane, toluene, and cumene at 70, 110, and 150°C, respectively, and then complete evaporation of a solvent in vacuum before the admission of acetylene was carried out. A film prepared in such a way has a density up to 1.0 g/cm and high mechanical durability. The PA film doped with has a conductivity of 2 x 10 S/cm. 

The catalytic activity of some of these polymers for the decomposition of hydrazine (19, 59), isopropanol (19), formic acid (19), hydrogen peroxide (60) and for the oxidation of cumene to its hydroperoxide has been studied (55). 2,5-Dihydroxybenzoquinone selectively precipitates thorium and zirconium in the presence of other rare earths (55). Analysis of beryllium by spectro-photometric studies of its complexes with naphthazarin and/or alkannin has been developed into a rapid, sensitive, and accurate method (134). The synthesis of many of the polymers in Table IX.2 (pp. 274-279) for use as dyes was performed in 1912 (48). 

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