Cumene design improvements

By 1992, UOP had selected the most promising catalyst, based on beta zeolite, for cumene production and then began to optimize a liquid phase based process design around this new catalyst. The result of this work led to the commercialization of the UOP Q-Max process and the QZ-2000 catalyst in 1996. More recently in 2001, UOP commercialized a new alkylation catalyst, QZ-2001, which offers improved stability and operation as low as 2B/P molar feed... 

Fresh and recycle cumene is oxidized with air to produce CHP in a series of oxidizers (1) having a unique internal design that improves selectivity and enhances safety. Oxidate is then concentrated in two evaporation stages (2) and fed to a two-stage cleavage section (3) in which CHP is decomposed to phenol and acetone under precisely controlled conditions. AMS is also formed in this section from certain precursors present in the oxidate. The cleavage section effluent is neutralized (4) and then fractionated (5). 

In the recent past, the focus of new developments was on alternative phenol processes that overcome the disadvantage of the coupled product acetone in the cumene oxidation process. These processes are based on the oxidation of benzene with nitrous oxide or hydrogen peroxide [7]. The main research on the cumene oxidation process is process intensification by improving the oxidation reaction and improved process and reactor design. 

UOP developed two varieties of zeolite catalyst designated as QZ-2000 and QZ-2001 (47,48). Its research indicated that the catalysts have Bronsted acidity values. As a result, oligomerization of propylene is essentially eliminated. Accelerated stability tests indicated that the percentage of the bed of catalyst employed for desired reactions increases with time of operation. QZ-2001 demonstrates improved stability and operation at benzene/propylene ratios of 2.0 in its liquid-phase process. Unreacted benzene and polyisopropylbenzenes are recovered and recycled so that cumene jdelds of about 99% are obtained. Four catalyst beds in series are employed. The catalysts need to be reactivated after about 2-5 years. UOP have licensed several units. 

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