Oxidants ethylbenzene hydroperoxide EBHP

Ethylbenzene Hydroperoxide Process. Figure 4 shows the process flow sheet for production of propylene oxide and styrene via the use of ethylbenzene hydroperoxide (EBHP). Liquid-phase oxidation of ethylbenzene with air or oxygen occurs at 206—275 kPa (30—40 psia) and 140—150°C, and 2—2.5 h are required for a 10—15% conversion to the hydroperoxide. Recycle of an inert gas, such as nitrogen, is used to control reactor temperature. Impurities ia the ethylbenzene, such as water, are controlled to minimize decomposition of the hydroperoxide product and are sometimes added to enhance product formation. Selectivity to by-products include 8—10% acetophenone, 5—7% 1-phenylethanol, and <1% organic acids. EBHP is concentrated to 30—35% by distillation. The overhead ethylbenzene is recycled back to the oxidation reactor (170—172). 

The epoxidation of propene with tert-butylhydroperoxide (TBHP) or ethylbenzene hydroperoxide (EBHP), for example, accounts for more than one million tons of propene oxide production on an annual basis (Fig. 4.19). 

Chemical vapor deposition (CVD) using TiC was used to prepare Ti/Si02, Ti/MCM-41, and Ti/MCM-48 catalysts. These catalysts were characterized by inductively coupled plasma-atomic emission spectroscopy (ICP-AES), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, nitrogen adsorption, and were used to catalyze the epoxidation of propylene to propylene oxide (PO) with in situ prepared ethylbenzene hydroperoxide (EBHP). CVD time and CVD temperature affected the catalyst performance significantly. The optimum temperature range was 800-900 °C, and the optimum deposition time was 2.5-3 h. The maximum PO yields obtained in a batch reactor were 87.2, 94.3, and 88.8% for Ti/Si02, Ti/ MCM-41, and Ti/MCM-48, respectively. Ti/MCM-41 had higher titanium... 

FIGURE 14.1 Influence of TiCU deposition time on ethylbenzene hydroperoxide (EBHP) conversion and propylene oxide yield for Ti/Si02 catalysts. 

High-valent early transition metals such as titanium(lV) and vanadium(V) have been shown to efficiently catalyze the epoxidation of aikenes. The preferred oxidants using these catalysts are various alkyl hydroperoxides, typically tert-butyUiydroperox-ide (TBHP) or ethylbenzene hydroperoxide (EBHP). One of the routes for the industrial production of propylene oxide is based on a heterogeneous Ii 7Si02 catalyst, which employs EBHP as the terminal oxidant [6],... 

Abbreviations p, ratio between ionic radii of cation and anion TBHP, rm-butyl hydroperoxide EBHP, ethylbenzene hydroperoxide PO, propylene oxide TBOT, tetrabutyl orthotitanate TEOT, tetraethyl orthotitanate TIOT, tetraisopropyl orthotitanate TEOS, tetraethyl orthosilicate THF, tetrahydrofuran TPA-OH, tetrapropylammonium hydroxide TMOS, tetramethyl orthosilicate TBA-OH, tetrabutylammonium hydroxide TBP-OH, tetrabutylphophonium hydroxide TEA-OH, tetraethylammonium hydroxide TMA-OH, tetramethylammonium hydroxide. 

Abbreviations AD, asymmetric dihydroxylation BPY, 2,2 -bipyridine DMTACN, 1,4-dimethyl-l,4,7-triazacyclonane EBHP, ethylbenzene hydroperoxide ee, enantiomeric excess HAP, hydroxyapatite LDH, layered double hydroxide or hydrotalcite-type structure mCPBA, meta-chloroperbenzoic acid MTO, methyltrioxorhenium NMO, A-methylmorpholine-A-oxide OMS, octahedral molecular sieve Pc, phthalocyanine phen, 1,10-phenantroline PILC, pillared clay PBI, polybenzimidazole PI, polyimide Por, porphyrin PPNO, 4-phenylpyridine-A-oxide PS, polystyrene PVP, polyvinylpyridine SLPC, supported liquid-phase catalysis f-BuOOH, tertiary butylhydroperoxide TEMPO, 2,2,6,6-tetramethyl-l-piperdinyloxy TEOS, tetraethoxysilane TS-1, titanium silicalite 1 XPS, X-ray photoelectron spectroscopy. 

PRpropylene, PO=propylene oxide, EB=ethylbenzene, EBHP= ethylbenzene hydroperoxide, and MBA=a-methylbenzyl alcohol, S=styrene... 

We turned our attention next to the autoxidation of ethylbenzene (EB) to the corresponding hydroperoxide (EBHP) which constitutes the first step in the SMPO (styrene monomer propene oxide) process for the co-production of styrene and propene oxide from ethylbenzene and propene (Scheme 7). The overall selectivity to propene oxide obviously depends on the selectivity to EBHP in the first step, which is believed to be 80-85% in the commercial process. This is lower than for cumene as a result of secondary (in the case of EB) versus tertiary (in the case of cumene) C-H bond oxidation. The main byproduct in the autoxidation of ethylbenzene is acetophenone (16). From an economic viewpoint die production of acetophenone should be kept as low as possible. 

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