Advances in development and industrial applications of ethylbenzene processes

The benzene alkylation process for the production of ethylbenzene has undergone significant improvements during recent decades.Various environmentally benign zeolite-catalyzed ethylbenzene processes,including ZSM-5-zeolite-based vapor-phase ethylbenzene processes and Y-,β-,and MCM-22-zeolite-based liquid-phase processes,have been developed and commercialized.Pure ethylene,ethanol,and dilute ethylene have been used as ethylation agents.Here,the development and industrial application of alkylation catalysts and benzene ethylation techniques are summarized,and some other promising innovations are discussed.Recent advances in benzene alkylation over hierarchical zeolites with improved access to active sites and molecular transport are also covered.Zeolites with short diffusion lengths are promising candidates as better alkylation catalysts.The key point is how to obtain such materials easily and economically.The structure-activity relationships of commercial zeolites in these processes are discussed.Liquid-phase processes catalyzed by β and MCM-22 are more profitable than vapor-phase processes catalyzed by ZSM-5.

Influence of the metal sites of M-N-C(M=Co, Fe, Mn) catalysts derived from metalloporphyrins in ethylbenzene oxidation

Transition metal catalysts M-N-C（M = Co,Fe,Mn） were synthesized by a template-free method by heating meso-tetraphenyl porphyrins（i.e.CoTPP,FeTPPCl,MnTPPCl） precursors.The catalysts were characterized by N2 adsorption-desorption,thermogravimetry,high-resolution transmission electron microscopy,and Raman and X-ray photoelectron spectroscopy.The selective oxidation of ethylbenzene with molecular oxygen under a solvent-free condition was carried out to explore the catalytic performance of the M-N-Cs,which exhibited different catalytic performance.That was ascribed to the difference in M（Co,Fe,Mn） and different graphitization degree forming during the heating process,in which M（Co,Fe,Mn） might have different catalytic activity on the formation of the M-N-C catalyst.All the M-N-C composites had remarkable recyclability in the selective oxidation of ethylbenzene.

Synthesis of zeolite Beta containing ultra-small CoO particles for ethylbenzene oxidation

Zeolite Beta containing ultra-small CoO particles was synthesized from a one-step hydrothermal process. The synthesis route involves the pre-mixture of hydrofluoric acid with tetraethylammo- nium hydroxide （in a molar ratio of 1.3-1.5：1） before the addition of a silicon and cobalt source.Investigations by scanning electron microscopy, X-ray diffraction, UV-Vi s spectroscopy, X-ray pho-toelectron spectroscopy, H 2 -temperature-programmed reduct i on and transmi ssi on el ectron mi -croscopy confirm the presence of ultra-small CoO particles in the zeolite Beta structure. The ul-tra-small CoO particles in zeolite Beta present high stability against both oxidation and reduction atmospheres at high temperatures. The catalytic performance of the CoO-containing zeolite Beta catalysts was compared with other Co-containing zeolites by evaluating ethylbenzene oxidation reactivity. The CoO-containing zeolite Beta exhibits high ethylbenzene conversion and high selectiv-ity to acetophenone and 1-phenylethanol. The high activity of this catalyst system can be attributed to the high dispersion of the ultra-small CoO particles in the Beta structure.

Selective oxidation of ethylbenzene catalyzed by fluorinated metalloporphyrins with molecular oxygen

This paper reported the oxidation of ethylbenzene catalyzed by fluorinated metalloporphyrins under mild conditions without any additives. The results showed that the cobalt(II)(5,10,15,20-tetrakis(pentafluorophenyl))porphyrin was the best catalyst among the fluorinated metalloporphyrins. The conversion of ethylbenzene reached 38.6%, the selectivity to acetophenone reached 94.0%, and the turnover number is 2719 under the optimal conditions.

Highly selective ethylbenzene production through alkylation of dilute ethylene with gas phase-liquid phase benzene and transalkylation feed

A novel industrial process was designed for the highly selective production of ethylbenzene. It comprised of a reactor vessel, vapor phase ethylene feed stream, benzene and transalkylation feed stream. Especially the product stream containing ethylbenzene was used to heat the reactor vessel, which consisted of an alkylation section, an upper heat exchange section, and a bottom heat exchange section. In such a novel reactor, vapor phase benzene and liquid phase benzene were coexisted due to the heat produced by isothermal reaction between the upper heat exchange section and the bottom heat exchange section. The process was demonstrated by the thermodynamic analysis and experimental results. In fact, during the 1010 hour-life-test of gas phase ethene with gas phase-liquid phase benzene alkylation reaction, the ethene conversion was above 95%, and the ethylbenzene selectivity was above 83% （only benzene feed） and even higher than 99% （benzene plus transalkylation feed）. At the same time, the xylene content in the ethylbenzene was less than 100 ppm when the reaction was carried out under the reaction conditions of 140-185℃ of temperature, 1.6-2.1 MPa of pressure, 3.0-5.5 of benzene/ethylene mole ratio, 4-6 v% of transalkylation feed/（benzene＋transalkylation feed）, 0.19-0.27 h^-1 of ethene space velocity, and 1000 g of 3998 catalyst loaded. Thus, compared with the conventional ethylbenzene synthesis route, the transalkylation reactor could be omitted in this novel industrial process.

Solvent-free aerobic oxidation of ethylbenzene over supported Ni catalysts using molecular oxygen at atmospheric pressure

We investigated the aerobic oxidation of ethylbenzene in the absence of solvent or any additive carried out over Ni on different types of supports namely SiO2, hydroxyapatite, SBA-15, and USY Zeolites. The oxidation of ethylbenzene activities was measured in a round bottom flask immersed in oil bath at known reaction temperature. The physicochemical characteristics of the catalysts were examined by BET surface area, XRD, FT-IR and the oxidation activities were correlated with the acidities of the catalysts obtained by TPD of NH3. It was observed that both hydroxyapatite and USY （13% Na2O） supported Ni catalysts displayed higher ethylbenzene conversion and 80% selectivity towards acetophenone.

Theoretical and Experimental Study on Reaction Coupling: Dehydrogenation of Ethylbenzene in the Presence of Carbon Dioxide

Dehydrogenation of ethylbenzene （EB） to styrene （ST） in the presence of CO2, in which EB dehydrogenation is coupled with the reverse water-gas shift （RWGS）, was investigated extensively through both theoretical analysis and experimental characterization. The reaction coupling proved to be superior to the single dehydrogenation in several respects. Thermodynamic analysis suggests that equilibrium conversion of EB can be improved greatly by reaction coupling due to the simultaneous elimination of the hydrogen produced from dehydrogenation. Catalytic tests proved that iron and vanadium supported on activated carbon or Al2O3 with certain promoters are potential catalysts for this coupling process. The catalysts of iron and vanadium are different in the reaction mechanism, although ST yield is always associated with CO2 conversion over various catalysts. The two-step pathway plays an important role in the coupling process over Fe/Al2O3, while the one-step pathway dominates the reaction over V/Al2O3. Coke deposition and deep reduction of active components are the major causes of catalyst deactivation. CO2 can alleviate the catalyst deactivation effectively through preserving the active species at high valence in the coupling process, though it can not suppress the coke deposition.

Efficient oxidation of ethylbenzene catalyzed by cobalt zeolitic imidazolate framework ZIF-67 and NHPI

Efficient catalytic oxidation of ethylbenzene to acetophenone was realized using the catalytic system of cobalt zeolitic imidazolate framework ZIF-67/N-hydroxyphthalimide （NHPI） under mild conditions. 95.2% conversion of ethylbenzene with 90.3% selectivity to acetophenone could be obtained at 373 K under 0.3 MPa 02 for 9 h. The results show that there exists synergetic effect between ZIF-67 and NHPI. 1-Phenylethyl hydroperoxide （PEHP） was generated via a radical process involving the hydrogen abstraction from ethylbenzene by phthalimide N-oxyl, and subsequently effectively decomposed to acetophenone by ZIF-67.

Bio-removal of mixture of benzene,toluene,ethylbenzene,and xylenes/total petroleum hydrocarbons/trichloroethylene from contaminated water

Four pure cultures were isolated from soil samples potentially contaminated with gasoline compounds either at a construction site near a gas station in Fai Chi Kei,Macao SAR or in the northern parts of China（Beijing,and Hebei and Shandong）.The effects of different concentrations of benzene,toluene,ethylbenzene,and three isomers（ortho-,meta-,and para-） of xylene（BTEX）,total petroleum hydrocarbons（TPH）,and trichloroethylene（TCE）,when they were present in mixtures,on the bio-removal effciencies of microbial isolates were investigated,together with their interactions during the bio-removal process.When the isolates were tested for the BTEX（50-350 mg/L）/TPH（2000 mg/L） mixture,BTEoX in BTEoX/TPH mixture was shown with higher bio-removal effciencies,while BTEmX in BTEmX/TPH mixture was shown with the lowest,regardless of isolates.The TPH in BTEmX/TPH mixture,on the other hand,were generally shown with higher bio-removal effciencies compared to when TPH mixed with BTEoX and BTEpX.When these BTEX mixtures（at 350 mg/L） were present with TCE（5-50 mg/L）,the stimulatory effect of TCE toward BTEoX bio-removal was observed for BTEoX/TCE mixture,while the inhibitory effect of TCE toward BTEmX for BTEmX/TCE mixture.The bio-removal effciency for TPH was shown lower in TPH（2000 mg/L）/TCE（5-50 mg/L） mixtures compared to TPH present alone,implying the inhibitory effect of TCE toward TPH bio-removal.For the mixture of BTEX（417 mg/L）,TPH（2000 mg/L） along with TCE（5- 50 mg/L）,TCE was shown co-metabolically removed more effciently at 15 mg/L,probably utilizing BTEX and/or TPH as primary substrates.

Disproportionation of ethylbenzene in the presence of C_8 aromatics

The selective synthesis of p-diethylbenzene （p-DEB） by disproportionation of ethylbenzene （EB） in the presence of aromatics like m- and p- xylene isomers has been studied over a pore size regulated HZSM-5 catalyst. The industrial feed having different compositions of ethylbenzene and xylene isomers was used for the experimentation. Hence, they were expected to hinder the movement of reactant molecules both on the external surface and within the zeolite channels. It was observed that irrespective of the different feed compositions the concentration of the xylene isomers was intact in the product. There is no other byproducts formation like para-ethylmethyl benzene. The effects of varying the concentration of aromatic compounds in the feed on ethylbenzene conversion and product distribution over the parent and modified H-ZSM-5 catalyst have been discussed. Ethylbenzene disproportionation reaction follows the pseudo first order reaction with an activation energy of 8.6 kcal/mol.

Influence of Addition of ZnO on Property of Fe_2O_3-K_2O System Catalyst for Ethylbenzene Dehydrogenation to Styrene

The incorporation of ZnO into Fe2O3-K2O system increases its activity, enhances its moisture stability and mechanical strength. The origin of the enhancement in activity and moisture stability is discussed in the light of experimental results obtained by BET, XRD, XPS. It was found that the addition of ZnO to Fe2O3-K2O system strengthens the interaction between Fe2O3 and K2O, reduces the formation temperature of KFe11O17 at least by 50 oC, and promotes the transformation of Fe3+ to Fe2+ further.

Vibrational Spectra and Quantum Calculations of Ethylbenzene

Normal vibrations of ethylbenzene in the first excited state have been studied using resonant two-photon ionization spectroscopy. The band origin of ethylbenzene of S1-S0 transition appeared at 37586 cm-1. A vibrational spectrum of 2000 cm-1 above the band origin in the first excited state has been obtained. Several chain torsions and normal vibrations are obtained in the spectrum. The energies of the first excited state are calculated by the time- dependent density function theory and configuration interaction singles （CIS） methods with various basis sets. The optimized structures and vibrational frequencies of the So and S1 states are calculated using Hartree-Fock and CIS methods with 6-311＋＋G（2d,2p） basis set. The calculated geometric structures in the So and $1 states are gauche conformations that the symmetric plane of ethyl group is perpendicular to the ring plane. All the observed spectral bands have been successfully assigned with the help of our calculations.

Boron nitride for enhanced oxidative dehydrogenation of ethylbenzene

It is demonstrated experimentally and confirmed theoretically that highly defective boron nitride showed outstanding performance for oxidative dehydrogenation of ethylbenzene.The catalyst is derived from carbon-doped hexagonal boron nitride nanosheets synthesized via a two-step reaction when participating the oxidative dehydrogenation reaction.The first step yields a polymeric precursor with the atomic positions of B,C,N relatively constrained,which is conducive for the formation of carbon atomic clusters uniformly dispersed throughout the BN framework.During the oxidative dehydrogenation of ethylbenzene to styrene,the nanoscale carbon clusters are removed and highly defective boron nitride(D-BN)is obtained,exposing boron-rich zigzag edges of BN that act as the catalytic sites.The catalytic performance of D-BN is therefore remarkably better than un-doped h-BN.Our results indicate that dispersed C-doping in h-BN is highly effective in terms of defect formation and resultant enhanced activity in oxidative dehydrogenation reactions.

Oxidative Dehydrogenation of Ethylbenzene over ZSM-5 Type Chromosilicates in the Presence of CO2

In this work, ZSM-5 type chromosilicate samples as K[Cr]ZSM-5(KCS) and Na[Cr]ZSM-5(NCS) were prepared by hydrothermal method and their catalytic properties were investigated for the oxidative dehydrogenation of ethylbenzene in the presence of CO2 as an oxidant using a fixed-bed stainless steel reactor. The prepared samples were characterized by their morphology (SEM), structural parameters (XRD), and textural parameters (BET). The performance of these catalysts was evaluated in terms of conversion, styrene yield, and selectivity. The KCSBW catalyst (potassium chromosilicate before washing with distilled water) afforded the highest styrene yield, 56.19%, with the selectivity of 96.05% in the presence of CO2 because of the coexistence of potassium ion and Cr2O3 in its structure and their synergistic effect. The influence of the presence of Cr2O3 and sodium or potassium ion on the catalytic activity of the chromosilicate samples in the catalytic EB dehydrogenation process was discussed in detail. Moreover, according to the results, the catalytic activity of the chromosilicate samples (CS) in EB dehydrogenation was increased by decreasing the surface area.

Immobilization of metalloporphyrins on CeO_2@SiO_2 with a core-shell structure prepared via microemulsion method for catalytic oxidation of ethylbenzene

Ce O2@Si O2 core-shell nanoparticles were prepared by microemulsion method, and metalloporphyrins were immobilized on the Ce O2@Si O2 core-shell nanoparticles surface via amide bond. The supported metalloporphyrin catalysts were characterized by N2 adsorption-desorption isotherm(BET), scanning electron microscopy(SEM), transmission electron microscopy(TEM), X-ray diffraction(XRD), ultraviolet and visible spectroscopy(UV-Vis), and Fourier transform infrared spectroscopy(FT-IR). The results show that the morphology of Ce O2@Si O2 nanoparticles is core-shell microspheres with about 30 nm in diameter, and metalloporphyrins are immobilized on the Ce O2@Si O2 core-shell nanoparticles via amide bond. Especially, the core-shell structure contains multi Ce O2 core and thin Si O2 shell, which may benefit the synergistic effect between the Ce O2 core and the porphyrin anchored on the very thin Si O2 shell. As a result, this supported metalloporphyrin catalysts present comparably high catalytic activity and stability for oxidation of ethylbenzene with molecular oxygen, namely, ethylbenzene conversion remains around 12% with identical selectivity of about 80% for acetophenone even after six-times reuse of the catalyst.

Measurements of the Critical Temperature and Pressure of Ethylene+Benzene+Ethylbenzene Mixture

Critical temperature (Tc) and critical pressure (pc) of the ternary mixture of ethylene+benzene+ethylbenzene (the mole ratio of ethylbenzene to benzene was fixed at 0.95:0.05) were measured by using a high=pressure view cell with direct visual observation.The interaction coefficients obtained from the critical properties of the relevant binary systems were used to predict the critical properties (Tc,pc) of the ternary mixture.The agreement between the prediction and experiments is satisfactory.

THE PREPARATION CHEMISTRY OF V/MgO CATALYST FOR OXIDATIVE DEHYDROGENATION OF ETHYLBENZENE

The structures and catalytic performances of V_2O_5, Mg_3V_2O_8 and V/MgO catalysts have been correlated by means of XRD, FTIR, TPR and flow micro-reactor tests. The postulation about active site has been made. Based on it, better catalysts have been first prepared via grafting and modification with Sb which are better than that via impregnation.

碳九原料中甲乙苯脱氢制备甲基苯乙烯催化剂研究

本试验制备了Fe-K-Mo甲乙苯脱氢制备甲基苯乙烯催化剂,确定了:反应温度600~620℃,水烃比(质量比)2.5~3.0,液空速0.7~1.0 h^(-1)为优选甲乙苯脱氢催化剂的考察条件。研究了催化剂焙烧温度、铁源、钾铁比、助剂Mo对催化剂性能的影响,结果表明:催化剂在焙烧温度850℃、Fe(NO_(3))_(3)铁源、钾铁比0.25、助剂Mo等条件下具备较好的转化率和选择性;通过XRD、TPR等测试表征显示,K_(2)Fe_(22)O_(34)相是甲乙苯脱氢的主要活性组分;Mo助剂的加入在改善催化剂结构及促进活性等方面具有明显的效果,同时提高了Fe-K催化剂的热稳定性、抗氧化性。

乙苯脱氢制苯乙烯反应过程专用模拟系统开发

为了实现对乙苯脱氢制苯乙烯反应过程的准确模拟计算,采用MySQL数据库软件建立专用物性数据库,构建等温积分动力学反应器计算模型,基于Cape-Open标准和C++语言,建立苯乙烯反应器模块,并集成到通用流程模拟软件中,形成乙苯脱氢制苯乙烯反应过程的专用模拟系统。采用工厂数据对所开发的模拟系统进行检验,并将计算值与实际值进行对比。结果表明:计算结果与工艺数据基本一致,产品组成、反应器温降和压降的模拟值与实际值的相对偏差都在1%以内,说明开发的专用反应过程模拟系统可进行较为准确的模拟计算。