Hydroalkylation of benzene and ethylbenzene over metal containing zeolite catalysts

Borodina, I. B.; Пономарева, О. А.; Fajula, François; Bousquet, Jacques; Ivanova, I. I.

doi:10.1016/j.micromeso.2007.05.058

Cited by 14 publications

(9 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As early as 1934, Truffault [25] reported the formation of cyclohexylbenzene during the hydrogenation of benzene in the presence of phosphoric anhydride and nickel-black catalysts. More recent studies [26][27][28][29][30] have reported results for this reaction over different supported transition metal catalysts. They all conclude that a combination of acidity and hydrogenation activity is necessary for the formation of cyclohexylbenzene.…”

Section: Introductionmentioning

confidence: 91%

Tuning the acid–metal balance in Pd/ and Pt/zeolite catalysts for the hydroalkylation of m-cresol

Anaya

Zhang

Tan

et al. 2015

Journal of Catalysis

View full text Add to dashboard Cite

a b s t r a c tThe liquid-phase hydroalkylation of m-cresol catalyzed by zeolite catalysts doped with noble metals was investigated at 473 K and 5200 kPa of H 2 . Metals (Pt and Pd) were incorporated in HY (Si/Al = 30) and HMor (Si/Al = 10) zeolites by incipient wetness impregnation. The structural properties of the samples were characterized by NMR, XPS, and BET. Hydroalkylation of m-cresol involves a series of steps that start with the ring saturation to 3-methylcyclohexanone (MCONE), which is the primary product and is further hydrogenated to methylcyclohexanol (MCNOL) on the metal function. This, in turn, is dehydrated on the acid sites to 3-methylcyclohexene, which readily alkylates the unreacted m-cresol to form bicyclic compounds that fall in the desirable fuel range. In these bifunctional catalysts, differences in intrinsic hydrogenation activity of metals play an important role in determining the final selectivity to alkylated products. In fact, the ratio of number of acid sites (n A ) to exposed metal sites (n M ) can be tuned to maximize the selectivity toward bicyclic compounds because this selectivity is determined by the fate of the intermediate 3-methylcyclohexene (MCENE). That is, if the C@C hydrogenation on the metal is fast compared to alkylation on the acid site, the selectivity decreases. However, if the hydrogenation is too slow, the overall product yield decreases. Thus, to optimize the hydroalkylation yield, a delicate metal/acid balance is required. Moreover, in the absence of metal, the zeolite would deactivate very quickly. Therefore, having the metal and acid functions together is also important for extending the catalyst life. Finally, it has been observed that 3D-pore zeolites, such as HY, are preferred over 1D-pore zeolites such as HMor, which sharply diminish the formation of alkylation compounds, despite being more acidic than HY.

show abstract

Section: Introductionmentioning

confidence: 91%

Tuning the acid–metal balance in Pd/ and Pt/zeolite catalysts for the hydroalkylation of m-cresol

Anaya

Zhang

Tan

et al. 2015

Journal of Catalysis

View full text Add to dashboard Cite

show abstract

“…The highest conversion rate and CHB selectivity were obtained at 200 °C (Figure b). Higher H 2 pressure led to higher benzene conversion, but the CHB selectivity decreased when the H 2 pressure exceeded 4.0 MPa (Figure c,d), because higher hydrogen pressure enhanced the adsorption of hydrogen on the catalyst − and led to the further hydrogenation of cyclohexene to byproduct cyclohexane. Figure e,f shows the CHB selectivity at 40% benzene conversion and the average formation rate of CHB from the beginning of the reaction until the achievement of maximum yield, and the maximum CHB selectivity (60.7%) and reaction rate (72.9 mmol·g –1 ·h –1 ) were obtained at the reaction conditions of 200 °C and 4.0 MPa of H 2 .…”

Section: Resultsmentioning

confidence: 99%

“…Third, the cycling stability of catalysts was not satisfying and needs to further improved, which is critical for the practical applications. 30,31 In the present work, a modified weakly capping growth approach (WCGA) 32 was employed to prepare bifunctional metal/acid catalysts with uniformly distributed palladium nanoparticles (Pd NPs) on Hβ zeolite. Methanol was used as a mild chemical reducing agent instead of high-temperature reduction, thus avoiding the aggregation of dispersed Pd NPs.…”

Section: ■ Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Identification of Metal/Acid Matching Balance over Bifunctional Pd/Hβ toward Benzene Hydroalkylation

Huang

Yang

et al. 2021

Ind. Eng. Chem. Res.

View full text Add to dashboard Cite

Bifunctional Pd/Hβ catalysts with uniformly distributed palladium nanoparticles (Pd NPs) were successfully synthesized by a facile methanol-mediated weakly capping growth approach (WCGA). A series of Pd/Hβ catalysts with different metal loadings and Si/Al ratios were used for benzene hydroalkylation, and the identification of metal/acid matching balance over bifunctional Pd/Hβ toward benzene hydroalkylation performance was investigated. The obtained characterization and catalytic activity test results demonstrated that the weak acid site and Lewis acid site have greatly affected the benzene conversion, and the strong acid site as well as Brønsted acid site had more of an effect on the alkylation process. The best hydroalkylation performance was achieved by tuning the acid/metal molar ratio at 22.4 μmol of H + /μmol of exposed Pd with a high cyclohexylbenzene (CHB) selectivity of 51.7% at a benzene conversion of 63.4%, which is the best CHB yield currently obtained for all we know. In addition, the stability of Pd/Hβ catalysts was tested and compared with that prepared by the incipient wetness impregnation (IWI) method, which showed good stability, and no obvious particle aggregation was found. This work provides guidance for exploring the construction of bifunctional catalysts and the balance of metal/acid sites.

show abstract

“…The formation of the terminal product and a mechanistic study of the alkylation of benzene with n-hexane are described elsewhere [17]. Some cyclohexylbenzene, which was a product of two benzene molecules [17,[24][25][26], was detected in the Production of 2-Phenylhexane from Benzene and n-Hexane 395 product mixture. As cracking products we assigned n-pentane and n-heptane, which are the likely products of classical dimerization and cracking over the acid sites of the zeolite; ethylbenzene, cumene, butylbenzene, and pentylbenzene are the cracking products of phenylhexane.…”

Section: Characterizationmentioning

confidence: 99%

Selective Production of 2-Phenylhexane from Benzene and n-Hexane Over Pt- and Ga-Modified Zeolites

et al. 2010

View full text Add to dashboard Cite

Alkylation of benzene with n-hexane was performed over H-ZSM-5 and monometallic Ga-and Pt-and bimetallic Ga-and Pt-modified ZSM-5. The influence of the particle size and the method of incorporation of Ga (during hydrothermal synthesis, by solid-state ion exchange, or by liquid-state ion exchange) was determined. The presence of Pt and well-dispersed extraframework Ga in H-ZSM-5 increased the selectivity in alkylation and suppressed cracking reactions. Well-dispersed Pt particles led to better catalytic performance. The method of Ga incorporation played an important role in obtaining higher selectivity to alkylation products and in the suppression of side reactions. Up to 93% selectivity in alkylation (of which [95% was to 2-phenylhexane) was reached over 2 wt% Pt/H-Ga f ZSM5, in which Ga occupied framework positions. We propose that the close proximity of very small Pt nanoparticles and Ga-(OH)-Si acid sites results in the optimal bifunctional catalyst for selective production of 2-phenylhexane from benzene and n-hexane. During the reaction, the catalyst deactivated, most probably due to the sintering of the Pt particles.

show abstract

Hydroalkylation of benzene and ethylbenzene over metal containing zeolite catalysts

Cited by 14 publications

References 5 publications

Tuning the acid–metal balance in Pd/ and Pt/zeolite catalysts for the hydroalkylation of m-cresol

Tuning the acid–metal balance in Pd/ and Pt/zeolite catalysts for the hydroalkylation of m-cresol

Identification of Metal/Acid Matching Balance over Bifunctional Pd/Hβ toward Benzene Hydroalkylation

Selective Production of 2-Phenylhexane from Benzene and n-Hexane Over Pt- and Ga-Modified Zeolites

Contact Info

Product

Resources

About