Alkylation of toluene with cyclohexene over phosphotungstic acid: A combined experimental and computational study

Nie, Genkuo; Li, Guozhu; Liang, Decheng; Zhang, Xiangwen

doi:10.1016/j.jcat.2017.09.008

Cited by 12 publications

(11 citation statements)

References 26 publications

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“…The solid-state 13 C CP MAS NMR spectrum (Figure 6) of the used catalyst after inert purge 573 K shows a resonance at 17.8 ppm consistent with a mobile Ar-CH 3 remaining within the catalyst. This species was successfully extracted with CD 2 Cl 2 , identified, and quantified by solution 1 H NMR as ∼2 o-xylene molecules per POM cluster (Figure S8).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Solid-state CP MAS 13 C and 31 P NMR spectra were collected on a 400 MHz VNMRS spectrometer (Varian) equipped with a conventional triple-resonance 5 mm probe head in double-resonance mode. Samples were packed in a zirconia rotor, and the spinning frequency was set at 10 kHz.…”

Section: ■ Experimental Methodsmentioning

confidence: 99%

“…Phosphotungstic acid (PTA, H 3 PW 12 O 40 ) is a Keggin polyoxometalate (POM) cluster that can provide the tungsten oxide active sites for the aforementioned model reactions owing to its activity for acid catalysis. For instance, pure PTA has been reported for depolymerization of polytetrahydrofuran and alkylation of toluene . Researchers have extensively studied PTA as heterogeneous acid catalysts on various supports.…”

Section: Introductionmentioning

confidence: 99%

“…For instance, pure PTA has been reported for depolymerization of polytetrahydrofuran 12 and alkylation of toluene. 13 Researchers have extensively studied PTA as heterogeneous acid catalysts on various supports. Kukovecz et al reported sol−gel incorporation of PTA on silica for alkene isomerization, 14 Devassy et al impregnated PTA on zirconia for phenol alkylation, 15 and Macht et al deposited PTA on SiO 2 via incipient wetness impregnation for alcohol dehydration.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Figure 6. Solid-state13 C CP MAS NMR spectra of 0.9 PW 12 @NU-1000 as synthesized (black) and after catalysis (blue). + indicates spinning sidebands, and * indicates new feature assigned as adsorbed (C 6 H 4 )(CH 3 ) 2 .…”

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confidence: 99%

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Pushing the Limits on Metal–Organic Frameworks as a Catalyst Support: NU-1000 Supported Tungsten Catalysts for o-Xylene Isomerization and Disproportionation

et al. 2018

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Acid-catalyzed skeletal C-C bond isomerizations are important benchmark reactions for the petrochemical industries. Among those, o-xylene isomerization/disproportionation is a probe reaction for strong Brønsted acid catalysis, and it is also sensitive to the local acid site density and pore topology. Here, we report on the use of phosphotungstic acid (PTA) encapsulated within NU-1000, a Zr-based metal-organic framework (MOF), as a catalyst for o-xylene isomerization at 523 K. Extended X-ray absorption fine structure (EXAFS), P NMR, N physisorption, and X-ray diffraction (XRD) show that the catalyst is structurally stable with time-on-stream and that WO clusters are necessary for detectable rates, consistent with conventional catalysts for the reaction. PTA and framework stability under these aggressive conditions requires maximal loading of PTA within the NU-1000 framework; materials with lower PTA loading lost structural integrity under the reaction conditions. Initial reaction rates over the NU-1000-supported catalyst were comparable to a control WO-ZrO, but the NU-1000 composite material was unusually active toward the transmethylation pathway that requires two adjacent active sites in a confined pore, as created when PTA is confined in NU-1000. This work shows the promise of metal-organic framework topologies in giving access to unique reactivity, even for aggressive reactions such as hydrocarbon isomerization.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: ■ Experimental Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%