Mechanism Studies of the Conversion of 13C‐Labeled n‐Butane on Zeolite H‐ZSM‐5 by Using 13C Magic Angle Spinning NMR Spectroscopy and GC–MS Analysis

Luzgin, Mikhail V.; Stepanov, Alexander G.; Arzumanov, Sergei S.; Rogov, Vladimir A.; Parmon, Valentin N.; Wang, Wei; Hunger, Michael; Freude, D.

doi:10.1002/chem.200500382

Cited by 36 publications

(33 citation statements)

References 56 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, ex situ GC-MS results exhibit formation of both unlabeled and double-labeled molecules in addition to single labeled i-butane after treating the sample at 293 K for 3 h, suggesting the possible bimolecular pathway although it is controversial because no propane and/or pentane appear in NMR spectra. The similar results are also found on H-MFI at 430-470 K. 106 Furthermore, the activation and skeletal arrangement of i-butane as a reverse reaction to View Online isomerisation of n-butane on SZ have been performed which shows that the isomerisation and its reverse reaction follow the same mechanism on the same catalyst under identical conditions. 107 It is also argued that the monomolecular mechanism of isomerisation is unfavorable in the case of n-butane.…”

Section: Isomerisation Of N-alkanessupporting

confidence: 77%

Recent development in in situ NMR study on heterogeneous catalysis: mechanisms of light alkane functionalisation

2012

View full text Add to dashboard Cite

show abstract

Section: Isomerisation Of N-alkanessupporting

confidence: 77%

Recent development in in situ NMR study on heterogeneous catalysis: mechanisms of light alkane functionalisation

2012

View full text Add to dashboard Cite

show abstract

“…As shown in Figure 1, besides methane, n-butane was also observed, as evidenced by the 13 CNMR signals at d = 26 (methylene group) and 14 ppm (methyl group). [14] Importantly,GC-MS analysis (Figure 1b-d) verified that the 13 C-labeled n-butane products could only have asingle 13 Clabel ([ 13 C 1 ]-nbutane,s ee also Table S1), thus indicating that the labeled n-butanes came from the 13 C-methylation of nonlabeled C 3 species.M eanwhile, the selective formation of [ 13 C 1 ]-nbutane rather than isobutane is in excellent agreement with those reported for propene methylation over acidic zeolites. [15] Thus,t he Scheme 2.…”

Section: Methodsmentioning

confidence: 92%

Alkane Activation Initiated by Hydride Transfer: Co‐conversion of Propane and Methanol over H‐ZSM‐5 Zeolite

Liu

et al. 2015

Angewandte Chemie

Self Cite

View full text Add to dashboard Cite

Co-conversion of alkane with another reactant over zeolite catalysts has emerged as an ew approach to the longstanding challenge of alkane transformation. With the aid of solid-state NMR spectroscopya nd GC-MS analysis,i tw as found that the co-conversion of propane and methanol can be readily initiated by hydride transfer at temperatures of ! 449 K over the acidic zeoliteH-ZSM-5. The formation of 13 C-labeled methane and singly 13 C-labeled n-butanes in selective labeling experiments provided the first evidence for the initial hydride transfer from propane to surface methoxy intermediates.T he results not only providenew insight into carbocation chemistry of solid acids,b ut also shed light on the low-temperature transformation of alkanes for industrial applications.Alkanes are the main components in natural gas and crude oil. Thec onversion of abundant but inert alkanes into highvalue-added products has been al ong-standing challenge to chemists. [1] Thed irect transformation of alkanes [2] suffers from the inertness of C À H/C À Cb onds and unfavorable thermodynamics which result in high reaction temperature, low product yield/selectivity,and unrealistic cost for industrial applications.Alternatively,the co-conversion of alkanes with reactive hydrocarbons [3] or oxygenates [4] over zeolites has recently been explored to overcome these limitations.M ethanol is ak ey platform chemical produced from various sources and can be readily converted over acidic zeolites through the industrial process. [5] Many efforts have accordingly been attempted to use methanol as the co-reactant [6] for coupling with methane, [6a] ethane, [6b] C 3 -C 4 alkanes, [6c] nbutane, [6d] n-hexane, [6e] and petroleum naphtha. [6f] However, the development of robust catalytic systems for efficient activation and further conversion of alkanes is severely hindered by the lack of mechanistic understanding.I nt his regard, solid-state NMR spectroscopy has been applied as ap owerful tool for monitoring the mechanistic events on heterogeneous catalysts. [7] In addition, GC-MS analysis on the distribution of either 13 Cor 2 Hlabels in the reaction products may offer the complementary information on many mechanistic details.T hrough solid-state magic-angle-spinning (MAS) NMR spectroscopy and GC-MS analysis,w ef ound herein, that upon addition of methanol, the C À Hb ond activation of propane was initiated by hydride transfer to surface methoxy species over zeolite H-ZSM-5 (Scheme 1). Initiated by hydride transfer, even at temperature as low as 449 K, the co-conversion of propane and methanol can be further achieved by secondary reactions,s uch as propene methylation (Scheme 2). This work not only details the longpursued evidence for hydride transfer over zeolite catalysts, but also offers insightful information on practical utilization of alkanes through the co-conversion strategy.To obtain unambiguous evidence for the initial hydride transfer, we chose 13 C-labeled methanol and nonlabeled propane (as the model compound of inert alkane) for ...

show abstract

“…Normally, 1 H and/or 13 C NMR signal plots are continuously recorded versus reaction time for obtaining the kinetic parameters involving apparent rate constants and activation energies. Reaction kinetics from conventional 1 H and 13 C NMR are obtained by concentration variations of reactant or product in the bulk state, 153 however, the kinetics in a confined space such as a nanocage or nanochannel can not be achieved easily. It has been shown that the laserhyperpolarized (HP) 129 Xe NMR technique is powerful for the studying of porous materials.…”

Section: Reaction Kinetics In Heterogeneous Catalysismentioning

confidence: 99%

In situsolid-state NMR for heterogeneous catalysis: a joint experimental and theoretical approach

et al. 2012

View full text Add to dashboard Cite

In situ solid-state NMR is a well-established tool for investigations of the structures of the adsorbed reactants, intermediates and products on the surface of solid catalysts. The techniques allow identifications of both the active sites such as acidic sites and reaction processes after introduction of adsorbates and reactants inside an NMR rotor under magic angle spinning (MAS). The in situ solid-state NMR studies of the reactions can be achieved in two ways, i.e. under batch-like or continuous-flow conditions. The former technique is low cost and accessible to the commercial instrument while the latter one is close to the real catalytic reactions on the solids. This critical review describes the research progress on the in situ solid-state NMR techniques and the applications in heterogeneous catalysis under batch-like and continuous-flow conditions in recent years. Some typical probe molecules are summarized here to detect the Brønsted and Lewis acidic sites by MAS NMR. The catalytic reactions discussed in this review include methane aromatization, olefin selective oxidation and olefin metathesis on the metal oxide-containing zeolites. With combining the in situ MAS NMR spectroscopy and the density functional theoretical (DFT) calculations, the intermediates on the catalyst can be identified, and the reaction mechanism is revealed. Reaction kinetic analysis in the nanospace instead of in the bulk state can also be performed by employing laser-enhanced MAS NMR techniques in the in situ flow mode (163 references).

show abstract

Mechanism Studies of the Conversion of ¹³C‐Labeled n‐Butane on Zeolite H‐ZSM‐5 by Using ¹³C Magic Angle Spinning NMR Spectroscopy and GC–MS Analysis

Cited by 36 publications

References 56 publications

Recent development in in situ NMR study on heterogeneous catalysis: mechanisms of light alkane functionalisation

Recent development in in situ NMR study on heterogeneous catalysis: mechanisms of light alkane functionalisation

Alkane Activation Initiated by Hydride Transfer: Co‐conversion of Propane and Methanol over H‐ZSM‐5 Zeolite

In situsolid-state NMR for heterogeneous catalysis: a joint experimental and theoretical approach

Contact Info

Product

Resources

About