Boric acid treated HZSM-5 for improved catalyst activity in non-oxidative methane dehydroaromatization

Balyan, Sonit; Haider, M. Ali; Khan, Tuhin Suvra; Pant, Kamal Kishore

doi:10.1039/d0cy00286k

Cited by 31 publications

(47 citation statements)

References 72 publications

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“…While 11 B NMR alone cannot distinguish between S2 sites on an isolated B atom and those in a cluster, the low total boron surface densities in these experiments and the recent results in B-containing zeolites suggest that the active species are most likely highly dispersed B–OH species on the silica surface but in close proximity to many SiOH species (Scheme ). Testing additional borate-treated zeolites or hydrated boron-substituted zeolites may shed further light on this assignment. Overall, this work identifies a potential active site for ODHP on silica-supported boron catalysts and a template for improving the activity of these materials.…”

Section: Discussionmentioning

confidence: 99%

Identifying Boron Active Sites for the Oxidative Dehydrogenation of Propane

Yan

Alayoǧlu

et al. 2021

ACS Catal.

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Oxidative dehydrogenation of propane (ODHP) to propylene could have a significant impact on the production of this critical chemical intermediate, if appropriate catalysts can be discovered. Recently, heterogeneous catalysts based on boron (oxides and nitrides) have been demonstrated to be promising for ODHP, but their active sites have not been conclusively identified. Here, we report that the deposition of differently sized boronic acids into the micropores of silica supports results in different distributions of surface borate species after calcination. These materials, in turn, display a wide range of rates in ODHP but similar selectivity, suggesting that they differ only in the numbers of active sites. Features identified by in situ Raman, IR, and magic-angle-spinning 11B solid-state NMR spectroscopies are compared to catalyst activity. This correlation identifies the S2 borate species, a hydroxylated nonring boron, as the likely active site and provides a target for directed syntheses of future catalysts.

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Section: Discussionmentioning

confidence: 99%

Identifying Boron Active Sites for the Oxidative Dehydrogenation of Propane

Yan

Alayoǧlu

et al. 2021

ACS Catal.

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“…was applied. A similar DFT setup has already been used extensively. − Acetonitrile solvent environment was simulated using a conductor-like screening model in which acetonitrile was represented by its respective dielectric constant (ε = 37.5). , Atomic charges for the host and the host–anion complexes were obtained using Mulliken population analysis.…”

Section: Methodsmentioning

confidence: 99%

Supersensitive Detection of Anions in Pure Organic and Aqueous Media by Amino Acid Conjugated Ellman’s Reagent

Dhawan

Devnani

Babu

et al. 2021

ACS Appl. Bio Mater.

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The last few decades witnessed a remarkable advancement in the field of molecular anion receptors. A variety of anion binding motifs have been discovered, and large number of designer molecular anion receptors with high selectivity are being reported. However, anion detection in an aqueous medium is still a formidable challenge as evident from only a miniscule of synthetic systems available in the literature. We, herein, report 5,5′-dithio-bis(2-nitrobenzoic acid) (Ellman’s reagent) appended with amino acids as supersensitive anion sensors that can detect F– and H2PO4 – ions in both aqueous as well as organic media. Interestingly, the sensors showed a dual response to anions, viz., chromogenic response in organic medium and electrochemical response in aqueous solutions. Various spectroscopic techniques such as UV–vis and 1H NMR are used to investigate the binding studies in acetonitrile, whereas electrochemical methods such as cyclic voltammetry (CV) and differential pulse voltammetry (DPV) are employed to explore the anion binding in water. The host–guest complex stoichiometry and binding constants are calculated using the BindFit software. The geometry of host–guest complex has been optimized by the density functional theory (DFT) method. These molecules are versatile sensors since these function in both water and acetonitrile with extremely low limit of detection (LOD) up to 0.07 fM and limit of quantification (LOQ) up to 0.23 fM. To our knowledge, the present system is the first example of a sensor that can detect the lowest concentration of anions in water quantitatively. The minimalistic design strategy presented here opens up the innumerable possibilities for designing dual anion sensors in a one fell swoop.

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“…The acid or alkali treatment also affects the acidity of the catalyst. Treating Mo/HZSM-5 with boronic acid can reduce the amount of strong acid sites and the total acid strength: it not only reduced coke deposits to 8 wt% during MDA but also increased the formation rate of benzene . Weak alkali treatment can dealuminize, while strong alkali treatment can desiliconize. , Due to the different treatment effects on active sites, acid treatment generally has more obvious anti-coking properties than alkali treatment at the same concentration .…”

Section: Strategies To Inhibit Carbon Depositionmentioning

confidence: 99%

Coke Formation over Zeolite Catalysts in Light Alkanes Aromatization and Anti-Carbon-Deposition Strategies and Perspectives: A Review

et al. 2023

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The price of light aromatics, which are important chemical intermediates, is greatly affected by fluctuations in the oil market, and there is a gap in the supply. It is urgent to expand the source of aromatics to match the market demand. Being highly accessible, oxygen-free aromatization of light alkanes (C1–C4), with high product selectivity and high cost-effectiveness, has attracted widespread interest from both academia and industry. However, the rapid deactivation of catalysts due to carbon deposition has seriously hindered the industrialization process. This Review presents the bifaciality of coke on catalysts and proposes a coke formation mechanism related to the dynamic migration of intermediates according to the type of catalyst active site. An emphasis is placed on creating a reaction microenvironment that resists carbon deposition by improving the mass-transfer efficiency, controlling the interaction between intermediates and active sites, adjusting silanol defects, and looking forward to future directions for development.

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Boric acid treated HZSM-5 for improved catalyst activity in non-oxidative methane dehydroaromatization

Abstract: The dehydroaromatization (DHA) reaction of methane under non-oxidative conditions is carried out over a molybdenum catalyst supported on HZSM-5 and boric acid (BA) treated HZSM-5 at 700 °C and atmospheric pressure.

Cited by 31 publications

References 72 publications

Identifying Boron Active Sites for the Oxidative Dehydrogenation of Propane

Identifying Boron Active Sites for the Oxidative Dehydrogenation of Propane

Supersensitive Detection of Anions in Pure Organic and Aqueous Media by Amino Acid Conjugated Ellman’s Reagent

Coke Formation over Zeolite Catalysts in Light Alkanes Aromatization and Anti-Carbon-Deposition Strategies and Perspectives: A Review

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