Comparison of Surface-Bound and Free-Standing Variations of HKUST-1 MOFs: Effect of Activation and Ammonia Exposure on Morphology, Crystallinity, and Composition

Metal-organic frameworks (MOFs) are extremely porous, crystalline materials with high surface area for potential use in gas storage, sequestration, and separations. Toward incorporation into structures for these applications, this study compares three variations of surface-bound and free-standing HKUST-1 MOF structures: surface-anchored MOF (surMOF) thin film, drop-cast film, and bulk powder. Herein, effects of HKUST-1 ammonia interaction and framework activation, which is removal of guest molecules via heat, are investigated. Impact on morphology and crystal structure as a function of surface confinement and size variance are examined. Scanning probe microscopy, scanning electron microscopy, powder X-ray diffraction, Fourier-transform infrared spectroscopy, and energy dispersive X-ray spectroscopy monitor changes in morphology and crystal structure, track ammonia uptake, and examine elemental composition. After fabrication, ammonia uptake is observed for all MOF variations, but reveals dramatic morphological and crystal structure changes. However, activation of the framework was found to stabilize morphology. For activated surMOF films, findings demonstrate consistent morphology throughout uptake, removal, and recycling of ammonia over multiple exposures. To understand morphological effects, additional ammonia exposure experiments with controlled post-synthetic solvent adsorbates were conducted utilizing a HKUST-1 standard powder. These findings are foundational for determining the capabilities and limitation of MOF films and powders.

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Non-Thermal Plasma-Modified Ru-Sn-Ti Catalyst for Chlorinated Volatile Organic Compound Degradation

Catalysts ◽

10.3390/catal10121456 ◽

2020 ◽

Vol 10 (12) ◽

pp. 1456

Author(s):

Yujie Fu ◽

You Zhang ◽

Qi Xin ◽

Zhong Zheng ◽

Yu Zhang ◽

...

Keyword(s):

Plasma Treatment ◽

Photoelectron Spectroscopy ◽

High Surface ◽

High Surface Area ◽

Surface Oxidation ◽

Treatment Method ◽

X Ray ◽

Chlorinated Volatile Organic Compounds ◽

Volatile Organic ◽

Doped Titania

Chlorinated volatile organic compounds (CVOCs) are vital environmental concerns due to their low biodegradability and long-term persistence. Catalytic combustion technology is one of the more commonly used technologies for the treatment of CVOCs. Catalysts with high low-temperature activity, superior selectivity of non-toxic products, and resistance to chlorine poisoning are desirable. Here we adopted a plasma treatment method to synthesize a tin-doped titania loaded with ruthenium dioxide (RuO2) catalyst, possessing enhanced activity (T90%, the temperature at which 90% of dichloromethane (DCM) is decomposed, is 262 °C) compared to the catalyst prepared by the conventional calcination method. As revealed by transmission electron microscopy, X-ray diffraction, N2 adsorption, X-ray photoelectron spectroscopy, and hydrogen temperature-programmed reduction, the high surface area of the tin-doped titania catalyst and the enhanced dispersion and surface oxidation of RuO2 induced by plasma treatment were found to be the main factors determining excellent catalytic activities.

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Attached β-cyclodextrin/γ-(2,3-epoxypropoxy) propyl trimethoxysilane to graphene oxide and its application in copper removal

Water Science & Technology ◽

10.2166/wst.2017.045 ◽

2017 ◽

Vol 75 (10) ◽

pp. 2403-2411 ◽

Cited By ~ 2

Author(s):

Zongxue Yu ◽

Qi Chen ◽

Liang Lv ◽

Yang Pan ◽

Guangyong Zeng ◽

...

Keyword(s):

Graphene Oxide ◽

High Surface ◽

High Surface Area ◽

Esterification Reaction ◽

X Ray Diffraction ◽

X Ray ◽

Cavity Structure ◽

Optimum Ph ◽

Exchange Adsorption ◽

Langmuir Isotherm Model

The environmental applications of graphene oxide and β-cyclodextrin (β-CD) have attracted great attention since their first discovery. Novel nanocomposites were successfully prepared by using an esterification reaction between β-cyclodextrin/γ-(2,3-epoxypropoxy) propyl trimethoxysilane grafted graphene oxide (β-CD/GPTMS/GO). The β-CD/GPTMS/GO nanocomposites were used to remove the Cu2+ from aqueous solutions. The characteristics of β-CD/GPTMS/GO were detected by scanning electron microscopy (SEM), Fourier transform infrared, X-ray diffraction (XRD), thermogravimetric analysis (TG) and energy dispersive X-ray (EDX). The dispersibility of graphene oxide was excellent due to the addition of β-CD. The adsorption isotherms data obtained at the optimum pH 7 were fitted by Langmuir isotherm model. The excellent adsorption properties of β-CD/GPTMS/GO for Cu2+ ions could be attributed to the apolar cavity structure of β-CD, the high surface area and abundant functional groups on the surface of GO. The adsorption patterns of β-CD/GPTMS/GO were electrostatic attraction, formation of host-guest inclusion complexes and the ion exchange adsorption. The efficient adsorption of β-CD/GPTMS/GO for Cu2+ ions suggested that these novel nanocomposites may be ideal candidates for removing other cation pollutants from waste water.

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Facile Synthesis of Unique Bismuth Vanadate Nano-Knitted Hollow Cage and its Application in Environmental Remediation

Zeitschrift für Naturforschung A ◽

10.1515/zna-2018-0432 ◽

2019 ◽

Vol 74 (3) ◽

pp. 259-263 ◽

Cited By ~ 1

Author(s):

M. Shamshi Hassan

Keyword(s):

Environmental Remediation ◽

Dye Degradation ◽

High Surface ◽

High Surface Area ◽

Bismuth Vanadate ◽

Bandgap Energy ◽

Blue Dye ◽

X Ray ◽

Photodegradation Efficiency ◽

Hollow Nanostructure

AbstractHierarchical bismuth vanadate (BiVO4) nano-knitted hollow cages have been synthesized by simple hydrothermal method and characterized by scanning electron microscopy, x-ray diffraction, energy-dispersive x-ray spectrometer, Fourier transform infrared, UV-Vis, and Raman. The photodegradation efficiency of BiVO4 nanocage for universally used methylene blue dye. The BiVO4 hollow nanostructure demonstrated better photocatalytic competence in dye degradation as compared to the commercial TiO2 powders (P25). The excellent dye degradation can be certified to the high crystallisation of monoclinic BiVO4 and hollow nanostructure, which leads to high surface area and small bandgap energy of 2.44 eV.

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Operando SAXS Study of a Pt/C Fuel Cell Catalyst with an X-ray Laboratory Source

10.26434/chemrxiv.14283788.v1 ◽

2021 ◽

Author(s):

Johanna Schröder ◽

Jonathan Quinson ◽

Jacob J. K. Kirkensgaard ◽

Matthias Arenz

Keyword(s):

Fuel Cell ◽

Background Subtraction ◽

Stress Test ◽

High Surface ◽

High Surface Area ◽

Carbon Support ◽

Grazing Incidence ◽

Saxs Data ◽

X Ray ◽

Fuel Cell Catalysts

Small angle X-ray scattering (SAXS) is a powerful technique to investigate the degradation of catalyst materials. Ideally such investigations are performed operando, i.e., during a catalytic reaction. An example of operando measurements is to observe the degradation of fuel cell catalysts during an accelerated stress test (AST). Fuel cell catalysts consist of Pt or Pt alloy nanoparticles (NPs) supported on a high surface area carbon. A key challenge of operando SAXS measurements is a proper background subtraction of the carbon support to extract the information of the size distribution of the Pt NPs as a function of the AST treatment. Typically, such operando studies require the use of synchrotron facilities. The background measurement can then be performed by anomalous SAXS (aSAXS) or in a grazing incidence con-figuration. In this work we present a proof-of-concept study demonstrating the use of a laboratory X-ray diffractometer for operando SAXS. Data acquisition of operando SAXS with a laboratory X-ray diffractometer is desirable due to the general challenging and limited accessibility of synchrotron facilities. They become even more crucial under the ongoing and foreseen restrictions related to the COVID-19 pandemic. Although, it is not the aim to completely replace synchrotron-based studies, it is shown that the background subtraction can be achieved by a simple experimental consideration in the setup that can ultimately facilitate operando SAXS measurements at a synchrotron facility.

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Organomineral nanocomposite carbon burial during Oceanic Anoxic Event 2

Biogeosciences Discussions ◽

10.5194/bgd-11-6815-2014 ◽

2014 ◽

Vol 11 (5) ◽

pp. 6815-6844

Author(s):

S. C. Löhr ◽

M. J. Kennedy

Keyword(s):

Surface Area ◽

High Surface ◽

High Surface Area ◽

Mineral Surfaces ◽

Mineral Surface ◽

X Ray ◽

Oceanic Anoxic Event ◽

Carbon Burial ◽

Anoxic Events ◽

Mineral Surface Area

Abstract. Organic carbon (OC) enrichment in sediments deposited during Oceanic Anoxic Events (OAEs) is commonly attributed to elevated productivity and marine anoxia. We find that OC enrichment in the late Cenomanian aged OAE2 at Demerara Rise was controlled by co-occurrence of anoxic bottom-water, sufficient productivity to saturate available mineral surfaces and variable deposition of high surface area detrital smectite clay. Redox indicators show consistently oxygen-depleted conditions, while a strong correlation between OC concentration and sediment mineral surface area (R2=0.92) occurs across a range of TOC values from 9–33%. X-ray diffraction data indicates intercalation of OC in smectite interlayers while electron, synchrotron infrared and X-ray microscopy show an intimate association between clay minerals and OC, consistent with preservation of OC as organomineral nanocomposites and aggregates rather than discrete, μm-scale pelagic detritus. Since the consistent ratio between TOC and mineral surface area suggests that excess OC relative to surface area is lost, we propose that it is the varying supply of smectite that best explains variable organic enrichment against a backdrop of continuous anoxia, which is conducive to generally high TOC during OAE2 at Demerara Rise. Smectitic clays are unique in their ability to form stable organomineral nanocomposites and aggregates that preserve organic matter, and are common weathering products of continental volcanic deposits. An increased flux of smectite coinciding with high carbon burial is consistent with evidence for widespread volcanism during OAE2, so that organomineral carbon burial may represent a potential feedback to volcanic degassing of CO2.

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Phase transformations in cucurbituril host-guest complexes

Acta Crystallographica Section A Foundations and Advances ◽

10.1107/s205327331409353x ◽

2014 ◽

Vol 70 (a1) ◽

pp. C646-C646

Author(s):

Oksana Danylyuk ◽

Karolina Kedra-Krolik ◽

Marta Worzakowska ◽

Joanna Osypiuk-Tomasik ◽

Vladimir Fedin

Keyword(s):

Single Crystal ◽

Crystal Lattice ◽

Supramolecular Assembly ◽

Water Molecules ◽

Guest Molecules ◽

X Ray ◽

Host Guest Complex ◽

Crystallographic Study ◽

Partial Dehydration ◽

Structure Changes

The retention of crystallinity upon desolvation of molecular crystals is not common, as the molecules are rigidly and densely packed in the crystals and the original framework usually collapses once solvent is removed from the structure. However, in rare cases the host framework remains substantially unaffected by solvent (guest) removal yielding structure with open channels or discrete lattice voids that can show permanent porosity. [1] Furthermore, sometimes happens, the desolvation process proceeds as single-crystal to single-crystal transformation resulting in distortion and sliding of the structure, changes in conformation, coordination modes and/or space group. Here we would like to present crystallographic study and thermal analysis on the dehydration process of the crystalline supramolecular complex between macrocyclic host cucurbit[6]uril and dopamine. In the solid state the 1:1 host-guest complex assembles into hexameric tubes with water-filled interior channels. Another set of water channels is created between three neighboring tubes in the crystal lattice. The crystals of such supramolecular assembly are not stable when out from mother solution and immediately start to loose water upon exposure to air. However, despite severe cracking the crystals dried in air maintained their integrity and still gave satisfactory diffraction pattern. The X-ray analysis showed significant decrease in the unit cell volume of the partially dehydrated crystals that corresponds to the liberation of some of the water molecules from the channels. Moreover, the reorganization of dopamine guest molecules has occurred in the crystal lattice as a response to the escape of water molecules from the structure. The partial dehydration and reorganization of the supramolecular framework proceeds via a single-crystal to single-crystal mechanism.

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Bosoite, a new silica clathrate mineral from Chiba Prefecture, Japan

Mineralogical Magazine ◽

10.1180/mgm.2020.91 ◽

2020 ◽

pp. 1-8

Author(s):

Koichi Momma ◽

Takuji Ikeda ◽

Toshiro Nagase ◽

Takahiro Kuribayashi ◽

Chibune Honma ◽

...

Keyword(s):

Crystal Structure ◽

Sedimentary Rocks ◽

X Ray Diffraction ◽

Unit Cell Parameters ◽

Average Model ◽

Guest Molecules ◽

Calculated Density ◽

X Ray ◽

Cell Parameters ◽

Chiba Prefecture

Abstract Bosoite (IMA2014-023) is a new silica clathrate mineral containing hydrocarbon molecules in its crystal structure. Bosoite can be considered structurally as a silica analogue of the structure-H gas hydrate, where guest molecules are trapped in cage-like voids constructed of the host framework. The mineral occurs in the Miocene tuffaceous sedimentary rocks at Arakawa, Minami-boso City, Chiba Prefecture, Japan. Bosoite is hexagonal, and it crystallises as an epitaxial intergrowth on chibaite crystals, with the {0001} of bosoite parallel to octahedral {111} form of chibaite. Crystals are colourless and transparent with vitreous lustre. The calculated density is 2.04 g/cm3. The empirical formula (based on 2 O apfu and guest molecules assumed as CH4) is Na0.01(Si0.98Al0.02)Σ1.00O2⋅0.50CH4; the end-member formula is SiO2⋅nC x H2x+2. Bosoite has the space group P6/mmm, with the unit-cell parameters a = 13.9020(3) Å, c = 11.2802(2) Å, V = 1887.99(6) Å3 and Z = 34. The crystal structure of bosoite was refined by single-crystal X-ray diffraction and converged to R1 = 4.26% for the average model and R1 = 2.96% for the model where all oxygen sites are split.

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Promoting Li/MgO Catalyst with Molybdenum Oxide for Oxidative Conversion of n-Hexane

Catalysts ◽

10.3390/catal10030354 ◽

2020 ◽

Vol 10 (3) ◽

pp. 354 ◽

Cited By ~ 1

Author(s):

Cassia Boyadjian ◽

Leon Lefferts

Keyword(s):

Raman Spectroscopy ◽

High Surface ◽

High Surface Area ◽

Deep Oxidation ◽

Oxidative Conversion ◽

X Ray Diffraction ◽

X Ray ◽

Anionic Species ◽

Dehydrogenation Reactions ◽

Lithium Molybdate

In this work, molybdena-promoted Li/MgO is studied as a catalyst for the oxidative conversion of n-hexane. The structure of the catalysts is investigated with X-ray Diffraction (XRD) and Raman spectroscopy. The MoO3/Li/MgO catalyst contains three types of molybdena-containing species, the presence of which depend on molybdena loading. At low Mo/Li ratios (i) isolated dispersed [MoO4]2− anionic species are observed. At high Mo/Li ratios, the formation of crystalline lithium molybdate phases such as (ii) monomeric Li2MoO4 and tentatively (iii) polymeric Li2Mo4O13 are concluded. The presence of these lithium molybdates diminishes the formation of Li2CO3 in the catalyst. Subsequently, the catalyst maintains high surface area and stability with time-on-stream during oxidative conversion. Molybdena loading as low as 0.5 wt % is sufficient to induce these improvements, maintaining the non-redox characteristics of the catalyst, whereas higher loadings enhance deep oxidation and oxidative dehydrogenation reactions. Promoting a Li/MgO catalyst with 0.5 wt % MoO3 is thus efficient for selective conversion of n-hexane to alkenes, giving alkene yield up to 24% as well as good stability.

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The crystal structure and thermal expansion of the CCl4 adduct of Dianin's compound

Canadian Journal of Chemistry ◽

10.1139/v90-207 ◽

1990 ◽

Vol 68 (8) ◽

pp. 1352-1356 ◽

Cited By ~ 12

Author(s):

Walter Abriel ◽

André Du Bois ◽

Marek Zakrzewski ◽

Mary Anne White

Keyword(s):

Crystal Structure ◽

Thermal Expansion ◽

Powder Diffraction ◽

Diffraction Data ◽

X Ray Diffraction ◽

Guest Molecules ◽

X Ray ◽

Thermal Expansion Coefficients ◽

Expansion Coefficients ◽

Dianin's Compound

The crystal structure of the title compound has been determined by single crystal X-ray diffraction data collected at 293 K, and refined to a final Rw of 0.057. The crystals are rhombohedral, space group [Formula: see text], with a = 27.134(8) Å, c = 10.933(2) Å, and Z = 18. The mole ratio of Dianin's compound (4-p-hydroxyphenyl-2,2,4-trimethylchroman) to CCl4 is 6:1. The guest molecules are disordered. X-ray powder diffraction was carried out in the temperature range from 10 to 300 K. From this, the thermal expansion coefficients for the a- and c-axes and the volume have been determined. Keywords: thermal expansion, crystal structure, clathrate.

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Enhanced Photocatalytic Activity of Titania by Co-Doping with Mo and W

Catalysts ◽

10.3390/catal8120631 ◽

2018 ◽

Vol 8 (12) ◽

pp. 631 ◽

Cited By ~ 16

Author(s):

Osmín Avilés-García ◽

Jaime Espino-Valencia ◽

Rubí Romero-Romero ◽

José Rico-Cerda ◽

Manuel Arroyo-Albiter ◽

...

Keyword(s):

Photoelectron Spectroscopy ◽

Diffuse Reflectance Spectroscopy ◽

High Surface ◽

High Surface Area ◽

Absorption Capacity ◽

Radiation Absorption ◽

Experimental Conditions ◽

X Ray ◽

Assembly Method ◽

Co Doped

Various W and Mo co-doped titanium dioxide (TiO2) materials were obtained through the EISA (Evaporation-Induced Self-Assembly) method and then tested as photocatalysts in the degradation of 4-chlorophenol. The synthesized materials were characterized by thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), Raman spectroscopy (RS), N2 physisorption, UV-vis diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The results showed that the W-Mo-TiO2 catalysts have a high surface area of about 191 m2/g, and the presence of an anatase crystalline phase. The co-doped materials exhibited smaller crystallite sizes than those with one dopant, since the crystallinity is inhibited by the presence of both species. In addition, tungsten and molybdenum dopants are distributed and are incorporated into the anatase structure of TiO2, due to changes in red parameters and lattice expansion. Under our experimental conditions, the co-doped TiO2 catalyst presented 46% more 4-chlorophenol degradation than Degussa P25. The incorporation of two dopant cations in titania improved its photocatalytic performance, which was attributed to a cooperative effect by decreasing the recombination of photogenerated charges, high radiation absorption capacity, high surface areas, and low crystallinity. When TiO2 is co-doped with the same amount of both cations (1 wt.%), the highest degradation and mineralization (97% and 74%, respectively) is achieved. Quinones were the main intermediates in the 4-chlorophenol oxidation by W-Mo-TiO2 and 1,2,4-benzenetriol was incompletely degraded.

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