Showing papers by "Thomas E. Rufford published in 2015"

Synthesis and characterization of three amino-functionalized metal–organic frameworks based on the 2-aminoterephthalic ligand

Abstract: The incorporation of Lewis base sites and open metal cation sites into metal-organic frameworks (MOFs) is a potential route to improve selective CO2 adsorption from gas mixtures. In this study, three novel amino-functionalized metal-organic frameworks (MOFs): Mg-ABDC [Mg3(ABDC)3(DMF)4], Co-ABDC [Co3(ABDC)3(DMF)4] and Sr-ABDC [Sr(ABDC)(DMF)] (ABDC = 2-aminoterephthalate) were synthesized by solvothermal reactions of 2-aminoterephthalic acid (H2ABDC) with magnesium, cobalt and strontium metal centers, respectively. Single-crystal structure analysis showed that Mg-ABDC and Co-ABDC were isostructural compounds comprising two-dimensional layered structures. The Sr-ABDC contained a three-dimensional motif isostructural to its known Ca analogue. The amino-functionalized MOFs were characterized by powder X-ray diffraction, thermal gravimetric analysis and N2 sorption. The CO2 and N2 equilibrium adsorption capacities were measured at different temperatures (0 and 25 °C). The CO2/N2 selectivities of the MOFs were 396 on Mg-ABDC, 326 on Co-ABDC and 18 on Sr-ABDC. Both Mg-ABDC and Co-ABDC exhibit high heat of CO2 adsorption (>30 kJ mol(-1)). The Sr-ABDC displays good thermal stability but had a low adsorption capacity resulting from narrow pore apertures.

In Situ Tetraethoxysilane‐Templated Porous Ba0.5Sr0.5Co0.8Fe0.2O3−δ Perovskite for the Oxygen Evolution Reaction

Abstract: The perovskite Ba0.5Sr0.5Co0.8Fe0.2O3- (BSCF) is one of the best catalysts for the oxygen evolution reaction (OER), which is critical to many energy-storage applications. However, the catalytic activity of BSCF perovskites is constrained by a low specific surface area (0.5m(2)g(-1)). We report here, for the first time, a facile, in situ template method using tetraethoxysilane (TEOS) to synthesize porous BSCF with surface areas of up to 32.1m(2)g(-1), which to our knowledge is the highest reported surface area in a BSCF perovskite, and with excellent catalytic activity for the OER. For example, the BCSF prepared using a TEOS-to-BSCF ratio of 3.4 exhibited up to 35.2Ag(-1) at 1.63V versus a reversible hydrogen electrode (overpotential, =0.4V) and this current is 5.3 times that exhibited by nonporous BSCF (6.6Ag(-1)). The high activity of the porous BCSF is attributed to the additional catalytic surface sites available in the pores created by the in situ TEOS-template method. The general application of this technique to produce porous perovskites is demonstrated in the synthesis of a second example, porous LaMnO3.

Structural sensitivity of mesoporous alumina for copper catalyst loading used for NO reduction in presence of CO

Abstract: Copper oxide supported on mesoporous alumina pre-treated at different temperatures was examined for catalytic reduction (SCR) of NO with CO. About 4.5% copper oxide was loaded on mesoporous alumina using wet impregnation method. Detailed investigations concluded that the activity of Cu/m-Al 2 O 3 is strongly influenced by the active Cu phase present on bulk copper aluminate. The Copper phase on the catalyst was strongly affected by pre-treatment temperature of the host material. The optimal pre-treatment temperature of the support was found to be around 900 °C. The reaction mechanism on the catalyst surface was suitably described using L-H mechanistic model with the reduced Cu δ + sites generated on the catalyst surface post CO oxidation playing a critical role in NO reduction.

The effect of rank and lithotype on coal wettability and its application to coal relative permeability models

Abstract: We report the effect of rank and lithotype on the wettability of artificial cleat channels in five coals from the Bowen Basin with ranks in the Rmax% range 0.98-1.91%. Wettability was assessed by measuring contact angles of air and water in the artificial cleats using a microfluidic Cleat Flow Cell (CFC) instrument. The artificial cleats were produced by reactive ion etching and had widths in the range 20-40 m that replicate the width and shape of some natural coal cleats under sub-surface reservoir conditions. These model cleats were developed to allow systematic laboratory investigations of water and gas relative permeability behaviour. Imbibition and drainage experiments were performed in the artificial channels using air and 0.1 %wt. fluorescein in fresh tap water to observe contact angles, the entry pressure of the air-water and water-air interface to the channel, and the pressure at which the channel was filled by the displacing fluid. Relative contact angles on the coal surface of 110 -140° were determined from images collected in the imbibition experiments. A trend of increasing contact angle with coal rank was observed. The low rank coal exhibited smaller contact angles and lower breakthrough pressures than the higher rank coal samples. In the drainage experiments the injection air displaced the water but left a residual liquid film on cleat walls across dull, inertinite rich bands. This residual film was not observed in the bright, vitrinite rich bands. The results of this study may provide the basis to consider an improved relative permeability model that explicitly accounts for wettability and the effect of coal rank.

Low-temperature synthesis of hierarchical amorphous basic nickel carbonate particles for water oxidation catalysis

Abstract: Amorphous nickel carbonate particles are catalysts for the oxygen evolution reaction (OER), which plays a critical role in the electrochemical splitting of water. The amorphous nickel carbonate particles can be prepared at a temperature as low as 60 degrees C by an evaporation-induced precipitation (EIP) method. The products feature hierarchical pore structures. The mass-normalized activity of the catalysts, measured at an overpotential of 0.35V, was 55.1Ag(-1), with a Tafel slope of only 60mVdec(-1). This catalytic activity is superior to the performance of crystalline NiOx particles and -Ni(OH)(2) particles, and compares favorably to state-of-the-art RuO2 catalysts. The activity of the amorphous nickel carbonate is remarkably stable during a 10000s chronoamperometry test. Further optimization of synthesis parameters reveals that the amorphous structure can be tuned by adjusting the H2O/Ni ratio in the precursor mixture. These results suggest the potential application of easily prepared hierarchical basic nickel carbonate particles as cheap and robust OER catalysts with high activity.

Functionalization of Carbon Nanotubes for Catalytic Applications

Abstract: Nanotubes and Nanosheets: Functionalization and Applications of Boron Nitride and Other Nanomaterials is the first book devoted to nanotubes and nanosheets made of boron nitride (BN). It shows how the properties of BN nanotubes and nanosheets have led to many exciting applications where carbon (C) materials cannot be used, including high-temperature metal-ceramic-based composites, substrates for graphene and other semiconducting layers in electronic devices, reusable absorbents for oil and other contaminants, dry solid lubricants, and biomedical applications. Researchers working on various aspects of BN nanomaterials share their knowledge and current work on the applications of BN nanotubes and nanosheets. They describe numerous applications, including BN nanotube-reinforced metal-ceramic-based composites, field emission, desalination, cleanup of oil spillages, biosensing and bioimaging, drug delivery, biomedical applications, and energy storage using BCN and TiO2 nanorods and nanosheets as electrode materials. The book also covers C and other nanotubes and nanosheets to give readers a broad view of the latest nanomaterials research.

Mechanistic modelling of counter-current slug flows in vertical annuli

Abstract: A range of mathematical models and correlations is used to estimate the pressure drop for co-current two-phase flows in vertical wells in the conventional oil and gas industry. However, in the annulus between casing and tubing of a coal seam gas (CSG) well, the upward flow of gas and downward flow of water results in counter-current two-phase flows. The flow regimes developed in such a counter-current system are noticeably different to co-current flow regimes, and thus the existing models used to predict pressure profiles in co-current wells do not adequately describe two phase flows in a (pumped) CSG well. In this study, we modified existing mechanistic models for co-current flow and counter-current flow in a pipe to predict liquid holdup and pressure profiles of counter-current flows in vertical annuli for the slug flow, which is the dominant flow regime. A model, based on the work of Taitel and Barnea (1983), was also developed to predict the transition from slug flow to annular flow in counter-current flows in annuli. Our comparison of the pressure profiles of co-current and counter-current flows in annuli for the slug flow regime indicates that the pressure loss of counter-current flows could be appreciably different to that in co-current flows under the same conditions. This highlights the need to modify the models that are currently applied in typical commercial well flow simulators to better predict the pressure drop across CSG wells.

Poly(vinylidene fluoride) as a porogen to prepare nitrogen-enriched porous carbon electrode materials from pyrolysis of melamine resin

Abstract: Nitrogen-enriched carbons with hierarchical pore structures were prepared by the direct pyrolysis of melamine resin and poly(vinylidene fluoride) (PVDF) in an inert atmosphere. Our preparation method produced carbons that feature high micropore surface areas of up to 966 m 2 g −1 , with the peak micropore width around 0.5–0.6 nm, and 3–4 nm mesopore channels without the need for a template or activation post-carbonization. The carbons were characterized using N 2 and CO 2 sorption analyses, X-ray photoelectron spectroscopy and elemental analysis. The concentrations of nitrogen at the carbon surface were in the range 3.1–4.5 at.%. The electrochemical performance of carbon electrodes was evaluated using cyclic voltammetry, galvanostatic charge-discharge techniques and impedance spectroscopy in 1 M H 2 SO 4 and 1 M TEABF 4 /acetonitrile. Electrochemical tests in aqueous electrolyte showed excellent rate performance with capacitive behaviour up to 500 mV s −1 and a specific capacitance of 125 F g −1 at the current density of 0.05 A g −1 in a two-electrode cell. In both aqueous and organic electrolytes, good cycling performance are obtain with 96% and 77% of the initial capacitance after 10,000 and 5000 cycles, respectively.

Coal bed-methane reservoir simulation study

Abstract: Coal-bed methane (CBM) production behaviour is difficult to predict or analyse due to its highly intricate reservoir characteristics. Gas production from (CBM) reservoirs is governed by complex interaction of diffusion from the matrix to fractures and two phase gas and water flows through the fracture system to the production wells. The parameters that control the flow physics of these two systems are highly variable during the fluid production process. Generally CBM reservoir performance is evaluated using simulation software which requires experimental or/and field data to parametize the various governing equations that determine performance. Amongst the parameters that affect simulation outcomes, coal absolute permeability and relative permeability are key factors controlling CBM productivity.