https://nova.newcastle.edu.au/vital/access/ /manager/Index ${session.getAttribute("locale")} 5 https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:38517 2O₃ (possessing weak acid sites, 9.2 nm) and Ru/SiO₂ (absence of acid sites, 15.2 nm) were also prepared and examined. It was observed that a decrease in the Si/Al ratio of the support results in an increase in the yield of cyclohexane and a decrease in the yield of 2-methoxycyclohexanol in HDO of guaiacol. This data also discloses the influence of the concentration of acid sites on the deoxygenation of 2-methoxycyclohexanol. Both Ru/BEA and Ru/ZSM-5, with both possessing low Si/Al ratios, display a high activity for HDO for guaiacol, while only the Ru/BEA catalyst exhibits a high activity for HDO of biocrude oil. Catalyst characterisation (BET, NH₃-TPD and NH₃ and acetonitrile-d3-FTIR) shows that the Ru/BEA catalyst, with a low Si/Al ratio, not only possesses strong Brønsted acid sites but also contains extensive mesoporosity. Notably, these mesopores appear to facilitate the hydrogenation, deoxygenation, and ring-opening of large oxygenated and condensed-ring hydrocarbons in biocrude oil which then leads to a high yield of cycloalkanes. As expected, the Ru/Al₂O₃ and Ru/SiO₂ catalysts exhibit a high hydrogenation activity but a lower deoxygenation activity in the HDO of guaiacol and biocrude oil. These results suggest that the larger pore support, with strong Brønsted acid sites, engendered the HDO activity observed. The reaction pathway for the main components of biocrude oil was proposed based on the observed reaction product distribution.]]> Wed 20 Oct 2021 11:28:59 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:37280 4) to organic oxygenates utilizing heterogeneous and homogeneous processes conducted in the gaseous or liquid phase is reviewed. The most active catalytic systems are examined in terms of rates, longevity, and reaction mechanisms. Despite significant effort, the successful heterogeneous mimicking of selective CH₄ oxidation performed in an enzymatic system (methane monooxygenase) is still elusive. Under mild reaction conditions, the reaction is too slow, and under harsh conditions, total oxidation prevails. Thus, of particular interest herein is the assessment of oxidation at intermediate temperatures to 1) reduce total oxidation and 2) obtain sufficient concentration of activated oxygen and CH₄ species. Important operational parameters such as reaction conditions, catalyst preparation methods, and cofeeding of chemicals, which significantly affect the yield of desired products, are discussed. One particular system that is successful is the catalytic conversion of CH₄ to methanol under mild conditions using nitrous oxide (N₂O) with Fe-based catalysts or oxygen (O₂) with Cu-based catalysts. Special attention is paid to the controversy related to the identification of active sites, where the oxygen species suitable for CH₄ oxidation are purportedly formed.]]> Wed 16 Sep 2020 18:36:19 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:45435 2O₃ catalyst for the hydrogenation of carbon oxides, in the presence of light hydrocarbons, was studied. Ni/Al₂O₃ displayed a high activity for the complete conversion of CO and CO₂ to methane and C₂₊ hydrocarbons. Moreover, over a discrete and relatively narrow temperature range, the net concentration of light C₂₊ hydrocarbons was elevated, with the exit stream containing a higher concentration of C₂₊ species than was present in the feed stream and the product stream being virtually free of carbon oxides. It is found that the addition of manganese can enhance the selectivity toward the production of light hydrocarbons. A series of Ni–Mn/Al₂O₃ catalysts, prepared with different Ni/Mn ratios, were studied. Various characterization techniques such as X-ray diffraction (XRD) analysis, CO and H₂ chemisorption, in situ nitric oxide adsorption Fourier transform infrared spectroscopy (NO-FTIR), and temperature-programmed reduction (TPR) were performed to gain an insight into how the addition of Mn to the primary catalyst enhances the yield of light hydrocarbons. The origin of Mn promotion was demonstrated through density functional theory (DFT) calculations, which revealed the favorable Mn substitution at the Ni(211) step edge sites under reducing conditions. The affinity of these Mn species toward oxidation stabilizes the CO dissociation product and thus provides a thermodynamic driving force that promotes C–O bond cleavage compared to the Mn-unmodified catalyst surface.]]> Wed 07 Feb 2024 15:34:43 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:43978 Wed 05 Oct 2022 14:29:44 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:47664 2.]]> Tue 24 Jan 2023 15:40:55 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:45912 Tue 08 Nov 2022 09:32:10 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:40849 Thu 21 Jul 2022 15:35:13 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:26398 Sat 24 Mar 2018 07:28:01 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:44056 2CO₃: 43.5%, Na₂CO₃: 31.5%, K₂CO₃: 25% mol), subjected to two different higher heating temperatures (350 °C and 600 °C). It is shown here that the addition of a carbonate eutectic affects char-making reactions through: tar generation modification, changes in the emitted volatile molecules, alteration of surface oxygenate bonds as well as transformation in the morphology of the remnant char. Initial results using Differential Thermal Gravimetric Analysis (DTG) show that, in carbonate treated samples, char yield is increased at both temperatures investigated. In treated cellulose, a reduced temperature onset of mass loss is observed, expected to be from modified depolymerisation and inhibition of levoglucosan formation for samples heated to both 350 °C and 600 °C. Gas analysis by micro-GC proves that carbonate is involved in the cracking of condensable volatiles, which generates a highly porous char structure and increases the emission of non-condensable volatiles. In addition, SEM results for carbonate treated cellulose demonstrate extensive pore generation including both surface and internally generated pores and interconnected tunnel-like structures at higher temperature (600 °C). This was not reflected however in BET results due to the melted salt blocking the available internal porous structure. Improvement in BET results for chars produced at 600 °C was regardless seen on carbonate addition in both biomass (improving from 371 m² g⁻¹ to 516 m² g⁻¹) and lignin (improving from 11 m² g⁻¹ to 209 m² g⁻¹).]]> Mon 29 Jan 2024 17:46:29 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:49155 Mon 29 Jan 2024 17:44:58 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:18680 Mon 20 Jul 2015 17:34:21 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:48260 ) and heat treatment on the physico-chemical properties of bovine bone powder. For this purpose, raw and alkali treated samples were heated separately at temperatures of 400 °C, 600 °C, 800 °C, and 1000 °C. A combination of characterization techniques, such as TGA, XRD, N2-adsorbtion isotherms, and EDX were used. It was found that the boiling of cleaned solid pieces of bones in 2 molar Ca(OH)₂ solution results in a mass loss of about 10 % (mainly discards oily liquid). TGA analysis affirms that the hydrocarbons of bone matrix are partially extractable (~ 10 %) in the boiling alkaline solution. The color of raw and treated bone samples remained similar, that is changing from yellowish white to grayish black before turning into white over temperatures ranging from 30 °C (room temperature), 400 – 600 °C, and 800 – 1000 °C, respectively. Moreover, XRD signatures were also comparable at unified temperature ranges, however, it was noted that carbonization due to heating engenders a significant change in the intensities of the x-ray reflections. Despite of having similarities, surface area of raw and treated bones at 400 °C, 600 °C and 800 °C were found to be different, indicative of a chemical interactions of calcium ions with bone. Quite interestingly, TGA, XRD, and N₂-adsorbtion isotherms support the argument that a limited amount of calcium ions diffuses into the vacancies or interstitial sites of bone lattice. Furthermore, EDX analysis of the samples calcined at 1000 °C confirms that the Ca(OH)₂ treatment increases the total calcium content of hydroxylapatite (inorganic part of bone matrix).]]> Mon 13 Mar 2023 14:46:37 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:53127 Fri 17 Nov 2023 11:38:24 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:49879 Fri 09 Jun 2023 09:54:44 AEST ]]>