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Johnson Matthey Technology Review - Fast Track
Accepted manuscripts have been peer reviewed (where appropriate) and accepted for publication but have not yet been copyedited, house styled, proofread or typeset. The final published version may contain differences as a result of these procedures.
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Fast Track articles
21 - 25 of 25 Fast Track articles
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Oxidation Kinetics of FeCr and FeCrAl Alloys: Influence of Secondary Processes
Available online: 29 February 2024More LessThe paper presents a mathematical model for describing of thermogravimetric curves of growth of scale with its simultaneous sublimation during oxidation of the surface of a metal or alloy. For alloys FeCr and FeCrAl, a decrease in the effective reaction area as a result of the formation of the oxide of the alloying element - lanthanum or yttrium (together with the formation of the main oxide - Cr2O3 or Al2O3) is considered. For metals, the case of increasing this area is also considered. During the oxidation of the chromia-forming alloy, another secondary process is added - the evaporation of Cr2O3. Therefore, the equations describing the kinetics of changes in mass of these alloys are different. Equations are also considered that make it possible to describe the kinetics of the oxidation process taking into account the initial non-isothermal heating. The formal equations of the oxidation process with an increase in the reaction surface as a result of crushing metal powder are also considered. The resulting equations are used to describe the kinetic curves of changes in the mass of the samples under study. The given equations can be considered as a more accurate approximation to describe the experimental data than the formulas known so far.
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Migration of Pt Nanoparticles via Volatile PtO2 during Lean High-Temperature Aging of Diesel Oxidation Catalysts
Available online: 14 February 2024More LessWhen Pt containing diesel oxidation catalysts (DOC) are exposed to high temperatures under lean conditions, the Pt nanoparticles form volatile PtO2 on the catalyst surface. The exhaust flow carries the volatile PtO2 to the downstream aftertreatment catalyst, such as the selective catalytic reduction (SCR) catalyst, that is responsible for reducing the NOx emissions, and can negatively impact its performance. Here we investigate the factors such as exposure time, temperature and DOC design characteristics for their impact on the PtO2 migration, by characterizing the amount of Pt deposited on the SCR catalyst at very low levels (< 5ppm), using ICP-OES (Inductively coupled plasma optical emission spectroscopy) fire assay technique. Our results indicate that well-dispersed Pt, not associated with Pd, is most prone to PtO2 migration. We also compare several methods to suppress the PtO2 migration from the DOC, such as sintering of the Pt nanoparticles, stabilizing the Pt nanoparticles via interaction with Pd or covering the Pt nanoparticles with a high surface area capture layer to trap the volatile PtO2.
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Synthesis and Characterization of Cellulose Acetate/Polyethylene Glycol Membrane from Pineapple Hump by Phase Inversion Method
Available online: 12 February 2024More LessCellulose is a natural polymer contained in growing fibers, such as pineapple fibers. Cellulose can be modified into cellulose acetate, a modified polymer that can be used in the synthesis of a cellulose acetate/polyethylene glycol (CA/PEG) membrane. The phase inversion method was used in this study to produce CA/PEG membranes. Variations in PEG concentration with a ratio of 1:1 to cellulose acetate, where variations in PEG concentrations used are 2%, 5%, and 8%. Acetone and dimethylformamide are used as organic solvents. Membrane morphological analysis using Scanning Electron Microscope (SEM) and functional group analysis using a Fourier Transform-Infrared (FT-IR) spectrometer were performed for membrane characterization. The result of the synthesis of the CA/PEG membrane is in the form of a thin white layer. The characterization results of the FT-IR spectrometer showed the vibration of the carbonyl bond at wavenumber 1729 cm-1 and the vibration of the hydroxyl bond torque at the wave number 648 cm-1, where the vibration intensity decreased with each addition to the concentration. The results of SEM characterization show that the increase in PEG concentration increases the percentage porosity of the membrane. The membranes with 2%, 5%, and 8% PEG have porosity percentages of 51.54%, 68.70%, and 73.50%, respectively. As the membrane with 2% PEG has the lowest percent porosity, it is more potential in removing or filtering solutes from a fluid.
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Ammonia Sprays for Combustion: A Review
Available online: 07 February 2024More LessAmmonia is a globally transported chemical used for a variety of applications, most notably, the production of fertilizer. Over the past decade, attention has been afforded to the use of ammonia as an energy carrier, coupling global supply of renewable energy to demand regions. Ammonia’s advantages as an energy carrier include its ease of liquefaction and established international transportation routes; overcoming its low reactivity, excessive production of nitrogen oxides, and its toxicity remain as challenges. For energy applications, fuel delivery is a critical aspect of effective combustion in boilers, burners and engines. Due to its adaptable phase change characteristics, ammonia fuel may be injected as a liquid or vapour, each with respective advantages or disadvantages. The focus of this review concerns the characterisation of liquid ammonia fuel injection for combustion, including recent research findings from experimental and simulation studies. Liquid ammonia injection can result in the highly dynamic so-called ‘flashing’ or ‘flash boiling’ phenomena. Research findings have been drawn from other related applications such as accidental hazardous releases. Bespoke optical experimental rigs together with diagnostic techniques and two-phase CFD simulations have enabled studies of the flashing jets under various initial/final conditions, with recent work also examining ammonia spray combustion. The review concludes with an insight into future trends and requirements for liquid ammonia combustion. Reciprocating engines for marine propulsion are cited as potential early adopters of ammonia energy.
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Preliminary Characterization of Thermal Upgrading of Nickel from Saprolite via Selective Reduction
Available online: 30 January 2024More LessAbstract. The mineralogical properties and distribution of information established in saprolite from Indonesia were investigated using X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy energy dispersion spectroscopy (SEM–EDS), and differential thermal analysis (DTA) measurements. The findings suggest that laterite ore has a complex inner core. The percentages of Ni, Fe, Mg, Al, and Si in saprolite are given in 1.82, 30.47, 10-20, 4.86, and 8.1 weight percent. Saprolite has 53.1 percent iron oxide/oxyhydroxide, 38.3 percent lizardite and 8.7 percent silicate. According to DTA, saprolite undergoes a phase shift from goethite to hematite at low temperatures (200-300ºC). This is a suitable phase to optimize nickel diffusion in iron. Furthermore, the thermal upgrading approach was utilized for this saprolite.
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