Hydroisomerization and Hydrocracking of n-Heptane over Nanoporous Trimetallic (Pt-Ni-Co/SBA-15 Catalyst)

The heterogeneous hydroisomerization and hydrocracking of n-heptane was carried out within the pores of the mesoporous SBA-15 silicas, within which was encapsulated trimetallic nanoparticles of Pt-Ni-Co. The structural and textural features of the nanoporoussilicas, both with and without encapsulated nanoparticles, were characterised using small angle X-ray diffraction, scanning electron microscopy (SEM), EDAX, nitrogen adsorption-desorptionporosimetry/BET surface area analysis,Fourier-transform infrared (FTIR) spectroscopyand transmission electron microscopy (TEM).Catalytic testing was conducted using a plug-flow reactor in a catalyst testing rig under tightly controlled conditions of temperature, reactant flow rate and pressure.Species were leaving the reactor andanalysed by Gas Chromatography. The results show thatPt-Ni-Co/SBA-15 had a high activity for conversion of n-heptane (around 85%). The catalyst was found to be stable to heating and did not undergo any significant deactivation during reaction at temperatures up to 400 °C

Waste peat ash mineralogy and transformation to microporous zeolites

The combustion of peat fuel for industrial scale power generation and domestic heating produces toxic ash, most of which is presently buried in landfill. In this study, the mineralogy of waste peat ash was determined, followed by its successful use as a starting reagent to prepare zeolites. X-ray diffraction (XRD) confirmed the presence of quartz, anhydrite, calcite, lime, merwinite and magnetite in peat ash, and that a single extraction step using mineral acid was sufficient to remove all non-quartz crystal phases. Alkali fusion of the acid-extracted samples produced GIS-type zeolite. LTA- and FAU-type were also prepared by altering the Si/Al ratio and extending the ageing time. Experiments confirmed that the LTA- and FAU-type zeolites were active in the simultaneous adsorption of lead, cadmium, cobalt, zinc and copper from aqueous solutions, with similar quantities of metals removed to those using a reference zeolite

Methane oxidation over zeolite catalysts prepared from geothermal fluids

Colloidal silica extracted from geothermal fluid was used as a reagent to produce zeolite Y with high purity. The characteristics of this sample were compared to a sample prepared with a conventional silica sol, namely Ludox. The two samples were treated with ammonium chloride and calcined to partially convert the samples into an H-form. The Na-FAU and H-FAU zeolites were then loaded with Pd and tested as catalysts in the combustion of methane. X-ray diffraction confirmed the characteristic FAU-type framework in all samples. Experiments showed that after addition of Pd, these zeolites were active catalysts in the complete combustion of methane, where the most active catalysts were those prepared from Na-FAU. These findings support the use of low Si/Al FAU-type frameworks in model studies of engine exhaust emissions abatement. The study further shows that the silica sol extracted from geothermal fluids can be successfully utilised for zeolites synthesis

FAU—Type Zeolite Synthesis from Clays and Its Use for the Simultaneous Adsorption of Five Divalent Metals from Aqueous Solutions

In this research, a vermiculite-kaolinite clay (VK) was used to prepare faujasite zeolites via alkaline fusion and hydrothermal crystallisation. The optimal synthesis conditions were 1 h fusion with NaOH at 800 °C, addition of deionised water to the fused sample at a sample to deionised water mass ratio of 1:5, 68 h of non-agitated ageing of the suspension, and 24 h of hydrothermal treatment at 90 °C. The efficacy of the prepared faujasite was compared to raw clay and a reference zeolite material through adsorption experiments of aqueous solutions containing five divalent cations—Cd, Co, Cu, Pb, and Zn. The results showed that in the presence of competing cations at concentrations of 300 mg L−1 and adsorbent loading of 5 g L−1, within the first 10 min, about 99% of Pb, 60% of Cu, 58% of Cd, 28% of Zn, and 19% of Co were removed by the faujasite prepared from clay. Two to four parameter nonlinear adsorption isotherms were used to fit the adsorption data and it was found that overall, three and four parameter isotherms had the best fit for the adsorption process

Effects of surfactant on morphology, chemical properties and catalytic activity of hydroxyapatite

Hydroxyapatite (HAP) was synthesised in the presence of surfactants and tested as a catalyst in CO oxidation. XRD confirmed that the characteristic HAP crystal phase was practically unaffected by the addition of surfactant. The surfactant altered both the Ca/P ratio and particle size of HAP. Catalyst tests showed that the activity of HAP increased for preparations using TWEEN, PEG and PVA. The temperature for 50% conversion, T50, values decreased from 340 °C for unmodified HAP, to 320 °C for TWEEN and to 315 °C for both PEG and PVA. This enhanced activity is rationalised by the higher BET surface areas and acid site densities in the surfactant-modified preparations: these increased from 52 m2 g−1 for HAP to 69, 76 and 68 m2 g−1, and from 101 μmol g−1 for HAP to 110, 170 and 126 μmol g−1 for TWEEN, PEG and PVA, respectively. These findings demonstrate that HAP i.e. without the addition of precious metals to either the surface or framework, is an active CO catalyst and that the straightforward inclusion of surfactant during preparation can optimise the catalytic performance

Scalable solvent-free synthesis of aggregated nanosized single-phase cancrinite zeolite

Pure cancrinite zeolite was prepared using a solvent-free method from a geophagic clay. The morphology of the zeolite could be controlled through the composition of the raw mixture. Aluminum sulfate octadecahydrate was used for the first time as a source of trace water in the solvent-free synthesis of a zeolite. Aggregated nanosized single-phase cancrinite zeolite were prepared using a mixture of the clay, aluminum sulfate octadecahydrate and sodium hydroxide. The mixture was manually mixed and heated at 150 °C for 6 h. Scaling up the synthesis to 2, 4 and 8 times resulted in products with remarkably consistent textural characteristics. The cancrinite prepared showed potential for use as a low-cost adsorbent for CO2 capture at very low CO2 concentrations

Improved corrosion and cavitation erosion resistance of laser-based powder bed fusion produced Ti-6Al-4V alloy by pulsed magnetic field treatment

The application of pulsed magnetic field (PMF) treatment demonstrated enhanced corrosion resistance in saline solution and prolonged resistance to cavitation erosion in deionised water for Ti-6AI-4V alloy manufactured by laser-based powder bed fusion (LPBF) and conventional wrought processing methods. The observed outcomes were attributed to the formation of a denser protective surface oxide layer and microstructural changes, resulting in a reduction of the α' phase by 0.13% and an increase in the presence of dislocations at the surface. Consequently, this led to an increase in the compressive residual stresses. Additionally, the application of this treatment resulted in the formation of highly refined and uniform precipitates, leading to a notable enhancement in microhardness by 5.73% and 5.85% for the conventionally manufactured (CM) and LPBF samples, respectively

Combined use of in situ and operando-FTIR, TPR and FESEM techniques to investigate the surface species along the simultaneous abatement of N2O and NO on Pt,Pd,Rh/TiO2-ZrO2 and Pt,Pd,Rh/TiO2-ZrO2-CeO2 catalysts

Pt,Pd,Rh supported on TiO2-ZrO2 and TiO2-ZrO2-CeO2 show a promising catalytic behavior for the simultaneous selective catalytic reduction of NO and N2O with CH4 in the presence of O2 (SCRsim). The nature of the catalytic species and the formation of intermediate species on the catalyst surface were investigated by combining several techniques. The co-existence of fully and partly reduced noble metals are strictly dependent on the O2/CH4 ratio in the feed which is crucial for a good catalytic activity. When the O2/CH4 ratio is less than 1, NO and N2O were efficiently and simultaneously reduced with negligible formation of by-products. As the O2/CH4 ratio was higher than 1, CH4 combustion prevailed. The CeO2 made the catalyst slightly more efficient, likely improving the solid redox properties at the interface between noble metal particles and gaseous reactants. The operando FT-IR analysis identified some surface intermediate species involved in the reaction pathways. In the presence of NO, surface nitrite/nitrate species that are strongly adsorbed on the catalysts surface competed with the N2O adsorption sites. An assay of the SCRsim catalytic behaviour in the presence of water revealed that the catalyst with ceria has a good catalytic activity and stability along tests simulating nearly real conditions

Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial

Background Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy

Biodiesel production by esterification of oleic acid over zeolite Y prepared from kaolin

Zeolite Y, with a Si/Al ratio 3.1, was prepared using Iraqi kaolin and tested as a catalyst in the liquid-phase esterification of oleic acid (a simulated free fatty acid frequently used as a model reaction for biodiesel production). XRD confirmed the presence of the characteristic faujasite structure of zeolite Y, and further analysis was conducted using BET adsorption, FTIR spectroscopy, XRF, DLS particle size and SEM. A range of experimental conditions were employed to study the reaction; alcohol/oleic acid molar ratio, temperature, and catalyst mass loading. The optimum conditions for the reaction were observed at 70 °C, 5 wt% catalyst loading and 6:1 ethanol to oleic acid molar ratio. The oleic acid conversion using the zeolite prepared from kaolin was 85% after 60 min, while the corresponding value for a commercial sample of HY zeolite was 76%. Our findings show that low Si/Al ratio zeolite Y is a suitable catalyst for esterification, which is in contrast to the widespread view of the unsuitability of zeolites, in general, for such applications