The evaluation of autothermal methane reforming for hydrogen production over Ni/CeO2 catalysts

Nanocrystalline Ni/CeO₂ catalysts with various loadings of Ni (10, 15, 20, and 25%) were synthesised by a facile solvent deficient precipitation method for methane autothermal reforming process. The characterisation techniques such as XRD, BET, TPH, H₂-TPR were carried out on fresh and spent samples to investigate the catalytic properties of the Ni/CeO₂. On the basis of characterisation results, the 20% Ni/CeO₂ performs the best activity among the catalysts with different Ni contents. The optimal reaction conditions for autothermal methane reforming has been investigated by evaluating the effect of reaction parameters including the reactivity temperature, the gas hourly space velocity (GHSV) and H₂O/CH₄ (S/C) and O₂/CH₄ (O/C) molar ratios. The stability of 20 wt% Ni/CeO₂ catalyst at 700 °C is examined for 20 h on-stream reaction. It reveals that the methane conversion starts a graduate decrease trend from the second 10 h, which is found to be because of the sintering of Ni nanoparticles by TPH and BET analysis.     

Development of a robust and efficient biogas processor for hydrogen production. Part 2: Experimental campaign

In this study, a robust and efficient decentralized fuel processor based on the direct autothermal reforming (ATR) of biogas with a nominal production rate of 50 Nm³/h of hydrogen and a plant efficiency of about 65% was developed and tested. The ATR unit is composed of a structured catalyst support for the biogas reforming close coupled to a catalytic wall-flow filter to retain eventual soot particles.The performance of the conventional random foam and homogeneous lattice supports structures for the production of hydrogen from the ATR reaction was investigated. 15–0.05 wt%-Ni-Rh/MgAl₂O₄-SiSiC structured catalyst and LiFeO₂-SiC monolith were selected for the conversion of biogas to hydrogen and for the syngas post-treatment process, respectively. For all the experiments, a model synthetic biogas was used and the catalytic activities were evaluated in three different experimental facilities: lab bench, pilot test rig and demonstration plant. High methane conversions (>95%) and hydrogen yields (>1.8) reached in the lab bench were also achieved in the pilot and demonstration plant operating at different GHSV.Results of duration test using a foam coupled to the filter has demonstrated that the pre-commercial processor is reliable while offering a satisfactory reproducibility and negligible pressure drop. A thermodynamic equilibrium and a cold gas efficiency of 90% were reached for an inlet temperature of 500 °C, O/C: 1.1 and S/C: 2.0, as predicted with the Aspen simulation.     

Determination of Polycyclic Aromatic Hydrocarbons (PAHs) in Olive and Refined Pomace Olive Oils with Modified Low Temperature and Ultrasound-Assisted Liquid–Liquid Extraction Method Followed by the HPLC/FLD

The cleanup method of modified low temperature was compared with the standardized method of modified ultrasound-assisted liquid–liquid (UALL) extraction for the analysis of 15 polycyclic aromatic hydrocarbons (PAHs) in olive oil and refined pomace olive oil. The modified UALL extraction consisted in purification on C₁₈ reversed-phase, Florisil-bonded-phase and NH₂ cartridges, and modified low-temperature extraction was followed by alumina-N and NH₂ solid-phase extraction (SPE) cartridges. Both methods are followed by reversed-phase high-performance liquid chromatography with fluorescence detection. The chromatograms of the final extracts showed lower interferences in both of the methods. The solvent consumption and cost for the modified UALL method were higher than those of the modified low temperature, and also, it needed more equipment, but its analysis time was less. The limit of detection and limit of quantitation of the modified UALL method were 0.16–0.97 and 0.57–2.93 μg kg^?1, respectively, and for the modified low temperature, they were 0.09–1.97 and 0.29–5.99 μg kg^?1, respectively. The PAH recoveries for the modified UALL extraction method ranged from 75.0 to 111.0 % (RSD?=?3–8 %), and for the modified low temperature, they ranged from 81.5 to 113.8 % (RSD?=?3–10 %).     

Effect of Particles Content on Microstructure,Mechanical Properties,and Electrochemical Behavior of Aluminum-Based Hybrid Composite Processed by Accumulative Roll Bonding Process

Metallurgical and Materials Transactions A - Effect of B4C/SiC particles content on the microstructure, deformation, and electrochemical behavior of aluminum-based hybrid composite processed by...     

Finite Element Analysis of Thermal Buckling of Rectangular Laminated Composite Plates with Circular Cut-Out

In this work, thermal buckling analysis of symmetric and anti-symmetric laminated composite plates with a cut-out is presented. The plate is assumed to be subjected to a uniform temperature rise for different boundary conditions. The thermal buckling analysis is performed using the code developed in MATLAB software. The stiffness matrices and thermal force vector are derived according to first-order shear deformation theory (FSDT). To have more control on the mesh pattern around the cut-out, convenient meshes are manually constructed using a mesh generation algorithm in which mesh density around the hole can be controlled. The results of FEM code is compared with ABAQUS's solutions and with those available in the literature. After that, the effects of cut-out size, boundary conditions, plate aspect ratio, and stacking sequence on critical thermal buckling temperature are investigated for symmetric and anti-symmetric plates. Also, plates with cut-out located at positions other than the center of plate are investigated and useful conclusions are derived from the numerical results.     

Methanol electrooxidation on synthesized PtRu nanocatalyst supported on acetylene black in half cell and in direct methanol fuel cell

We reported the direct reduction of H₂PtCl₆ and RuCl₃ solution containing acetylene black powder by Na₂S₂O₄ to make Pt–Ru (20–10 wt%) supported on acetylene black (Pt–Ru/AB) as a nanocatalyst for methanol electrooxidation in acidic media. The electrochemical activity of catalyst was studied by electrochemical impedance spectroscopy, linear sweep voltammetry, cyclic voltammetry and chronoamperometry. Structural aspects of the Pt–Ru (20–10 wt%)/AB were studied by transmission electron microscopy (TEM) and X-ray diffraction (XRD) techniques. The analysis of electrochemical results indicated lower charge transfer resistance, higher peak current for Pt–Ru (20–10 wt%)/AB compared to the commercial catalyst, Pt–Ru (20–10 wt%)/carbon Vulcan. XRD spectra verified a face centered cubic structure for the synthesized Pt–Ru/AB and its particle size was mostly 10 nm according to TEM and XRD images. In DMFC, Pt–Ru/AB had superior performance compared to the commercial catalyst in all current densities, which could be attributed to enhancement of the methanol oxidation kinetics, higher conductivity, and more uniform distribution of the ionomer in anode catalyst layer.     

Extraction of Essential Oils From the Seeds of Pomegranate Using Organic Solvents and Supercritical CO2

In this study, essential oils from pomegranate seeds of the Malas variety from Shahreza, Iran, were extracted using hexane and petroleum benzene applying four extraction methods: normal stirring, soxhlet, microwave irradiation, and ultrasonic irradiation. Also, supercritical fluid extraction (SFE) using CO₂ under different conditions was used for comparison. Different methods of extraction with organic solvents (normal stirring, soxhlet, microwave irradiation, and ultrasonic irradiation) showed significant differences in the extraction yields. However, no differences were found when a given method (e.g., microwave irradiation) was applied using different organic solvents. On the other hand, different extraction conditions from the various runs of SFE resulted in different extraction yields, all of which were lower than those of the other extraction methods using organic solvents. No significant differences were observed in the fatty acid compositions of the extracted oils using organic solvents. However, the fatty acid compositions of the oils extracted under different conditions of the SFE system indicated significant differences among several fatty acids including unsaturated fatty acids.     

The pozzolanic reactivity of monodispersed nanosilica hydrosols and their influence on the hydration characteristics of Portland cement

This study reveals that the nanosilica hydrosols with higher specific surface areas had faster pozzolanic reactivity, especially at early ages; moreover, the results are indicative of the accelerating influence of nanosilicas and silica fume on the hydration of cement. Faster initial and final setting times observed for cement pastes containing nanosilicas are consequence of these mechanisms. However, less hydration degree of cement compared to the plain paste was observed at age of 7 days and after. This can be attributed to the entrapment of some of mix water in the aggregates of nanosilicas formed in cement paste environment, making less water available for the progress of cement hydration. The same mechanism is believed to be responsible for the reduction of flowability of cement pastes.     

Synthesis of A<Subscript>2</Subscript>B<Subscript>2</Subscript> miktoarm star copolymers from a new heterobifunctional initiator by combination of ROP and ATRP

Abstract  

A new heterobifunctional initiator, 2,3-bis(2-bromo-2-methylpropionyloxy) succinic acid, was synthesized and used in preparation of A₂B₂ miktoarm star copolymers, (polystyrene)₂(poly(ε-caprolactone))₂, by combination of atom transfer radical polymerization (ATRP) and Controlled ring-opening polymerization (ROP). The structures of products were confirmed by the ¹H NMR, ¹³C NMR, FT–IR, elemental analysis, differential scanning calorimetry (DSC), and gel permeation chromatography (GPC). GPC traces show that the obtained polymers have a relatively narrow molecular weight distribution. The compositions of resulting miktoarm star copolymers were very close to theoretical.