New Catalytic Materials for the Direct Epoxidation of Propylene by Oxygen: Application of High-Throughput Pulsed Laser Ablation

New catalytic materials were prepared by depositing nanoparticles of 35 different metals as well as their select binary combinations on Al₂O₃, CeO₂, SiO₂, TiO_2, and ZrO₂ supports. Nanoparticles were synthesized by high-throughput pulsed laser ablation (PLA). Catalytic materials were then screened for their selectivities towards the synthesis propylene oxide (PO) from propylene and oxygen using array channel microreactors at 1 atm and 300, 333, and 367 °C. A gas hourly space velocity (GHSV) of 20,000 h^?1 was used at the feed gas composition of 20% O₂, 20% C₃H₆ and the balance He. Initial screening experiments resulted in the discovery of SiO₂ supported Cr, Mn, Cu, Ru, Pd, Ag, Sn, and Ir as the most promising leads for PO synthesis. Subsequent experiments pointed to bimetallic Cu-on-Mn/SiO₂, for which the PO yields increased several fold over single metal catalysts. For multimetallic materials, the sequence of deposition of the active metals was shown to have a significant effect on the resulting catalytic activity and selectivity.     

Propylene Epoxidation: High-Throughput Screening of Supported Metal Catalysts Combinatorially Prepared by Rapid Sol–Gel Method

The gas phase oxidation of propylene using molecular oxygen was studied on a variety of supported metal catalysts. The most promising PO activity was obtained for Cu supported on high surface area SiO₂ and the multimetallic systems exhibit synergistic effects that increased the desired PO yield by several folds for Ag promoted with Cu on SiO₂ after screening a large number of catalysts by a high throughput testing technique.     

Pineapple leaf fibers (PALF) as the sustainable carbon anode material for lithium-ion batteries

Journal of Materials Science: Materials in Electronics - Pineapple leaf fiber (PALF) is considered as a promising low cost carbon precursor to produce a high graphitic carbon material, regarding to...     

Investigation of CO2 adsorption by bagasse-based activated carbon

Bagasse-based activated carbon (BAC) and amine-modified BAC were prepared and investigated for CO₂ adsorption capacity. Modifying BAC with amines resulted in a decrease of surface area, but the decreasing magnitude varied depending on type and loading rate of amines. At room temperature, the unmodified BAC was able to adsorb more CO₂ than the amine-modified BAC. This ability was related to the higher surface area of unmodified than that of the modified BAC. When temperature increased, CO₂ adsorption capacity of all absorbents was decreased. However, above 323 K and a concentration of CO₂ lower than 30% v/v, the BAC modified with PEI at 5 and 25 wt% showed higher adsorption capacity. Among all adsorbents under 15% CO₂ and 348 K, BAC-PEI25 showed the highest adsorption capacity (0.20 mmol/g).     

An investigation of the heat transfer behavior of longitudinal finned membrane water wall tubes in circulating fluidized bed boilers

Experiments were conducted in a cold model circulating fluidized bed (CFB) having riser cross sectional area of 100 mm × 100 mm, height of 4.8 m, bed temperature of 75°C and superficial velocity of 8 ms^− 1. Local sand having average diameter of 231 μm, particle density of 2774 kg m^− 3 and bulk density of 1515 kg m^− 3 was used as bed material. The experiments were conducted for three tube configurations: a membrane tube, a membrane tube with a longitudinal fin at the tube crest and a membrane tube with two longitudinal fins at 45° on both sides of the tube crest. Heat transfer, heat transfer coefficient ratio and heat transfer ratio of the three tubes are presented as a function of cross sectional average suspension density. The results show that membrane tubes with one and two longitudinal fins have higher heat transfer than membrane tubes although they have lower heat transfer coefficient. In addition, numerical simulations were conducted to investigate the heat transfer behavior of the three tubes under the normal operating conditions of CFB boilers. It was found that the membrane tube with two longitudinal fins at 45° on both sides of the tube crest had the flattest inner wall tube heat flux profile. Moreover, in terms of temperature distribution in the tube material, it has the lowest profile.     

Investigation of the temperature distribution and material limits of membrane water wall tubes of circulating fluidized bed boilers

Assuming steady state, constant bed temperature and constant tube thermal conductivity, the three‐dimensional heat conduction equations were numerically solved. It was found that the temperature distribution can be expressed as dimensionless temperature in terms of Froude number, particle to furnace diameter ratio, and local to total furnace height ratio. The models for predicting the dimensionless wall temperature distribution and dimensionless mean wall temperature were also developed in this work. Finally, the limits of common tube materials used as water wall tubes based on maximum allowable stress and oxidation criteria were also investigated.     

Comparative evaluation of the effect of microfluidisation on physicochemical properties and usability as food thickener and Pickering emulsifier of autoclaved and TEMPO-oxidised nanofibrillated cellulose

Although chemical-free production processes of nanofibrillated cellulose (NFC) have been investigated, comparative studies on the effect of chemical and chemical-free processes to produce NFCs are limited. Combined effect of either of these production routes and defibrillation condition has also never been studied. Here, thermally treated NFCs were produced through microfluidisation for 6–12 passes (ANFC6-ANFC12), while TEMPO-oxidised NFC (TONFC) was prepared at six passes. Proportion of nanocellulose, viscosity, Gʹ and Gʺ values increased with increased microfluidisation pass in the cases of ANFCs. ANFC12 exhibited gel-like behaviour with strongest three-dimensional network structure and required lowest concentration to enhance thin liquid foods into honey-like consistency. TONFC needed to be added by as much as 8.5, 1.3 and 2.3 times the amount of ANFC12 to achieve the same consistency in thickened water, milk and soup, respectively. ANFC12 can also be well used as Pickering emulsifier due to its higher viscosity and gel-like property.     

An experimental investigation of the effect of longitudinal fin orientation on heat transfer in membrane water wall tubes in a circulating fluidized bed

Experiments were conducted in a cold model circulating fluidized bed having riser cross-sectional area of 100 mm × 100 mm, height of 4.8 m, bed temperature of 75 °C and superficial velocity of 8 m s^?1. Local sand having average diameter of 231 μm was used as bed material. The experiments were conducted for three tube configurations: membrane tube, membrane tube with a longitudinal fin at the tube crest and membrane tube with two longitudinal fins at 45° on both sides of the tube crest. The results show that membrane tubes with one and two longitudinal fins have higher heat transfer than membrane tubes and the heat is mainly transferred in the combination portion of tube and membrane fins. In addition, the membrane tube has the highest heat transfer coefficient.     

Single wall carbon nanotube scaffolds for photoelectrochemical solar cells. Capture and transport of photogenerated electrons

Single wall carbon nanotube (SWCNT) architecture when employed as conducting scaffolds in a TiO2 semiconductor based photoelectrochemical cell can boost the photoconversion efficiency by a factor of 2. Titanium dioxide nanoparticles were dispersed on SWCNT films to improve photoinduced charge separation and transport of carriers to the collecting electrode surface. The shift of approximately 100 mV in apparent Fermi level of the SWCNT-TiO2 system as compared to the unsupported TiO2 system indicates the Fermi level equilibration between the two systems. The interplay between the TiO2 and SWCNT of attaining charge equilibration is an important factor for improving photoelectrochemical performance of nanostructured semiconductor based solar cells. The feasibility of employing a SWCNT-TiO2 composite to drive the water photoelectrolysis reaction has also been explored.