Mild hydrocracking of 1-methyl naphthalene (1-MN) over alumina modified zeolite

The catalytic activity and life of the NiMoS supported on alumina–USY zeolite (physical mixture of alumina and USY (NMAZ), USY zeolite coated with alumina (NMACZ-2)) were compared in the hydrocracking of 1-methyl naphthalene by a single run at the several reaction temperatures between 360 and 400 °C as well as repeated runs at 360 °C. The relative activity of NMAZ is slightly higher after 1 h at all reaction temperatures, but was lower after 2 h at reaction temperatures above 380 °C. The preference of NMACZ-2 became distinct and definite by further increasing the reaction time at all reaction temperatures. Too long reaction time, particularly at higher reaction temperature, decreased the yield of (alkyl)benzenes, indicating the significant progress of the successive reactions. Thus, the highest yield of alkyl(benzenes) of about 97% was obtained over NMACZ-2 after 4 h at 380–390 °C. This was much less than the yield of about 82% obtained over NMAZ after 4 h at 370 °C. Ten repeated runs at 360 °C for 6 h resulted in marked decrease of yield over NMAZ from 73% to 64%, while the decrease in yield over NMACZ-2 was only from about 80% to 78%. The decrease of catalytic activity appears to reflect the coke formation on the USY which occurs on the naked acidic site of the substrate, which are rather isolated from the NiMoS on alumina. In contrast, alumina-coated support keeps USY underneath the alumina, which carries NiMoS and acidic sites on the same surface. The acidity of surface alumina is moderated by the underneath USY. The adequate acidity of the neighboring NiMoS and high hydrogenation activity provide a good balance resulting in an excellent catalytic activity and life of NiMoS supported on alumina-coated USY zeolite.     

Acid leaching of CaOSiO2 resources

Waste resources containing CaO and SiO₂ were leached by an acetic acid solution. Most CaO exist as calcium aluminosilicate and calcium silicate in steel slag and wollastonite, respectively. Silicate leaching was enhanced steeply by heating to 50 °C or increasing acid concentrations to 4 wt%. The Si and/or Al in the leachate then precipitated independently, depending on the solubility. This enabled to improve the selectivities of Ca and Si in the leachate and precipitate, respectively. However, CaO and SiO₂ are separate constituents of waste cement. The dissolution of Ca thus took place relatively fast while the ‘free’ silica leached little.     

Improved photo-catalytic activity of single-crystalline TiO2 nanowires surrounded by Pt cube nanoparticles

We report improved photo-catalytic properties of single-crystalline TiO₂ nanowires surrounded by Pt cubes for methanol electrooxidation under UV illumination. The TiO₂–Pt consists of single-crystalline TiO₂ nanowires grown along [0 0 1] direction and Pt cube nanoparticles with dominantly exposed {1 0 0} facets confirmed by transmission electron microscopy images and fast Fourier transform patterns. The nanostructure electrode consisting of TiO₂ nanowires and Pt cubes exhibits a remarkably improved performance for methanol electrooxidation in acid solution as compared to that of TiO₂ nanowires.     

Catalytic dechlorination of C5 compounds over metal-oxide/ZSM-5 catalysts

In this research, the dechlorination of 2-chloro-2-butene in C5 oil from the fluid catalytic cracking (FCC) process was performed through a catalytic reaction. Metal oxides were used as active materials and ZSM-5 was used as the supporting material for the catalysts; the metal was cobalt, iron, or manganese. After the preparation of three types of metal-oxide/ZSM-5 catalysts through the ion-exchange method, the activities and characteristics of each catalyst were evaluated. Through screening tests, the Co₃O₄/ZSM-5 catalyst was selected as the dechlorination catalyst, and the performance of catalysts containing different amounts of Co₃O₄ relative to ZSM-5 were tested.     

Conjugated polymer mediated synthesis of nanoparticle clusters and core/shell nanoparticles

Two water soluble conjugated polymers, poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and ammonium ion stabilized poly(phenylene vinylene) (P2), are found to be able to reduce noble metal ions to zero-valent metals via a direct chemical deposition technique. Au nanoparticle clusters can be obtained through reduction of Au³⁺ ions by PEDOT:PSS and the electronic coupling between them can be controlled by HAuCl₄ concentration. Core/shell Ag/polymer nanostructures are prepared from reduction of Ag⁺ ions by P2, which have a ppb detection limit for 4-MBA using surface-enhanced Raman spectroscopy (SERS). This conjugated polymer mediated synthesis of metal nanoparticles may open a new avenue for fabricating nanomaterials and nanocomposites with tunable optical properties that are dominated by their structure and electronic coupling between nanoparticles.     

Piezoelectric properties of highly densified 0.01Pb (Mg1/2W1/2)O3–0.41Pb (Ni1/3Nb2/3)O3–0.35PbTiO3–0.23PbZrO3+0.1 wt% Y2O3+1.5 wt% ZnO thick films on alumina substrate

This paper reports on the formation of highly densified piezoelectric thick films of 0.01Pb(Mg_1/2W_1/2)O₃–0.41Pb(Ni_1/3Nb_2/3)O₃–0.35PbTiO₃–0.23PbZrO₃+0.1 wt% Y₂O₃+1.5 wt% ZnO (PMW–PNN–PT–PZ+YZ) on alumina substrate by the screen-printing method. To increase the packing density of powder in screen-printing paste, attrition milled nano-scale powder was mixed with ball milled micro-scale powder, while the particle size distribution was properly controlled. Furthermore, the cold isostatic pressing process was used to improve the green density of the piezoelectric thick films. As a result of these processes, the PMW–PNN–PT–PZ+YZ thick film, sintered at 890 °C for 2 h, showed enhanced piezoelectric properties such as P_r=42 μC/cm², E_c=25 kV/cm, and d₃₃=100 pC/N, in comparison with other reports. Such prominent piezoelectric properties of PMW–PNN–PT–PZ+YZ thick films using bi-modal particle distribution and the CIP process can be applied to functional thick films in MEMS applications such as micro actuators and sensors.     

Electrical conductivity and thermoelectric power studies of solution-combustion-processed Ca2.76Cu0.24Co4O9

Nanocrystalline Ca_2.76Cu_0.24Co₄O₉ powders (25 nm in crystallite size) are synthesized by the solution combustion method, using aspartic acid as the combustion fuel. In this study, we discuss the effect of sintering temperature on the microstructure and thermoelectric properties of Ca_2.76Cu_0.24Co₄O₉. The density and grain size increase with an increase in sintering temperature. The Ca_2.76Cu_0.24Co₄O₉ sintered at 900 °C shows the largest value of electrical conductivity and Seebeck coefficient, resulting in the largest power factor (3.8×10^?4 W m^?1 K^?2 at 800 °C). This value is more than 22 times larger than that of the Ca_2.76Cu_0.24Co₄O₉ sintered at 940 °C (1.7×10^?5 W m^?1 K^?2 at 800 °C).     

Multi-physics analysis on a unimorphic piezoelectric diaphragm according to its shape and boundary conditions for the performance enhancement

A micro-viscometer for measuring viscosity change in small amount of liquid in real time has been proposed recently. The advantages of the device are the use of minimal liquid and maximized sensitivity for measuring viscosity. However, in previous research, even though the multi-physical simulation including electrical, mechanical, and acoustical phenomenon is necessary for design of micro-viscometer, only acoustical aspects have been considered. Thus, combined physical phenomena could not be reflected for an optimum design process. In this research, a multi-physical approach is developed for designing a micro-viscometer, and an optimized micro-viscometer design is proposed. The proposed method is able to capture multi-physical phenomena such as near field effect and added mass effect. It also has the advantage of flexible design of various shape and materials, leading to savings of cost and time.     

A green and facile one-pot synthesis of Ag–ZnO/RGO nanocomposite with effective photocatalytic activity for removal of organic pollutants

In this study, Ag–ZnO/reduced graphene oxide (Ag–ZnO/RGO) composite was synthesized by a green and facile one-step hydrothermal process. Aqueous suspension containing Ag and ZnO precursors with graphene oxide (GO) sheets was heated at 140 °C for 2 h. The morphology and structure of as-synthesized particles were characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, and Photoluminescence (PL) spectroscopy which revealed the formation of composite of metal, metal oxide and RGO. It was observed that the presence of Ag precursor and GO sheets in the hydrothermal solution could sufficiently decrease the size of ZnO flowers. The hybrid nanostructure, with unique morphology, obtained from this convenient method (low temperature, less time, and less number of reagents) was found to have good photocatalytic and antibacterial activity. The perfect recovery of catalyst after reaction and its unchanged efficiency for cyclic use showed that it will be an economically and environmentally friendly photocatalyst.     

Highly ordered microstructures of poly(styrene-b-isoprene) block copolymers induced by solution meniscus

Microstructures of hundreds of micron thick poly(styrene-block-isoprene) copolymer films solution-cast in a cylindrical tube with the solvent evaporation controlled were investigated by transmission electron microscope (TEM), small angle X-ray scattering (SAXS) and optical microscope (OM). In a block copolymer with cylindrical polyisoprene microdomains, the orientation of the cylinders was varied along radial direction of the cylindrical tube. Highly aligned hexagonal arrays of in-plane polyisoprene cylinders were formed with their cylindrical axis parallel to the circumference of the tube in the regimes close to the wall edge. In contrast randomly ordered microdomains were observed at the center of the tube. We have also found that the orientation depends on the solvent evaporation rate and an intermediate rate (∼2.3 nL/s) provides the best orientation. In the case of a block copolymer with a bicontinuous double gyroid structure, we obtained a globally ordered microstructure where [111] crystallographic direction was parallel to the circumference of the tube. For both block copolymers, the area of highly ordered arrays of nanoscopic domains is over 1 mm². Development of the orientation was explained by coupling two orthogonal fields: (1) The flow of a solution induced by strong capillary force at a meniscus between the cylindrical tube wall and the block copolymer solution and (2) the solvent evaporation.