Cyclohexylammonium nitrate

In the title salt, C6H14N+.NO3_, the cyclohexyl ring adopts a chair conformation. The ammonium group occupies an equatorial position and the crystal struture is stabilized by intermolecular N—H� � �O hydrogen-bonding interactions, resulting in a three-dimensional network

Radially oriented mesoporous TiO2 microspheres with single-crystal–like anatase walls for high-efficiency optoelectronic devices

Highly crystalline mesoporous materials with oriented configurations are in demand for high-performance energy conversion devices. We report a simple evaporation-driven oriented assembly method to synthesize three-dimensional open mesoporous TiO2 microspheres with a diameter of ~800 nm, well-controlled radially oriented hexagonal mesochannels, and crystalline anatase walls. The mesoporous TiO2 spheres have a large accessible surface area (112 m2/g), a large pore volume (0.164 cm3/g), and highly single-crystal–like anatase walls with dominant (101) exposed facets, making them ideal for conducting mesoscopic photoanode films. Dye-sensitized solar cells (DSSCs) based on the mesoporous TiO2 microspheres and commercial dye N719 have a photoelectric conversion efficiency of up to 12.1%. This evaporation-driven approach can create opportunities for tailoring the orientation of inorganic building blocks in the assembly of various mesoporous materials.State Key Basic Research Program of China (2013CB934104 and 2012CB224805), the National Science Foundation (21210004), the Science and Technology Commission of Shanghai Municipality (08DZ2270500), the Shanghai Leading Academic Discipline Project (B108), King Abdulaziz City for Science and Technology (project no. 29-280), and Deanship of Scientific Research, King Saud University–The International Highly Cited Research Group Program (IHCRG#14-102). Y.L. also acknowledges the Interdisciplinary Outstanding Doctoral Research Funding of Fudan University (EZH2203302/001)

Impact of ammonia treatment and platinum group or nickel metal decoration on the activated carbon storage of carbon dioxide and methane

Greenhouse gases, chiefly carbon dioxide (CO _2 ) and methane (CH _4 ), emission is responsible for the global warming and heat waves which strike the world causing floods and droughts everywhere with more CO _2 attributions. The adsorption and desorption capacities of CO _2 and CH _4 at room temperature and up to 5.0 and 100 bar, respectively, were investigated for the untreated and ammonia-treated activated carbons (ACs), metal-anchored (metal: Ru, Rh, Pd, Ir or Ni) samples. We merged ammonia treatment and metal decoration to discover their influences on the CO _2 and CH _4 storage capability of ACs and the potential use of such modified ACs for capturing greenhouse gases and purifying natural gas from CO _2 . The CO _2 storage capacities ranged between 25.2 and 27.7 wt% at 5.0 bar with complete regeneration upon desorption, while the uptakes for CH _4 were in the range of 9.6 − 12.6 wt% at 35 bar with hysteresis behavior of the adsorbed gas. The highest adsorption capacities were achieved for the pristine samples, showing that metal decoration reduced slightly the adsorption. Ammonia-treated samples showed minor enhancing effect on the CH _4 adsorption in comparison to the CO _2 adsorption. The higher adsorption capacities of CO _2 than those of CH _4 could be employed for upgrading the natural gas, while the 9.6 wt% (2.2 mmol g ^−1 ) CO _2 storage capacity would allow for its removal from the flue gases at ambient temperature and pressure. The higher adsorption capacity and preferentiality of CO _2 over CH _4 could be attributed mainly to its higher quadrupole moment and its higher clustering above the AC surfaces, while a minor effect, if any, would be attributed to the modifications of the ACs, implying that physisorption mechanism acted significantly in the adsorption process in comparison to chemisorption mechanism at the studied conditions

Hydrogen Storage in Untreated/Ammonia-Treated and Transition Metal-Decorated (Pt, Pd, Ni, Rh, Ir and Ru) Activated Carbons

Hydrogen storage may be the bottle neck in hydrogen economy, where hydrogen spillover is in dispute as an effective mechanism. In this context, activated carbon (AC) was doped with nitrogen by using ammonia gas, and was further decorated with platinum, palladium, nickel, rhodium, iridium and ruthenium, via an ultrasound-assisted impregnation method, with average particle sizes of around 74, 60, 78, 61, 67 and 38 nm, respectively. The hydrogen storage was compared, before and after modification at both ambient and cryogenic temperatures, for exploring the spillover effect, induced by the decorating transition metals. Ammonia treatment improved hydrogen storage at both 298 K and 77 K, for the samples, where this enhancement was more remarkable at 298 K. Nevertheless, metal decoration reduced the hydrogen uptake of AC for all of the decorated samples other than palladium at cryogenic temperature, but improved it remarkably, especially for iridium and palladium, at room temperature. This observation suggested that metal decoration’s counter effect overcomes hydrogen spillover at cryogenic temperatures, while the opposite takes place at ambient temperature

Storage and separation of methane and carbon dioxide using platinum- decorated activated carbons treated with ammonia

Activated carbon (AC) was treated with ammonia for nitrogen doping and then was further anchored with platinum nanoparticles through ultrasound-assisted impregnation method. Methane (CH _4 ) and carbon dioxide (CO _2 ) storage of the pristine and modified activated carbon were determined at ambient temperature. All the samples showed high storage capacities with preference towards carbon dioxide storage, which would be favorable for both energy and environmental applications. Ammonia treatment slightly improved the storage of both CH _4 and CO _2 for all the samples, which could be attributed to the little improvement in the micropore properties upon nitrogen doping. Platinum decoration had an opposite influence on both CH _4 and CO _2 storage, which might be due to the absence of metal encouraging storage mechanism such as gas dissociation or reconstruction on platinum’s surface in addition to the harmful effect of metal pore-blocking and higher density of metal particles

Turbulent Convective Heat Transfer and Pressure Drop of Dilute CuO (Copper Oxide)- Water Nanofluid Inside a Circular Tube

Abstract Turbulent forced convective heat transfer and pressure drop of 0.01 vol. % CuO-water nanofluid was assessed experimentally. The nanofluids were made flow into a heated horizontal tube under uniform constant heat flux within Reynolds number range of 11,500 to 32,000. The first objective is to know how close traditional correlation/formula for, both, heat transfer and pressure drop can predict nanofluid’s heat transfer and pressure drop. The second is to know how nanofluid’s convective heat transfer and pressure drop are compared to those of its base fluid; in this case water. The results showed that the abovementioned characteristics of the nanofluid can be predicted by the traditional correlation available. It is also found that the nanofluid’s Nusselt number and friction factor, which represent the heat transfer rate and pressure drop, respectively, are close to those of water. Hence, there is no anomaly due to the dispersed nanoparticles within the water

Highly Selective Gas-Phase Catalytic Hydrogenation of Acetone to Isopropyl Alcohol

Current industrial synthesis procedures of isopropyl alcohol (IPA), by the direct or indirect hydration of propylene in the gas or liquid phase, suffer from the low conversion of propylene, the requirement for high pressure, and the harmfulness to the environment. In this context, we report a single-step, gas-phase process for the green synthesis of IPA via acetone hydrogenation, in a fixed-bed reactor, under ambient pressure and within a temperature range of 100–350 °C. Composite catalysts with various ratios of ruthenium nanoparticles supported on activated charcoal and nano-zinc oxide (n-Ru/AC/n-ZnO) were used. Catalytic activity and selectivity were functions of n-Ru/AC/n-ZnO loading ratios, reaction temperature, and the hydrogen to acetone molar ratio. The composite catalysts were characterized by X-ray powder diffraction (XRPD), transmission electron microscopy (TEM), hydrogen temperature-programmed reduction (H2-TPR) analysis, and nitrogen physisorption. High yields of IPA were obtained over 3n-Ru/AC/2n-ZnO) catalyst, which showed the highest selectivity of 98.7% toward isopropyl alcohol and acetone conversion of 96.0% under a hydrogen to acetone mole ratio of 1.5 at 100 °C. Reaction rates, calculated from the model equation, were in reasonable agreement with those measured experimentally. The apparent activation energy (Ea) value for acetone hydrogenation was found to be 17.2 kJ/mol. This study proved that immobilized Ru catalysts were potential superior catalysts for the selective hydrogenation of acetone to IPA in exceptionally mild green synthesis conditions

Crystal structure of cyclohexylammonium thiocyanate

In the title salt, C6H11NH3+·SCN−, the cyclohexylammonium ring adopts a slightly distorted chair conformation. The ammonium group occupies an equatorial position to minimize 1,3 and 1,5 diaxial interactions. In the crystal, the components are linked by N—H...N and N—H...S hydrogen-bonding interactions, resulting in a three-dimensional network