Search Results
You are looking at 1 - 10 of 18 items for
- Author or Editor: Jun Wu x
- Refine by Access: All Content x
Abstract
The dehydrogenation of isobutane to produce isobutene coupled with reverse water gas shift (RWGS) reaction in the presence of carbon dioxide was investigated over a NiO/γ-Al2O3 catalyst. The results illustrated that the coupling dehydrogenation of isobutane in carbon dioxide over NiO/γ-Al2O3 catalyst is effective, and the NiO/Al2O3 catalyst was modified with deposited carbon by impregnation of alumina with an aqueous solution of Ni(H2NCH2CH2NH2) x (NO3)2. Carbon modification can decrease the total acidity of the NiO/γ-Al2O3 catalyst and enhance the dispersion of NiO active phase. Furthermore, carbon has low acidity and anti-coking performance, so the carbon modification is effective in suppressing the coke formation and side reactions occurrence. Therefore, the catalyst stability and the isobutene selectivity are improved significantly by the carbon modification.
Abstract
The catalytic hydrogenation of p-nitrophenol to produce p-aminophenol (PAP) was carried out over the catalyst nickel supported on active carbon (AC). The calcination temperature was one of the most important technical conditions: temperature higher than 450 °C would result in the reduction of NiO to Ni phase by AC and the loss of support. The surface area and nickel dispersion over catalyst decreased obviously after 450 °C calcination temperature because of the loss of support and the Ni phase sintering. Addition of K2O enhanced the alkalinity of the Ni/AC catalyst, and the p-nitrophenol stuff performed rather stronger acidity. Therefore, the level of p-nitrophenol adsorption over Ni/AC catalyst was improved, and the reaction efficiency was enhanced consequently. The p-nitrophenol conversion and PAP selectivity reached 97.7 and 99.3% over Ni–K2O/AC catalyst, respectively. During the process of catalytic hydrogenation, higher PAP selectivity was kept successively. It indicated that no side reactions happened during the catalytic hydrogenation of p-nitrophenol.
Abstract
The action of three kinds of the selenomorpholine compounds on a strain ofEscherichia coli was studied by microcalorimetry. Differences in their capacities to affect the metabolism of this bacterium were observed. The extent and duration of the effect on the metabolism as judged from the rate constant (k) of Escherichia coli (in log phase) varied with the different drugs. The kinetics show that selenomorpholine compounds had an effect on the metabolism process of Escherichia coli. The k of Escherichia coli in the presence of the drugs increased with the increasing concentrations of the drugs (C) at low concentration; but at high concentration, the rate constant decreased with the increasing concentrations of the drugs. The experimental results reveal that the sequence of antibiotic activity of selenomorpholines is: N-selenomorpholinemethyl succinimide and its hydrochloride>N-(α-selenomorpholinebenzyl) succinimide.
Summary
A new air radon monitor is proposed based on the combination of an aluminum disk and an electric multilevel clearance system (EMCS). The positively charged, small aluminum disk has a high collection ability to radon with a collection efficiency of about 60%. The old radon progenies were eliminated by the EMCS in the air entrance of the monitor with an efficiency of about 99%. The monitor was calibrated in the national standard radon chamber in Hengyang, China. Compared to the radon double-filter equipment, the results, gained by both apparatus, coincide with each other.
The housefly is an important resource insect and the housefly larvae are ideal source of food additives. The housefly larvae protein hydrolysates were obtained by enzymatic hydrolysis by alcalase and neutral proteinase. Their antioxidant activities were investigated, including the superoxide and hydroxyl radicalscavenging activity, 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging activity, reducing power and metal chelating activity. The antioxidant activities of both hydrolysates increased with their increasing concentrations. The alcalase hydrolysate (AH) showed higher scavenging activities against hydroxyl radical and superoxide anion radical at low concentrations and higher metal-chelating activity than the neutral proteinase hydrolysate (NPH). The NPH exhibited higher scavenging activity against DPPH free radical and higher reducing power than the AH. Both hydrolysates showed more than 50% superoxide anion radical-scavenging activity at 10 μg/mL. These results indicate that both housefly larvae protein hydrolysates display high antioxidant activities and they could serve as potential natural antioxidant food additives.
Abstract
Supported Ag/TS-1 catalysts were prepared by the cool plasma sputtering technique and characterized by BET, SEM/EDX, XRD, UV–Vis and TEM techniques. The Ag loading and particle size on TS-1 were tailored by sputtering time. The catalytic performance of the supported catalysts was tested in the gas-phase propene epoxidation reaction using H2 and O2 at a space velocity of 4000 h−1, and atmospheric pressure. Ag/TS-1 with 1.0–19.9 wt% Ag loading and a Ag particle size around 10–40 nm exhibited a selectivity above 90% in the propene epoxidation reaction at a suitable temperature. Catalysts with high Ag loading and large Ag size cause H2 combustion in O2, leading to propene combustion. The heat evolved in the reaction process may lead to over-oxidation of propene to CO2.
Octachlorodipropyl ether (OCDPE) is a chloroalkyl ether widely used as an insecticide synergist, which was considered as a widespread persistent pollutant. Photodegradation kinetics of OCDPE in selected organic solvents was studied using the high-performance thin-layer chromatography (HPTLC) method in this paper. The results showed that photochemical reaction of OCDPE in organic solvents such as n-hexane, methanol, acetonitrile, and acetone under the irradiation of ultraviolet light could well be described by the first-order kinetic equation. The photodegradation rate constants of OCDPE in methanol, acetone, acetonitrile, and n-hexane were 0.3310, 0.2382, 0.0287, and 0.0276 h−1, and the corresponding half-lives were 2.09, 2.91, 24.1, and 25.1 h, respectively. Photodegradation kinetics of OCDPE under sunlight was slower than UV light, the half-lives of which were 8.87 and 2.09 h, respectively. The main photodegradation products of OCDPE in acetone and methanol under UV light were detected by HPTLC, which included product 01 (R F = 0.19) and product 02 (R F = 0.82). Identification of the main photodegradation products of OCDPE requires further studies.
Abstract
The thermal behavior of D-type Ni–MH battery during charging was investigated at a wide range of ambient temperatures in this work. The temperature measurement of the battery was conducted by using a thermal infrared imager put in a high–low temperature chamber. The ambient temperatures were controlled to −10, 0, 10, 20, 30, and 40 °C during charging. The battery was charged to SOC of 110% in the rate of 1C, 3C, and 5C. Real-time infrared thermal images of battery surface were obtained during charging, as well as temperature change curves. The maximum surface temperature of the battery at the end of charging was stimulated at a higher ambient temperature by curve fitting. It is indicated that the temperature gradient on battery surface will increase with charging rate increase, and the rate of actual temperature rise is almost unrelated to ambient temperature. The simulating result shows that the maximum surface temperature would be over 101 °C if the battery is charged in the rate of 5C under an ambient temperature of 70 °C, which may lead to a safe accident.
