scholarly journals Activated Bio-Carbons Prepared from the Residue of Supercritical Extraction of Raw Plants and Their Application for Removal of Nitrogen Dioxide and Hydrogen Sulfide from the Gas Phase

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3192
Author(s):  
Aleksandra Bazan-Wozniak ◽  
Piotr Nowicki ◽  
Robert Wolski ◽  
Robert Pietrzak
Keyword(s):  
Nitrogen Dioxide ◽  
Gas Phase ◽  
Thermal Activation ◽  
Supercritical Extraction ◽  
Structure Development ◽  
Acid Base ◽  
Developed Surface ◽  
Gas Removal ◽  
Activation Procedure ◽  
Surface Nature

The waste materials left after supercritical extraction of hop cones and marigold flowers were tested as precursors of activated bio-carbons. Adsorbents were produced by means of the physical (also called thermal) activation method using CO2 as the gasifying agent. All the activated bio-carbons were tested for the removal of NO2 and H2S from the gas phase under dry and wet conditions. The effects of the type of precursor and the activation procedure on the porous structure development, the acid-base properties of the surface, as well as the sorption capacities of the materials produced were also checked. The final products were bio-carbons of medium developed surface area with a basic surface nature, characterized by their high effectiveness in removal of gas pollutants of acidic character, especially nitrogen dioxide (sorption capacities in the range from 12.5 to 102.6 mg/g). It was proved that the toxic gas removal efficiency depends considerably on the sorption conditions and the activation procedure. All materials showed greater effectiveness in gas removal when the process of adsorption was carried out in the presence of steam.

scholarly journals Towards High Efficacy of Pd-Au/C Catalyst for Tetrachloromethane Hydrodechlorination

Chemistry ◽  
2021 ◽  
Vol 3 (1) ◽  
pp. 338-359
Author(s):  
Magdalena Bonarowska ◽  
Zbigniew Kaszkur ◽  
Krzysztof Matus ◽  
Alicja Drelinkiewicz ◽  
Tomasz Szumełda ◽  
...  
Keyword(s):  
Microwave Irradiation ◽  
Gas Phase ◽  
Thermal Activation ◽  
Supported Catalysts ◽  
Carbon Support ◽  
Thermal Reduction ◽  
Microwave Oven ◽  
Optimal Conditions ◽  
Catalyst Activation ◽  
Critical Part

We present an efficient strategy for synthesising the PdAu catalysts with a homogeneous PdAu alloy phase for environmentally important hydrodechlorination of tetrachloromethane in the gas phase. The synthesis of carbon-supported catalysts involved two major steps: (i) incorporation of palladium and gold nanoparticles into carbon support and (ii) activation of the catalysts. The critical part of this work was to find the optimal conditions for both steps. Thus, the incorporation of the nanoparticles was carried out in two ways, by impregnation and direct redox reaction method using acetone solutions of metal precursor salts. The activation was performed either by a conventional thermal reduction in hydrogen or flash irradiation in a microwave oven. The homogeneity and structure of the PdAu alloy were found to depend on the catalyst activation method critically. In all cases, we observed better homogeneity for catalysts that were subject to microwave irradiation. Moreover, the flash microwave irradiation of prepared catalysts provided catalysts of better stability and selectivity towards the desired products (hydrocarbons) in the hydrodechlorination of tetrachloromethane as compared to the catalyst obtained by conventional thermal activation in hydrogen.

CONDITIONS FOR THE PHOTOCHEMICAL NITRATION OF BENZENE

1965 ◽  
Vol 43 (6) ◽  
pp. 1714-1719 ◽  
Author(s):  
David L. Bunbury
Keyword(s):  
Liquid Phase ◽  
Quantum Yield ◽  
Nitrogen Dioxide ◽  
Gas Phase ◽  
Dark Reaction ◽  
Gas Phases

The reaction of benzene and nitrogen dioxide to produce nitrobenzene has been studied in the liquid and gas phases, in the dark, and with irradiation by light of 439 mμ and of 366 mμ. The concentration of NO2 in the liquid was varied from 0.08 to 1.6 moles/1 and in the gas from 0.0035 to 0.053 moles/1. No nitrobenzene was produced under any conditions in the liquid phase. Nitrobenzene is produced in the gas phase at high NO2 concentrations with irradiation by 366 mμ light. The quantum yield is 0.2. At 439 mμ the quantum yield is not more than 0.02. There is a very small dark reaction. As the concentration of NO2 in the gas is reduced the yield of nitrobenzene falls off very rapidly and is zero at the lowest concentration used, both in dark and light.

ChemInform Abstract: GAS-PHASE REACTION OF 1,1-DIMETHYLHYDRAZINE WITH NITROGEN DIOXIDE

1983 ◽  
Vol 14 (31) ◽  
Author(s):  
E. C. TUAZON ◽  
W. P. L. CARTER ◽  
R. V. BROWN ◽  
A. M. WINER ◽  
J. N. JUN. PITTS
Keyword(s):  
Nitrogen Dioxide ◽  
Gas Phase ◽  
Phase Reaction ◽  
Gas Phase Reaction

scholarly journals Gas-Phase Epoxidation of Propylene to Propylene Oxide on a Supported Catalyst Modified with Various Dopants

Catalysts ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 638 ◽  
Author(s):  
Sugiyama ◽  
Sakuwa ◽  
Ogino ◽  
Sakamoto ◽  
Shimoda ◽  
...  
Keyword(s):  
Gas Phase ◽  
Propylene Oxide ◽  
Active Catalyst ◽  
Supported Catalyst ◽  
Acid Base ◽  
Epoxidation Of Propylene ◽  
Highly Active ◽  
Acidic Catalysts ◽  
Carbonate Species ◽  
Metal Doped

In the present study, the production of propylene oxide (PO) from propylene via gas-phase epoxidation was investigated using various catalysts. Although Ag is known to be a highly active catalyst for the epoxidation of ethylene, it was not active in the present reaction. Both Al and Ti showed high levels of activity, however, which resulted in confusion. The present study was conducted to solve such confusion. Although the employment of MCM-41 modified with Ti and/or Al was reported as an active catalyst for epoxidation, the combination resulted in the formation of PO at a less than 0.1% yield. Since this research revealed that the acidic catalyst seemed favorable for the formation of PO, versions of ZSM-5 that were both undoped and doped with Na, Ti, and Ag were used as catalysts. In these cases, small improvements of 0.67% and 0.57% were achieved in the PO yield on H‒ZSM-5 and Ti‒ZSM-5, respectively. Based on the results of the Ti-dopant and acidic catalysts, Ag metal doped on carbonate species with a smaller surface area was used as a catalyst. As reported, Ag‒Na/CaCO3 showed a greater yield of PO at 1.29%. Furthermore, the use of SrCO3 for CaCO3 resulted in a further improvement in the PO yield to 2.17%. An experiment using CO2 and NH3 pulse together with SEM and TEM examinations for Ag‒Na/CaCO3 revealed that the greatest activity was the result of the greater particle size of metallic Ag rather than the acid‒base properties of the catalysts.

Acid−Base Equilibria in Nonpolar Media. 4. Extension of the Self-Consistent Basicity Scale in THF Medium. Gas-Phase Basicities of Phosphazenes

2003 ◽  
Vol 68 (26) ◽  
pp. 9988-9993 ◽  
Author(s):  
Ivari Kaljurand ◽  
Toomas Rodima ◽  
Aino Pihl ◽  
Vahur Mäemets ◽  
Ivo Leito ◽  
...  
Keyword(s):  
Gas Phase ◽  
The Self ◽  
Acid Base ◽  
Self Consistent ◽  
Gas Phase Basicities
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