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1
Content available remote Characteristic of physicochemical properties of Pd/MgO catalysts used in the hydrodechlorination process with CCI4
100%
Góralski J. , Szczepaniak B. , Grams J. , Maniukiewicz W. , Paryjczak T.
Polish Journal of Chemical Technology
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2007
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tom 9
|
nr 3
77-80
EN
The aim of this paper was to investigate the physicochemical properties of palladium catalyst containing basic support MgO which was used in hydrodechlorination reaction with carbon tetrachloride. In order to characterize the investigated sample the catalyst was put to tests of XRD, TOF - SIMS, TG-DTA-MS and TPRH2 measurements, activity tests were also performed. The XRD and TPR results demonstrated the presence of PdOxCly species whose decomposition takes place above 700°C. The calcination of the Pd/MgO catalyst at 700°C resulted in the transformation of PdOxCly to PdO.
2
Catalytic removal of chlorine from organic compounds.
100%
Karpiński Z. , Pielaszek J. , Bonarowska M.
|
|
tom Vol. 10, nr 57
137-142
EN
Several carbon-supported, bimetallic palladinum-gold systems were prepared and screened as catalysts for the hydrodechlorination of dichlorodifluoromethane (CFC-12). Since catalytic behavior depends very much on the extent of Pd-Au alloying, it was necessary to ensure proper conditions for mutual interaction of both alloy components after their deposition on the support. The direct redox reaction, which involves a reductive deposition of gold ions on pre-reduced palladinum material appeared very useful. Characterizing these catalysts by x-ray diffraction and other methods showed a higher degree of Pd-Au interaction than that in Pd-Au/C catalysts prepared by impregnation. Kinetic studies indicated an intimate contact of Pd and Au is essential to improve selectivity to difluoromethane (from ~70% for Pd/C to ~90% for Pd-Au/C catalysts prepared by direct redox method). Large amounts of carbon originated from the CFC-12 molecule enter palladinum lattice during hydrodechlorination. During reaction part of this carbon can be hydrogenated from the catalyst, giving rise to higher selectivity towards methane. Well-mixed, highly selective toward CH2F2, Pd-Au catalysts absorb much less carbon.
3
Content available remote Alumina modified by niobia supported nickel catalysts for hydrodechlorination of 1,2-dichloroethane
100%
Śrębowata A.
Recyclable Catalysis
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2015
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tom 2
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nr 1
EN
Nb2O5/Al2O3 materials prepared by sol-gel method using aluminium hydroxychloride and potassium niobate solutions were used as supports for nickel catalyst. 2 wt. % Ni catalysts were investigated by temperatureprogrammed reduction, TEM, X-ray diffraction, hydrogen chemisorption and high-resolution transmission electron microscopy (HRTEM). Hydrodechlorination (HDC) of 1,2-dichloroethane (1,2-DCA) over alumina modified by niobia supported nickel catalysts led to formation of ethylene as desired product. Selectivity toward C2H4 increases from ~35% for 2%Ni/Al2O3 up to 90% for Ni/Nb2O5- Al2O3. This phenomenon is an effect of the coexistence of Nb2O5 and Al2O3. Niobia is preferentially located over alumina, shaping the overall catalytic behavior of Nb2O5 – Al2O3 supported catalysts. This phenomenon could be related with the changes between Brönsted and Lewis acidic active sites ratio. Temperature programmed hydrogenation (TPH) of post-reaction deposits showed that during HDC on catalysts surface both carbon and chlorine-containing species were formed. Application of regeneration procedure (3h, 10%H2/Ar, 600°C) for spent samples led to efficient reconstruction of active sites.
4
Content available remote Turbostratic carbon supported Ni-Pd alloys in aqueous-phase hydrodechlorination of 1,1,2-trichloroethene
88%
Śrębowata A. , Kamińska I. I.
Recyclable Catalysis
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2015
|
tom 2
|
nr 1
EN
Two step modification of Norit CNR115 active carbon led to formation of mesoporous turbostratic carbon structure. Ni-Pd catalysts were prepared by incipient wetness impregnation of turbostratic active carbon with an aqueous solution of nickel and palladium chloride salts and were investigated by the Temperature-Programmed Reduction (TPR), Scanning Electron Microscopy (SEM), High Resolution Transmission Electron Microscopy (HRTEM), X-Ray Diffraction (XRD) and Temperature- Programmed Hydrogenation (TPH). The aqueous-phase hydrodechlorination of 1,1,2-trichloroethene (TCE) were carried out in a batch reactor at room temperature. Addition of palladium to nickel catalysts resulted in increasing of TCE conversion from 85% for Ni100 to more than 90% for Ni95Pd05 after 150 minutes of reaction. Aqueous-phase hydrodechlorination of TCE led to the formation of hydrocarbons (ethane and ethene) as the main products. Temperature-programmed hydrogenation of the catalysts after kinetic run have shown that during reactions with TCE only a small amount of carbon species were deposited on the catalysts surface and that chloride species were not observed.
5
Content available remote ToF-SIMS studies of the surface of Pd/ZrO2-TiO2catalyst used in the hydrodechlorination process
75%
Grams J. , Góralski J. , Kleczewska J. , Szczepaniak B. , Paryjczak T.
Polish Journal of Chemical Technology
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2007
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tom 9
|
nr 3
81-85
EN
Time-of-flight secondary ion mass spectrometry (ToF-SIMS) was used in order to obtain the information about the surface composition of Pd/ZrO2-TiO2 catalyst and to estimate the changes in the concentration of particular components on its surface during the hydrodechlorination of CCl4. The results demonstrated that the hydrodechlorination process led to the increase in the concentration of chlorine and the drop in the amount of surface accessible palladium, while the quantity of Pd-Cl bounds did not change considerably. It suggested that the presence of ZrO2 protected the surface of the studied catalyst against the formation of PdCl2.
6
Chlorine Removal from 1,2-Dichloroethane over Ni/C Catalysts
75%
Śrębowata A. , Stefanowicz-Pięta I. , Juszczyk W. , Karpiński Z.
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2007
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tom Vol. 81, nr 8
1521-1529
EN
Active carbon-supported nickel catalysts prepared from nitrate and sulfate nickel salts have been investigated in the hydrodechlorination of 1,2-dichloroethane at 210–230°C. The ex-sulfate catalyst showed practically 100% selectivity towards ethene. In contrast, the ex-nitrate sample, which additionally has been subjected to a high temperature pretreatment exhibited a steadily increasing selectivity towards vinyl chloride (up to 11%), resembling the catalytic behavior of previously investigated Ni/C catalysts characterized by low metal dispersions. The X-ray diffraction study of reduced and used catalysts as well as the temperature programmed hydrogenation of deposited coke from used catalysts showed a different extent of nickel carbiding during hydrodechlorination. The presence of residual sulfur in the ex-sulfate catalyst clearly inhibits carbon incorporation into nickel.
7
Content available SCREENING OF THE CATALYTIC ACTIVITY OF Pd0 AND Pd2+- SUPPORTED ON CHITOSAN BEADS AND CRYOGELS
75%
Pestov A. , Mekhaev A. , Privar Y. , Prokuda N. , Modin E. , Bratskaya S.
Progress on Chemistry and Application of Chitin and its Derivatives
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2018
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tom 23
149 - 158
EN
Here, we report the results of screening of the catalytic activity of Pd-containing chitosan beads and cryogels in the cross-coupling reaction, hydrogenation of alkenes, nitro-, and carbonyl compounds and the hydrodechlorination of chlorophenols. Pd0-containing chitosan beads and cryogels show moderate catalytic activity in the reduction of alkenes and nitroaromatics. The conversion of nitroaromatics decreases for substrates with electron-withdrawing substituents, while the conversion of alkenes increases with the activation of carbon-carbon double bonds. For several substrates, a significant difference in kinetics and conversion degrees was observed for Pd nanoparticles supported on chitosan beads and cryogels. It was found that conversion in the hydrodechlorination reaction depends on substrate structure, being higher for substrates containing substituents with a positive mesomeric effect. Pd2+-chitosan catalysts showed high catalytic activity in cross-coupling (Heck reaction) offering the following advantages over known catalytic systems: lower reaction temperature, the selective functionalisation of C-I bonds, and the possibility to perform reactions with iodobenzene without base addition.
8
Content available remote Możliwości zagospodarowania odpadów chloroorganicznych
63%
Myszkowski J. , Milchert E. , Paździoch W. , Bartkowiak M. , Pełech R.
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2010
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tom [Z] 64, 5-6
493-506
EN
Possible ways of utilization of waste chloroorganic compounds have been presented. The methods like isomerization, hydrodechlorination, ammonolysis and chlorolysis have been described. Practical application of these methods allows the management of chloroorganic wastes coming from waste water and waste streams formed e.g. in the production of vinyl chloride by dichloroethane method [2] and in the production of propylene oxide by chlorohydrin method [1]. Four valuable methods of chlorocompounds utilization have been discussed. The first one is isomerization of 1,1,2-trichloroethane [3, 4] to 1,1,1-trichloroethane as the valuable product with a less toxicity than the substrate. The second method is ammonolysis of waste 1,2-dichloropropane and 1,2,3-trichloropropane. Third described method is hydrodechlorination [5, 6] of chloroorganic compounds, especially used for reduction of chlorophenols, vinyl chloride and 1,2-dichloroethan. The last discussed method is the chlorolysis [1, 7]. This method can be used for utilization of all types of waste chloroorganics. Separation of waste chloroorganic compounds by adsorption methods [8–11] has also been described in the article.
9
Content available Badania nad hydrorafinacją frakcji węglowodorowej z destrukcyjnej przeróbki odpadowych tworzyw sztucznych
51%
Budzyńska-Józwiak A. , Sosnowska-Maciukiewicz L. , Szumacher S.
|
2008
|
tom nr 4
25-37
PL
W wyniku krakingu mieszaniny tworzyw sztucznych otrzymano frakcję węglowodorową o szerokim zakresie temperatury wrzenia, zawierającą związki heteroorganiczne. Z otrzymanego produktu wydzielono frakcję o zakresie temperatury wrzenia do 330°C. Frakcję tę poddano hydrorafinacji na katalizatorze stosowanym w rafineryjnych instalacjach hydroodsiarczania (NiMo/Al2O3). Stwierdzono całkowite hydroodchlorowanie frakcji pod ciśnieniem 3 MPa, przy przepływie surowca LHSV = 1 h-1, stosunku wodór/surowiec 300 Ndm3/dm3, w temperaturze 260°C i wyższej. W trakcie procesu przebiegało także nasycanie węglowodorów olefinowych. Konwersja rosła wraz ze wzrostem temperatury prowadzenia procesu. Ustalono, że chlorek amonu, tworzący się podczas chłodzenia produktu hydrorafinacji, osadza się na ściankach rurociągów i aparatów.
EN
The hydrocarbon fraction of vast boiling temperature range was obtained from cracking of waste plastics. The product contained heterorganic compounds. The fraction of boiling temperature below 330°C was isolated from the product by distillation and hydrorefined on NiMo/Al2O3 catalyst. Thecomplete hydrodechlorination was found at 3 MPa, LHSV=1 h-1, hydrogen/crude ratio 300 Ndm3/dm3 and temperature equal to 260°C and higher. Saturation of olefins during the process was also noticed. The higher temperature, the higher yield of olefins hydrogenation. The by- product of process was ammonium chloride fouled on pipes and vessels after cooling.
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