6326-88-1Relevant academic research and scientific papers
Melting Points of Potential Liquid Organic Hydrogen Carrier Systems Consisting of N-Alkylcarbazoles
Stark, Katharina,Keil, Philipp,Schug, Sebastian,Müller, Karsten,Wasserscheid, Peter,Arlt, Wolfgang
, p. 1441 - 1448 (2016)
Liquid organic hydrogen carriers (LOHCs) represent an attractive concept for storing hydrogen by the hydrogenation of usually aromatic compounds. One of the best investigated LOHCs is N-ethylcarbazole because of its favorable thermodynamic properties. However, its high melting point of 343.1 K could be a major drawback particularly in mobile applications. Therefore, it is desired to decrease the melting point of N-ethylcarbazole without significantly changing favorable properties such as the storage density or the reaction behavior of the carrier compound. To investigate the solid-liquid behavior during hydrogenation, the melting points of pure N-ethylcarbazole derivatives with increasing degree of hydrogenation as well as the liquidus line of the binary mixture of N-ethylcarbazole and N-ethyl-dodecahydro-carbazole were measured. Because of their structural and chemical resemblance binary mixtures consisting of different alkylcarbazole combinations were analyzed regarding their potential for a melting point depression. By the appropriate combination of N-alkylcarbazoles, it is possible to achieve a considerable melting point decrease to 297.1 K.
Solvent free selective dehydrogenation of indolic and carbazolic molecules with an iridium pincer catalyst
Brayton, Daniel F.,Jensen, Craig M.
, p. 5987 - 5989 (2014/05/20)
A previously known iridium POCOP pincer catalyst was found to selectively dehydrogenate the heterocyclic portion of several indolic and carbazolic molecules. These molecules were found to have an "activity window" (172-178 °C) upon which only the heterocyclic ring underwent dehydrogenation. All reactions were run solvent free, yields for selected substrates were excellent, and the products were isolated by either distillation or alumina plug filtration. the Partner Organisations 2014.
The effect of the N atom on the dehydrogenation of heterocycles used for hydrogen storage
Sotoodeh, Farnaz,Huber, Benjamin J.M.,Smith, Kevin J.
experimental part, p. 67 - 72 (2012/06/29)
The effect of the N atom on the hydrogen release rate from heterocyclic compounds was studied by comparing the dehydrogenation rate of dodecahydro-N-ethylcarbazole, dodecahydrocarbazole and dodecahydrofluorene. Over a 5 wt% Pd/C catalyst, hydrogen recovery was fastest (TOF ～60 min -1 at 443 K and 101 kPa) from dodecahydro-N-ethylcarbazole and ～3 times faster than that of dodecahydrocarbazole. Dodecahydrofluorene dehydrogenation was the slowest among the compounds examined, with less than 1 wt% H2 recovered after more than 20 h at 443 K, although selectivity to the completely dehydrogenated product was 95%. Despite catalyst poisoning by the N in dodecahydrocarbazole and its dehydrogenated product, the presence of the N in the heterocycle increased the dehydrogenation reaction rate compared to dodecahydrofluorene, demonstrating that heterocycles are better candidates for H2 storage than polycycles.
Hydrogenation of arenes and N-heteroaromatic compounds over ruthenium nanoparticles on poly(4-vinylpyridine): A versatile catalyst operating by a substrate-dependent dual site mechanism
Fang, Minfeng,MacHalaba, Nataliya,Sanchez-Delgado, Roberto A.
experimental part, p. 10621 - 10632 (2011/11/29)
A nanostructured catalyst composed of Ru nanoparticles immobilized on poly(4-vinylpyridine) (PVPy) has been synthesized by NaBH4 reduction of RuCl3·3H2O in the presence of the polymer in methanol at room temperature. TEM measurements show well-dispersed Ru nanoparticles with an average diameter of 3.1 nm. Both powder XRD patterns and XPS data indicate that the Ru particles are predominantly in the zerovalent state. The new catalyst is efficient for the hydrogenation of a wide variety of aromatic hydrocarbons and N-heteroaromatic compounds representative of components of petroleum-derived fuels. The experimental data indicate the existence of two distinct active sites in the nanostructure that lead to two parallel hydrogenation pathways, one for simple aromatics involving conventional homolytic hydrogen splitting on Ru and a second one for N-heteroaromatics taking place via a novel heterolytic hydrogen activation on the catalyst surface, assisted by the basic pyridine groups of the support.
Catalytic activity and surface properties of nitrided molybdena-alumina for carbazole hydrodenitrogenation
Nagai, Masatoshi,Goto, Yosuke,Irisawa, Atsushi,Omi, Shinzo
, p. 128 - 137 (2007/10/03)
The catalytic activity and surface properties of nitrided 12.5% Mo/Al2O3 catalysts were studied using TPR and diffuse reflectance FTIR and XPS spectroscopy for the HDN of carbazole. The catalytic activity of the 43, 58, 77.3, and 97.1% MoO3/Al2O3 catalysts was compared to that of nitrided 12.5% Mo/Al2O3 catalysts. The MoO3/Al2O3 precursors with various molybdenum loadings were nitrided by the TPR with ammonia, showing that the nitrided Mo/Al2O3 catalysts had a broad peak, which was deconvoluted to 6 nitrogen peaks. The IR spectra of ammonia showed that the 1173 K nitrided catalyst was less acidic than the 773 K nitrided catalyst, but its Lewis/Broensted acidity ratio was 25 times higher. The 1173 K nitrided 12.5% Mo/Al2O3 catalyst had the highest TOF for the HDN of carbazole. The XPS measurement showed that metallic Mo and Mo2+ were predominant in the 12.5% Mo/Al2O3 catalysts and led to the hydrogenation in HDN of carbazole.
MECHANISTIC CONSIDERATIONS OF THE CATALYTIC HYDRODENITROGENATION OF CARBAZOLE AND ITS DERIVATIVES
Sarbak, Zenon
, p. 359 - 369 (2007/10/02)
The influence of hydrogen pressure and reaction temperature on the amount and kind of products formed during hydrodenitrogenation (HDN) of carbazole catalyzed on NiMo/Al2O3 is discussed. It was found that products of carbazole hydrogenation and those of the hydrogenolysis of C-N bond were produced.A mechanism of catalyst action in the HDN reaction of carbazole and its partially hydrogenated products was proposed.It is assumed that an interaction between the molecule containing nitrogen atom and a catalyst pair of centres: acid and basic ones, takes place. From among the acid centres the Broensted ones are preferred, whereas the Lewis centres are less favored.In the latter case a planar adsorption of molecule occurs as a result of which the adsorption of other molecules on the active centres of the catalyst is hindered.
Zinc/Acid Reduction of 2,3,4,5-Tetraalkylpyrroles
Anderson-McKay, Janet E.,Lawlor, John M.
, p. 1013 - 1024 (2007/10/02)
The stereo- and regio-chemical course of the zinc/acid reduction of C-tetraalkylpyrroles to pyrrolines and pyrrolidines is strongly influenced by experimental conditions, especially the acidity and the nature of the N-substituent
Regiospecific Hydrogenation of Quinolines and Indoles in the Heterocyclic Ring
Shaw, J.E.,Stapp, P.R.
, p. 1477 - 1483 (2007/10/02)
Quinolines, indoles, acridine and carbazole were hydrogenated using a large variety of heterogeneous catalysts in hydrocarbon solvents in an effort to achieve selective hydrogenation of the heterocyclic ring.When quinolines were hydrogenated using supported platinum, palladium, rhodium, ruthenium, or nickel metal catalysts in the presence of hydrogen sulfide, carbon disulfide, or carbon monoxide, there was exclusive hydrogenation of the heterocyclic ring to give only 1,2,3,4-tetrahydroquinolines.Use of iridium, rhenium, molybdenum(VI) oxide, tungsten(VI) oxide, chromium(III) oxide, iron(III) oxide, cobalt(II) oxide-molybdenum(VI) oxide, or copper chromite catalysts also caused exclusive hydrogenation of the heterocyclic ring even without addition of sulfur compounds or carbon monoxide.Hydrogenation of indoles using platinum, rhenium, or, in some cases, nickel catalysts (with or without sulfur compounds) occurred exclusively in the heterocyclic ring to give indolines, but conversions were affected by indole-indoline equilibria.
