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Yield of aromatics from naphthenics upon catalytic cracking
Pujro, Richard A.;Falco, Marisa G.;Pedrosa, Anne M. Garrido;Souza, Marcelo J. B.;Morgado Jr., Edisson;Sedran, Ulises;
Journal of the Brazilian Chemical Society , 2012, DOI: 10.1590/S0103-50532012000700023
Abstract: cis- and trans-decalin were reacted over cracking catalysts to study the formation of aromatics in a particular fraction of the liquid products obtained in the fluid catalytic cracking process (fcc). a batch, fluidized bed crec riser simulator reactor was used at 673 and 723 k and contact times varied from 3 to 15 s. cis-decalin was much more reactive. despite differences induced and measured in their accessibility indices, the catalysts led to similar activity profiles, suggesting that diffusion restrictions do not prevail. products were c1-c12 hydrocarbons while coke was very low. isomerization, cracking, hydrogen transfer, ring opening, ring contraction and alkylation reactions occurred and products from the various reactions were observed at very short reaction times. bicyclic c10 naphthenics and alkyl-substituted c7-c11 aromatics or naphtheno-aromatics were the most important products. a reaction mechanism with three initial routes (isomerization, ring opening and direct hydrogen transfer reactions) was proposed.
Template-assisted formation of microsized nanocrystalline CeO2 tubes and their catalytic performance in the carboxylation of methanol  [cached]
J?rg J. Schneider,Meike Naumann,Christian Sch?fer,Armin Brandner
Beilstein Journal of Nanotechnology , 2011, DOI: 10.3762/bjnano.2.86
Abstract: Polymethylmethacrylate (PMMA)/ceria composite fibres were synthesized by using a sequential combination of polymer electrospinning, spray-coating with a sol, and a final calcination step to yield microstructured ceria tubes, which are composed of nanocrystalline ceria particles. The PMMA template is removed from the organic/inorganic hybrid material by radio frequency (rf) plasma etching followed by calcination of the ceramic green-body fibres. Microsized ceria (CeO2) tubes, with a diameter of ca. 0.75 μm, composed of nanocrystalline agglomerated ceria particles were thus obtained. The 1-D ceramic ceria material was characterized by X-ray diffraction, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), UV–vis and photoluminescence spectroscopy (PL), as well as thermogravimetric analysis (TGA). Its catalytic performance was studied in the direct carboxylation of methanol with carbon dioxide leading to dimethyl carbonate [(CH3O)2CO, DMC], which is widely employed as a phosgene and dimethyl sulfate substitute, and as well as a fuel additive.
Metal–ligand multiple bonds as frustrated Lewis pairs for C–H functionalization  [cached]
Matthew T. Whited
Beilstein Journal of Organic Chemistry , 2012, DOI: 10.3762/bjoc.8.177
Abstract: The concept of frustrated Lewis pairs (FLPs) has received considerable attention of late, and numerous reports have demonstrated the power of non- or weakly interacting Lewis acid–base pairs for the cooperative activation of small molecules. Although most studies have focused on the use of organic or main-group FLPs that utilize steric encumbrance to prevent adduct formation, a related strategy can be envisioned for both organic and inorganic complexes, in which "electronic frustration" engenders reactivity consistent with both nucleophilic (basic) and electrophilic (acidic) character. Here we propose that such a description is consistent with the behavior of many coordinatively unsaturated transition-metal species featuring metal–ligand multiple bonds, and we further demonstrate that the resultant reactivity may be a powerful tool for the functionalization of C–H and E–H bonds.
Functionalization of Graphene using Carboxylation process  [PDF]
Varun A. Chhabra,Akash Deep,Rajnish Kaur,Rupesh Kumar
International Journal for Science and Emerging Technologies with Latest Trends , 2012,
Abstract: Graphene, the starting material for all the carbon nanostructures has attracted strong scientific and technological interest in recent years. It has shown great promise in many applications, such as electronics, energy storage and conversion (super capacitors, batteries, fuel cells, solar cells, and bioscience/biotechnologies. Graphene is a zero-gap semiconductor material, which is electroactive and transparent. Because of its interesting properties, graphene has found its way into a wide variety of biosensing schemes. It has been used as a transducer in bio-field-effect transistors, electrochemical biosensors impedance biosensors, electrochemiluminescence, and fluorescence biosensors, as well as bimolecular labels.so Functionalization and dispersion of graphene sheets are of crucial importance for their end applications. In our article, we have functionalized Graphene using carboxylation process for its application in biosensors.
4-N,N-Dimethylaminopyridine Promoted Selective Oxidation of Methyl Aromatics with Molecular Oxygen  [PDF]
Zhan Zhang,Jin Gao,Feng Wang,Jie Xu
Molecules , 2012, DOI: 10.3390/molecules17043957
Abstract: 4-N,N-Dimethylaminopyridine (DMAP) as catalyst in combination with benzyl bromide was developed for the selective oxidation of methyl aromatics. DMAP exhibited higher catalytic activity than other pyridine analogues, such as 4-carboxypyridine, 4-cyanopyridine and pyridine. The sp3 hybrid carbon-hydrogen (C–H) bonds of different methyl aromatics were successfully oxygenated with molecular oxygen. The real catalyst is due to the formation of a pyridine onium salt from the bromide and DMAP. The onium salt was well characterized by NMR and the reaction mechanism was discussed.
On the parameters of Lewis metric for the Lewis class  [PDF]
M. F. A. da Silva,L. Herrera,F. M. Paiva,N. O. Santos
Physics , 1996, DOI: 10.1088/0264-9381/12/1/009
Abstract: The physical and geometrical meaning of the four parameters of Lewis metric for the Lewis class are investigated. Matching this spacetime to a completely anisotropic, rigidly rotating, fluid cylinder, we obtain from the junction conditions that the four parameters are related to the vorticity of the source. Furthermore it is shown that one of the parameters must vanish if one wishes to reduce the Lewis class to a locally static spacetime. Using the Cartan scalars it is shown that the Lewis class does not include globally Minkowski as special class, and that it is not locally equivalent to the Levi-Civita metric. Also it is shown that, in contrast with the Weyl class, the parameter responsible for the vorticity appears explicitly in the expression for the Cartan scalars. Finally, to enhance our understanding of the Lewis class, we analyse the van Stockum metric.
Catalytic reactions of C4 hydrocarbons on the fluid catalytic cracking catalyst
YAN Ping-xiang,MENG Xiang-hai,XU Chun-ming,GAO Jin-sen,

燃料化学学报 , 2008,
Abstract: The catalytic reactions of C4 hydrocarbons on a fluid catalytic cracking (FCC) catalyst were studied in a confined fluidized bed reactor. The effect of reaction temperature and space velocity on product yields and distribution was investigated. The results show that the FCC catalyst has the good performance of aromatization and cracking of C4 hydrocarbons and can be used to produce propylene and aromatics under the suitable reaction conditions. It is mainly the butylene in the C4 hydrocarbons that undergoes catalytic reactions over the FCC catalyst and butane is hard to convert. Low reaction temperature favors the production of aromatics, while high reaction temperature favors the production of propylene. Low space velocity is beneficial to promote the conversion of butylene and the production of both aromatics and propylene. According to the bimolecular mechanism and reaction results, the reaction network for the catalytic reactions of C4 hydrocarbons on the FCC catalyst is proposed. The analysis on the this reaction mechanism indicates that the main reason of resulting in the lower yields of ethylene and propylene could be the poor secondary cracking performances of C5 and C6 olefins formed in the catalytic conversion of C4 hydrocarbons on the FCC catalyst.
Development of Fluorous Lewis Acid-Catalyzed Reactions  [PDF]
Akihiro Yoshida,Xiuhua Hao,Osamu Yamazaki,Joji Nishikido
Molecules , 2006, DOI: 10.3390/11080627
Abstract: Organic synthetic methodology in the 21st century aims to conform to the principles of green sustainable chemistry (GSC) and we may expect that in the future, the realization of GSC will be an important objective for chemical industries. An important aim of synthetic organic chemistry is to implement waste-free and environmentally-benign industrial processes using Lewis acids as versatile as aluminum choride. A key technological objective of our work in this area has been to achieve a “catalyst recycling system that utilizes the high activity and structural features of fluorous Lewis acid catalysts”. Thus, we have developed a series of novel fluorous Lewis acid catalysts, namely the ytterbium(III), scandium(III), tin(IV) or hafnium(IV) bis(perfluoroalkanesulfonyl)amides or tris(perfluoro- alkanesulfonyl)methides. Our catalysts are recyclable and effective for acylations of alcohols and aromatics, Baeyer-Villiger reactions, direct esterifications and transesterifications in a fluorous biphasic system (FBS), in supercritical carbon dioxide and on fluorous silica gel supports.
C. S. Lewis, The Abolition of Man  [cached]
Rodica Albu
Journal for the Study of Religions and Ideologies , 2006,
Abstract: C. S. Lewis, The Abolition of Man HarperCollins Publishers, New York, 2001.
Brazilian Journal of Chemical Engineering , 1997, DOI: 10.1590/S0104-66321997000200006
Abstract: abstract - a pilot-scale catalytic incineration system was used to investigate the effectiveness of catalytic incineration as a means of reducing volatile organic compound (voc) air pollutants. the objectives of the study were: 1) to investigate the effects of operating and design variables on the reduction efficiency of vocs; and 2) to evaluate reduction efficiencies for specific compounds in different chemical classes. the study results verified that the following factors affect the catalyst performance: inlet temperature, space velocity, compound type, and compound inlet concentration. tests showed that reduction efficiencies exceeding 98% were possible, given sufficiently high inlet gas temperatures for the following classes of compounds: alcohols, acetates, ketones, hydrocarbons, and aromatics
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