Thesis (Ph. D.)--Johns Hopkins University, 1925. / Biography.

Mo Kai For. / Thesis submitted in: November 2001. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 78-81). / Abstracts in English and Chinese. / Contents --- p.i / Acknowledgement --- p.iii / Abstract --- p.iv / Chapter I --- Introduction --- p.1 / Chapter II --- Results and Discussion --- p.14 / Chapter II.1 --- Synthesis of racemic planar chiral PPV by bimolecular polymerization using the Horner-Emmons-Wadsworth reaction --- p.14 / Chapter II.2 --- Formation of racemic [n]paracyclophane-based homo-PPVs from rac- bis(chloromethyl)[n]paracyclophanes by the Gilch reaction --- p.17 / Chapter II.3 --- Preparation of enantiopure bis(halomethyl)[n]paracyclophanes to be used as monomers for the synthesis of planar chiral non-racemic PPVs --- p.21 / Chapter II.4 --- Synthesis of [ 14] [ 14]metaparacyclophane ´ؤthe first example of a [m] [n]metaparacyclophane --- p.24 / Chapter II.5 --- Synthesis of enantiopure [n]paracyclophane-based homo-PPVs from enantiopure bis(bromomethyl)[n]paracyclophanes by the Gilch reaction --- p.29 / Chapter II.6 --- "Copolymers formation from enantiopure bis(bromomethyl)[n]paracyclophanes and racemic α,α'-dibromo-2,5-bis(3,7-dimethyloctyloxy)-p-xylene by the Gilch reaction" --- p.32 / Chapter II.7 --- "Characterization of the chiral non-racemic poly[(pR/pS)-[n]-2,5-paracyclo-1,4- phanylene-(E)-vinylene]-co-[2,5-bis(3,7-dimethyloctyloxy)-l,4-phenylene- (E)-vinylene] polymers" --- p.35 / Chapter III --- Conclusion --- p.53 / Chapter IV --- Experimental --- p.54 / References --- p.78 / Spectra --- p.82

*Please refer to dissertation for diagrams. / In addition, a precursor of tetraphenylene-based monodentate ligand ( S,S)-114 was also prepared, and the structures of five compounds, namely 89, 124, 125, 133 and 137 were examined by X-ray crystallographic analysis. These structural determinations were relevant in establishing regiochemistry and absolute stereochemistry.* / In the synthesis of enantiopure (S,R,S)-48 and (R,S,R)-48, two routes were successfully employed. One way was to follow the same pathway for the synthesis of racemic 48 by using enantiopure (S,S)- and (R,R)-1,8,9,16-teramethoxytetraphenylenes [(S,S)-89 and (R,R)- 89] as staring materials. Another way was by direct resolution of racemic 48 via derivatization into its two diastereomeric hexakis-(S)-camphorsulfonates 135 and 136. / In the synthesis of racemic 48, 3-nitrophenol (115) was employed as the starting material which upon a series of standard reactions provided 2,2'-diiodo-1,1'-biphenyl (119). Through sequential lithium-iodine exchange and Cu(II)-mediated oxidative cyclocoupling, 119 was converted to 1,8,9,16-tetramethoxytetraphenylene (89) . The key intermediate 1,8-dihydroxy-9,16-dimethoxytetraphenylene (87) was obtained by partial demethylation of 89. This intermediate was transformed to 1,4,5,8-tetrahydroxy-9,16-dimethoxytetraphenylene (126) by a quinone-hydroquinone strategy. Demethylation of 126 furnished the target compound 48. / This thesis describes the synthesis of 1,4,5,8,9,16-hexahydroxytetraphenylene (48)* in its racemic and enantiopure (S,R,S) and ( R,S,R) forms. Some essential background and previous works in this area are presented in the first chapter. / Wu Anhui. / "August 2006." / Adviser: Henry N. C. Wong. / Source: Dissertation Abstracts International, Volume: 68-03, Section: B, page: 1649. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (p. 80-85). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Thesis (M.S.)--University of Missouri--Rolla, 2007. / Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed November 16, 2007) Includes bibliographical references (p. 85-89).

Considerando que o metoprolol é metabolizado preferencialmente pelos CYP3A e CYP2D e que o etilbenzeno é um indutor do CYP3A em ratos, o presente estudo visa investigar a influência da exposição ao etilbenzeno, por via inalatória, na disposição cinética e no metabolismo estereosseletivos do metoprolol. Foram utilizados ratos Wistar machos, tratados com dose única de 15 mg/kg ou 30mg/kg de metoprolol racêmico (gavagem). Os animais foram divididos em 4 grupos, sendo dois controles (15 e 30mg/kg) e dois expostos ao etilbenzeno em concentrações de 434mg/m3 e 1736mg/m3 e tratados com 15mg/kg de metoprolol. Os animais foram expostos ao etilbenzeno durante 6 horas/dia, por 5 dias consecutivos, em câmara de exposição do tipo somente pelo nariz. As amostras seriadas de sangue (n=6 animais por tempo de coleta) foram coletadas até 6 horas após a administração do metoprolol. Os enantiômeros foram analisados no plasma por cromatografia líquida de alta eficiência com detecção por fluorescência e a farmacocinética do metoprolol foi avaliada empregando modelo bicompartimental. O metoprolol na dose de 30mg/kg exibe farmacocinética não linear, com acúmulo plasmático de ambos os enantiômeros do metoprolol e redução do clearance do enantiômero R-(+)-metoprolol (39,91 vs 78,37 L/h/kg) quando comparado ao grupo de animais tratados com a dose de 15mg/kg. A farmacocinética do metoprolol na dose de 15mg/kg é linear e não enantiosseletiva. A exposição ao etilbenzeno inalado na concentração de 434mg/m3 (1 LEO) não altera a farmacocinética de ambos os enantiômeros do metoprolol. A exposição ao etilbenzeno inalado na concentração de 1736mg/m3 (4 LEO) aumenta o clearance de ambos os enantiômeros do metoprolol em aproximadamente 3 vezes (224,66 vs 78,37 L/h/kg e 213,62 vs 73,63 L/h/kg), respectivamente para os enantiômeros R-(+)- e S-(-)-metoprolol. O aumento do clearance de ambos os enantiômeros do metoprolol no grupo de animais expostos ao etilbenzeno inalado na concentração de 1736mg/m3 (4 LEO) pode ser explicado pelo aumento na formação de ambos os enantiômeros dos metabólitos O-desmetilmetoprolol (AUC0-122,84 vs 61,57 ng/h/mL e 92,33 vs 58,56 ng/h/mL, respectivamente para os enantiômeros R-(+)- e S-(-)-) e ácido O-desmetilmetoprolóico (AUC0- 8592,0 vs 6812,5 ng/h/mL e 8733,0 vs 6787,0 ng/h/mL respectivamente para os enantiômeros R-(+)- e S-(-)-). Os dados permitem inferir que ratos expostos durante 5 dias, 6h/dia, ao etilbenzeno na concentração de 4 vezes o LEO, mostram indução de maneira não enantiosseletiva no metabolismo de ambos os isômeros do metoprolol. / Metoprolol is mainly metabolized by CYP3A and CYP2D and ethylbenzene is an inducer of CYP3A in rats. In view of these considerations, the objective of the present study was to investigate the influence of low-level inhalation exposure to ethylbenzene on the kinetic dispo¬sition and metabolism of metoprolol enantiomers. Male Wistar rats were received a single dose of 15 or 30 mg/kg racemic metoprolol by gavage. The animals were divided into 4 groups: two control groups (15 and 30 mg/kg) and two groups exposed to ethylbenzene at concentrations of 434 and 1736 mg/m3. The animals were exposed to ethylbenzene in a nose-only exposure chamber for 6 h/day during 5 consecutive days. Serial blood samples (n=6 animals per sampling time) were collected during the first 6 h after metoprolol administration. The isomers of metoprolol and its metabolites were analyzed in plasma samples by high-performance liquid chromatography with fluorescence detection. Pharmacokinetic analysis was performed using a two-compartment model. Metoprolol administered at a dose of 30 mg/kg showed nonlinear pharmacokinetics, with plasma accumulation of both metoprolol enantiomers and a reduction in the clearance of R-(+)-metoprolol (39.91 vs 78.37 L/h/kg) when compared to the group receiving the dose of 15 mg/kg. The kinetic disposition of the enantiomers of metoprolol administered at a dose of 15 mg/kg was linear and non-enantioselective. Exposure to 434 mg/m3 ethylbenzene did not influence the pharmacokinetics of either metoprolol enantiomer. Exposure to 1736 mg/m3 ethylbenzene increased the clearance of both metoprolol enantiomers by approximately 300% (224.66 vs 78.37 L/h/kg and 213.62 vs 73.63 L/h/kg for the R-(+)- and S-(-)-metoprolol enantiomer, respectively). These changes in clearance might be explained by an increase in the formation of the enantiomers of the two metabolites O-demethylmetoprolol (AUC0-: 122.84 vs 61.57 ng/h/mL and 92.33 vs 58.56 ng/h/mL for the R-(+)- and S-(-)- enantiomer, respectively) and O-demethylmetoprolol acid (AUC0-: 8592.0 vs 6812.5 ng/h/mL and 8733.0 vs 6787.0 ng/h/mL). In conclusion, inhalation exposure of rats to ethylbenzene at a concentration of 1736 mg/m3 for 5 days, 6 h per day, resulted in the non-enantioselective induction of the metabolism of metoprolol.

A fundamental kinetic model based upon the Hougen-Watson formalism was derived as a basis not only for a better understanding of the reaction behavior but also for the design and simulation of industrial reactors. Kinetic experiments were carried out using a commercial potassium-promoted iron catalyst in a tubular reactor under atmospheric pressure. Typical reaction conditions were temperature = 620oC, steam to ethylbenzene mole ratio = 11, and partial pressure of N2 diluent = 0.432 bar. Experimental data were obtained for different operating conditions, i.e., temperature, feed molar ratio of steam to ethylbenzene, styrene to ethylbenzene, and hydrogen to ethylbenzene and space time. The effluent of the reactor was analyzed on-line using two GCs. Kinetic experiments for the formation of minor by-products, i.e. phenylacetylene, α-methylstyrene, β-methylstyrene, etc, were conducted as well. The reaction conditions were: temperature = 600oC ~ 640oC, a molar ratio of steam to ethylbenzene = 6.5, and partial pressure of N2 diluent = 0.43 bar and 0.64 bar. The products were analyzed by off-line GC. The mathematical model developed for the ethylbenzene dehydrogenation consists of nonlinear simultaneous differential equations in multiple dependent variables. The parameters were estimated from the minimization of the multiresponse objective function which was performed by means of the Marquardt algorithm. All the estimated parameters satisfied the statistical tests and physicochemical criteria. The kinetic model yielded an excellent fit of the experimental data. The intrinsic kinetic parameters were used with the heterogeneous fixed bed reactor model which is explicitly accounting for the diffusional limitations inside the porous catalyst. Multi-bed industrial adiabatic reactors with axial flow and radial flow were simulated and the effect of the operating conditions on the reactor performance was investigated. The dynamic equilibrium coke content was calculated using detailed kinetic model for coke formation and gasification, which was coupled to the kinetic model for the main reactions. The calculation of the dynamic equilibrium coke content provided a crucial guideline for the selection of the steam to ethylbenzene ratio leading to optimum operating conditions.

Considerando que o metoprolol é metabolizado preferencialmente pelos CYP3A e CYP2D e que o etilbenzeno é um indutor do CYP3A em ratos, o presente estudo visa investigar a influência da exposição ao etilbenzeno, por via inalatória, na disposição cinética e no metabolismo estereosseletivos do metoprolol. Foram utilizados ratos Wistar machos, tratados com dose única de 15 mg/kg ou 30mg/kg de metoprolol racêmico (gavagem). Os animais foram divididos em 4 grupos, sendo dois controles (15 e 30mg/kg) e dois expostos ao etilbenzeno em concentrações de 434mg/m3 e 1736mg/m3 e tratados com 15mg/kg de metoprolol. Os animais foram expostos ao etilbenzeno durante 6 horas/dia, por 5 dias consecutivos, em câmara de exposição do tipo somente pelo nariz. As amostras seriadas de sangue (n=6 animais por tempo de coleta) foram coletadas até 6 horas após a administração do metoprolol. Os enantiômeros foram analisados no plasma por cromatografia líquida de alta eficiência com detecção por fluorescência e a farmacocinética do metoprolol foi avaliada empregando modelo bicompartimental. O metoprolol na dose de 30mg/kg exibe farmacocinética não linear, com acúmulo plasmático de ambos os enantiômeros do metoprolol e redução do clearance do enantiômero R-(+)-metoprolol (39,91 vs 78,37 L/h/kg) quando comparado ao grupo de animais tratados com a dose de 15mg/kg. A farmacocinética do metoprolol na dose de 15mg/kg é linear e não enantiosseletiva. A exposição ao etilbenzeno inalado na concentração de 434mg/m3 (1 LEO) não altera a farmacocinética de ambos os enantiômeros do metoprolol. A exposição ao etilbenzeno inalado na concentração de 1736mg/m3 (4 LEO) aumenta o clearance de ambos os enantiômeros do metoprolol em aproximadamente 3 vezes (224,66 vs 78,37 L/h/kg e 213,62 vs 73,63 L/h/kg), respectivamente para os enantiômeros R-(+)- e S-(-)-metoprolol. O aumento do clearance de ambos os enantiômeros do metoprolol no grupo de animais expostos ao etilbenzeno inalado na concentração de 1736mg/m3 (4 LEO) pode ser explicado pelo aumento na formação de ambos os enantiômeros dos metabólitos O-desmetilmetoprolol (AUC0-122,84 vs 61,57 ng/h/mL e 92,33 vs 58,56 ng/h/mL, respectivamente para os enantiômeros R-(+)- e S-(-)-) e ácido O-desmetilmetoprolóico (AUC0- 8592,0 vs 6812,5 ng/h/mL e 8733,0 vs 6787,0 ng/h/mL respectivamente para os enantiômeros R-(+)- e S-(-)-). Os dados permitem inferir que ratos expostos durante 5 dias, 6h/dia, ao etilbenzeno na concentração de 4 vezes o LEO, mostram indução de maneira não enantiosseletiva no metabolismo de ambos os isômeros do metoprolol. / Metoprolol is mainly metabolized by CYP3A and CYP2D and ethylbenzene is an inducer of CYP3A in rats. In view of these considerations, the objective of the present study was to investigate the influence of low-level inhalation exposure to ethylbenzene on the kinetic dispo¬sition and metabolism of metoprolol enantiomers. Male Wistar rats were received a single dose of 15 or 30 mg/kg racemic metoprolol by gavage. The animals were divided into 4 groups: two control groups (15 and 30 mg/kg) and two groups exposed to ethylbenzene at concentrations of 434 and 1736 mg/m3. The animals were exposed to ethylbenzene in a nose-only exposure chamber for 6 h/day during 5 consecutive days. Serial blood samples (n=6 animals per sampling time) were collected during the first 6 h after metoprolol administration. The isomers of metoprolol and its metabolites were analyzed in plasma samples by high-performance liquid chromatography with fluorescence detection. Pharmacokinetic analysis was performed using a two-compartment model. Metoprolol administered at a dose of 30 mg/kg showed nonlinear pharmacokinetics, with plasma accumulation of both metoprolol enantiomers and a reduction in the clearance of R-(+)-metoprolol (39.91 vs 78.37 L/h/kg) when compared to the group receiving the dose of 15 mg/kg. The kinetic disposition of the enantiomers of metoprolol administered at a dose of 15 mg/kg was linear and non-enantioselective. Exposure to 434 mg/m3 ethylbenzene did not influence the pharmacokinetics of either metoprolol enantiomer. Exposure to 1736 mg/m3 ethylbenzene increased the clearance of both metoprolol enantiomers by approximately 300% (224.66 vs 78.37 L/h/kg and 213.62 vs 73.63 L/h/kg for the R-(+)- and S-(-)-metoprolol enantiomer, respectively). These changes in clearance might be explained by an increase in the formation of the enantiomers of the two metabolites O-demethylmetoprolol (AUC0-: 122.84 vs 61.57 ng/h/mL and 92.33 vs 58.56 ng/h/mL for the R-(+)- and S-(-)- enantiomer, respectively) and O-demethylmetoprolol acid (AUC0-: 8592.0 vs 6812.5 ng/h/mL and 8733.0 vs 6787.0 ng/h/mL). In conclusion, inhalation exposure of rats to ethylbenzene at a concentration of 1736 mg/m3 for 5 days, 6 h per day, resulted in the non-enantioselective induction of the metabolism of metoprolol.

Orientador: Meuris Gurgel Carlos da Silva / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-22T16:47:28Z (GMT). No. of bitstreams: 1 Souza_RenatadosSantos_D.pdf: 2889400 bytes, checksum: 692c0c9b405b4f550e07f530c56c124c (MD5) Previous issue date: 2013 / Resumo: Muitos compostos orgânicos derivados do petróleo são encontrados na água subterrânea, oriundos de processos industriais ou, principalmente, dos vazamentos de combustível em postos de distribuição. Dentre esses compostos encontram-se benzeno, tolueno e xileno (BTX), substâncias tóxicas e carcinogênicas e que se constituem nos componentes mais poluidores da gasolina. Processos de remoção dos BTX devem atender aos limites da legislação e, nesse sentido, a adsorção é um dos métodos mais eficientes. Neste trabalho foi proposto avaliar a lama vermelha, resíduo da indústria de beneficiamento do alumínio, nas formas bruta, calcinada e quimicamente tratada, como material adsorvente alternativo para remoção dos BTX em soluções sintéticas com um e dois adsorbatos. A caracterização da lama vermelha indicou que o material é macroporoso, muito heterogêneo e constituído de uma mistura de óxidos principalmente sodalita, hematita, goetita, gibbsita e quartzo. A calcinação provocou alterações na estrutura do adsorvente, aumentando a área superficial e a quantidade e tamanho de macroporos. O estudo do pHzpc mostrou que o pH natural da lama vermelha tornou a superfície carregada negativamente, atraindo assim o anel benzênico e melhorando a adsorção. Os ensaios de cinética de adsorção mostraram um processo rápido com no máximo 2h para atingir o equilíbrio e o percentual de remoção foi acima de 85% para todos os compostos. Nos ensaios de equilíbrio com monocomposto a ordem decrescente de adsorção foi benzeno, tolueno e xileno. As maiores capacidades de adsorção de benzeno foram qe = 0,332 mmol/g com lama bruta, e com lama calcinada qe = 0,335 mmol/g, esses valores são elevados quando comparados com adsorventes do tipo argilominerais. Os modelos Langmuir com dois sítios e múltiplos espaços de adsorção foram os que melhor se ajustaram aos resultados experimentais de adsorção com monocomposto, porém não conseguiram prever as multicamadas existentes nas isotermas. Foi verificada uma diminuição na remoção de todos os BTX na condição de mistura binária. A ordem de remoção de BTX foi inversa e com maiores remoções de xileno (qe = 0,3406 mmol/g). O modelo de Langmuir se ajustou adequadamente aos resultados experimentais, nessa condição / Abstract: Many organic compounds derived from oil are found in groundwater from industrial processes or specially from leaks at fuel tanks in gas stations. Among these compounds are benzene, toluene and xylene (BTX), toxic and carcinogenic substances that are the most polluters compounds from gasoline. BTX removal processes must attend to legislation limits and thus the adsorption process is one of the most efficient methods. In this work it was used red mud, an aluminum industry waste, in the raw, calcined forms and chemically treated forms, as an alternative adsorbent, to remove the BTX from single and two-component aqueous solutions. The characterization of the red mud indicated that this material is macroporous, very heterogeneous and compound from an oxides mixture, mainly sodalite, hematite, goethite, gibbsite and quartz. The calcination caused changes in the adsorbent structure, increasing the superficial area and the macroporous quantities and size. The pHpzc study showed that the natural red mud pH lets the surface negatively charged, attracting then the benzene rings and improving the adsorption. The kinetic adsorption showed a fast process that needs 2 h to achieve the equilibrium and a removal percentage of 85% for all compounds. In the single component equilibrium studies the adsorption order was benzene, toluene e xylene. The maximum adsorption capacities were qe = 0,332 mmol/g on raw red mud (RM), and on calcined red mud (CRM), qe = 0,335 mmol/g. DSL and MSAM models were the best fit to the experimental data in the single component adsorption, although they could not to predict the multiple layers existing in the isotherms. It was verified a decrease in the removal of all BTX in the two-component adsorption. There was a change in the BTX removal order and more removal of xylene (qe = 0,3406 mmol/g). The Langmuir model showed good fit to the experimental data in this condition / Doutorado / Engenharia de Processos / Doutora em Engenharia Quimica

ABSTRACT COMPARISON OF SORPTION CAPACITIES OF HYDROCARBONS ON DIFFERENT SAMPLES OF MCM-41 AYDOGDU, Birsu M. Sc., Department of Chemical Engineering Supervisor: Prof. Dr. Hayrettin Y&Uuml / CEL Co-Supervisor: Prof. Dr. G&uuml / rkan KARAKAS January 2013, 69 pages MCM-41(Mobil Composition Matter-41) is one of the three members of M41S family and has a highly ordered hexagonal honeycomb like structure with a narrow pore size distribution in mesopore range, high surface area, high pore volume and high thermal stability. These features make MCM-41 proper to use for adsorption, catalysis, ion exchange and separation processes. . In this study sorption capacities of C8 aromatics (o-, m-, p-xylene and ethylbenzene at 30 &deg / C, 50 &deg / C and 65 &deg / C) on a MCM-41 sample synthesized in our laboratory were determined gravimetrically by using a commercial automated electro balance system and compared with results obtained in a previous and similar MSc thesis study with a sample of different origin and characteristics / specifically low BET surface area (492 m2/g). MCM-41 sample was synthesized by hydrothermal synthesis method with cetyltrimethylammoniumbromide (CTAMBr as surfactant) and tetraethyl ortosilicate (TEOS as silica source) in basic conditions. This MCM-41 sample was calcined at 540 oC for 8 h and characterized by XRD, nitrogen adsorption at 77 K, TGA, TEM, SEM and SEM-EDX. According to XRD data, main characteristic peak for synthesized MCM-41 was obtained at 2&theta / =2.28&deg / . Three small reflection peaks can be seen at 2&theta / values of 2.59, 4.27&deg / and 4.5&deg / . XRD pattern of the MCM-41, indicated that the desired structure of MCM-41 was successfully synthesized. Surface area, pore volume and average pore diameter were obtained from the nitrogen adsorption data at 77 K as 1154 m2/g, 1.306 cm3/g and 2.75 nm respectively. TGA analysis showed that the 540 oC is proper for the calcination. SEM -EDX analysis gave an oxygen atomic concentration 66.40% and silicon atomic concentration 33.60%. These results showed that the chemical composition of the synthesize material was in almost pure SiO2 form. The adsorbed amount for all isomers at the same pressure decreased as the temperature of the adsorption isotherms increases as expected for physical adsorption. Nitrogen adsorption of MCM-41 in this study showed type IV isotherm with H2 type hysteresis loop according the IUPAC classification. However, for o-,m-, and p-xylene an approximately linear increase in the adsorbed amount as a function of relative pressure was observed from the adsorption isotherms. Except for adsorption isotherms of m-xylene and p-xylene at 65 oC all isotherms of xylenes showed hysteresis loops. Hysteresis loops narrowed down with increasing temperature. p-xylene and m-xylene adsorption isotherms at 65 oC were reversible and did not show any hysteresis loop. Ethylbenzene adsorption isotherms at 30 oC, 50 &deg / C and 65 oC also showed a linear increase in the adsorption amount as a function of relative pressure like xylenes. At 50 &deg / C and 65 oC adsorption isotherms of ethylbenzene were reversible without a hysteresis loop. For all adsorbates volume of adsorbed amounts were calculated on the assumption that they exist as saturated liquids at the isotherm temperature and found to be significantly lower than pore volume obtained from nitrogen adsorption isotherm at 77K. Sorption capacities of these hydrocarbons on MCM-41 were also very low when compared to values found in a previous study which involved a MCM-41 sample of significantly lower surface area ( 492 m2/g ). This may be attributed to structure degradation which requires further investigation.

Submitted by Edileide Reis (leyde-landy@hotmail.com) on 2013-04-23T13:14:32Z No. of bitstreams: 1 Raphael Holt.pdf: 5449117 bytes, checksum: 052b88f3a4242aebdef5fdf978a8b5ce (MD5) / Made available in DSpace on 2013-04-23T13:14:32Z (GMT). No. of bitstreams: 1 Raphael Holt.pdf: 5449117 bytes, checksum: 052b88f3a4242aebdef5fdf978a8b5ce (MD5) Previous issue date: 2008 / A principal rota utilizada industrialmente para a produção de estireno é a desidrogenação catalítica do etilbenzeno, responsável por mais de 90% da produção mundial de estireno. O processo industrial é operado na faixa de temperatura de 550-700 oC, em excesso de vapor d’água aquecido, sobre catalisadores de óxido de ferro promovidos com potássio e cromo, que são tóxicos e possuem vida útil limitada a 2 anos. Neste contexto, existe a demanda por catalisadores que sejam ativos e seletivos nessa reação e que apresentem elevada vida útil, além de não serem tóxicos. Na busca de sistemas alternativos, neste trabalho foram desenvolvidos catalisadores de vanádio e magnésio suportados em carvão ativado obtido pela pirólise do copolímero estireno-divinilbenzeno, em atmosfera não oxidativa. Os catalisadores foram caracterizados pela medida da área superficial específica e de porosidade, difração de raios X, termogravimetria, análise térmica diferencial, espectrofotometria de absorção atômica, microscopia eletrônica de varredura acoplada ao sistema de quantificação por energia dispersiva. Os catalisadores foram avaliados na desidrogenação do etilbenzeno em ausência de vapor d’água, a 530 oC e 1 atm, para a produção de estireno. Verificou-se a presença de trióxido de vanádio e de aglomerados de vanádio e magnésio de diferentes tamanhos, nos sólidos. Os materiais apresentaram isotermas de adsorção e dessorção de nitrogênio do Tipo II ou IV, que são típicas de sólidos meso e macroporos com microporos associados, e uma histerese do Tipo H I, característica de materiais com poros cilíndricos. Estes sólidos apresentaram áreas superficiais específicas entre 378 e 611 m2/g. Os catalisadores com vanádio e magnésio apresentaram menor perda da área superficial específica que o carvão ativado, durante a desidrogenação do etilbenzeno. A adição de magnésio e vanádio provocou um aumento da atividade catalítica do carvão ativado e da seletividade ao estireno. Todos catalisadores foram mais ativos que uma amostra de catalisador comercial. O catalisador contendo 5 % de vanádio foi o mais promissor. Esta amostra conduziu, em ausência de vapor d’água, 35% de conversão do etilbenzeno, que é cerca de três vezes o valor obtido com uma amostra de catalisador comercial em presença de vapor d’água. Isto foi atribuído à ação catalítica do vanádio e à presença de grupos oxigenados na superfície do carvão que possuem atividade na desidrogenação do etilbenzeno. / Salvador