<p>This thesis studies dynamic modelling, estimation and optimization of the methanol synthesis with catalyst deactivation. Conversion of natural gas is of special interest in Norway for both economic and political reasons. In June 1997 Statoil opened a methanol plant at Tjeldbergodden. It is among the largest in the word with a capacity of 830 000 metric tons per year, which equals 1/4 of Europe's capacity. Methanol is today mainly used as a building block to produce chemical intermediates, and it is also a promising fuel for fuel cells.</p><p>The overall theme for this thesis is to find the optimal operation of the methanol synthesis when undergoing catalyst deactivation by dynamic optimization. There has been an increase in method development, tool development and industrial use of dynamic optimization in the past decade. Few realistic, large-scale applications with nonlinear, first principle models, exist apart from this thesis.</p><p>A rigorous pseudo-steady state model of the total methanol synthesis loop is developed. The model has been verified against a design flow sheet and to some extent, validated against process data. Overall, good agreement was found.</p><p>Optimal operation policy of the methanol synthesis is found by dynamic optimization. Both the reactor and the reactor system with recycle are studied, and it is shown that the total reactor system with recycle must be considered to find the optimal operating policy. It is also shown that a heterogeneous reactor model gives different optimal policy and more accurate results than a pseudohomogeneous reactor model. Optimization of the loop leads to USD 3 165 000, or 0.75 per cent, increased profit over four years compared to a selected reference case with a constant operation policy. Optimal operation policy is compared with an operating procedure recommended for the Tjeldbergodden methanol plant. The calculated optimal operation policy gives higher profit. However, there are two important advantages of optimization: The ability to find the optimal operation if some of the variables in the optimization problem change, and the ability to track changes in the process by model updating and repeated optimization.</p><p>During modelling and optimization, it became evident that a good industrialscale deactivation model is needed for the methanol synthesis. The sensitivity in the dynamic optimization of the methanol synthesis is analysed with regards to the deactivation model by a first order error propagation - approach. It is found that 20 per cent standard deviation in the deactivation parameters is suffcient for optimization purposes.</p><p>A deactivation model for the methanol synthesis catalyst is estimated from historic process data from a methanol plant. A model on the generalized power law form was successfully fitted to process data from a limited period of time. The estimated model is of second order. No measurable effect of water was found, probably because the variations in the feed compositions were too small. The model parameters found are confidential, and are not valid for the total catalyst lifetime because the deactivation process is fast in the beginning and slower after some time. It is necessary to use data from a longer period of time to obtain a model that is valid over the total catalyst lifetime.</p><p>The work presented in this thesis serves as a framework for the implementation of dynamic optimization in the control system of a methanol synthesis plant. The dynamic optimization should be implemented in the optimization layer of the control system with feedback to update the activity. A new catalyst deactivation model should be estimated whenever the commercial catalyst type is changed. A shrinking horizon algorithm with repeated optimization is proposed.</p><p>The main contribution in this thesis is a realistic, large-scale case study on modelling, estimation and dynamic optimization. Several researchers have studied optimal operation of fixed bed reactors experiencing catalyst deactivation. This work adopts an approach which is more realistic. A rigorous model of the total reactor system with recycle, with varying model parameters and thermodynamic properties is used. A thorough analysis of the process is enployed to formulate the optimization problem. The actual time varying control variables in the reactor system, the recycle rate and coolant temperature, are optimized with regards to an economic objective, and path constrains on the reactor temperature are considered. An optimal operation strategy for the methanol synthesis has not been published before. Similar studies have probably been performed in industry without being published.</p>

This thesis studies dynamic modelling, estimation and optimization of the methanol synthesis with catalyst deactivation. Conversion of natural gas is of special interest in Norway for both economic and political reasons. In June 1997 Statoil opened a methanol plant at Tjeldbergodden. It is among the largest in the word with a capacity of 830 000 metric tons per year, which equals 1/4 of Europe's capacity. Methanol is today mainly used as a building block to produce chemical intermediates, and it is also a promising fuel for fuel cells. The overall theme for this thesis is to find the optimal operation of the methanol synthesis when undergoing catalyst deactivation by dynamic optimization. There has been an increase in method development, tool development and industrial use of dynamic optimization in the past decade. Few realistic, large-scale applications with nonlinear, first principle models, exist apart from this thesis. A rigorous pseudo-steady state model of the total methanol synthesis loop is developed. The model has been verified against a design flow sheet and to some extent, validated against process data. Overall, good agreement was found. Optimal operation policy of the methanol synthesis is found by dynamic optimization. Both the reactor and the reactor system with recycle are studied, and it is shown that the total reactor system with recycle must be considered to find the optimal operating policy. It is also shown that a heterogeneous reactor model gives different optimal policy and more accurate results than a pseudohomogeneous reactor model. Optimization of the loop leads to USD 3 165 000, or 0.75 per cent, increased profit over four years compared to a selected reference case with a constant operation policy. Optimal operation policy is compared with an operating procedure recommended for the Tjeldbergodden methanol plant. The calculated optimal operation policy gives higher profit. However, there are two important advantages of optimization: The ability to find the optimal operation if some of the variables in the optimization problem change, and the ability to track changes in the process by model updating and repeated optimization. During modelling and optimization, it became evident that a good industrialscale deactivation model is needed for the methanol synthesis. The sensitivity in the dynamic optimization of the methanol synthesis is analysed with regards to the deactivation model by a first order error propagation - approach. It is found that 20 per cent standard deviation in the deactivation parameters is suffcient for optimization purposes. A deactivation model for the methanol synthesis catalyst is estimated from historic process data from a methanol plant. A model on the generalized power law form was successfully fitted to process data from a limited period of time. The estimated model is of second order. No measurable effect of water was found, probably because the variations in the feed compositions were too small. The model parameters found are confidential, and are not valid for the total catalyst lifetime because the deactivation process is fast in the beginning and slower after some time. It is necessary to use data from a longer period of time to obtain a model that is valid over the total catalyst lifetime. The work presented in this thesis serves as a framework for the implementation of dynamic optimization in the control system of a methanol synthesis plant. The dynamic optimization should be implemented in the optimization layer of the control system with feedback to update the activity. A new catalyst deactivation model should be estimated whenever the commercial catalyst type is changed. A shrinking horizon algorithm with repeated optimization is proposed. The main contribution in this thesis is a realistic, large-scale case study on modelling, estimation and dynamic optimization. Several researchers have studied optimal operation of fixed bed reactors experiencing catalyst deactivation. This work adopts an approach which is more realistic. A rigorous model of the total reactor system with recycle, with varying model parameters and thermodynamic properties is used. A thorough analysis of the process is enployed to formulate the optimization problem. The actual time varying control variables in the reactor system, the recycle rate and coolant temperature, are optimized with regards to an economic objective, and path constrains on the reactor temperature are considered. An optimal operation strategy for the methanol synthesis has not been published before. Similar studies have probably been performed in industry without being published.

Orientador: Mario de Jesus Mendes / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Campinas / Made available in DSpace on 2018-07-16T17:55:15Z (GMT). No. of bitstreams: 1 Nascimento_AlvimarFerreirado_M.pdf: 2565624 bytes, checksum: 179d503d584f787cb2b7d36381ea59aa (MD5) Previous issue date: 1987 / Resumo: O interesse no estudo da reação de síntese do metanol baseia-se em dois aspectos principais: Por um lado, a obtenção do metanol, um importante produto da indústria química e um combustível automotivo potencial. No Brasil, esta segunda utilização do metanol oferece grandes possibilidades, pelas reservas de madeira, matéria prima básica da produção do monóxido de carbono e hidrogênio, reagentes básicos da reação de síntese. Por outro lado, o desafio que representa ao entendimento dos fenômenos catalíticos. A produção do metanol via hidrogenação do monóxido ou dióxido de carbono é, pela termodinâmica, francamente desfavorecida. A síntese só é possível quando é utilizado um catalisador altamente seletivo o conhecimento profundo do mecanismo da reação poderá tornar ainda mais viável, economicamente, a produção do metanol, quando a pressão de síntese, atualmente na faixa de 50 a 100atm, puder ser reduzida a níveis de 5 a 10atm. Neste trabalho é apresentada uma discussão dos catalisadores e do mecanismo de reação de síntese do metanol, é descrita uma instalação utilizada para coleta de dados cinéticos, e são apresentados os resultados experimentais obtidos / Abstract: The interest in studying the methanol synthesis reaction is based on two principal aspects: On the one hand, the obtainment of methanol, an important product of the chemical industry and a potential automotive fuel. In Brazil, this second methanol usefulness offers large possibilities, owing to its huge reservoirs of wood, a raw material for the sybthesis gas production. On the other hand, the challenge that it represents to the understanding of the catalytic phenomena. The methanol production through hydrogenation of carbon monoxide or of carbon dioxide is outspokenly deseteemed by thermodynamics. The synthesis is only possible when a highly selective catalyst is utilized. The knowledge about the reaction mechanism may however have a high economic value, if it makes it possible to reduce the synthesis pressure, today at a value from 50 to 100atm, to the level of 5 to 10atm. In this work we first discuss the catalysts and the reaction mechanism of the methanol synthesis; then we describe the installation utilized to collect kinetic data, and finally we present the experimental results / Mestrado / Mestre em Engenharia Química

Dissertação (mestrado)—Universidade de Brasília, Instituto de Química, 2012. / Texto parcialmente liberado pelo autor. Conteúdo: foram restritos os capítulos 3 e 4, as conclusões e perspectivas. / Submitted by Tania Milca Carvalho Malheiros (tania@bce.unb.br) on 2012-04-20T14:31:53Z No. of bitstreams: 1 2012_TainãRappPy-Daniel_Parcial.pdf: 2428484 bytes, checksum: ef471fdcf33431fabc18ebe4cfdfefc7 (MD5) / Rejected by Patrícia Nunes da Silva(patricia@bce.unb.br), reason: Tânia, você adicionou o arquivo errado. on 2012-04-23T21:06:48Z (GMT) / Submitted by Tania Milca Carvalho Malheiros (tania@bce.unb.br) on 2012-04-24T16:12:14Z No. of bitstreams: 1 2012_GuilhermeBandeiraCandidoMartins_Parcial.pdf: 1933038 bytes, checksum: f15cfd5493d5cec082e49a1b4af880b8 (MD5) / Approved for entry into archive by Patrícia Nunes da Silva(patricia@bce.unb.br) on 2012-04-24T16:30:14Z (GMT) No. of bitstreams: 1 2012_GuilhermeBandeiraCandidoMartins_Parcial.pdf: 1933038 bytes, checksum: f15cfd5493d5cec082e49a1b4af880b8 (MD5) / Made available in DSpace on 2012-04-24T16:30:14Z (GMT). No. of bitstreams: 1 2012_GuilhermeBandeiraCandidoMartins_Parcial.pdf: 1933038 bytes, checksum: f15cfd5493d5cec082e49a1b4af880b8 (MD5) / Neste trabalho foi desenvolvida uma metodologia colorimétrica quantitativa e qualitativa utilizando o reagente de Schiff para detecção de metanol em etanol, álcool etílico hidratado combustível, gasolina, cerveja e cachaça, assim como uma metodologia colorimétrica qualitativa para detecção de aldeídos, visando a detecção de formol em xampu e detergente. Com o método qualitativo para detecção de metanol e aldeídos consegue-se distinguir intervalos de concentração do analíto de 0 a 100 % desde que utilizadas amostras com concentração de referência, de modo que é possível realizar uma análise semi-quantitativa. As amostras que não possuem o analíto não geram cor, facilitando a detecção. As análises quantitativas possuem baixa reprodutibilidade devido a vários fatores cinéticos envolvidos na reação como a presença de duas espécies cromóforas e reações paralelas do analíto. Por meio de estudos cinéticos por espectroscopia na região do visível das amostras tradadas pelo método foi identificada a presença de duas espécies cromóforas relativas aos adutos de Schiff em comprimentos de ondas distintos, sendo 1= 588 nm e 2 = 591 nm. Foi identificado um intervalo de estabilidade da reação de formação do aduto de 45 a 55 min. Sílica, papel, alumina e amido foram impregnados com reagente de Schiff, sendo que apenas a sílica e o papel conseguiram suportar e estabilizar o reagente e serem ativas para detecção de aldeídos.A metodologia qualitativa para ambas as análises foi adaptada na forma de um kit, para aplicação em campo. _____________________________________________________________________________ ABSTRACT / In this work was developed a qualitative and quantitative colorimetrical methodology using Schiff s reagent for detection of methanol contamination in ethanol, hydrated ethylic alcohol fuel, gasoline, beer and cachaça, as well as a qualitative colorimetrical methodology for detection of aldehydes, aiming to detect formaldehyde, in shampoos and detergents. Using references samples, the qualitative method for detection of methanol and aldehydes can distinguish concentrations of the analyte from 0 to 100 % and can be used as a semi quantitative analysis. In the absence of the analyte in the samples it doesn't appear colors, facilitating the detection. The quantitative analysis have low reproducibility because of many kinetics factors involved in the reaction, like the presence of two chromophore species and parallel reactions of the analyte. Indeed, the kinetic studies by spectroscopy in the visible region of the samples previously treated by the analytic method identified the presence of two chromophore species relative to the formation of two Schiff adducts in different wavelengths ( 1= 588 nm e 2 = 591 nm). It was also identified an interval of stability for the adducts from 45 to 55 min. Silica, paper, alumina and starch were impregnated with the Schiff reagent, and only silica and paper were able to support and stabilize the reagent and keep it active for detection of aldehydes. The qualitative methodology for both analyses was adapted in a portable kit, to apply in field.

No description available.

Tese de mestrado integrado. Engenharia Mecânica. Faculdade de Engenharia. Universidade do Porto. 2010

Estágio realizado na SONAE e orientado pelo Eng.º Miguel Gil Mata / Tese de mestrado integrado. Engenharia Química. Faculdade de Engenharia. Universidade do Porto. 2009

Made available in DSpace on 2015-03-03T11:52:43Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-09-19Bitstream added on 2015-03-03T12:07:07Z : No. of bitstreams: 1 000808691.pdf: 3421628 bytes, checksum: 4faf9e5aa212397d6bb7d5e04bf3cc45 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / As células a combustível de metanol direto (DMFCs) são promissoras devido à capacidade de geração de alta densidade de energia elétrica, no entanto, a alta permeabilidade da membrana de troca protônica ao combustível permite seu cruzamento do ânolo para o cátodo, que somado à lenta cinética de exidação do metanol, prejudicam a inserção destes dispositivos no mercado. Neste contexto, o presente trabalho tem como objetivo a melhoria do desempenho de DMFCs utilizando a técnica de automontagem LbL (layer-by-layer) na modificação da membrana trocadora de prótons e construção de eletrodos para oxidação de metanol. Para a nanoesetruturação dos filmes, nanofolhas de óxido de grafeno (GO) e óxido de grafeno reduzido estabilizados em PSS (poly(4styrenesulfonic acid) sodium salt), denominado GPSS, foram sintetizdos e aplicados como suspensões carregadaos negativamente na fabricação dos filmes LbL. Quando depositados sobre membranas comerciais de Nafion 212, apresentaram redução na permeabilidade ao metanol de até 80% e condutividade protônica superior a membrana pura. Os testes em DMFCs indicaram maior potencial de circuito aberto quando se empregou a membrana de Nafion revestida com os filmes LbL e densidade de potência de 83,5 mW.cm-2 (à 70ºC), superior ao resultado com a membrana pura (63,1 mW.com-2), devido à redução do cruzamento de metanol. Em relação a capacidade catalítica para oxidação de metanol, nanopartículas de platina foram sintetizadas por diferentes rotas e empregadas na fabricação de filmes LbL com polieletrólitos e/ou nanofolhas de grafeno sendo que os testes eletroquímicos indicaram correntes de oxidação superiores quando as nanopartículas foram depositadas sobre as nanofolhas de óxido de grafeno reduzidos. Sendo assim, filmes ultrafinos compostos por nanofolhas de grafeno podem contribuir significativamente para o desenvolvimento da tecnologia de DMFCs / The Direct Methanol fuel Cel (DMFC) are promising to clean and high energy density generation, however, the fuel permeability from anode to the cathode and slow methanol oxidation kinetics hinder its rising in market. Within this context, the aim here is inhance the DMFCs performance using the Layer-by-Layer (LbL) technique to modify the polymer electrolyte membrane and build up of electrodes for methanol oxidation. Graphene oxide nanosheets and reduced graphene oxide nanosheets stabilized in PSS (poly(4-styrenesulfonic acid) sodium salt) were synthesized and used as negatively suspensions in the LbL film fabrication. When deposited onto commercial Nafion 212 membranes it was observed a reducition of ~80% in the methanol permeability, and also higher proton conductivity than that of pristine Nafion. DMFC tests indicated a high open circuit voltage with the LbL modified membranes due to a decrease in the methanol crossover, and a power density of 83,5 mW.com-2, superior to the pristine Nafion, at 70ºC (63,1 mW.com-2). Regarding to the catalytic capacity for methanol oxidation, platinum nanoparticles were synthesized from different ways and self-assembled with polyelectrolyte and/or graphene nanosheets and the electrochemical analysis indicated that when supported onto reduce graphene oxide nanosheets, it was produced higher oxidation peak currents. Consequently, composite ultrathin films of graphene nanosheets can contribute significantly to the development of DMFCs

O zebrafish (Danio rerio) é um modelo experimental consolidado em diversas áreas da ciência, como a neurociências e toxicologia. O genoma desta espécie já está quase todo seqüenciado e estudos demonstraram que muitos genes deste peixe são similares ao de mamíferos, incluindo a espécie humana. Evidências demonstram que nucleotídeos e nucleosídeos, principalmente o ATP e a adenosina exercem diversos efeitos sinalizadores no espaço extracelular. No sistema nervoso, o neurotransmissor ATP é armazenado de forma vesicular e liberado na fenda sináptica, onde pode agir em receptores específicos localizados na membrana celular denominados receptores purinérgicos do tipo P2. Estes receptores são subdivididos em receptores ionotrópicos P2X e receptores metabotrópicos P2Y. A inativação do sinal mediado pelo ATP extracelular é realizada por uma família de enzimas denominadas ecto-nucleotidases. Dentre este grupo de enzimas, destacam-se as NTPDases (nucleosídeo trifosfato difosfoidrolases) e a ecto-5’-nucleotidase. Após sofrer catabolismo pelas ectonucleotidases, o neurotransmissor ATP é hidrolisado ao neuromodulador adenosina. Este nucleosídeo exerce seus efeitos através dos receptores metabotrópicos denominados purinoceptores P1. Estudos do nosso laboratório demonstraram a presença de ectonucleotidases como as NTPDases e a ecto-5’-nucleotidase no SNC de zebrafish. Além disso, já foi descrito na literatura que esta espécie apresenta purinoceptores do tipo P2X e P2Y. A acetilcolina é um neurotransmissor secretado pelos nervos colinérgicos terminais, juntamente com o ATP. Após exercido seu sinal nos receptores nicotínicos e muscarínicos, a acetilcolina é inativada pela ação de uma enzima denominada acetilcolinesterase (AChE), que hidrolisa a acetilcolina até colina e acetato. O gene da AChE já foi clonado e seqüenciado e esta atividade enzimática foi detectada em cérebro de zebrafish. O metanol é um composto neurotóxico responsável por sérios danos ao SNC. Além de ser encontrado como um contaminante ambiental, este álcool é também empregado como componente de soluções crioprotetoras para embriões de zebrafish. Os efeitos do consumo agudo de etanol exercem uma variedade de modificações como coordenação motora, percepção sensorial e cognição. O etanol promove diversas alterações bioquímicas e fisiológicas em células do sistema nervoso central. Portanto, nós investigamos o efeito in vitro e in vivo dos álcoois metanol e etanol sobre as ectonucleotidases e acetilcolinesterase em SNC de zebrafish. Após o tratamento agudo com metanol a 0,5 e 1,0% houve uma redução significativa na hidrólise de ATP e ADP. Entretanto, não foram verificadas alterações na atividade da ecto-5´-nucleotidase em cérebro de zebrafish. Uma inibição significativa na atividade da AChE foi observada na faixa de 0,25 a 1,0% de exposição ao metanol. Quatro seqüências de NTPDase foram identificadas através de uma análise filogenética, na qual uma é similar a NTPDase1 e as outras a NTPDase2. O metanol foi capaz de inibir os transcritos para a NTPDase1, duas isoformas da NTPDase2 e AChE. Metanol a 1,5 e 3,0% inibiu in vitro a hidrólise de ATP, e a hidrólise de ADP somente a 3,0%. No entanto, a hidrólise de AMP e a atividade da AChE não foram alteradas. A exposição ao etanol a 0,5 e 1,0% diminuiu a hidrólise de ATP e ADP, enquanto que a atividade da AChE apresentou um aumento significativo a 1,0%. Nenhuma alteração foi observada na atividade da ecto-5’- nucleotidase. Etanol in vitro a 0,5 e 1,0% não alterou a hidrólise de ATP, ADP e a atividade da AChE, mas a hidrólise de AMP foi inibida. Acetaldeído in vitro, na faixa de 0,5-1,0%, inibiu a hidrólise de ATP e ADP, mas a hidrólise de AMP e acetiltiocolina foi reduzida a 0,25, 0,5 e 1,0%. Acetato in vitro não alterou a atividade destas enzimas. O tratamento com etanol reduziu os níveis de mRNA para AChE, NTPDase1 as três isoformas de NTPDase2. Estes resultados demonstram que a intoxicação aguda por metanol e etanol pode influenciar as enzimas envolvidas na degradação dos neurotransmissores ATP e acetilcolina, sugerindo que os sistemas purinérgico e colinérgico podem ser alvos para os efeitos neurotóxicos destes álcoois. / Zebrafish (Danio rerio) is a consolidated model system in many research areas, including neuroscience and toxicology. The genome of this specie is almost sequenced and studies have shown that many genes of this specie are similar to mammals, including the human specie. Evidence has shown that nucleotides and nucleosides, mainly ATP and adenosine, exert extracellular signaling effects. In the nervous system, the neurotransmitter ATP is stored in vesicles and released in the synaptic cleft, where can act on specific cellular membrane receptors named purinergic P2 receptors. These receptors are subdivided on ionotropic P2X receptors and metabotropic P2Y receptors. The inactivation of ATP extracellular signaling is mediated by a family of enzymes named ectonucleotidases. This group of enzymes includes NTPDases (nucleoside triphosphate diphosphohydrolases) and ecto-5’-nucleotidase. After the catabolism promoted by ectonucleotidases, the neurotransmitter ATP is hydrolyzed to the neuromodulator adenosine. This nucleoside exerts its effects by the activation of P1 metabotropic receptors. Studies from our laboratory have demonstrated the presence of NTPDases and ecto-5’-nucleotidase in CNS of zebrafish. Furthermore, P2X and P2Y purinoceptors already are described in this specie. Acetylcholine (ACh) is a neurotransmitter secreted by the cholinergic nerve endings and ATP is co-released with ACh. After exerts its signaling on nicotinic e muscarinic receptors, ACh is inactivated through an enzyme named acetylcholinesterase (AChE), that can hydrolyze ACh into choline and acetate. The AChE gene is already cloned and sequenced and this enzyme activity was detected in zebrafish brain. Methanol is a neurotoxic compound responsible for serious damage on CNS. Besides it can be found as an environmental contaminant, this alcohol is also employed as a component of cryoprotector solutions for zebrafish embryos. The effects of acute ethanol consumption promote several changes related to motor coordination, sensory perception and cognition. Ethanol promotes many biochemical and physiological alterations on nervous cells. Therefore, we investigated the in vitro and in vivo effect of alcohols methanol and ethanol on ectonucleotidases and acetilcholinesterase in CNS of zebrafish. After acute treatment, there was a significant decrease of ATP and ADP hydrolysis at 0.5 and 1.0%. However, no significant alteration on ecto-5´-nucleotidase activity was verified in zebrafish brain. A significant inhibition on AChE activity was observed in the range of 0.25 to 1.0% methanol exposure. Four NTPDase sequences were identified from phylogenetic analyses, which one is similar to NTPDase1 and the others to NTPDase2. Methanol was able to inhibit NTPDase1, two isoforms of NTPDase2 and AChE transcripts. Methanol inhibited in vitro ATP hydrolysis at 1.5 and 3.0% and ADP hydrolysis only at 3.0%. Nevertheless, AMP hydrolysis and AChE activity were not changed. Ethanol exposure decreased ATP and ADP hydrolysis at 0.5 and 1.0%, while the AChE activity presented a significant increased at 1.0%. No changes on ecto-5’-nucleotidase activity were observed in zebrafish brain membranes. Ethanol in vitro did not alter ATP, ADP hydrolysis and AChE activity, but AMP hydrolysis was inhibited at 0.5 and 1.0%. Acetaldehyde in vitro, in the range 0.5-1.0%, inhibited ATP and ADP hydrolysis, but AMP and acetylthiocholine hydrolysis were reduced at 0.25, 0.5 and 1.0%. Acetate in vitro did not alter these enzyme activities. Semi-quantitative expression analysis of NTPDase and ecto-5´- nucleotidase was performed. Ethanol treatment reduced AChE, NTPDase1 and three isoforms of NTPDase2 mRNA levels. These results demonstrate that acute methanol and ethanol intoxication may influence the enzymes involved in the degradation of neurotransmitters ATP and ACh, suggesting that the purinergic and colinergic system can be a target to the neurotoxic effects of these alcohols.

SILVA JÚNIOR, M. J. Transformação química do glicerol via catálise heterogênea em fase gás . 2008. 64 f. Dissertação (Mestrado em Química) - Centro de Ciências, Universidade Federal do Ceará, Fortaleza, 2008. / Submitted by Daniel Eduardo Alencar da Silva (dealencar.silva@gmail.com) on 2014-11-26T20:48:56Z No. of bitstreams: 1 2014_dis_mjsjunior.pdf: 1866899 bytes, checksum: 97694276d525e0940241c38b11de4888 (MD5) / Approved for entry into archive by José Jairo Viana de Sousa(jairo@ufc.br) on 2016-03-22T15:42:58Z (GMT) No. of bitstreams: 1 2014_dis_mjsjunior.pdf: 1866899 bytes, checksum: 97694276d525e0940241c38b11de4888 (MD5) / Made available in DSpace on 2016-03-22T15:42:58Z (GMT). No. of bitstreams: 1 2014_dis_mjsjunior.pdf: 1866899 bytes, checksum: 97694276d525e0940241c38b11de4888 (MD5) Previous issue date: 2014 / In order to promote the dehydration/dehydrogenation of reaction of glycerol in a heterogeneous environment, different catalysts were synthesized comprising copper oxide dispersed on different supports: aluminum oxide, aluminum oxide containing iron oxide, aluminum oxide containing niobium oxide and, silicon oxide containing iron oxide. The synthesis route applied was the polymeric precursor method. Acetol was the main reaction production, but other products were observed in low content, such as methanol, ethanol, acrolein, acetone, amyl alcohol, 1-propanol , 1,2- propanediol and 1,3-propanediol. High selectivity for acrolein was observed using the catalyst comprising of copper, iron and aluminum oxides. The effect of calcination temperature on catalyst performance was observed with the catalyst comprising of copper, iron and silicon oxides, and the best results were obtained by calcination at 600 °C. The analysis by X-ray diffraction highlight the preferential formation of CuO phase, iron oxide and aluminum oxide phases were observed even after calcination at 600 °C. The analysis of temperature programmed reduction (TPR) indicate the formation of samples with significant interaction between the oxides, suggesting high dispersion of iron oxide. The reuse test (twice) showed stability in conversion capacity and selectivity. The analyzes carried out by thermogravimetry and infrared spectroscopy, performed after the catalytic test, point to the formation/retention alkoxides on the catalyst surface. / Com o intuito de promover a reação de desidratação/desidrogenação do glicerol em meio heterogêneo, foram sintetizados diferentes catalisadores compostos de óxido de cobre disperso em diferentes suportes: óxido de alumínio, óxido de alumínio contendo óxido de ferro, óxido de alumínio contendo óxido de nióbio, e óxido de silício contendo óxido de ferro. A rota de síntese utilizada foi a dos precursores poliméricos. O principal produto reacional obtido foi o acetol, porém foram observados outros produtos em baixo teor, como: metanol, etanol, acroleína, acetona, álcool amílico, 1-propanol, 1,2-propanodiol e 1,3-propanodiol. Foi observada alta seletividade para acroleína empregando-se o catalisador composto pelos óxidos de cobre, ferro e alumínio. O efeito da temperatura de calcinação sobre o desempenho catalítico foi verificado com o catalisador composto pelos óxidos de cobre, ferro e silício, e melhores resultados foram obtidos através da calcinação em 600°C. As análises por difração de raios-X destacam a formação preferencial da fase CuO, não sendo observadas as fases de óxido de ferro e óxido de alumínio, mesmo após calcinação a 600°C. As análises de redução em temperatura programada (TPR) apontam formação de amostras com significativa interação entre os óxidos, sugerindo elevada dispersão do óxido de ferro. Seu teste de reuso (duas vezes) mostrou estabilidade na capacidade de conversão e na seletividade. As análises realizadas por termogravimetria e a espectroscopia na região do infravermelho, realizadas após o teste catalítico, apontam para a formação/retenção de alcóxidos na superfície do catalisador.