Produção de etilenoglicóis e derivados por reações catalíticas do óxido de eteno

Products resulting from the ethoxylation of hydroxylated compounds, especially water and ethanol, are of great commercial importance. This work presents several aspects concerning the catalytic reactions of ethylene oxide, a chemical substance used in the production of a wide variety of products. Mechanisms of ethoxylation, distribution of products, formation of undesired by-products and perspectives for new processes using heterogeneous catalysis are also reviewed and discussed.

Comparação da eficiência do processo de ozonização e ozonização catalítica (Mn II e Cu II) na degradação de fenol

This paper discusses the results obtained with homogeneous catalytic ozonation [Mn (II) and Cu (II)] in phenol degradation. The reduction of total phenols and total organic carbon (TOC) and the ozone consumption were evaluated. The efficiency in phenol degradation (total phenol removal) at pH 3, with the catalytic process (Mn (II)), increased from 37% to 55% while the TOC removal increased from 4 to 63% in a seven-minute treatment. The ozonation process efficiency at pH 10 was 43% and 39% for phenol and TOC removal, respectively. The presence of both metallic ions (Mn2+ and Cu+2) in the ozonation process resulted in a positive effect.

Aplicação catalítica de peneiras moleculares básicas micro e mesoporosas

Catalysis by solid acids has received much attention due to its importance in petroleum refining and petrochemical processes. Relatively few studies have focused on catalysis by bases and even les on using basic molecular sieves. This paper deals with the potential application of micro and mesoporous molecular sieves in base catalysis reactions. The paper is divided in two parts, the first one dedicated to the design of the catalysts and the second to some relevant examples of catalytic reactions, which find a huge field of applications essentially in the synthesis of fine chemicals. Here, recent developments in catalysis by basic molecular sieves and the perspectives of applications in correlated catalytic processes are described.

Síntese e emprego do ciclometalado [Pd(dmba)(N3)(PPh3)] em processos catalíticos envolvendo a n-carbonilação redutiva de nitroarenos a carbamatos e na síntese de derivados da uréia

This work deals with the use of the cyclometallated compound [Pd(dmba)(N3)(PPh3)] in homogeneous catalytic processes comprising the reductive N-carbonylation of nitrobenzene and p-nitrotoluene to ethyl-phenylcarbamate and ethyl-4-methylphenylcarbamate, respectively. The cyclopalladated compound was also employed in the synthesis of urea derivatives by reacting p-nitrotoluene and m-nitrotoluene, respectively, with p-toluidine and and m-chloroaniline.

Principais aplicações das microondas na produção e refino de petróleo

Microwave irradiation offers a clean, inexpensive, and convenient method of heating, which is an alternative way of introducing energy into chemical systems. In particular, applications of microwave irradiation technology for petroleum processing have been developed in the last twenty years. The main objective of this paper is to review the use of microwave irradiation technology as an alternative technique applied during petroleum refining and primary processing of petroleum fluids, presenting and discussing successful applications of this technology as a tool for petroleum emulsion separation and catalytic reactions normally found at hydrorefining plants.

Nanotecnologia: aspectos gerais e potencial de aplicação em catálise

In recent years nanomaterials, such as metallic nanoparticles, nanowires, nanotapes, nanotubes and nanocomposites, have attracted increasing interest for several technological applications. In catalysis, the great potential of nanomaterials is related to the high catalytic activity exhibited by these materials as a function of the high surface/volume ratio when the particles acquire diameter below 5 nm. In this work, a review about concepts and background of nanoscience and nanotechnology is presented with emphasis in catalysis. Special attention is given to gold nanoparticles and carbon nanotubes, focusing the properties and characteristics of these materials in several catalytic reactions.

Estudo de reações químicas homogêneas via método de Monte Carlo

By using the Monte Carlo simulation platform with probabilistic mathematical functions of the Boltzmann type, , having activation energy and temperature as parameters, it was possible to assess important dynamic aspects of homogeneous chemical reactions of the types A → B and A B. The protocol proved a useful tool in work with the basic concepts of Kinetics and Thermodynamics allowing its application both in class activities and for assisting experimental procedures.

Preferential exposure of certain crystallographic planes on the surface of spinel ferrites: a study by LEIS on polycrystalline spinel ferrite surfaces

Spinel ferrites are commercially important because of their excellent magnetic and catalytic properties. The study by Low Energy Ion Scattering (LEIS) can reveal atomic scale information on the surface. The surface of selected spinel ferrites was investigated by LEIS. It has been found that it is the octahedral sites which are preferentially exposed on the surface of the spinel ferrites. So the probable planes which are exposed on spinel ferrite surfaces are D(110) or B(111). This prediction using LEIS gives scope for tailor-making compounds with catalytically active ions on the surface for various catalytic reactions.

Polimerização de propeno com catalisadores metalocênicos via suportação in-situ utilizando SMAO como suporte

Os catalisadores metalocênicos Me2Si(Ind)2ZrCl2 e Me2Si(2-Me-Ind)2ZrCl2 foram suportados in-situ sobre SMAO e empregados na polimerização de propeno na presença de alquilalumínios tais como TEA, IPRA ou TIBA. Os resultados obtidos demonstraram que o tipo e a concentração de alquilalumínio presente no meio reacional influenciaram tanto a atividade catalítica quanto as propriedades dos polímeros gerados. Os polímeros obtidos com o catalisador suportado in-situ apresentaram propriedades distintas das obtidas no polímero gerado através da polimerização homogênea, além de morfologia controlada, confirmando que de fato a polimerização ocorreu sobre a superfície do SMAO. Através da deconvolução das curvas de GPC foi constatado o aumento do número de tipos de sítios ativos no sistema catalítico suportado in-situ, resultado que também confirmou a heterogeneização do catalisador sobre o suporte. Com o auxílio de cálculos teóricos e da deconvolução das curvas de GPC foi possível propor estruturas para os sítios ativos dos sistemas homogêneo metaloceno/MAO e heterogêneo (suportado in-situ) metaloceno/SMAO/alquilalumínio. Quando eteno foi utilizado como monômero, o comportamento do sistema catalítico metaloceno/SMAO/alquilalumínio suportado in-situ foi distinto do obtido com propeno. O catalisador Me2Si(Ind)2ZrCl2 suportado ex-situ sobre SMAO através de técnicas convencionais de suportação foi avaliado por EXAFS e foi constatado que a vizinhança eletrônica do zircônio é influenciada pela razão Zr/SMAO. Os resultados obtidos por EXAFS foram correlacionados com a variação na atividade catalítica na polimerização de eteno em função da alteração na razão Zr/SMAO.

Síntese de zeólitas tipo ton utilizando um sal de imidazólio como agente direcionador de estrutura

This work reports the synthesis of zeolites with different compositions (pure silica, Si/Ti and Si/Al), via hydroxide and fluoride medium using the cation 1-butyl-3- methylimidazolium as structure directing agent. Initially, the cation was synthesized in chloride form and used for the synthesis in hydroxide medium. An anion-exchange (Cl- for OH-) was required for the synthesis in fluoride medium. Different reactants were used for the formation of gels synthesis, resulting in the crystallization of MFI and TON phases, the latter predominant in many compositions. The cation and synthesized zeolites obtained were characterized by different techniques such as NMR, TG/DTG, XRD, SEM, N2 adsorption and desorption, DRS and EPMA. Besides characterizing the cation and zeolites, the mother liquor of hydroxide synthesis was characterized and it was possible to observe a modification of the cation in the synthesis conditions employed. The materials synthesized in this work can be applied in catalytic reactions and adsorption

Síntese e emprego do ciclometalado [Pd(dmba)(N3)(PPh3)] em processos catalíticos envolvendo a n-carbonilação redutiva de nitroarenos a carbamatos e na síntese de derivados da uréia

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Análise termoquímica de reformador de etanol: produção de hidrogênio para acionamento de uma célula combustível do tipo PEM de 1 KW

Pós-graduação em Engenharia Mecânica - FEG

Estudo das lignanas de Peperomia blanda (Piperaceae): abordagem de aspectos estruturais, metabólitos e biossintéticos

Pós-graduação em Química - IQ

Kinetic study of the co-firing of bagasse-sludge blends

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Automotive diesel engine transient operation: modeling, optimization and control

Traditionally, the study of internal combustion engines operation has focused on the steady-state performance. However, the daily driving schedule of automotive engines is inherently related to unsteady conditions. There are various operating conditions experienced by (diesel) engines that can be classified as transient. Besides the variation of the engine operating point, in terms of engine speed and torque, also the warm up phase can be considered as a transient condition. Chapter 2 has to do with this thermal transient condition; more precisely the main issue is the performance of a Selective Catalytic Reduction (SCR) system during cold start and warm up phases of the engine. The proposal of the underlying work is to investigate and identify optimal exhaust line heating strategies, to provide a fast activation of the catalytic reactions on SCR. Chapters 3 and 4 focus the attention on the dynamic behavior of the engine, when considering typical driving conditions. The common approach to dynamic optimization involves the solution of a single optimal-control problem. However, this approach requires the availability of models that are valid throughout the whole engine operating range and actuator ranges. In addition, the result of the optimization is meaningful only if the model is very accurate. Chapter 3 proposes a methodology to circumvent those demanding requirements: an iteration between transient measurements to refine a purpose-built model and a dynamic optimization which is constrained to the model validity region. Moreover all numerical methods required to implement this procedure are presented. Chapter 4 proposes an approach to derive a transient feedforward control system in an automated way. It relies on optimal control theory to solve a dynamic optimization problem for fast transients. From the optimal solutions, the relevant information is extracted and stored in maps spanned by the engine speed and the torque gradient.