Syngas Production Using Natural Gas from the Environmental Point of View

The search for clean and low-cost fuels as alternative for petroleum is a popular research focus in the energy field. The demand of natural gas as an energy source has increased steadily. The high H:C ratio and the absence of heteroatoms make natural gas an attractive feedstock for synthetic fuels and chemicals that can replace those that are typically petroleum-derived. The search for efficient routes to convert methane to other higher added-value products is a challenge for the scientific community. In addition, new fields of oil and gas contain associated CO2 (8–18%), and, in some specific fields, the associated gas encloses a higher CO2 content (79%). In this context, the tri-reforming process combines two of the most problematic greenhouse gases (CH4 and CO2) to generate syngas for the synthesis of clean liquid fuels and valuable chemicals. Developments in tri-reforming processes, which include the new catalysts, are presented in this chapter

Mathematical modeling of styrene/divinylbenzene copolymerization comprising diffusional effects and cyclization kinetics

Mathematical Modeling of Styrene/Divinylbenzene Copolymerization Comprising Diffusional Effects and Cyclization KineticsEuropean Commission - Marie Curie Initial Training Networ

Microkinetic modeling of the Water-Gas Shift reaction over cobalt catalysts supported on multi-walled carbon nanotubes

The development of microkinetic models allows gaining an understanding of fundamental catalyst surface phenomena in terms of elementary reaction steps without a priori defining a rate-determining step, yielding more meaningful and physically reliable reaction rates. This work aimed at developing such a microkinetic model that accurately describes the Water-Gas Shift (WGS) reaction, i.e., one of the major routes for hydrogen production, over cobalt (Co) catalysts supported on multi-walled carbon nanotubes (MWCNTs). Co is known for its sulfur-tolerance and the functionalized MWCNT support has exceptional conductivity properties and defects that facilitate electron transfer on its surface. The model was formulated based on a well-known mechanism for the WGS reaction involving the highly reactive carboxyl (COOH*) intermediate. The kinetic parameters were computed by a combination of calculation via theoretical prediction models (such as the Collision and Transition-State theory) and via regression to the experimental data. The derived system of differential-algebraic equations was solved using the DDAPLUS package available in the Athena VISUAL Studio. The developed model was capable of simulating the experimental data (R² = 0.96), presenting statistically significant kinetic parameters. Furthermore, some of the catalyst descriptors in the model have been related to the catalyst properties as determined by characterization techniques, such as the specific surface area (SP = 22,000 m²/kgcat) and the density of active sites (σ = 0.012 molAct.Surf./kgcat). The modelling and characterization efforts allowed identifying the COOH* formation reaction (CO* + OH* → COOH* + *) as the surface reaction with the highest activation energy. Optimal catalyst performance, resulting in a CO conversion exceeding 85%, was simulated at elevated temperatures (350–450 °C) and space times (70–80 kg·s/mol), in agreement with the experimental observations

Assessment of Sugarcane-Based Ethanol Production

This chapter aims to explain how bio-ethanol has been drawn to become a successful alternative to partially replace petroleum as a source of liquid fuels in Brazil. A brief historical analysis about the production of bio-ethanol from sugarcane is presented. The motivation to start the production of the ethanol as biofuel in the 1970s and how the governmental policies have contributed to the ups and downs, successes, and failures of the sugarcane industry is shown. Then, the efficiency of the sector is addressed; firstly, the increasing efficiency of the agricultural sector is discussed, showing how the productivity per hectare has increased in the last decades and which improvements are further expected in a near future. Finally, the industrial process is discussed: the current efficiency in processing sugarcane to produce ethanol and the emerging technologies, not only to process sugarcane juice, but also to harness bagasse, vinasse, and sugarcane straw

Modeling of ethylene oxide reactor: study of thermal parameters and strategies of catalyst dilution.

O trabalho constou de um estudo experimental de transferência de calor em reator de leito fixo e de estudo de simulação matemática do reator industrial. Foi proposto e testado um novo tipo de sensor anelar de temperatura, de fácil construção, que permite filtrar as flutuações aleatórias de temperatura observadas em leitos fixos quando se usam sensores pontuais. Os parâmetros efetivos foram estimados usando-se o modelo bidimensional com dispersão axial. Uma análise de sensibilidade paramétrica deste modelo permitiu explicar o ajuste pobre que o coeficiente de dispersão axial costuma apresentar. Os estudos de simulação do reator de oxidação de eteno mostraram que estrategias de diluição de atividade catalítica do leito podem aumentar a faixa de operação segura do reator, e que a simples mistura de partículas catalíticas e inertes pode, entretanto, levar a ocorrência de pontos quentes localizados. O ajuste de certos parâmetros térmicos e cinéticos do modelo frente a medidas experimentais possibilitou representar adequadamente o comportamento de um reator industrial.Mathematical modeling of fixed-bed catalytic reactor was the main scope of this work. A new type of ring-shaped temperature sensor in experimental studies on fixed-bed heat transfer is proposed. This ring-shaped sensor is easy-to-build and allows to filter randomic temperature fluctuations observed when point sensors are used. Radial effective thermal parameters were estimated by using an axially dispersed bidimensional model. A parametric sensitivity analysis of this model showed that sensitivity to axial thermal dispersion coefficient is very small, a result which explains the poor estimation of this parameter. Simulation studies on ethylene oxide reactor demonstrated that catalyst dilution strategies may extend significantly the reactor operability range by reducing reactor sensitivity. However, when a catalytic bed is diluted by simple mixture of inert and catalytic particles, local hot spots may occur at the agglomerations of active particles. By adjusting some kinetic and thermal parameters the mathematical model could represent adequately the behaviour of an industrial reactor

Mathematical modeling and simulation of biomass gasification process in an moving bed electrothermal reactor.

A gaseificação de Madeira com vapor é baseada na reação entre carbono e vapor de água, a qual é fortemente endotérmica. Nos processos convencionais de gaseificação a energia para esta reação é obtida da combustão de parte do sólido que alimenta o gaseificador. No processo eletrotérmico o calor é suprido pela passage de corrente elétrica entre eletrodos colocados no topo e no fundo do leito. O leito funciona como um aquecedor a resistência. Neste trabalho é desenvolvido um modelo unidimensional estacionário para o gaseificador eletrotérmico de leito móvel. A cinética das reações heterogêneas gás-sólido é descrita pelo modelo de núcleo exposto e a pirólise da Madeira por modelo de equilíbrio. Foi obtido um sistema de equações diferenciais ordinárias de 1ª ordem. A solução foi obtida por um método semi implícito de Runge-Kutta. O modelo é capaz de prever a curva elétrica característica do reator, o perfil de temperature, o consume de Madeira e a produção e composição do gás de síntese. As previsões do modelo são comparadas com dados de planta piloto de gaseificadores eletrotérmicos da Companhia Energética de São Paulo (CESP).Gasification of wood by reaction with steam is based upon the highly endothermic carbon-steam reaction. In the conventional gasification processes, the energy for this reaction is provided by combustion of part of the solid fed to the gasifier. In the electrothermal process heat is supplied electrically by passing current between electrodes placed in the top and botton of bed. The bed works as resistance heater. In this work is developed a one-dimensional steady state model for the moving bed electrothermal gasifier. The kinetics of heterogeneous gas-solid reactions is described by ash segregated model and the wood pyrolysis by equilibrium model. A system of nonlinear ordinary differential equations was obtained. The solution has been undertaken by a semi-implicit Runge Kutta method. The model is capable of predicting the characteristic electric curve, temperature profile, wood consumption and synthesis gas production and composition. Model predictions are compared to available pilot plant data for electrothermal gasifiers from Companhia Energética de São Paulo (CESP)

El rancho indio

Fresco de la rotonda inferior en el vestíbulo del Museo de La Plata. Fotografía c. 200

Incendio de campo y caza de ñandú

Fresco de la rotonda inferior en el vestíbulo del Museo de La Plata. Fotografía c. 200

El rancho indio

Fresco de la rotonda inferior en el vestíbulo del Museo de La Plata. Fotografía c. 200