Carbon Dioxide: Problems and Decisions

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作者: Dantiele W.S. Albuquerque, Elisângela S. Costa, Jussara Lopes de Miranda, Rosana Drumond Gonçalves, Luiza Cristina de Moura
摘要: Several compounds are being investigated for CO2 capture, besides alkolamines, including solid materials as activated charcoal, zeolites, metal organic frameworks, metal oxides and hydrotalcites. Hydrotalcites, also called layered double hydroxides (LDHs), present some characteristics that are very interesting for CO2 capture, including their speed to achieve equilibrium and their high regeneration. These compounds can be represented by the general formula [M1-x2+Mx3+(OH)2]x+ [(An-)x/n.yH2O]x, where M2+ and M3+ are divalent metals and trivalent cations, respectively, and An- is an anion of valency n which occupies the interlayer region, and maintains electrical neutrality of these materials. In the present work, we have synthesized specific LDHs, thermally modified for CO2 sorption. LDH’s were synthesized intercalated with carbonate anions employing the heterogeneous precipitation method, also known as co precipitation method. After LDH's calcination at different temperatures, the formation of oxides was observed with different surface areas and therefore a varied adsorption capacity. The products were characterized by X-ray diffraction, infrared absorption spectroscopy and thermo gravimetric analysis. The maximum efficiency of CO2 adsorption was observed at reduced pressure with the calcined sample of LDH-CO3, Mg2Al which indicates that the material maintained stable and with a high crystallinity. These properties presented for LDH-CO3, Mg2Al synthesized in this work indicate that these materials can be good and also cheap candidates for CO2 capture.
作者: Cíntia de Castro Costa, Dulce Maria de Araújo Melo, Antonio Eduardo Martinelli, Maria do Socorro Braga Fontes, Marcus Antônio de Freitas Melo, Joana Maria de Farias Barros
摘要: The CO2 adsorption technology using solid adsorbent shas been considered as a promising approach to reduce CO2 emissions. Therefore, research has been developed to obtain efficient and economically viable adsorbents. The mesoporous materials of the MCM-41 type are among the candidates for effective adsorbents as a result of easy synthesis and structure which favors the flow of gas. The aim of this study was to improve the synthesis of MCM-41 using mixtures of cationic surfactants and apply in CO2 capture. The cationic surfactants used weretetradecyltrimetylammonium bromide (TTMABr - C17H38NBr) and cetyltrimethylammonium bromide (C19H42NBr) and their mixture in a ratio of 1:1. The CO2 adsorption was investigated using the gravimetric method at 298K and pressure varying up to 40 bar. The resulting materials, C17, C19 and C17C19, were characterized by XRD, FTIR, TG and SEM. The results revealed significant differences in the structure of the materials and amount of of CO2 adsorbed.
作者: E. Diego Tachy, C.S. José Andrade, B. Sérgio Neves
摘要: There is a necessity to reduce GHG emission because climate change may have critical consequences in many places around the world. The main gas which causes climate change is CO2 which is released into atmosphere mainly by industries and vehicles. This research aims to compare two technologies for CO2 capture: chemical absorption with membranes, and to present hybrid processes using both of these. A review of the state of art for CO2 capture is used in this research. The capture by absorption with amines is the state of the art for post-combustion because it produces CO2 with higher purity and is cheaper. However, the energy and installation cost are high which does do not encourage its applicability. Membrane for CO2 capture from natural gas is promissory because of this. Thus, researchers have studied other technologies for CO2 capture to replace or add through including hybrid processes. Capture by membrane is a promising technology for this, provided that since it presents appropriate selectivity and permeability. This paper presents a comparison between CO2 capture by absorption with amines and by membranes. The goal is to discuss hybrid processes with these two technologies in series.
作者: Renato Dias Barbosa, Gilberto Marques da Cruz, Pedro Henrique Lopes Nunes Abreu dos Santos, Gilberto Garcia Cortez, José Augusto Jorge Rodrigues
摘要: Chemical-Looping Combustion (CLC) and Chemical-Looping Reforming (CLR) processes are technologies in development, considered as economically viable alternatives for CO2 mitigation. Both processes employ two interconnected reactors (air reactor and fuel reactor), by which oxides particles (called oxygen carriers) circulate. CLC process produces heat with inherent separation of CO2 from gaseous hydrocarbons combustion. CLR process performs the fuel partial oxidation, generating synthesis gas (H2 and CO), which is the major industrial intermediate for hydrogen (H2) and other hydrocarbons production, thru Fischer-Tropsch reactions. The employment of OCs enables the total or partial oxidation of fuel, in the absence of atmospheric air, which allows great reduction of the separation costs. Nickel-based OCs are the most investigated, showing high performance and reactivity. This work presents the synthesis of OCs composed by different contents of nickel oxides supported on alumina, textural, physical and chemical characterizations by several techniques, and experimental results obtained when these materials were applied to CLC and CLR processes, using CH4 as fuel, mixed or not, with H2O or CO2. The results showed the potential industrial applications of these materials, which are preferentially selective to the CLR process, and the addiction of H2O or CO2 greatly reduces the carbon deposition.
作者: Leonardo Hadlich de Oliveira, Joziane Gimenes Meneguin, Edson Antonio da Silva, Maria Angélica Simões Dornellas de Barros, Pedro Augusto Arroyo, Wilson Mantovani Grava, Jailton Ferreira do Nascimento
摘要: In this work, experimental data of CO2 capture by adsorption was determined gravimetrically, at 30 °C and pressures up to 40 bar, and in a fixed bed unit at 20 bar, using NaY as adsorbent. Langmuir, Sips and Tóth isotherm models were used to correlate the equilibrium data. Sips and Tóth models were best fitted allowing estimate the maximum CO2 adsorbed amount. The breakthrough curve was modeled using Linear Driving Force (LDF) and Thomas models. The LDF model represented better the CO2 breakthrough curve than Thomas model. The mass transfer resistance in NaY micropores can be assumed as the limiting step for CO2 adsorption in fixed bed, since the intraparticle mass transfer coefficient of LDF model was smaller than the experimental overall volumetric mass transfer coefficient, although external film resistance is not negligible.
作者: Camilla C.N. de Oliveira, Alexandre Szklo, Pedro R.R. Rochedo
摘要: Cement industry has always been among the largest industrial CO2 emission sources, accounting for 7% of global CO2 emission from stationary sources. CCS technology appears as a major option, in addition to fuel saving and fuel switching measures, able to mitigate CO2 emissions. This study evaluates the potential application of carbon capture in the Brazilian cement sector. Among the CO2 capture technologies studied, the only commercially available for the existing cement plants in Brazil is based on the post-combustion capture route, relying on chemical absorption. To calculate the potential of retroffiting Brazilian cement facilities, it was assumed that the steam and power needed by the capture plant would be generated from a cogeneration plant with natural gas or petroleum coke, or a petroleum coke boiler or even a natural gas boiler would generate steam, and power would be purchased from the grid. Findings indicated an abatement cost hovering between $ 114/tCO2 (in Southeast, South and Midwest of Brazil) and $ 117/tCO2 (in North and Northeast). The gross potential equaled 47 MtCO2/year, being reduced to 31 MtCO2/year after discounting the fraction withouth water availability to implement a carbon capture facility.
作者: José Luiz de Medeiros, Ofélia Queiroz Fernandes de Araújo
摘要: This paper approaches CO2 pipelines operating with high dense compressible flow for Enhanced Oil Recovery (EOR) and/or Carbon Capture & Geological Storage (CCGS). The idiosyncrasies of high pressure CO2 flow are discussed and an appropriate and rigorous steady-state compressible flow pipeline model is disclosed. The model gives three Ordinary Differential Equations (ODE) which result from one-dimensional, one-phase, Mass, Momentum & Energy Balances along the pipeline axial direction. This ODE set is numerically integrated leading to profiles of temperature, pressure and inventory along the pipeline, which are basic for design. An example is explored in the context of a hypothetical EOR CO2 pipeline aligned to the production of CO2 rich natural gas in the Pre-Salt offshore oil and gas fields on the southeast coast of Brazil.
作者: Eric Yuji Yasuda, Erika Tomie Koroishi, Osvair Vidal Trevisan, Euclides José Bonet
摘要: Carbon dioxide (CO2) injection in reservoirs promotes reactions which depend on rock nature, brine composition, partial pressure of CO2, reservoir temperature and pressure among other conditions. The reactions may cause changes in the petrophysics properties, including porosity and permeability, that are important parameters to the fluid flow. The present study focus on the effects of carbonated brine injection in carbonate rocks similar to pre salt reservoirs. The effects are evaluated through the changes of the rock absolute permeability provoked by the acidic action of the injected fluid. Experiments were designed to detail permeability changes along the length of a long carbonate core using using a coreholder equipped with multiple pressure taps. The experiments were conducted in dynamic regime, at the temperature of 22°C and at the mean pressure of 2,000 psi, at flow rates of 0.5; 1 and 2 cc/min. The results show significant permeability alterations at the different segments of the sample, which are also highly dependent on the injection rate.
作者: Adriana Lopes Barros, Eleani Maria da Costa, Natalia Lopes, Juliane Bernardes Marcolino, Martimiano K. Moraes, Rodrigo Soriano Fay
摘要: The performance of SAE 1010, API K55 and API N80 steels were evaluated in terms of resistance to corrosion with the use of two CO2-saturated saline solutions (NaCl and CaCl2, both at the concentration of 0.5 M) and wet supercritical CO2 at a temperature of 90°C under 15 MPa for 07 days. Mass loss tests were performed to determine corrosion rates and the films of corrosion product evaluated by scanning electron microscopy and potentiodynamic polarization technique. Lower corrosion rates were obtained in a wet supercritical CO2 medium. The degree of protection offered by corrosion products films depended not only on the steel but also on the corrosive medium and kind of salt present.