Mineral sequestration of carbon dioxide in San Carlos olivine: An atomic level reaction study.

摘要

Since the late 19th century, atmospheric carbon dioxide (CO2) levels have been steadily on the rise. Approximately one third of all human emissions come from fossil fuel power plants. As countries become more dependent on electrical energy and bring on line new power plants, these atmospheric CO2 levels will continue to rise, generating strong environmental concern. Potential avenues to address this problem convert the CO2 from the gaseous phase to a liquid, supercritical fluid, or solid state and store it. Oceans, subsurface reservoirs such as depleted oil fields, and terrestrial carbon pools have all been suggested. The essential problem with all of these possible solutions is the issue of permanency.; Mineral sequestration of CO2 is a candidate technology for reducing the amount of anthropogenic CO2 that is being released into the atmosphere. Olivine (e.g. forsterite, Mg2SiO4) is a widely available mineral that reacts with CO2 to form magnesite (MgCO3) and silica (SiO2). Magnesite is capable of immobilizing CO2 over geological time periods. Thus the issue of permanency has been addressed.; The most promising mineral sequestration process developed to date is aqueous solution mineral carbonation. The solid/aqueous solution reaction interface provides insight to the mechanisms that govern the carbonation reactivity of olivine. Study of these mechanisms at the atomic level is critically important to facilitate engineering new processes that will enhance the reactivity of olivine with CO2 bearing media and to lower process costs.; The study of the olivine carbonation reaction herein can be divided into three separate areas of research. The first area is a comprehensive study of olivine under conditions of electron irradiation. Analyzing radiation damage is critical to the verification and reliability of data collected from the samples using electron beam techniques. The next area of research is the analysis of the reaction layer composition and structure using High Resolution Electron Microscopy (HREM), Scanning Electron Microscopy (SEM), Scanning Transmission Electron Microscopy (STEM), Electron Energy Loss Spectroscopy (EELS), and Energy Dispersive Spectroscopy (EDS). And finally a model describing the reaction mechanism and diffusion processes involved in the reaction will complete the research. Experiments using Secondary Ion Mass Spectroscopy (SIMS) aide in determining the chemical gradients of the reaction layer that will be used in the model.; The goal of the research is to provide a comprehensive analysis of the olivine carbonation reaction layer to aide in the development of designing an economically viable process for the mineral sequestration of carbon dioxide.