Carbon sequestration via aqueous olivine mineral carbonation:: Role of passivating layer formation
Carbon sequestration via aqueous olivine mineral carbonation:: Role of passivating layer formation
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DOI：
10.1021/es0523340
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发表时间：
2006-08-01
影响因子：
11.4
通讯作者：
Wolf, George H.
中科院分区：
文献类型：
--
作者：
Bearat, Hamdallah;McKelvy, Michael J.;Wolf, George H.
通过广泛使用的低成本矿物（如橄榄石）的碳酸化作用来封存二氧化碳，可以以环境友好和地质稳定的形式永久处置二氧化碳。我们报告的机制，限制水橄榄石碳酸化反应的最佳封存反应条件下观察到的研究结果：1 M NaCl + 0.64 M NaHCO3在T约185 C和P CO2约135巴。反应限制富硅钝化层（PL）在原料颗粒上形成，减缓碳酸盐形成并提高工艺成本。的钝化层的形态和成分进行了研究，使用扫描和透射电子显微镜和原子级建模。反应后分析原料颗粒，回收搅拌高压釜实验在1500 rpm，提供了明确的证据，局部机械去除（碎裂）的PL材料，表明颗粒磨损。这是证实了我们的观察，碳酸化显着增加固体颗粒浓度在搅拌实验。多相流体力学计算与实验相结合，以更好地了解相关的浆体流动的影响。反应区的大规模原子级模拟表明，PL具有“玻璃状”，但高度缺陷的SiO2结构，可以允许扩散的关键反应物。减轻钝化层的有效性对于增强碳酸化和降低封存过程成本是至关重要的。
CO2 sequestration via carbonation of widely available low-cost minerals, such as olivine, can permanently dispose of CO2 in an environmentally benign and a geologically stable form. We report the results of studies of the mechanisms that limit aqueous olivine carbonation reactivity under the optimum sequestration reaction conditions observed to date: 1 M NaCl + 0.64 M NaHCO3 at T approximate to 185 C and P CO2 approximate to 135 bar. A reaction limiting silica-rich passivating layer (PL) forms on the feedstock grains, slowing carbonate formation and raising process cost. The morphology and composition of the passivating layers are investigated using scanning and transmission electron microscopy and atomic level modeling. Postreaction analysis of feedstock particles, recovered from stirred autoclave experiments at 1500 rpm, provides unequivocal evidence of local mechanical removal ( chipping) of PL material, suggesting particle abrasion. This is corroborated by our observation that carbonation increases dramatically with solid particle concentration in stirred experiments. Multiphase hydrodynamic calculations are combined with experiment to better understand the associated slurry-flow effects. Largescale atomic-level simulations of the reaction zone suggest that the PL possesses a "glassy" but highly defective SiO2 structure that can permit diffusion of key reactants. Mitigating passivating layer effectiveness is critical to enhancing carbonation and lowering sequestration process cost.