利用二氧化碳合成片钠铝石的实验条件及其固碳意义

    Experimental conditions and carbon sequestration significance of synthesizing dawsonite using CO2

    • 摘要: 二氧化碳的矿物捕获是最持久、最稳定的地质封存形式。片钠铝石作为一种天然的CO2示踪矿物,其形成与CO2注入密切相关,也是CO2地质封存的重要固碳矿物。片钠铝石在地质背景中大量稳定存在的条件是制约CO2矿化捕获的关键问题,也是寻找CO2地质埋藏地点的重要影响因素。为了探索利用CO2快速合成片钠铝石的条件,对温度(100/120/140/160/180/200 ℃)、pH(8.5/9/9/9.5/10/10/10.5)和反应时间(6/12小时)三个主要影响因素进行了比较实验,并基于扫描电镜、X射线衍射分析阐明了合成片钠铝石的最佳条件。实验表明:在pH 8.5~10.5和温度100~180 ℃的范围内,产物均为纯片钠铝石,合成量随pH和温度的升高呈先增加后减少的趋势,在200 ℃的温度下,片钠铝岩的结晶度降低,拟薄水铝石的含量增加。延长反应时间对产品质量没有明显的促进作用,在200 ℃下延长反应时间反而会加速片钠铝石的溶解。总的来说,140 ℃和pH 9.5是CO2合成片钠铝石的最佳条件,也可能是地质封存二氧化碳的理想条件。

       

      Abstract: Mineral trapping of CO2 is the most durable and stable form of geological storage. As a natural CO2 tracer mineral, the formation of dawsonite is closely related to CO2 infusion, and it also be an important carbon fixation mineral for CO2 geological storage. The condition of massive and stable presence of dawsonite in geological background is a key issue that constrains the CO2 mineralization capture, and is also an important influencing factor in the search for CO2 geological burial sites. To explore the conditions for the rapid synthesis of dawsonite with CO2, we conducted comparative experiments for three main influencing factors of temperature (100/120/140/160/180/200 ℃), pH (8.5/9/9.5/10/10.5), and reaction time (6/12 h). Based on scanning electron microscopy, X-ray diffraction analysis was conducted to clarify the optimal conditions for the synthesis of dawsonite. The experiments suggested that in the range of pH 8.5–10.5 and temperature 100–180 ℃, the products were all pure dawsonite, and the synthesis amount showed a trend of increasing and then decreasing with the increase of pH and temperature. At 200 ℃, the crystallinity of dawsonite decreased and the content of pseudo boehmite increased. The prolongation of reaction time did not have an obvious promotion effect on the quality of the products, and the prolongation of reaction time at 200 ℃ would accelerate the dissolution of dawsonite instead. Overall, 140 ℃ and pH 9.5 are the best conditions for the synthesis of dawsonite from carbon dioxide and probably the ideal conditions for geological sequestration of carbon dioxide.

       

    /

    返回文章
    返回