Pyroxene control of H2 production and carbon storage during water-peridotite-CO2 hydrothermal reactions
Pyroxene control of H2 production and carbon storage during water-peridotite-CO2 hydrothermal reactions
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DOI：
10.1016/j.ijhydene.2019.08.161
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发表时间：
2019-10
影响因子：
7.2
通讯作者：
Jiajie Wang;N. Watanabe;A. Okamoto;Kengo Nakamura;T. Komai
中科院分区：
文献类型：
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作者：
Jiajie Wang;N. Watanabe;A. Okamoto;Kengo Nakamura;T. Komai
在富co2热液体系中，通过橄榄石[(Mg,Fe)2SiO4]蛇纹石化和碳酸化，将产氢和co2矿化策略结合起来。然而，天然地幔橄榄岩通常不仅含有橄榄石，还含有正辉石和/或斜辉石，其作用尚不清楚。本研究在0.5 M nahco3溶液中，在300°C和10 MPa条件下，对h2o -橄榄石/正映辉石- co2体系中的反应进行了水热实验。h2h和HCOOH的产率在正吡咯烯的存在下首先受到抑制；而消耗正硝石后，h2产率显著提高。反应开始时，在20%正硝基蒽的存在下，h2收率在120 h时提高到348.3 mmol/kgminera。在高SiO2（aq）浓度体系中，蛇纹石[(Mg,Fe)3Si2O5(OH)4]中掺入了更多的Fe(II)，从而抑制了H2generation。正辉石的存在也极大地加速了蛇纹石的形成。而正辉石的加入抑制了菱镁矿[(Mg,Fe)CO3]的形成，也促进了Fe（II）的释放。因此，含辉石≤20%的橄榄岩比纯橄榄石更适合长期产氢。当考虑水-橄榄岩-二氧化碳系统的反应输出时，控制起始矿物中辉石质的百分比可能比预期的更重要。
Strategies of H2production and CO2mineralization were combined through olivine [(Mg,Fe)2SiO4] serpentinization and carbonation in a CO2-rich hydrothermal system. However, natural mantle peridotites commonly contain not only olivine but also orthopyroxene and/or clinopyroxene, which have effects that are not well understood. The present study investigated the reactions in H2O-olivine/orthopyroxene-CO2systems by performing hydrothermal experiments in 0.5 M NaHCO3solutions at 300 °C and 10 MPa.The yields of H2and HCOOH initially were first suppressed in the presence of orthopyroxene; however, after orthopyroxene consumption, the rate of H2production increased significantly. H2yield increased to 348.3 mmol/kgmineralin 120 h with the presence of 20 wt% orthopyroxene at the beginning of the reaction. The initial suppression of H2generation was due to incorporation of more Fe(II) into serpentine [(Mg,Fe)3Si2O5(OH)4] in the high SiO2(aq)concentration system. The presence of orthopyroxene also dramatically accelerated serpentine formation. In contrast, magnesite [(Mg,Fe)CO3] formation was inhibited upon addition of orthopyroxene, which also contributed to the release of Fe(II). Therefore, peridotite containing ≤20 wt% of pyroxenes is more suitable for long-term H2production than pure olivine. When considering the reaction output of a water-peridotite-CO2system, controlling the percentage of pyroxenes in the starting mineral may be more important than expected.