Adsorption of Hydrogen Gas and Redox Processes in Clays

详细信息    查看全文

• 作者：Mathilde Didier ; Laura Leone ; Jean-Marc Greneche ; Eric Giffaut ; Laurent Charlet
• 刊名：Environmental Science & Technology (ES&T)
• 出版年：2012
• 出版时间：March 20, 2012
• 年：2012
• 卷：46
• 期：6
• 页码：3574-3579
• 全文大小：293K
• 年卷期：v.46,no.6(March 20, 2012)
• ISSN：1520-5851

文摘

In order to assess the adsorption properties of hydrogen gas and reactivity of adsorbed hydrogen, we measured H₂(g) adsorption on Na synthetic montmorillonite-type clays and Callovo-Oxfordian (COx) clayrock using gas chromatography. Synthetic montmorillonites with increasing structural Fe(III) substitution (0 wt %, 3.2 wt %, and 6.4 wt % Fe) were used. Fe in the synthetic montmorillonites is principally present as structural Fe(III) ions. We studied the concomitant reduction of structural Fe(III) in the clays using ⁵⁷Fe M枚ssbauer spectrometry. The COx, which mainly contains smectite/illite and calcite minerals, is also studied together with the pure clay fraction of this clayrock. Experiments were performed with dry clay samples which were reacted with hydrogen gas at 90 and 120 掳C for 30 to 45 days at a hydrogen partial pressure close to 0.45 bar. Results indicate that up to 0.11 wt % of hydrogen is adsorbed on the clays at 90 掳C under 0.45 bar of relative pressure. ⁵⁷Fe M枚ssbauer spectrometry shows that up to 6% of the total structural Fe(III) initially present in these synthetic clays is reduced upon adsorption of hydrogen gas. No reduction is observed with the COx sample in the present experimental conditions.