thumbnail

Diamond dissolution and the production of methane and other carbon-bearing species in hydrothermal diamond-anvil cells

Geochimica et Cosmochimica Acta

By:
and
DOI: 10.1016/j.gca.2009.07.028

Links

Abstract

Raman analysis of the vapor phase formed after heating pure water to near critical (355-374 ??C) temperatures in a hydrothermal diamond-anvil cell (HDAC) reveals the synthesis of abiogenic methane. This unexpected result demonstrates the chemical reactivity of diamond at relatively low temperatures. The rate of methane production from the reaction between water and diamond increases with increasing temperature and is enhanced by the presence of a metal gasket (Re, Ir, or Inconel) which is compressed between the diamond anvils to seal the aqueous sample. The minimum detection limit for methane using Raman spectroscopy was determined to be ca. 0.047 MPa, indicating that more than 1.4 nanograms (or 8.6 ?? 10-11 mol) of methane were produced in the HDAC at 355 ??C and 30 MPa over a period of ten minutes. At temperatures of 650 ??C and greater, hydrogen and carbon dioxide were detected in addition to methane. The production of abiogenic methane, observed in all HDAC experiments where a gasket was used, necessitates a reexamination of the assumed chemical systems and intensive parameters reported in previous hydrothermal investigations employing diamonds. The results also demonstrate the need to minimize or eliminate the production of methane and other carbonic species in experiments by containing the sample within a HDAC without using a metal gasket.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Diamond dissolution and the production of methane and other carbon-bearing species in hydrothermal diamond-anvil cells
Series title:
Geochimica et Cosmochimica Acta
DOI:
10.1016/j.gca.2009.07.028
Volume
73
Issue:
20
Year Published:
2009
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Geochimica et Cosmochimica Acta
First page:
6360
Last page:
6366
Number of Pages:
7