Synthesis of Graphite and Hydrocarbons by Reaction between Calcite and Hydrogen

Abstract

The reaction of calcite with hydrogen was investigated over a range of pressure, temperature, and time. The reaction initiates at about 500 degrees C. Its primarily temperature-dependent rateproceeds in a crystallographically anisotropic manner, and reaction products are CaO, Ca(OH)(2), H(2)O, CO, CH(4), C2H(6), and C (graphite), plus a black solid residue that may be hydrocarbon.

Hydrogenation of Inorganic Metal Carbonates: A Review on Its Potential for Carbon Dioxide Utilization and Emission Reduction

“…Giardini and Salotti from the University of Georgia, USA, were the first to report on reactions between mineral calcite, dolomite, and siderite with pressurized hydrogen and the concomitant formation of hydrocarbons 11, 45, 46. The primary purpose of their study was to address geological issues, such as the formation of hydrocarbons from inorganic sources occurring in the earth's crust.…”

“…Giardini and Salotti reported the formation of CH 4 and ethane (C 2 H 6 ) through heating (693–1243 K) of calcite and dolomite under a pressurized hydrogen atmosphere (0.7–80 MPa H 2 ); however, it was not comprehensible whether the pure minerals were used or if the reaction was catalytically accelerated 11, 45, 46, 47. In their main publication,11 they stated that metallic Ni, Pt, Cu, Ti, Mg, and Fe; commercial mixtures of 0.5 % Pd, Pt, Rh on alumina and dried silica gel; activated alumina; hematite, magnetite; chromic oxide; chromium trioxide; and Kieselguhr mixtures were added, but no precise information was given on the type of catalyst for individual experimental data.…”

“…The reaction kinetics were thus expected to fit the uncatalyzed hydrogenation of calcite. Due to high initial hydrogen concentrations relative to calcite, the reaction kinetics simplified to pseudo‐first‐order kinetics, with an activation energy of 75 kJ mol −1 at 14 MPa 45. Hydrogenation of calcite started at 773 K. It was primarily dependent on temperature and secondarily dependent on pressure and time and proceeded in a crystallographically anisotropic manner.…”

Microbial hydrocarbon gases in the Witwatersrand Basin, South Africa: Implications for the deep biosphere

“…Subsequently abiogenic hydrocarbon gases similar to those first identified at Kidd Creek have been described at four other Precambrian Shield sites in Canada and South Africa (Sherwood Lollar et al, 2002a). Potential mechanisms for abiogenic gas synthesis include: surface-catalyzed polymerization from reduction of CO in the Fischer-Tropsch synthesis (Anderson, 1984); heating or metamorphism of graphite-carbonate-bearing rocks (Giardini and Salotti, 1968;Holloway, 1984); or other vapor-water-rock alteration reactions in the presence of catalytically active metals (McCollom and Seewald, 2001). Confirmation of the exact mechanism responsible for the gases in the Ventersdorp lavas is not possible at this point, but with the exception of serpentinization any of the above processes are feasible in this geologic environment.…”

Isotopic signatures of CH4 and higher hydrocarbon gases from Precambrian Shield sites: A model for abiogenic polymerization of hydrocarbons

“…Over the past decade however, there has been a growing body of literature that indicates that not all abiogenic gases are mantle-derived. A variety of water-rock interactions have been shown to produce CH 4 , as well as higher hydrocarbons gases, by reactions such as surface-catalyzed polymerization from reduction of CO or CO 2 in a FischerTropsch-type synthesis (Anderson, 1984;Szatmari, 1989;Horita and Berndt, 1999;Foustoukos and Seyfried, 2004;McCollom and Seewald, 2006;Taran et al, 2007;Proskurowski et al, 2008); heating or metamorphism of graphite-or carbonate-bearing rocks (Giardini and Salotti, 1968;Holloway, 1984;Kenney et al, 2002;McCollom, 2003); and other gas-water-rock alteration reactions associated with serpentinization (McCollom and Seewald, 2001;Kelley et al, 2001Kelley et al, , 2005Charlou et al, 2002). Significantly, several experimental studies have demonstrated that production of abiogenic hydrocarbons by these types of water-rock interactions can result in d 13 C values as depleted as À57&, well within the range of isotopically ''light" values that were once assumed to be an indication of biological activity (Szatmari, 1989;Yuen et al, 1990;Hu et al, 1998;Horita and Berndt, 1999;McCollom and Seewald, 2006;Taran et al, 2007).…”