Hydrous pyrolysis of alkanes, alkenes, alcohols and ethers

Volume II: near-field and altered-zone environment report

“…Thermal degradation of diesel fuel is not enhanced in the presence of cementitious material or at alkaline pH. Similarly, diesel fuel hydrous pyrolysis is not catalyzed by FiberCretem or by Topopah Spring Tuff and does not accelerate dissolution of silicate minerals found in these solids at 200"C. These results agree with previous studies that show that water inhiiits the catalytic effects of clay minerals in contact with alkanes, allcenes, alcohols, and ethers (Weres et al, 1988;Tannenbaum and Kaplan, 1985). In a preliminary study, Bell et al (1992) show that acetate decarboxylation reactions are enhanced in the presence of magnetite, hematite, Ca-and Fe-montmorillonite, and nonstoichiometric pyrite, indicating the Fes+ -Fe+ redox couple as an important catalyst.…”

Hydrogen isotope exchange between n-alkanes and water under hydrothermal conditions

“…alkenes is also likely to have occurred, but cannot be assessed due to the lack of concentration data for individual alkene isomers during the experiment and thermodynamic data for nonterminal n-alkenes. Numerous studies have shown that terminal alkene double bonds can migrate internally in aqueous aliphatic hydrocarbons at elevated temperatures and pressures (Hoering, 1984;Weres et al, 1988;Siskin et al, 1990;Simoneit, 1995, 2000;Seewald, 2001aSeewald, , 2001b and it is likely that this process occurred during both experiments. ΣC 5 n-alkene concentrations remain relatively constant or gradually increase with time in both experiments, and are greater than predicted equilibrium values for 1-pentene, suggesting that numerous C 5 n-alkene isomers were present and possibly attained metastable thermodynamic equilibrium with npentane.…”

“…isomerize) to internal positions under acidic conditions at elevated temperatures. Seewald (2001a) observed rapid isomerization of 1-butene to all possible n-butene isomers on timescales of hours at 300°C under PPM-buffered conditions and extensive double bond migration has also been observed during hydrous pyrolysis of C 10 , C 14 and C 16 terminal alkenes, leading to substantial 2 H incorporation when pure 2 H 2 O was used (Hoering, 1984;Weres et al, 1988;Siskin et al, 1990;Simoneit, 1995, 2000). Hydrogenation of internal double bonds would contribute to 2 H/ 1 H exchange on internal C-H bonds in n-alkanes.…”

Pyrolysis of Sedum plumbizincicola, a zinc and cadmium hyperaccumulator: pyrolysis kinetics, heavy metal behaviour and bio-oil production

“…The main compound in this group is Octadecanoic acid (22.3 %, at 650°C) and the group of acids with 18 carbon atoms (30.9 % at 450°C). The presence of acetic acid is specifically attributed to the deacetylation of hemicelluloses (Weres et al 1988). The presence of these carboxylic acids is responsible for the strong acidity of the bio-oil (pH 2.0-3.0).…”

“…These alkanes are possibly generated from the conversion of unsaturated fatty acids in algal cells (Zhou et al 2010) or dehydration of alcohols and ethers (Weres et al 1988).…”