Effects of general zero-valent metals power of Co/W/Ni/Fe on hydrogen production with H 2 S as a reductant under hydrothermal conditions

Effects of Metals and Ni3S2 on Reactions of Sulfur Species (HS–, S, and S2O32–) under Alkaline Hydrothermal Conditions

“…Furthermore, in the case of adding Co, Ni, and Ni 3 S 2 , there was no S 2 O 3 2– species detected, indicating these materials would promote the transformation of S 2 O 3 2– or inhibit its formation. In the case of adding W and Ni 3 S 2 , there was an increase in SO 3 2– , which was also found by our previous research in the Hastelloy alloy lined reactor . Besides, two unknown peaks (peaks 5 and 6 in Figure , possibly attributed to S 3 O 6 2– , S 2 O 8 2– , or S 4 O 6 2– ) were found in the electropherograms of liquid samples after the reactions in the case of adding W and Hastelloy alloy, suggesting that HS – was oxidized into new sulfur oxyanions due to their presence.…”

“…However, Fe would enhance the formation of polysulfides by reacting with HS – . In sum, the difference of the distribution of sulfur oxyanions (S 2 O 3 2– , SO 3 2– , and SO 4 2– ) from HS – at 250 °C between the case of adding metals and Ni 3 S 2 and the case of blank solution is not so distinctive as the results obtained at 300–350 °C. ,, The different reaction temperatures may account for the distinction of results, since hydrothermal water exhibited great changes of physical and chemical properties from 250 to 350 °C …”

“…As pointed out above, the formation of a little amount of S 2 O 3 2– , SO 4 2– , and SO 3 2– can be partly attributed to the setup of experiments including analysis procedure. Another reason for this was the oxidation of HS – by water via eq that can also lead to formation of a sulfur oxyanion. − , One method of evaluating the extent of oxidation of HS – by water is to determine the hydrogen production via eq . Our previous research showed that considerable hydrogen amount (H 2 /HS – : 1.7) can be produced in the Hastelloy C-276 lined reactor at 300 °C for 2 h and the addition of Ni 3 S 2 would increase the hydrogen production (H 2 /HS – : 2.6).…”

Temperature- and pH-dependent mechanism of hydrogen production from hydrothermal reactions of sulfide

“…This present study was designed to confirm the effect of temperature proposed in our previous work and to observe the influence of pH on hydrogen production by examining reaction at 230e320 C and corresponding saturated vapor pressures at pH values of 9e13, specifically in case of using Hastelloy C-22 reactor due to the possible catalytic effect of the reactor wall [17]. It should be noted that the other possible hydrogen production due to sulfidation of nickel (Ni) and cobalt (Co) from the reactor wall [17] is expected to be negligible, because the reported amounts of hydrogen produced by adding 1 mmol Ni and Co powders were only approximately 0.2 mmol and 0.8 mmol, respectively, despite of the considerable amounts of the metal powders. The reaction mechanism of hydrogen production and the effects of pH and temperature are described based on analysis results.…”

Reservoir souring: sulfur chemistry in offshore oil and gas reservoir fluids

“…The presence of ferric ion promotes the oxidation of trithionate at pH near to neutral Zhang et al 2011). …”