Pyrolysis mechanism of the n-octane/H2S mixture at 70MPa and 603–623K

Influence of H2S on the thermal cracking of alkylbenzenes at high pressure (70 MPa) and moderate temperature (583–623 K)

“…As previously shown, H 2 S has an acceleration effect on the pyrolysis of butylbenzene. However, the experimental study conducted by Nguyen et al [17] on the n-octane/H 2 S mixture showed an inhibition effect. Thus, the kinetic influence of H 2 S depends on the nature of the hydrocarbon (n-alkane vs alkylaromatic), while the overall kinetics will depend on the competitive contributions of H 2 S vs organo-sulfur compounds.…”

“…Further understanding of the inhibition/acceleration effect induced by H 2 S can be investigated by comparing the results of the n-butylbenzene/H 2 S system to the n-octane/H 2 S system obtained under the same operating conditions [17]. For the n-octane/H 2 S mixture, the inhibition effect of H 2 S increases when the temperature increases.…”

“…For the n-octane/H 2 S mixture, the inhibition effect of H 2 S increases when the temperature increases. A detailed kinetic model for the pyrolysis of the n-octane-H 2 S mixture was previously constructed and validated at 70 MPa, 603-623 K and for durations ranging from 3 to 15 days (conversion up to 15% [17]). This kinetic model has been extrapolated to lower temperature and simulations have been performed using the software package CHEMKIN II [41] and more precisely SENKIN at constant pressure and temperature.…”

“…In experimental studies, much attention has been paid to the formation of H 2 S and sulfur compounds arising from reaction within the water phase or at the interface with the hydrocarbon phase. Very few studies deal with the consequence of a direct reaction of H 2 S on the hydrocarbons ( [14] [15] [16] [17] [18]) within the organic phase or at the oil-gas interface, especially in the absence of TSR conditions. Yet, such information would be of great value since an improved understanding of the fate of H 2 S and organic sulfur compounds would be highly beneficial for petroleum exploration, exploitation of high sulfur petroleum fields, recovery of heavy oil by steam injection, enhanced recovery by gas injection and sequestration of H 2 S in depleted petroleum reservoirs.…”

“…Up to now, published studies about the influence of H 2 S on hydrocarbons concern either oils [18] or pure alkanes (n-octane or n-hexadecane) as model compounds ([14] [15] [16] [17]). The reaction of H 2 S in the presence of an alkane leads to organosulfur compounds that are mostly thiols, thiacycloalkanes and thiophenes, whereas naphthenoaromatic species with 1-3 S atoms are produced during the pyrolysis of oils in the presence of H 2 S. Moreover, it has been shown that H 2 S slightly inhibits the pyrolysis of n-octane at 70 MPa and 603-623 K and this result enabled the construction of a detailed kinetic model [17]. In the conversion range studied, no sulfur naphthenoaromatic species were produced from n-octane, although they are formed from oils.…”