Computational model of dihydrogen sulfide adsorption

S. SIMONETTI, D. DAMIANI, G. BRIZUELA, A. JUAN

Santa Marta, Colombia

Congreso; CLACSA XIII: Congreso Latinoamericano de Física de Superficies y sus Aplicacioens; 2007

Since natural gas is essentially odorless, natural gas distribution companies odorize the gas prior to distribution to residential, commercial and industrial facilities. In most cases, odorizing is performed using substances which contain sulfur (mercaptans, sulfides or thiophane). Without these critical components, the safety could not be assumed.   The use of scents in the natural gas is not exempt of problems. One specific problem is the fade of the odor. Odor-fading can occur by catalytic effects. Therefore, the odorant adsorption study on solid surfaces can afford important dates to elucidate this problem. The electronic structure of H2S molecular adsorption on FeOOH(110) (goethite is a common Fe oxide associated with corroded surfaces) has been studied by ASED-MO cluster calculations. We have analyzed the horizontal and the perpendicular H2S molecular adsorption. The rotation in the plane was also considered. The calculations show that the selected surface zone offers a place for several possible geometrical H2S adsorption configurations. The most stable configuration results to be the flat non rotated molecule on goethite surface. For this configuration, the S-H(goethite) is the major interaction with OP values of 0.199 at the distance of 1.90 Å. There is also a H(H2S)-Fe small interaction. The interaction mainly involves Fe 3dx2-y2 atomic orbitals with lesser participation of the rest Fe atomic orbitals. There is an electron transfer of 0.31 e- to the Fe atom from the H(H2S) atom. On the other hand, there is an electron transfer of 0.02 e- from the S atom to H(goetithe) atom. No others important OP values have been obtained for the studied configuration.