The direct oxidation of hydrogen sulphide over activated carbons prepared from lignite coal and biochar

Abstract

Physically (steam) and chemically (KOH) activated carbons prepared from Luscar coal and biochar were used for removal of low concentrations of hydrogen sulphide (1 mol%) in methane. A modification method including acid treatment and thermal desorption in an inert atmosphere was used and the effects of this modification on the porous structure, surface chemistry, and ash content were studied. It increased total pore volume of activated carbons prepared from coal and biochar by 43% and 11%, respectively. Acid treatment changed the surface chemistry of activated carbons. Also, thermal desorption removed most of the acidic groups, especially carboxylic groups. The break-through times corresponding to 80% removal of H 2 S using modified activated carbons prepared from coal and biochar were increased to 102 and 131 min, respectively. Also, the production of SO 2 as an undesirable by-product was less than 1.9% of H 2 S fed into the reactor.Les charbons activés physiquement (vapeur) et chimiquement (hydroxyde de potassium) et préparésà partir de charbon de Luscar et de charbon de bois ontété utilisés pouréliminer les faibles concentrations d'acide sulfhydrique (1 mol%) dans le méthane. Une méthode de modification comprenant un traitement acide et une thermodésorption dans une atmosphère inerte aété utilisée et les effets de cette modification sur la structure poreuse, la composition chimique superficielle et la composition des cendres ontétéétudiés. Cette méthode augmente le volume total des pores des charbons activés préparésà base de charbon de Luscar et de charbon de bois de 43% et 11%, respectivement. Un traitement acide a modifié la composition chimique superficielle des charbons actifs. La thermodésorption aégalementéliminé la plupart des groupes acides, et plus particulièrement les groupes carboxyliques. En utilisant les charbons activés modifiés préparésà base de charbon de Luscar et de charbon de bois, les durées de pénétration correspondantà 80% de l'élimination du H 2 S sont passées respectivementà 102 et 131 min. De plus, la production de SO 2 comme sous-produit indésirable correspondaità moins de 1,9% du H 2 S alimentant le réacteur.

Biochar’s role as an alternative N-fertilizer: ammonia capture

“…However, the actual chemical make-up of the surface groups on black carbon materials can exert more direction over chemical sorption than the previously mentioned physical parameters (Ania et al 2007;Biniak et al 1997;Fletcher et al 2007;Franz et al 2000;Hina et al 2010;Mattson et al 1969;Pereira et al 2003;Pesavento et al 2003;Qiu et al 2008;Uchimiya et al 2011). Only a limited number of recent studies (e.g., Azargohar and Dalai 2011;Cheng et al 2006;Chun et al 2004;Hina et al 2010;Mukherjee et al 2011;Nguyen et al 2008;Qiu et al 2009;Singh et al 2010;Zhou et al 2010) have characterized groups responsible for surface acidity. The composition of the surface groups is an important characteristic for the successful implementation of black carbon materials as a soil amendment at field scales, and could aid in understanding the aged or delayed response to biochar amendments occasionally observed (Ascough et al 2011;Cheng et al 2008;.…”

Removal of Hydrogen Sulfide from Gas Streams Using Porous Materials: A Review

“…Nonspecific physisorption involved weak van der Waals’ forces while the chemisorption of H 2 S by functional groups present on the activated carbon can convert it to elemental sulfur or sulfur oxide in the presence of oxygen. The adsorption performance of activated carbons is highly controlled by their surface chemistry which is originally attributed to the content of ash and some elements presented such as oxygen, nitrogen, and sulfur . In a density functional theory (DFT) study, the role of various oxygen groups on the H 2 S adsorption on the AC surface was investigated .…”

Effectiveness and mechanisms of hydrogen sulfide adsorption by camphor-derived biochar

“…The primary sources of H 2 S in the atmosphere are manmade fiber production, natural gas purification, sulfur dyes, petroleum refining, gas production, sewage treatment, paper manufacturing, and other production processes (Latos et al, 2011;Lebrero et al, 2011). Any exposure to concentrations exceeding 500 ppm results in a loss of consciousness and can be fatal (Azargohar and Dalai, 2011). H 2 S removal from gas has been the subject of a great deal of research due to the restrictive emission standards that are implemented worldwide (Xiao et al, 2008).…”