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- Arvidsson, Adam, 1990, et al.
(författare)
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First-principles microkinetic study of methane and hydrogen sulfide catalytic conversion to methanethiol/dimethyl sulfide on Mo 6 S 8 clusters: Activity/selectivity of different promoters
- 2019
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Ingår i: Catalysis Science and Technology. - : Royal Society of Chemistry (RSC). - 2044-4753 .- 2044-4761. ; 9:17, s. 4573-4580
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Tidskriftsartikel (refereegranskat)abstract
- A large fraction of the global natural gas reserves is in the form of sour gas, i.e. contains hydrogen sulfide (H2S) and carbon dioxide (CO2), and needs to be sweetened before utilization. The traditional amine-based separation process is energy-intensive, thereby lowering the value of the sour gas. Thus, there is a need to find alternative processes to remove, e.g., hydrogen sulfide. Mo6S8 clusters are promising candidates for transforming methane (CH4) and hydrogen sulfide into methanethiol (CH3SH) and dimethyl sulfide (CH3SCH3), which are high-value sulfur-containing products that can be further used in the chemical industry. Here first-principles microkinetics is used to investigate the activity and selectivity of bare and promoted (K, Ni, Cl) Mo6S8. The results show that methanethiol is produced via two different pathways (direct and stepwise), while dimethyl sulfide is formed via a competing pathway in the stepwise formation of methanethiol. Moreover, there is an increase in activity and a decrease in selectivity when adding an electropositive promoter (K), whereas the reverse behaviour is observed when adding an electronegative promoter (Cl). When adding Ni there is also a decrease in activity and an increase in selectivity; however, Ni is acting as an electron donor. The results provide insights and guidance as to what catalyst formulation is preferred for the removal of hydrogen sulfide in sour gas.
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| 2. |
- Taifan, W., et al.
(författare)
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CH4 and H2S reforming to CH3SH and H-2 catalyzed by metal-promoted Mo6S8 clusters: a first-principles micro-kinetic study
- 2017
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Ingår i: Catalysis Science and Technology. - : Royal Society of Chemistry (RSC). - 2044-4753 .- 2044-4761. ; 7:16, s. 3546-3554
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Tidskriftsartikel (refereegranskat)abstract
- Direct processing of sour, e.g. containing large amounts of acidic H2S and/or CO2 molecules, natural gas is of direct interest as vast amounts of it are available and accessible but are underutilized. While sour natural gas is still treated using energy-intensive amine absorption/desorption, here we propose and describe a first step in catalytically producing a value added chemical and energy carrier, CH3SH and H-2, respectively. For this purpose, we performed Density Functional Theory (DFT) and microkinetic modelling of CH4 and H2S reaction pathways to form CH3SH and H-2 as a first step in elucidating complex yet not explored pathways in oxygen-free sour gas reforming. For this purpose, we utilized bare unpromoted and K-or Nipromoted Mo6S8 clusters. CH4 dissociation was found to be the rate-determining step above 1100 K on Ni-promoted Mo6S8 while H-2 formation was the rate-determining step on the bare and K-promoted Mo6S8. At lower reaction temperatures between 800 and 1100 K, CH3SH formation becomes an important step, especially on Ni-Mo6S8. This method presents an interesting route of direct catalytic sour natural gas processing which potentially leads to high-value hydrocarbons, such as ethylene, using CH3SH as a reactive intermediate.
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