First-principles microkinetic study of methane and hydrogen sulfide catalytic conversion to methanethiol/dimethyl sulfide on MoS clusters: activity/selectivity of different promoters
A large fraction of the global natural gas reserves is in the form of sour gas, i.e. contains hydrogen sulfide (H 2 S) and carbon dioxide (CO 2 ), and needs to be sweetened before utilization. The traditional amine-based separation process is energy-intensive, thereby lowering the value of the sour...
Saved in:
| Published in | Catalysis science & technology Vol. 9; no. 17; pp. 4573 - 458 |
|---|---|
| Main Authors | , , , |
| Format | Journal Article |
| Published |
27.08.2019
|
| Online Access | Get full text |
Cover
Loading…
| Summary: | A large fraction of the global natural gas reserves is in the form of sour gas,
i.e.
contains hydrogen sulfide (H
2
S) and carbon dioxide (CO
2
), 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. Mo
6
S
8
clusters are promising candidates for transforming methane (CH
4
) and hydrogen sulfide into methanethiol (CH
3
SH) and dimethyl sulfide (CH
3
SCH
3
), 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) Mo
6
S
8
. 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.
A large fraction of the global natural gas reserves is in the form of sour gas,
i.e.
contains hydrogen sulfide (H
2
S) and carbon dioxide (CO
2
), and needs to be sweetened before utilization. |
|---|---|
| Bibliography: | Electronic supplementary information (ESI) available: A zip file with all structures and figures of the reaction mechanism for the K-, Ni-, and Cl-promoted clusters, a free energy landscape, a comparison of the TOF for all clusters, tables with kinetic information, the steady-state coverages, the effect of the diffusion barrier on the TOF and selectivity, a degree of rate control analysis for all clusters, and the projected crystal orbital Hamiltonian populations. See DOI 10.1039/c9cy00375d |
| ISSN: | 2044-4753 2044-4761 |
| DOI: | 10.1039/c9cy00375d |