A DFT Insight into the Tuning Effect of Potassium Promoter on the Formation of Carbon Atoms via Carburization Gases Dissociation on Iron-Based Catalysts

Catalysts

卷:10

Cheng Cao¹  Haigang Hao¹  Rui Gao¹  Ruiqin Sun¹  Juhui Gong¹  Linxia Cui¹ 

[1] College of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021, China;

关键词: DFT;    Fischer-Tropsch synthesis;    dissociation;    potassium;    iron-based catalyst;   

DOI  :  10.3390/catal10050527

来源: DOAJ

【 摘 要 】

The research of the formation mechanism of iron carbides is significant to design the high-performance catalysts for the Fischer–Tropsch synthesis (FTS) process. In this paper, the effect of potassium promoter on the formation of atomic carbon via carburization gases dissociation on the iron-based catalyst, the C₂H₄, C₂H₂ and CO/H₂ adsorption energies and dissociation paths as well as the rate constants of the corresponding elementary steps are investigated by DFT on the Fe(110), Fe(110)-K₂O, Fe(211) and Fe(211)-K₂O surfaces. The calculation results demonstrated that the K₂O promoter can modify the capabilities of surface C formation via the thermodynamic method as well as the kinetical method. The K₂O promoter can increase the CO adsorption energy while decreasing the C₂H₄ adsorption energy both on Fe(110) and Fe(211) surfaces. Kinetically, via tuning the catalyst surfaces from Fe(110) to Fe(211), the K₂O promoter can inhibit the ability of C₂H₄/C₂H₂ dissociation to atomic carbon, while enhancing the ability of CO/H₂ decomposition to atomic carbon. The C₂H₄/C₂H₂ dissociation rate constants on Fe(211) and Fe(211)-K₂O are about 10⁷ times slower than that on Fe(110) and Fe(110)-K₂O, whereas the dissociation rate constants of CO/H₂ on Fe(211) are about 10⁶ times faster than that on Fe(110), and about 10⁷ times faster on Fe(211)-K₂O than on Fe(110)-K₂O.

【 授权许可】

Unknown