期刊
CHEMICAL ENGINEERING JOURNAL
卷 446, 期 -, 页码 -出版社
ELSEVIER SCIENCE SA
DOI: 10.1016/j.cej.2022.137169
关键词
Ethylene-to-propylene; Propylene production; Olefin interconversion; SSZ-13; Phosphorus modification; Intracrystalline diffusivity
资金
- Korea Research Institute of Chemical Technology (KRICT)
- R&D Convergence Program of MSIP (Ministry of Science, ICT and Future Planning)
- NST (National Research Council of Science & Technology) of Republic of Korea [CRC-14-1-KRICT]
To improve the catalytic activity of the ethylene-to-propylene (ETP) reaction for propylene production, a phosphorus-modified SSZ-13 zeolite catalyst was prepared. The phosphorus species weakened the acidity of the zeolite and partially blocked the pores, leading to increased propylene selectivity and yield.
A highly selective means of producing propylene via the ethylene-to-propylene (ETP) reaction is required to manage the supply-demand balance of light olefins. To improve the catalytic activity of the ETP reaction, a phosphorus-modified SSZ-13 zeolite (P-SSZ-13) was prepared by introducing phosphorus to the SSZ-13 zeolite via a simple impregnation method. The P-SSZ-13 catalyst exhibited increased propylene selectivity and yield compared to the pristine catalyst. According to solid-state NMR spectroscopy and STEM-EDS observation, the phosphorus species were mainly located on the outer part of the crystal as a form of polyphosphate. To reveal the effect of the phosphorus loading on the enhancement of ETP reactivity, a series of surface-modified SSZ-13 catalysts were prepared and investigated. It was found that the polyphosphate species in the P-SSZ-13 catalyst not only weakened the acidity of the zeolite by bonding with the framework aluminum species but also reduced the diffusion out of the relatively large-sized hydrocarbon species by partially blocking the pore mouths. The change in the diffusivity of the hydrocarbons over the SSZ-13 catalysts also affected the ETP reactivity. The relationship between the amount of phosphorus and the ETP reactivity of the P-SSZ-13 catalysts could also be clearly demonstrated in terms of the change in both acidity and intracrystalline diffusivity. Moreover, 13C MAS NMR measurement with isotopic switch experiment confirmed the alkyl naphthalene-based hydrocarbon pool mechanism over the P-SSZ-13 for the ETP reaction.
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