Effect of lanthanum species on the physicochemical properties of La/SAPO-11 molecular sieve

Yuxiang Liu, Xinmei Liu, Lianming Zhao, Yuchao Lyu, Lu Xu, Mark J. Rood, Ling Wei, Zhen Liu, Zifeng Yan

Research output: Contribution to journalArticlepeer-review

Abstract

La/SAPO-11 was synthesized via one-pot method. Lanthanum ions protect framework from distortion under the severe thermal (600 °C, 4 h) and hydrothermal (800 °C, 4 h) conditions. A higher retention of Brønsted acid sites (45.5%) is obtained after hydrothermal treatment. Lanthanum ions enhance the depolymerization of phosphorus species and interaction with phosphorus and aluminum species. In the coexistence of silicon and lanthanum ions, lanthanum ions could not incorporate into zeolite framework. LaPO4preserves framework structure from steam attack. In addition, [La(OH)2]+ions compensate structure tensions and increase the bond strength of Al–O inhibiting the desilication reaction during the thermal treatment. The hydrolyzed species of Si (4Al) and Si (3Al) can be recovered by dehydroxylation. In the cracking reaction of n-dodecane, La/SAPO-11 molecular sieve possessing moderate acid sites enhance isomerization reaction (increasing iso-paraffin by 9.5%) and inhibit cracking. The narrow pore has restriction for di-molecular reactions (e.g., hydrogen transfer reaction).

Original languageEnglish (US)
Pages (from-to)170-184
Number of pages15
JournalJournal of Catalysis
Volume347
DOIs
StatePublished - 2017

Keywords

  • Crystallization
  • DFT
  • Isomerization
  • Lanthanum ion
  • SAPO-11
  • Stability

ASJC Scopus subject areas

  • Catalysis
  • Physical and Theoretical Chemistry

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