Fluoride-free synthesis of mesoporous [Al]-[B]-ZSM-5 using cetyltrimethylammonium bromide and methanol-to-olefin activity with high propene selectivity


Yalcin B. K. , İpek Torun B.

APPLIED CATALYSIS A-GENERAL, vol.610, 2021 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 610
  • Publication Date: 2021
  • Doi Number: 10.1016/j.apcata.2020.117915
  • Title of Journal : APPLIED CATALYSIS A-GENERAL

Abstract

Large ZSM-5 crystals containing [B]-sites and mesopores with 2.5 nm pore sizes are synthesized in a fluoride-free, low OH- medium using cethyltrimethylammonium bromide as mesoporogen and 1,6-diaminohexane as structure directing agent. Absence of extra-framework Al sites and low concentrations of silanol sites are evidenced by Al-27 MAS-NMR and in-situ FTIR analysis. The low-defect containing [Al]-[B]-ZSM-5 (Mes-[Al]-[B]-ZSM-5) is evaluated for catalyzing the methanol-to-olefins reaction and found to result in low coke formation (4.1 mg g(-1) h(-1)) and very low alkane and aromatic formation rates. The propene to ethene ratio of 4.3 observed using Mes-[Al]-[B]-ZSM-5 is found to be superior to that (1.9) of a nano-sized [Al]-[B]-ZSM-5 (crystal sizes around 36 nm). Small particle sizes for nano-sized [Al]-[B]-ZSM-5 is found to be effective for supplying a higher coke tolerance, but insignificant for olefin product selectivity.