Synthesis and characterization of aluminium containing CIT-1 and their structure-property relationship to hydrocarbon trap performance

Thomas Mathew, S. P. Elangovan, Toshiyuki Yokoi, Takashi Tatsumi, Masaru Ogura, Yoshihiro Kubota, Atsushi Shimojima, Tatsuya Okubo

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

The present work focuses on the synthesis of Al-CIT-1 by various post-modification procedures of B-CIT-1 and their structure-property relation to hydrocarbon trap performance. Al substitution in B-CIT-1 was carried out by three different post-modification procedures, viz., direct exchange (Al-CIT-1_DEX), insertion (Al-CIT-1_INS), and impregnation (Al-CIT-1_IMP), and characterized in detail by various physico-chemical techniques such as XRD, N2 adsorption, SEM, NH3-TPD, XPS, and solid state 27Al and 29Si MAS NMR. The Al-CIT-1 samples were tested for their adsorption-desorption characteristics of toluene, and 2,2,4-trimethylpentane (2,2,4-TMP) to understand the Al distribution in CIT-1 as well as the efficacy of these materials as hydrocarbon traps. The Al distribution in Al-CIT-1 plays a critical role in the adsorption-desorption characteristics of toluene and 2,2,4-TMP. Al-CIT-1 with high relative proportion of framework Al and less extraframework Al (Al-CIT-1_DEX) showed maximum toluene and 2,2,4-TMP adsorption capacity. The presence of finely distributed extraframework Al2O3 species in Al-CIT-1_INS modify the pores and causes a slow release of toluene during desorption. Al-CIT-1_IMP with less Al content and acidity showed the lowest toluene desorption temperature. Large amount of surface Al species hinder a relatively bulky molecule 2,2,4-TMP to access the available active sites of tetrahedral Al and the associated Brφ{symbol}nsted sites in the zeolite, and as a result, Al-CIT-1_INS showed hardly any adsorption towards 2,2,4-TMP. Thus, by varying the post-modification method and treatment condition, it is possible to tune the performance of Al incorporated CIT-1 as a useful material for hydrocarbon trap.

Original languageEnglish
Pages (from-to)126-135
Number of pages10
JournalMicroporous and Mesoporous Materials
Volume129
Issue number1-2
DOIs
Publication statusPublished - 2010 Apr 1

Keywords

  • CIT-1
  • CON topology
  • Hydrocarbon trap
  • Vehicle emission
  • Zeolites

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials

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