Shape selectivity in linear paraffins hydroconversion in 10-membered-ring pore zeolites

Douglas Romero, Roderigh Rohling, Lingqian Meng, Marcello Rigutto, Emiel J.M. Hensen (Corresponding author)

Research output: Contribution to journalArticleAcademicpeer-review

2 Citations (Scopus)

Abstract

Pd/zeolite-catalyzed hydroconversion of n-hexadecane (n-C16) and n-heptane (n-C7) was studied for 10MR (ZSM-5, ZSM-22), 12MR (ZSM-12), and EMM-23 (21MR × 10MR) zeolites. The catalytic activity depended on the Brønsted acidity and the crystalline domain size. n-C16 hydroconversion benefited from short diffusion lengths in ZSM-5 nanosheets compared to bulk ZSM-5. In general, over-cracking is dominant in ZSM-5 with a cracked product distribution skewed to C4 products, to be explained by a snug fit of particular dibranched isomers at zeolite intersections. This effect is less pronounced for the 1D 10MR pores in ZSM-22, which lacks intersections. Although large pores in ZSM-12 offer relatively high activity, those in EMM-23 do not. Based on selectivity patterns, EMM-23 behaves like ZSM-5, probably because of the trilobe shape of its 21MR pores acting as 10MR pores. Only ZSM-12 offers operation in the ideal hydrocracking regime, in the sense of impediments neither by hydrogenation nor by diffusion. Faster intrazeolite diffusion of n-C7 in comparison to n-C16 leads to a higher yield of isomers for the nanostructured zeolites. Overall, the hydroconversion of the smaller alkane is more substantially impacted by variations in the crystalline zeolite domain size.

Original languageEnglish
Pages (from-to)284-298
Number of pages15
JournalJournal of Catalysis
Volume394
Early online date12 Nov 2020
DOIs
Publication statusPublished - Feb 2021

Keywords

  • EMM-23
  • N-paraffins hydroconversion
  • Zeolite
  • ZSM-22
  • ZSM-5

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