Isobutane Dehydrogenation over Bulk and Supported Molybdenum Sulfide Catalysts

Emily Cheng, Lauren McCullough, Hyunho Noh, Omar Farha, Joseph Hupp, Justin Notestein*

*Corresponding author for this work

Research output: Contribution to journalArticle

1 Scopus citations

Abstract

Bulk and supported MoSx materials have gained interest as alternative catalysts for light alkane dehydrogenation, but there is little kinetic data published with which rigorous comparisons can be made to other catalysts. Here, rates, selectivities, and activation barriers are collected under conditions of differential conversion for the dehydrogenation of isobutane over various morphologies of molybdenum sulfide. We find that a "rag-like" MoS2 composed of small, disordered crystallites exhibits higher catalytic rates than layered, highly crystalline MoS2 (52 vs 2.7 μmol ks-1 gcat -1 at 360 °C). This is in part not only due to increased surface area but also due to intrinsically more active edge and defect sites exposed by the rag-like structure, as shown by a decrease in apparent activation energy from 61 to 43 kJ mol-1. Supporting MoSx on metal oxides or metal organic frameworks gives small MoSx clusters that have up to 7-fold higher rates per mass of MoS2 than even the rag-like MoS2. Rates are support-dependent, with the highest rates per mass of MoS2 observed over MoSx/TiO2. Pt/Al2O3 has a 50-fold higher rate than the best MoS2 catalysts (2700 μmol ks-1 gcat -1 at 360 °C), but it has an apparent activation energy of 41 kJ mol-1, similar to that of the rag-like MoS2. Therefore, the rates over MoS2 appear to be limited by a small number of active sites on the surface, rather than intrinsically poor activity. Given the data provided in this manuscript and the enormous phase space available to metal sulfides, these materials warrant further investigation as alternative light alkane dehydrogenation catalysts, especially for use under conditions that would deactivate a precious metal catalyst.

Original languageEnglish (US)
Pages (from-to)1113-1122
Number of pages10
JournalIndustrial and Engineering Chemistry Research
Volume59
Issue number3
DOIs
StatePublished - Jan 22 2020

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Industrial and Manufacturing Engineering

Fingerprint Dive into the research topics of 'Isobutane Dehydrogenation over Bulk and Supported Molybdenum Sulfide Catalysts'. Together they form a unique fingerprint.

  • Cite this