(694c) MOF-Derived Catalysts for Propane Dehydrogenation

With emerging shale gas resources, the dehydrogenation of alkanes is a viable route to produce light alkenes, which are building blocks for valuable polymers and chemicals. The selectivity and stability of these catalysts, in both oxidative and nonoxidative pathways, is pertinent in designing new, cheaper materials because several undesired side reactions like hydrogenolysis, isomerization, and coke formation can occur. Previously, our group has investigated iron/phosphorous nanoparticles supported on alumina, mesoporous cobalt aluminate spinels, and In₂O₃–Ga₂O₃–Al₂O₃ mixed oxides as catalysts for nonoxidative propane dehydrogenation (PDH) [1-3]. These catalysts, however, have various limitations such as deactivation, decreased selectivity to propylene at long reaction times and/or low surface areas.

In this study, we aim to synthesize small (i.e. < 10 nm), stable mono- and bimetallic nanoparticles via pyrolysis of metal organic frameworks (MOFs). The resulting carbon-encapsulated nanoparticles have been reported as active and stable catalysts for Fischer-Tropsch synthesis at 613 K, when made using Fe-containing MOFs [4]. The temperature of pyrolysis was found to influence the phase (oxide, metal, carbide) and the size of the nanoparticles formed, as well as the surface area of the carbon support; the state of these MOF-derived catalysts under the higher temperature reduction and reaction conditions needed for PDH (773-873 K) is investigated here. The reactivity and selectivity of these MOF-derived catalysts are dependent on the pyrolysis temperature, which affects the phase and/or structure of the catalysts, as determined from various characterization techniques. This work provides an example of using MOFs as precursors to synthesize unique, stable catalyst structures for desired rates and selectivities of hydrocarbon processes.

[1] S. Tan, C.W. Jones, et al., ACS Catal. 6 (2016).

[2] S. Tan, C.W. Jones, et al., ChemCatChem 8 (2016).

[3] B. Hu, M. L. Sarazen, C.W. Jones, et al., ChemCatChem 9 (2017).

[4] V.P. Santos, J. Gascon, et al., Nat Commun 6 (2015).