Manufacture of highly loaded silica-supported cobalt Fischer\u2013Tropsch catalysts from a metal organic framework

Xiaohui Sun,Jorge Gascon,Tom Van Deelen,Freek Kapteijn,Jovana ZečEvić,Krijn P De Jong,Mark Meijerink,Alma I Olivos Suarez,Samy Ould-Chikh

doi:10.1038/s41467-017-01910-9

Abstract

The development of synthetic protocols for the preparation of highly loaded metal nanoparticle-supported catalysts has received a great deal of attention over the last few decades. Independently controlling metal loading, nanoparticle size, distribution, and accessibility has proven challenging because of the clear interdependence between these crucial performance parameters. Here we present a stepwise methodology that, making use of a cobalt-containing metal organic framework as hard template (ZIF-67), allows addressing this long-standing challenge. Condensation of silica in the Co-metal organic framework pore space followed by pyrolysis and subsequent calcination of these composites renders highly loaded cobalt nanocomposites (~ 50 wt.% Co), with cobalt oxide reducibility in the order of 80% and a good particle dispersion, that exhibit high activity, C5 + selectivity and stability in Fischer–Tropsch synthesis.

Highlights

The development of synthetic protocols for the preparation of highly loaded metal nanoparticle-supported catalysts has received a great deal of attention over the last few decades
Among the different strategies suggested in literature, the use of metal organic-frameworks (MOFs) as precursors for the synthesis of nanomaterials such as metal nanoparticles[23,24,25,26], porous silica[27, 28], or nanoporous carbons[29] offers unrivaled design possibilities, as we demonstrate in this work
A tetramethyl orthosilicate (TMOS) impregnated ZIF-67 was first subjected to a wet N2 flow under ambient conditions to facilitate TMOS hydrolysis inside the pores of the MOF

Summary

Introduction

The development of synthetic protocols for the preparation of highly loaded metal nanoparticle-supported catalysts has received a great deal of attention over the last few decades. For the methods described above, metal loading and particle size usually go hand in hand as a result of the fact that bigger nanoparticles and/or clusters are formed when high metal loadings are used This interdependence is a clear drawback for the development of more efficient nanoparticle based composites for application in, i.e., heterogeneous catalysis. A large fraction of irreducible species (i.e., metal silicates and/or aluminates) is formed, resulting in non-optimal utilization of the active phase (that requires to be in the metallic form under reaction conditions)[21, 22] In this respect, it is not surprising that the development of alternative methods for the preparation of these composites is gaining a tremendous attention in both the open and patent literature. These catalysts exhibit high activity, C5 + selectivity, and excellent stability

Methods

Results

Conclusion