Highly Selective, Active and Stable Fischer-Tropsch Catalyst Using Entrapped Iron Nanoparticles in Silicalite-1
Author | : Joffrey Huve |
Publisher | : |
Total Pages | : 0 |
Release | : 2017 |
ISBN-10 | : OCLC:990046495 |
ISBN-13 | : |
Rating | : 4/5 ( Downloads) |
Download or read book Highly Selective, Active and Stable Fischer-Tropsch Catalyst Using Entrapped Iron Nanoparticles in Silicalite-1 written by Joffrey Huve and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fischer-Tropsch synthesis (FTS) is gaining renewed interests as it allows converting alternative feedstocks (biomass) into liquid fuels. Compared to Co-based catalysts, state of the art Fe catalysts show lower activity, faster deactivation and lower selectivity as it produces an undesirable amount of CO2. Despite decades of studies, the origins of low activity and selectivity and fast deactivation are still unclear. Typical Fe based catalysts are highly metal loaded (>70 wt.%) and composed of many different phases, which strongly impedes the establishment of structure-activity relationships. There is a need to develop more active, more selective and more stable iron FTS catalysts by rational approaches.The synthesis of well-controlled 3.5 nm iron nanoparticles encapsulated in the walls of a hollow-silicalite-1 zeolite (Fe@hollow-silicalite-1) is presented. The encapsulation prevents particle sintering under FTS conditions leading to a high and stable Fe dispersion. The catalyst Fe@hollow-silicalite-1 is active and highly selective in FTS. Most importantly, Fe@hollow-silicalite-1 does not produce CO2 in contrast to all other Fe-based catalysts. The strong hydrophobicity of the silicalite-1 is likely the origin of the lack of CO2 production by inhibition of the forward WGS reaction. We demonstrated that Fe@hollow-silicalite-1converts CO2 into CO by the reverse WGS reaction. In order to establish a structure-activity relationship, a series of Fe-based catalysts with well-controlled particle sizes were synthesized and characterized (TEM, in-situ XANES, in-situ Mössbauer, XRD). We observed two distinct categories of TOFs depending on the particle size, ~10-2 s-1 for larger (>20 nm) and ~10-3 s-1 for smaller ones.