The role of Cu on the reduction behavior and surface properties of Fe-based Fischer–Tropsch catalysts

Abstract

The effect of Cu on the reduction behavior and surface properties of supported and unsupported Fe-based Fischer-Tropsch synthesis (FTS) catalysts was investigated using in situ X-ray photoelectron spectroscopy (XPS) and in situ X-ray absorption spectroscopy (XAS) in combination with ex situ bulk characterization. During exposure to 0. After the reduction treatment, XPS showed that the concentration of oxygen and carbon surface species was higher in the presence of Cu. Furthermore, it was observed that the unsupported, Cu-containing catalyst showed higher CO 2 concentration in the product gas stream during and after reduction and Fe surface species were slightly oxidized after prolonged exposure to CO-H 2 . These observations suggest that, in addition to facilitating the reduction of the iron oxide phase, Cu also plays a direct role in altering the surface chemistry of Fe-based FTS catalysts.

The application of synchrotron methods in characterizing iron and cobalt Fischer–Tropsch synthesis catalysts

“…Researchers have also explored the carburization of iron oxides by examining Fe edge data [35,36,38,62]. In other cases, however, direct information regarding the oxidation state and local atomic structure of the promoter itself has been gained [12,22,23,[63][64][65][66][67][68][69][70][71][72][73][74][75][76][77]. In certain instances, the local atomic structure of promoters has led to satisfactory explanations regarding catalytic behavior (e.g., observed changes in conversion and/or selectivity [69,71]).…”

Structural and elemental influence from various MOFs on the performance of Fe@C catalysts for Fischer–Tropsch synthesis

“…Additionally, increased activity from S promotion was shown by DFT calculations to originate from a decrease in the Fe-CO bond strength 52 . Cu is reported to increase the reduction of Fe 2 O 3 by a combination of textural and H 2 spillover effects, and promotes the reaction rates in FTS and WGS 41,53 . Apparently, it is the exact combination of the abovementioned promotors that distinguishes KFe@C-F300 as the best catalyst tested in this study.…”

Surface Composition Changes of Redox Stabilized Bimetallic CoCu Nanoparticles Supported on Silica under H2 and O2 Atmospheres and During Reaction between CO2 and H2: In Situ X-ray Spectroscopic Characterization

“…We have previously reviewed the exploitation of synchrotron-based X-ray spectroscopic techniques for studies of this kind, 18 (1:2) by using ambient pressure X-ray photoelectron spectroscopy (APXPS) and in situ near edge X-ray absorption fine structure (NEXAFS) spectroscopy. 21,22 The two-way effect of Cu on Co and Co on Cu in reactive atmospheres has, however, not been explored in detail previously and as discussed above is of significant importance in understanding the catalytic mechanisms of CO hydrogenation reactions over CoCu catalysts. Here, we report a detailed study combining the preparation of well-defined bimetallic CoCu nanoparticles that are stable following redox treatments and deposition within the pores of mesoporous silica (studied ex situ using TEM, EDS and EELS), and their behavior in reactive gases studied by APXPS and in situ NEXAFS (Co and Cu L-edge) and EXAFS (Co and Cu K-edge) spectroscopy under redox atmospheres and during CO 2/ H 2 reactions.…”