While Fischer‐Tropsch (FT) provides a commercially operated route to long‐chain alkanes for fuels, little is reported showing realistic routes to long‐chain linear alcohols and linear olefins. Linear olefins and alcohols have significant commercial value for lubricants, plasticizers, detergents and base chemicals, and in this contribution, FT has gained considerable recent attention due to the potential for bio or waste feeds for fuels and chemicals, while here we demonstrate that controlling the promotion of a cobalt catalyst with manganese can lead to major shifts in selectivity towards high value chemicals. In this contribution, we demonstrate the unusual effect of adjusting manganese from 0–10 % for making long‐chain linear alcohols and olefins using industrially relevant conditions. A full evaluation of the catalysts is provided to demonstrate catalyst changes as a result of increased promotion that gives rise to this effect. Advanced wax‐product analysis is shown to demonstrate the changes in selectivity. Temperature‐programmed reduction, transmission electron microscopy elemental mapping and in situ x‐ray diffraction show the formation of CoxMnyO4 species on titania during synthesis, with cobalt‐manganese alloys after reduction, while 2D gas chromatography (GCxGC) and 1H nmR were used to analyse the FT wax product with over 50 % alcohols at long carbon numbers.

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Comprehensive two-dimensional gas chromatography (GCxGC) analysis for 1-alcohols and gas chromatography–mass spectrometry (GC-MS) analysis for carboxylic acids, derivatised as their methyl esters, have been applied to liquid and wax Fischer-Tropsch (FT) hydrocarbon products. These methods in combination with conventional one-dimensional gas chromatography (GC) analysis of the aqueous, gaseous, liquid hydrocarbon and wax products plus conventional high-performance liquid chromatography (HPLC) analysis of the aqueous phase has allowed a quantitative distribution analysis of FT hydrocarbon and oxygenated products to be demonstrated for a Co/TiO2 catalyst operating in a fixed bed gas phase pilot plant utilising CANSTM catalyst carrier devices. The GC-MS method used is, to the best of our knowledge, the first application of this derivatisation route for the quantification of individual carboxylic acids in FT hydrocarbon product streams. Whilst the hydrocarbons and oxygenates that were identified are known compounds formed during the low temperature, Co catalysed, FT process the combination of the multiple analysis techniques used has allowed a level of detail to be gained on the product composition that is seldom reported. Additionally, 1H nuclear magnetic resonance spectroscopy (NMR) and 13C NMR analyses were used to quantify the average concentration of 1-olefin, cis- and trans-2-olefins, 1-alcohol and aldehyde as appropriate for the technique used. Comparison of GCxGC versus 1H NMR and GC-MS versus a KOH titration confirmed the applicability of the chromatographic methods for the quantitative analysis of FT oxygenated compounds. Long-chain 1-alcohols and carboxylic acids, ≥ C3, were found to be present at levels of 1/10th and 1/1000th that of hydrocarbons of equivalent carbon chain length respectively. The 1-olefin:n-paraffin ratio in the hydrocarbon liquid and wax products was found to decrease significantly with increasing carbon chain length and much more so than those of the 2-olefin or 1-alcohol.

Catalyst promoters are often used to tune or improve performance with little understanding as to how they work. Here we present a fundamental evaluation of cobalt‐manganese interactions in Fischer‐Tropsch (FT) catalysis and evaluate a new bifunctional catalyst for CO dissociation and CO insertion mechanisms. FT has gained considerable attention recently due to the potential to convert bio or municipal waste feeds into commercial fuels and chemicals. Products are commonly highly linear paraffins, but here we show how the role of manganese can tune selectivity for linear olefins and alcohols in a copper, iron and alkali metal free cobalt bifunctional catalyst. These products also have significant commercial value for lubricants, plasticizers, detergents and base chemicals. Advanced catalyst characterization is shown with in situ techniques (XRD, EXAFS, PDF & TEM), while the FT products are fully analysed by NMR, GC and GCxGC. The role of manganese during catalyst synthesis is reviewed while fundamental understanding of the formation of a mixed metal oxide spinel is presented. The Co–Mn interactions change during catalyst reduction, with EXAFS showing cobalt metal and MnO as the main species present.