Formic acid as flexible intermediate in biofuel production

Titelangaben

Glowienka, Kevin ; Kern, Christoph ; Jess, Andreas:
Formic acid as flexible intermediate in biofuel production.
2016
Veranstaltung: DGMK Conference "Catalysis - Novel Aspects in Petrochemistry and Refining" , 26.-28.09.2016 , Berlin, Deutschland.
(Veranstaltungsbeitrag: Kongress/Konferenz/Symposium/Tagung , Poster )

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Abstract

The reduced availability of crude oil in the longer run and negative environmental effects of fossil fuels combustion forces the petrochemical industries and academia around the world to find alternative sources for fuel production within the next decades. For this purpose, the Fischer-Tropsch-Synthesis (FTS) seems particularly suitable. Here, synthesis gas (CO/H2) converts catalytically to sulfur free hydrocarbons of different chain length which can be easily transformed into both diesel and gasoline. However, even though water-splitting using renewable energies can generate the hydrogen needed, a sustainable carbon source has to be available as well. From our perspective, formic acid (FA) is a promising candidate for this purpose as FA can be decomposed to CO and H2O as co-product. As Wölfel et al. have shown, FA forms from biomass with high selectivity in the OxFA process [1]. Furthermore, the OxFA process allows the conversion of almost every kind of biomass, even waste biomass and leads to CO2 as the only carbon bearing byproduct. The formic acid can be removed by in situ extraction in high purity, leaving inorganic residues of the biomass such as sulphur and phosphorus salts behind in the aqueous phase. The formic acid obtained from the extraction can be used directly for synthesis gas production. However, there are two different reaction pathways known for the decomposition of formic acid. Depending on the reaction conditions, the C1-acid decomposes either into CO and water (dehydration reaction/thermal decomposition) or into CO2 and H2 (dehydrogenation reaction/catalytic decomposition). Thus, FA is not only to be recognized as an effective carbon source, but as a suitable hydrogen source as well.
In our research, we try to answer the question whether formic acid is a useful intermediate in the value chain of 2nd generation biofuels. Therefore, the selectivity and activity of the dehydration reaction to CO and H2O is investigated in both ways as thermal decomposition and catalytic decomposition. Two kinds of setups are in use: i) a continuous tubular reactor for the gas-phase decomposition and ii) a semi-batch autoclave with a reflux condenser for liquid-phase decomposition.
The experimental data have shown that acids like zeolites or sulphuric acid catalyse the dehydration and thus the formation of CO, whereas catalysts containing noble metals like Ruthenium accelerate the dehydrogenation reaction, that is hydrogen formation. Currently, further experimental studies and simulations are conducted to reveal if formic acid from biomass is an effective and sustainable intermediate in biofuel production.
References
[1] R. Wölfel, N. Taccardi, A. Bösmann, P. Wasserscheid: Green Chem. 13, 2759–2763 (2011).