In the first paper of this series, the bulk, surface and transport properties of porous transport layer materials (PTL) for polymer electrolyte water electrolysis cells (PEWE) are characterized. A systematic PTL matrix of Ti fiber materials with 3 fiber diameters and 2 nominal porosities as well as a state of the art sintered powder material are investigated to get a better understanding of the governing parameters in electrolysis cells. X-ray tomographic microscopy analysis of ex situ PTL structures and post operando membrane electrode assemblies is performed. On the tomographic structures, bulk (porosity, pore/solid size distributions, fiber orientation), mass transport (diffusivity, permeability, conductivities) and surface parameters (roughness, membrane deformation, PTL surface area and interfacial contact area) are determined. The second paper of this series will correlate the structural parameters with in-depth electrochemical analysis. The new insights into the effect of PTL properties on PEWE performance allow to isolate governing key parameters. From know-how obtained on the fiber based materials fundamental design guidelines for optimization of PTL structures are deduced.

Saturated cyclic ethers are being proposed as next-generation bio-derived fuels. However, their pyrolysis and combustion chemistry has not been well established. In this work, the pyrolysis and combustion chemistry of 2-methyl-tetrahydrofuran (MTHF) was investigated through experiments and detailed kinetic modeling. Pyrolysis experiments were performed in a dedicated plug flow reactor at 170 kPa, temperatures between 900 and 1100K and a N 2 (diluent) to MTHF molar ratio of 10. The combustion chemistry of MTHF was investigated by measuring mole fraction profiles of stable species in premixed flat flames at 6.7 kPa and equivalence ratios 0.7, 1.0 and 1.3 and by determining laminar burning velocities of MTHF/air flat flames with unburned gas temperatures of 298, 358 and 398K and equivalence ratios between 0.6 and 1.6. Furthermore, a kinetic model for pyrolysis and combustion of MTHF was developed, which contains a detailed description of the reactions of MTHF and its derived radicals with the aid of new high-level theoretical calculations. Model calculated mole fraction profiles and laminar burning velocities are in relatively good agreement with the obtained experimental data. At the applied pyrolysis conditions, unimolecular decomposition of MTHF by scission of the methyl group and concerted ring opening to 4-penten-1-ol dominates over scission of the ring bonds; the latter reactions were significant in tetrahydrofuran pyrolysis. MTHF is mainly consumed by hydrogen abstraction reactions. Subsequent decomposition of the resulting radicals by β-scission results in the observed product spectrum including small alkenes, formaldehyde, acetaldehyde and ketene. In the studied flames, unimolecular ring opening of MTHF is insignificant and consumption of MTHF through radical chemistry dominates. Recombination of 2-oxo-ethyl and 2-oxo-propyl, primary radicals in MTHF decomposition, with hydrogen atoms and carboncentered radicals results in a wide range of oxygenated molecules.

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. Understanding the reactivity of unsaturated alcohols: Experimental and kinetic modeling study of the pyrolysis and oxidation of 3-methyl-2-butenol and 3-methyl-3-butenol. Combustion and Flame, Elsevier, 2016, 171, pp.237-251. 1 Understanding the reactivity of unsaturated alcohols: Experimental and kinetic modeling study of the pyrolysis and oxidation of 3-methyl-2-butenol and 3-methyl-3-butenol AbstractThe reactivity of unsaturated alcohols with a C=C double bond in the β-and γ-positions to the hydroxyl group is not well established. The pyrolysis and oxidation of two such unsaturated alcohols have been studied, i.e. 3-methyl-2-butenol (prenol) and 3-methyl-3-butenol (isoprenol). Experiments at three equivalence ratios, i.e. φ = 0.5, φ = 1.0 and φ = ∞ (pyrolysis), were performed using an isothermal jet-stirred quartz reactor at temperatures ranging from 500 to 1100 K, a pressure of 0.107 MPa and a residence time of 2 s. The reactant and product concentrations were quantified using gas chromatography. A kinetic model has been developed using the automatic network generation tool "Genesys". Several important rate coefficients are obtained from new quantum chemical calculations. Overall, there is a good agreement between model calculated mole fraction profiles and experimental data. Reaction path analysis reveals that isoprenol consumption is dominated by a unimolecular reaction to formaldehyde and isobutene. At the applied operating conditions, the equivalence ratio has no effect on the isoprenol conversion profile. Pyrolysis and oxidation of prenol is dominated by radical chemistry, with hydrogen abstractions from prenol forming resonantly stabilized radicals as dominating conversion path. Oxidation and decomposition of the resulting radicals are predicted to form 3-methyl-2-butenal and 2-methyl-1,3-butadiene, which have been detected as important products in the reactor effluent.

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The activity of a commercial NiMo hydrotreating catalyst was investigated to convert distilled tall oil (DTO), a byproduct of the pulp and paper industry, into feedstocks for the production of base chemicals with reduced oxygen content. The experiments were conducted in a fixed bed continuous flow reactor covering a wide temperature range (325−450 °C). Hydrotreating of DTO resulted in the formation of a hydrocarbon fraction consisting of up to ∼50 wt % nC 17 +C 18 paraffins. Comprehensive 2D GC and GC−MS analysis shows that the resin acids in DTO are converted at temperatures above 400 °C to cycloalkanes and aromatics. However, at these temperatures the yield of nC 17 +C 18 hydrocarbons irrespective of space time is drastically reduced because of cracking reactions that produce aromatics. The commercial NiMo catalyst was not deactivated during extended on-stream tests of more than 30 h. Modeling the steam cracking of the highly paraffinic liquid obtained during hydrotreatment of DTO at different process conditions indicates high ethylene yields (>32 wt %).

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Crude tall oil (CTO) is a cost-competitive biomaterial available from the Kraft pulping process that contains approximately 50% fatty acids, 30% resin acids and 20% neutral polycyclic oxygenated species such as sterols. Although CTO differs drastically from conventional fossil-derived feedstocks, it proves to be an interesting drop-in alternative to produce renewable base chemicals. The proposed two-step process in which, first, CTO is converted into a highly paraffinic/naphthenic feedstock through hydrodeoxygenation (HDO) over a NiMo catalyst, followed by steam cracking, produces up to 34 wt % of ethylene, 15 wt % of propylene and 5 wt % of 1,3-butadiene. A dedicated kinetic model was developed for HDO-CTO steam cracking containing over 500 species to further optimize its industrial potential. Reaction path analysis shows that the HDO severity must be optimized to remove all oxygen but dehydrogenation should be avoided so that valuable light olefins and aromatic production are maximized instead of low value fuel-oil.