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The feasibility of α-Fe2O3 catalyst addition in the in-situ catalytic fast pyrolysis of Pinewood was considered with the focus on the variation in its shape: nano-sized non-ideal spheres, nanotubes, hollow nano/microtubes, and octadecahedral crystals. Nano-sized spheres strongly promoted the formation of acetaldehyde, something that was also observed for the octadecahedral crystals. The formation of acids was primarily facilitated through the addition of nanotube catalysts and octadecahedral crystals. Newly formed alicyclic ketonic compounds were promoted through the addition of nano-sized spheres, hollow nano/microtubes, and octadecahedral crystals. The latter two catalysts also showed a moderate selectivity in the formation of furfural. All applied catalysts showed loss of activity, though at different degrees, on the formation of lignin derived phenolic compounds, which can be primarily attributed to favoring the formation of char with simultaneous release of CO2. All used α-Fe2O3 catalysts with different shapes maintained their original morphology after the rapid heating with the rate of 20 K/ms followed by catalytic fast pyrolysis at 500 °C, indicating that nanomaterials with targeted dimensions can be applied as catalysts in the catalytic fast pyrolysis of biomass to enhance conversion of undesired oxygenated compounds to higher quality bio-oil and valuable chemicals.

The chapter discusses the reactivity between initial components in the ceria-perovskite composites during their fabrication. It is shown that a complex approach including the application of X-ray phase and Rietveld structural analyses, extended X-ray absorption fine structure technique, X-ray photoelectron spectroscopy, analytical microscopy, and thermogravimetric analysis is required to achieve reliable conclusions about the chemical stability of individual components in composite materials, as their modification could have a strong impact on functional properties of materials. The discussion presented in the chapter is based on the experimental data obtained for manganates, cobaltites, nickelates, and ferrites with perovskite structure and composites on their basis; and with the aid of thermodynamic calculations it is extended toward chemical reactivity in composites composed of ceria and perovskites containing selected 3d-, 4d-, and 5d- transition metal cations on the B-sublattice. The results obtained indicate that a higher chemical stability of individual components in the composites on the basis of ABO3 (B = Ti, V, Nb, Mo, Ta, and W) and pure/Gd,Sm-doped CeO2 is expected during their fabrication. Factors defining the reactivity of components in the ceria-perovskite composites have been discussed. An impact of elements redistribution on conductivity and redox behavior of composites is briefly illustrated.

The total conductivity of the compositions containing Zr0.89Sс0.1Ce0.01О2 or Zr0.92Y0.08О2 powders and Cr2O3 was studied to evaluate a potential impact of the chromium deposition on the surface of electrolyte grains in the porous composite cathode. The compositions were fabricated in the corresponding ratios: (100-х) mol% Zr0.89Sс0.1Ce0.01О2 - х mol% CrO1.5 (10Sc1CeSZ-Cr) and (100-х) mol% Zr0.92Y0.08О2 - х mol% CrO1.5 (8YSZ-Cr) with х = 0.25, 0.5, 1, and 2. Porous ceramic Zr0.89Sс0.1Ce0.01О2 with 49% relative density exhibits higher conductivity than Zr0.92Y0.08О2. In general, a small addition of chromium decreases the conductivity of Zr0.89Sс0.1Ce0.01О2 and Zr0.92Y0.08О2, although the values of the conductivity change in a non-linear way, reaching minimum for 10Sc1CeSZ-Cr1 and 8YSZ-Cr0.25 compositions. This is accompanied by the decrease in the activation energy of the conductivity from 1.35 eV to 1.19 eV in the 10Sc1CeSZ-Cr series and from 1.28 eV to 1.19 eV in the 8YSZ-Cr series with the rise in the chromium content. Evolution of the conductivity values is associated with the interstitial incorporation of chromium into the fluorite structure as well as with its segregation on the surface of grains and grain boundaries. Chromium coexists in the multivalent states (Cr3+ and Cr6+) on the surface of grains. Considering a long-term operation of the SOFC system, one could suggest that Zr0.89Sс0.1Ce0.01О2 will show more promising transport characteristics in the presence of the chromium containing interconnects.

The impact of CaO on oakwood pyrolysis was explored by the Py-GC/MS at 500 °C. Ca(OH)2 presents on the CaO surface, indicating its partial hydration (noted as CaOOH). CaOOH promoted the ketonisation of carboxylic acids to aliphatic ketones, furfural to cyclopentanone/2-cyclopentenone, facilitated the elimination of the methoxy-phenolic compounds. The catalyst loading did not show any significant effect on the formation of acetone, while a noticeable reduction in the phenolics was revealed. Increasing catalyst loading almost eliminated CO2, acids, furans, aldehydes, ether groups, whilst the fractions of alcohols, esters, sugars, and alkoxybenzene decreased noticeably. The use of partially hydrated CaOOH in the CFP can create conditions where by-products generated during the ketonisation and phenolics upgrading reactions (CO2, H2O, CO) interact through the adsorption enhance water-gas-shift reaction and through coking reactions with formation of H2 used for hydrogenation during multistep conversion of furfural to cyclopentanone in a vapour phase.

Quantitative analysis of Cr-adsorption from a gas phase on CeO 2 , pure and doped BaCeO 3 was performed in combination with surface techniques and electrochemical impedance spectroscopy. The Cr-adsorption on BaCeO 3 is 3 times higher than on CeO 2 and it increases by 12–25% on In doping in Ba(Ce 1−x In x )O 3 (x = 0.1–0.3) in the temperature range of 600–700 °C. These perovskites adsorb chromium with the formation of a multi-phase surface layer containing BaCr 6+ O 4 and cerium oxide. Coexistence of small fractions of Cr 3+ and Cr 5+ cations in the surface layer was identified by X-ray photoelectron spectroscopy. The thickness of the surface layer and its morphology vary with temperature, affecting the conductivity of Ce containing perovskites below 700 °C. BaCrO 4 exhibits under air noticeably larger anisotropic thermal expansion than BaCeO 3 . The results indicate that high tolerance to Cr-gaseous species should be considered as an important criterion for further development of materials for proton-conducting SOFCs.

Red mud, a by-product of the Bayer process in the aluminium industry, is co-processed with beechwood for the in-situ upgrading of fast pyrolysis vapour products. It is revealed that the co-processing of beechwood with thermally pre-treated red mud enhanced the vapour upgrading effect. Individual oxides (α-Al 2 O 3 , Fe 2 O 3 , SiO 2 , and TiO 2 ), which are the main constituents of red mud were also tested for the identification of their individual impact on the upgrading process. A biomass/catalyst weight ratio of 1:4 showed the strongest effect on the product distribution. Red mud was found to reduce the yield of phenolic compounds and promote the formation of cellulose- and hemicellulose-derived furfurals and hemicellulose-derived acetic acid, which can be used for the production of a broad range of chemicals and liquid transportation fuels. α-Al 2 O 3 and Fe 2 O 3 reduced the relative yield of phenols as well, whereas the formation of furfurals was promoted by Fe 2 O 3 and TiO 2 . SiO 2 showed negligible effect on fast pyrolysis vapours. The impact of catalysts on the product distribution is discussed for phenols, furfurals, and acids, for which the strongest effects were observed.

SrCrO4 crystallizes in monoclinic space group P21/n and under static air exhibits a low total conductivity (1.8 x 10-4 Ohm-1 x cm-1 at 800 oC). Composites fabricated from La0.58Sr0.4Co0.2Fe0.8O3 perovskite and SrCrO4 remain two phases after heating at 900 oC for a short period of time. Model experiments were carried out to identify an influence of current load on the stability of SrCrO4 surface layer and redistribution of chromium between the surface and volume of cathode, thereby giving insight in to the mechanism of Cr-poisoning of Co-containing perovskite cathodes.