Fe Al Catalysts Research Articles

Steam reforming of toluene as model biomass tar to H2-rich syngas in a DBD plasma-catalytic system

Biomass tar is one of the most troublesome issues limiting the further development of biomass pyrolysis and gasification. In this study, a plasma enhanced catalytic steam reforming technology was applied for biomass tar removal. Toluene was selected as biomass tar surrogate. The nano-sized alumina-supported nickel and iron catalysts with different molar ratios of M/Al (M: Ni or Fe, 0:1, 1:3, 1:1, 3:1, 1:0) were prepared for catalytic steam reforming of toluene in a non-thermal plasma reactor featuring dielectric barrier discharge (DBD). The results showed that syngas was the dominant gas product of toluene decomposition. The conversion efficiency of toluene and energy efficiency using Ni-Al and Fe-Al catalysts both followed a sequence: M1Al3 > M1Al1 > M3Al1, which is in line with the BET surface area and pore volume. However, the selectivity of H2 and CO catalysed by Ni-Al and Fe-Al catalysts follows the order of M1Al3 < M1Al1 < M3Al1. Presumably, toluene dissociation is a process composed of adsorption-reaction-desorption. The formation of syngas is supposed to proceed as a series of ionic and free radical reactions occurring preferably in the gas phase. Ni1Al3 catalyst shows the largest potential in converting biomass tar into H2-rich syngas, with a maximum toluene conversion of 96% and a largest H2 yield of 2.18 mol/mol-toluene. Besides, the results showed that this hybrid plasma-catalysis system was potential in anti-carbon deposition.

Ordered Mesoporous Ni–Fe–Al Catalysts for CO Methanation with Enhanced Activity and Resistance to Deactivation

A series of ordered mesoporous Ni–Fe–Al ternary oxide composites were prepared via a one-pot evaporation-induced self-assembly (EISA) method and applied in a CO methanation reaction to produce synthetic natural gas. The results showed that the ordered mesoporous Ni–Fe–Al catalyst with proper amount of Fe species (10N1FOMA) had better both CO conversion and CH4 selectivity than the impregnation-derived 10N1FA catalyst with unordered mesopores and identical component, owing to the higher Ni dispersion and larger H2 uptake. In a 120 h atmospheric-pressure lifetime test, the ordered mesoporous 10N1FOMA catalyst showed significant enhancement in both antisintering and anticoking properties in comparison with the unordered mesoporous 10N1FA, mainly because of the confinement effect of the mesopore channels, the weak acidity of ordered mesoporous alumina support, and the smaller Ni particle size (<5.0 nm).

Synthesis, characterisation and catalytic performance of Cu- and Co-modified Fe-Al co-precipitated catalysts for the steam reforming of ethanol

&lt;p&gt;This paper reports the synthesis and the investigation of the properties and performance of Fe-Al catalysts modified with Cu or Co for the steam reforming of ethanol. The materials were prepared by the precipitation method with different Fe/Al ratios. The samples were characterised by the S&lt;sub&gt;BET&lt;/sub&gt;, TG/DTG, XRD, H&lt;sub&gt;2&lt;/sub&gt;-TPR and TPO/DTA analyses. The increase in the Fe/Al ratio leads to a decrease in the specific surface area and shifts the reduction peaks towards higher temperatures. The partial substitution of Fe by Co or Cu modifies the structure of the materials because higher specific surface areas and crystallites of iron oxides with smaller sizes are formed. The promotion also improves the reducibility of the iron species. These changes provide higher activity and selectivity towards H&lt;sub&gt;2&lt;/sub&gt; and CO for the modified samples and for the samples with lower Fe/Al ratio. The Co-containing catalyst showed the best performance because this sample exhibited the highest conversions and selectivity towards both H&lt;sub&gt;2&lt;/sub&gt; and CO and the lowest formation of coke according to the TPO analysis.&lt;/p&gt;

Steam reforming of biomass tar model compound at relatively low steam-to-carbon condition over CaO-doped nickel–iron alloy supported over iron–alumina catalysts

CaO doped iron–alumina-supported nickel–iron alloy catalysts were tested in a fixed-bed reactor for steam reforming of toluene as a biomass tar model compound at a relatively low steam-to-carbon (S/C) ratio of 2. The influence of doping CaO to iron–alumina support was also explored for the steam reforming reaction. Ni supported on a CaO(1.5)–Fe2O3–Al2O3 support (Ni/Ca(1.5)–Fe–Al) gave superior catalytic performance in terms of activity and stability over other catalysts. Ni/Ca(1.5)–Fe–Al gave a toluene conversion of more than 80% for a period of 22h testing at a S/C ratio of 2. XRD analysis showed that the Ni–Fe alloys formed were stable throughout the reforming reaction. It was observed from XPS results that the surface of the reduced Ni/Ca(1.5)–Fe–Al catalyst was enriched with Fe species compared to other catalysts. These enriched surface Fe species play the role of co-catalysts by increasing the coverage of oxygen species during the reforming reaction to enhance the reaction of toluene and to suppress coke formation. The temperature-programmed surface reaction (TPSR) with water reveals that the Ni/Ca(1.5)–Fe–Al catalyst can activate water molecule at relatively lower temperature over other CaO doped catalysts. TGA analysis on spent catalysts reveals that all CaO-containing catalysts generally result in lower carbon formation rates as compared to Ni/Fe–Al catalyst.

Production of Hydrogen and Nanocarbon from Catalytic Decomposition of Methane over a Ni–Fe/Al2O3 Catalyst

A Ni–Fe–Al catalyst derived from a hydrotalcite-like structured precursor prepared with a co-precipitation technique is employed in the methane catalytic decomposition reaction producing carbon nanofibers (CNFs) and COx-free hydrogen. The effect of doping with iron on the activity and stability is investigated. The performance of the catalyst is evaluated with a temperature-programmed reaction and a constant temperature reaction. The catalyst with a Ni/Fe/Al mole ratio of 2:1:1 shows an extremely stable activity and is still active after 210 h of reaction. The carbon yield on this catalyst reaches 562 g of C/g of catalyst. The post-reaction characterization results indicate that the Ni–Fe alloy is formed in the Ni–Fe–Al catalyst and is proposed to be the active phase for the CNF growth. The addition of an appropriate amount of Fe may enhance the carbon diffusion rate and decrease the carbon formation rate. Thus, the balance among the carbon atom formation, diffusion, and precipitation rates is maintained,...

Steam reforming of naphthalene as model biomass tar over iron–aluminum and iron–zirconium oxide catalyst catalysts

In this study the catalytic properties of iron-based mixed metal oxides such as iron–alumina (Fe–Al) and iron–zirconia (Fe–Zr) were investigated at 850 °C in a fixed bed reactor for the steam reforming of naphthalene as a model biomass tar compound. The effects of addition of copper species (CuO) to the iron-based mixed metal oxide catalysts were also examined. For Fe–Al catalysts, the catalytic activities for naphthalene conversion increased with increasing Fe content except for 100Fe–0Al. The catalytic activities of Fe–Al and Fe–Zr were comparable at steady state conditions. Compound oxides were formed in the cases of Fe–Al, but not in Fe–Zr. A strong peak in the vicinity of 2θ = 45° for metallic iron was observed after catalytic experiments in the XRD patterns of all catalysts, which could be related to the active sites of the catalysts. The addition of CuO increased the activities and stability of the Fe–Al catalysts. The reasons for catalytic activity enhancement due to CuO addition can be explained as follows: copper dispersed evenly in the compound oxides facilitate the reduction of iron oxides to metallic iron and prevent the catalytic deactivation due to decrease in surface area of the catalysts during the reaction.

Aligned Carbon Nanotube Stationary Phases for Electrochromatographic Chip Separations

This paper reports a novel approach for developing a microfluidic electrochromatographic chip device using patterned vertically aligned carbon nanotubes as the stationary phase material. Patterned growth of nanotubes in a specific location of the channel is carried out using a solid phase Fe–Al catalyst as well as a vapor deposited ferrocene catalyst. Proof-of-concept applications are demonstrated using reversed phase capillary electrochromatographic separations as well as solid phase extraction of a glycosylated protein using concanavalin A immobilized onto the nanotube bed.

Development of chromium-free iron-based catalysts for high-temperature water-gas shift reaction

Chromium-free iron-based catalysts were prepared and studied in regard to their performance in the high-temperature water-gas shift reaction (HTS). The effects of various catalyst preparation variables (i.e., Fe/promoter ratio, pH of precipitation medium, calcination and reduction temperatures) and preparation methods were investigated. Aluminum is a potential chromium replacement in HTS catalysts. Further improvement in WGS activity of Fe–Al catalysts can be achieved by the addition of small amounts of copper or cobalt. Catalysts were characterized using BET surface area measurements, temperature-programmed reduction (TPR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). As a textural promoter, aluminum and chromium prevent the sintering of iron oxides and stabilize magnetite phase by retarding its further reduction to FeO and metallic Fe. The promotional effect of Cu is found to be strongly dependent on the preparation method.