NixCuy/Al2O3 based catalysts for hydrogen production

Ni(x wt.%) Cu(y wt.%)/Al2O3 samples were investigated as active and thermally stable catalysts for methanol and ethanol steam reforming. XRD data clearly evidenced the formation of a NiCu alloy under the adopted preparation procedure. The bimetallic systems exhibited improved activity in the methanol steam reforming with respect to the monometallic ones. The introduction of copper in the catalyst formulation showed a positive effect inhibiting the formation of methane, an undesirable by-product. On the other hand, in the ethanol steam reforming, the catalytic performance was less promising. Furthermore, the Ni : Cu ratio did not seem to affect the product distribution. However, enhanced stability was observed in the two subsequent run-up experiments, indicating the positive role played by the bimetallic systems

FeMo-based catalysts for H2 production by NH3 decomposition

Active and stable catalysts for ammonia decomposition were obtained by deposition of Fe(5 wt%)\u2013Mo(5 wt%) on commercial stabilized zirconia and modified aluminas. The adopted preparation methodology, combined with a severe reduction treatment, allowed obtaining highly dispersed nanoparticles of Fe\u2013Mo alloy, as revealed by powder XRD. The bimetallic catalysts demonstrated a higher activity with respect to the monometallic ones with the same metal loading (10 wt%). The best performances were obtained for a bimetallic Fe5Mo5/La2O3-modified Al2O3 sample. During ammonia decomposition reaction, the Fe\u2013Mo alloy was progressively converted into a mixture of Fe/Mo nitrides, while good catalytic activity was maintained. The performances of the present catalysts well fit with the requirements of catalysts for application in ammonia-fueled SOFCs or for internal combustion engines

Effect of the Catalyst Load on Syngas Production in Short Contact Time Catalytic Partial Oxidation Reactors

Short contact time catalytic partial oxidation (SCT-CPO) of natural gas is a promising technology for syngas production, representing ail appealing alternative to existing processes. This process is likely to become more important in the future due to its advantages in thermodynamics, mildly exothermic overall reaction, and H(2)/CO ratio of 2, ideal for downstream processes. Rh catalysts are preferred among those based on noble metals because they avoid coke deposition. However, Rh is very expensive. Thus, the design of nanocomposite catalysts with the minimum Rh load for a feasible industrial process is the aim of the present work: 0.25, 0.5, and 1% Rh load were considered. The catalytic reactor is made of a fixed bed of Rh deposited on both Al(2)O(3) spheres in ail egg-shell Configuration and Al(2)O(3) irregular particles in an egg-yolk configuration. The weight hourly space velocity (WHSV) was varied from 130 to 460 N L h(-1) g(cat)(-1). The 0.5% Rh in the egg-yolk configuration allowed the highest CH(4) Conversion (>90%) and H(2) selectivity (>98%) values at my tested WHSV

The identification of the structural phases of CexZr1-xO2 by Eu(III) luminescence studies

Despite the wide application of ceria-zirconia based materials in Three Way Catalysts (TWCs), Solid Oxides Fuel Cells (SOFCs), and H2 production and purification reactions, an active debate is still open on the correlation between their structure and redox/catalytic performances. Existing reports support the need of either (i) a homogeneous solid solution or (ii) materials with nanoscale heterogeneity to obtain high activity and stability. Here we report on a simple and inexpensive approach to solve this problem taking advantage of the luminescence properties of Eu(III), used as a structural probe introduced either in the bulk or on the surface of the samples. In this way, the real structure of ceria-zirconia materials can be revealed even for amorphous high surface area samples. Formation of small domains is observed in catalytically important metastable samples which appear homogeneous by conventional XRD

Hydrogen production through alcohol steamreforming on Cu/ZnO-based catalysts

Hydrogen production by steam reforming of methanol and ethanol is studied over a series of Cu/ZnO/Al2O3 catalysts prepared by different coprecipitation procedures and modified with the introduction of Ni and Co. The catalysts are characterized using N2 physisorption, X-ray diffraction (XRD), temperature programmed reduction (TPR) techniques, N2O decomposition, high resolution transmission electron microscopy (HR-TEM) and thermogravimetric analysis (TGA). Despite the influence of the preparation method on the texture and structure of Cu/ZnO/Al2O3 catalysts, their catalytic behavior appears not significantly affected. While Cu/ZnO/Al2O3 shows poor H2 selectivity in the ethanol steam reforming reaction, the presence of a second metal (Ni or Co) significantly improves the reforming reaction. Although coke deposition remains a drawback for these systems, formation of an alloy between Ni and Cu appreciably reduces carbon deposition with respect to the Co/Cu-based system

Embedded Ru@ZrO2 catalysts for H2 production by ammonia decomposition

Ammonia can be used as fuel in internal combustion engines (ICEs). In this case, a flame accelerator, such as hydrogen, is needed. H2 can be produced on-board by partial decomposition of ammonia. In this work, ruthenium nanoparticles were embedded into a lanthanum-stabilized zirconia (LSZ) support to obtain active and stable heterogeneous catalysts for NH3 decomposition. The effects of the preparation of both Ru nanoparticles and LSZ support were investigated. The embedded catalysts present high metal dispersion and good metal accessibility. Despite the relatively low metal loading (3\u2005wt\u2009%), activity was very high in the temperature range 400\u2013600\u2009\ub0C. The activity of the reference catalysts prepared by using classical impregnation was significantly lower under the same working conditions. Although many factors contribute to the final catalyst performances, the data reported confirm that the embedding strategy minimizes the undesirable sintering of the Ru nanoparticles, leading to promising and stable catalytic activity