Ternary Ni–Al–Fe catalysts for ethanol steam reforming

Abstract

Ternary mixed oxides prepared from takovite/reevesite Ni 3 Al 1−x Fe x precursors were tested in ethanol steam reforming for hydrogen production. The influence of the trivalent cation (Al 3+ or Fe 3+ ) on phase composition and derived catalytic performance of the resulting oxides was studied. The physico-chemical properties of the hydrotalcite-like precursors and related oxides were characterized by ICP, XRD, TGA-DSC, Raman, H 2 -TPR, and TEM analyses. Compared to pure binary systems (Ni 3 Al and Ni 3 Fe), the ternary systems showed the best performance in ethanol reforming, leading to high and stable hydrogen selectivity of up to ca. 70% in 100 h reaction tests. The increase in activity can be attributed to a cooperative effect between aluminum and iron, favoring ethanol dehydrogenation as the primary step, followed by acetaldehyde reforming and/or cracking, reverse water gas shift, and methanation, and concomitantly limiting the dehydration route to ethylene.

A novel synthetic route to transition metal phosphide nanoparticles

“…5a-c) that the morphologies of M-800, N-800 and C-800 were very similar; they were composed of nanoparticles with sizes of below 100 nm. Noticeably, unlike the traditional TPR-H 2 30 method that produced clusters of irregularly shaped phosphide nanoparticles and nanoplatelets, 9,27,33,40 M-800, N-800 and C-800 obtained by RHR-DME method showed well-dispersed nanoparticles. Especially, it was clear that very small nanoparticles can be nicely depicted for the N-800 sample.…”

“…X-ray photoelectron spectroscopy (XPS) was performed with a Kratos Axis ultra (DLD) equipped with Al Kα X-ray source. 30 Charging effects were corrected on the basis of adventitious carbon (284.6 eV) referencing. The morphology of asprepared samples was characterized by scanning electron microscopy (SEM, Hitachi S-4800) equipped with energy dispersive (EDX) X-ray spectroscopy.…”

“…It was clear from Table 1 that pure MoP and Co 2 P can be obtained by 25 reduction of their corresponding precursors in DME at above 700 o C. In the case of Ni phosphide, reduction temperature was the key factor in the synthesis. Although the phase composition of as-prepared Ni phosphide was gradually to be predominantly Ni 2 P with increasing temperature, the Ni 12 P 5 30 was still present as a very minor phase up to a temperature as high as 800 o C. It was suggested that precursor mole ratio of Ni/P was another important factor for the synthesis of pure phosphide. 27 Further studies to optimize the preparation conditions are in progress.…”

“…2,9 Since the discovery of size- 25 dependent catalytic properties for materials with size scales of less than 100 nm, extensive effort has been focused on synthetic routes for the preparation of nanoscale metal phosphides. In the lastest review published in 2013, a wide range of methods have been summarized for the synthesis of 30 nano-sized metal phosphides, 10 such as direct reduction of phosphate in H 2 , 11 a solid-state reaction route using red or white phosphorus, 12,13 decomposition of single-source precursors in solution or by chemical vapor deposition, 14,15 decomposition of high-boiling point tri-n-octylphosphine 35 (TOP) 16,17 or P(SiMe 3 ) 3 , 18,19 and solvothermal or hydrothermal synthesis. 20 There are various kinds of phosphides with high quality obtained by these methods mentioned above.…”

Synthesis and characterization of Fe–Ni/ɣ-Al2O3 egg-shell catalyst for H2 generation by ammonia decomposition

“…High resolution imaging of ɣ-Al 2 O 3 supported nanoparticles is a challenging task, due to the crystalline nature of this support which leads to abundance of visible lattice fringes and to the creation of thickness and diffraction contrast that can be confused with the contrast given by the supported nanoparticles. As a consequence, only a few low magnification images of Fe-Ni nanoparticles have been reported in the literature [62][63][64][65]. In order to acquire high resolution images and make sure that the visible contrast was given by Fe-Ni nanoparticles rather than the ɣ-Al 2 O 3 support, particular attention has been given to the sample preparation for TEM (see Experimental Section).…”