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hydrocarbons [ 17 – 22 ] and unsaturated aldehydes [ 12 , 23 – 25 ], water–gas shift reaction [ 26 ], and many other processes [ 27 , 28 ] where the optimal carriers for platinum are a major issue. Magnesium aluminate spinel (MgAl 2 O 4 ) is a favorable
Abstract
Cu-based mixed oxides were prepared by a co-precipitation method and characterized by XRD analysis, BET and H2-TPR. For all catalytic systems, it was found by XRD analysis that the spinel phase is the majority phase. Catalysts were tested for the production of hydrogen via the water gas shift reaction between 150 and 250 °C. It was demonstrated by TPR that Cu–Zn–Al and Cu–Al were easily reduced. This may be responsible for relatively high catalytic activity in comparison with the results obtained by Cu–Co and Zn–Al catalysts prepared by the same method. The oxide systems can be ranked as follows: Cu–Zn–Al > Cu–Al > Cu–Mn, Cu–Cr > Cu–Fe ≫ Zn–Al > Cu–Co at 250 °C.
Introduction Nanostructured metal aluminate spinels constitute an interesting class of oxide ceramics with important technological applications such as lower temperature sinterability, greater thermal stability, increased
, “ Highly efficient catalysts of Mn 1−x Ag x Co 2 O 4 spinel oxide for soot combustion ,” Catal. Commun. , vol. 101 , pp. 134 – 137 , 2017 . 10.1016/j.catcom.2017.08.007 [27] C. Cao , L. Xing , Y. Yang , Y. Tian , T. Ding , and J. Zhang
Lithium cobaltate LiCoO 2 and Li-Mn oxides nanopowders are synthesized by plasma chemical method in RF-IC plasma flow. Plasma forming gases are air or nitrogen, additionally air is used as oxidizing and quenching gas. As-synthesized and annealed in air nanopowders are investigated by powder XRD, BET, DTA/TGA, SEM, TEM methods and wet chemical analysis; lattice parameters are estimated by the programme SCANIX. Evaporation of initial powder mixtures Li 2 CO 3 +Co with Li/Co molar ratio 1:1 or Li 2 CO 3 +(Mn 2 O 3 +MnO 2 ) with various Li/Mn molar ratios, subsequent quenching and condensation of products results in obtaining of nanopowders with SSA of 13-23 m 2 /g and average particle size of 67-95 nm. After synthesis nanopowders contain admixtures of lithium nitrate hydrate LiNO 3 ·nH 2 O by-phase because of plasma flow composition and air environment. After heat-treating at 600-1000°C pure LiCoO 2 , LiMn 2 O 4 spinel, Li 2 MnO 3 , LiMn 2 O 4 +Li 2 MnO 3 are formed with good crystallinity and average particle size of 70-240 nm. Prepared nanopowders can be applied as cathode materials for Li-ion batteries with appropriate electrochemical properties for high discharge rate.
Introduction Ferrite spinels are important catalysts for various chemical reactions like the water gas shift reaction, carbon monoxide (CO) oxidation, alkylation reactions etc. [ 1 – 3 ] due to their structural and redox
obtained ((NH 4 )[Fe 2 Cu(C 4 H 4 O 6 ) 2 (OH) 5 ]·9H 2 O) was submitted to thermal treatment, 800 °C for 2 h in order to obtain well crystallized copper spinel. The specific surface and the pore size distribution of the samples were determined from
objects of fundamental studies: the supports possess the same spinel structure and similar specific surface area; they differ, however, depending on cation M II , in physicochemical properties, in particular, reducibility. A correlation between the
-stoichiometric Ni–Al spinel-like phase, which may be hypothesized to be located at the interface between NiO and the alumina-type phase and Phase III: an alumina-type phase doped with small amounts of Ni 2+ ions, probably ‘grafted’ on the spinel-like phase. The
TPR pattern indicated the possible presence of non-stoichiometric Ni–Al spinel on catalyst surface, but in the XRD patterns, it was hard to distinguish this from γ-Al 2 O 3 due to their similar morphology and characteristic peaks. For all samples, the
