Crystal structure and surface species of CuFe2O4 spinel catalysts in steam reforming of dimethyl ether

Abstract

Copper-iron spinel (CuFe 2 O 4) in cubic phase was prepared via a simple citrate solgel method, and was transformed into tetragonal phase of high crystallinity by calcining in air at 900 °C. Composites of CuFe 2 O 4 spinel and -Al 2 O 3 were investigated for catalytic production of hydrogen from dimethyl ether steam reforming (DME SR). X-ray photoelectron spectroscopy showed Cu 1+-rich surface species (Cu 1+ /Cu 0 = ca. 3/2 with negligible Cu 2+) over the calcined CuFe 2 O 4 subjected to in situ H 2 reduction. The spineloxides with lower content of reducible Cu species possessed higher amount of Cu 1+ species under the reducing atmosphere, corresponding to higher DME SR activity. Copper clusters highly dispersed in the matrix of iron oxides were reduced from the spinel structure, and the strong interaction between them should result in the high activity and durability. The degraded catalysts after DME SR were regenerated by calcining in air in the temperature range of 350 to 800 ºC. Slow deactivation of the composites observed during DME SR at 375 ºC was mainly attributable to non-graphitic carbonaceous species deposited on the catalyst surface.

Synthesis of 2-Methylpyrazine Over Highly Dispersed Copper Catalysts

“…On the other hand, the similar variations are also found for the pore volume and pore diameter, which indicates that the pore structure of the catalysts are affected by the pronounced increase in particle sizes [32]. Nevertheless, these catalysts show much higher surface area than those spinels obtained from sol-gel methods [33,34]. Furthermore, the BET surface area of CCA-IM (112 m 2 /g) decreases compared to that of Al 2 O 3 (250 m 2 /g), which is due to the pore blockage by the metal oxides particles.…”

Degradation of polychlorinated biphenyls using mesoporous iron-based spinels

“…In recent years, considerable efforts have been made to develop multicomponent materials for the decomposition of organic pollutants because of the remarkable reaction properties such as high surface areas, high melting points and multifunctionality that single metal oxides cannot realize [6][7][8][9][10][11][12][13]. Spinel oxides are a class of complex oxides with chemical formula AB 2 O 4 , containing the normal and inverse structures.…”

Microstructural characterization of CoMnFeO4thin films deposited by radio-frequency sputtering

“…In fact, their magnetic and electrical properties allow the use of these materials in information storage [1,2], in gas sensor [3,4] and in catalysts [5,6]. Spinels are often used in the form of thin films that are prepared by physical vapor deposition (PVD) techniques such as the radio-frequency sputtering.…”