Hydrogen Generation by Hydrolysis of an Al/Al₂O₃‐Composite Powder After Heat Treatment

Abstract

Hydrogen generation by reaction of aluminum (Al) with water is generally hindered by the presence of the dense oxide layer on its surface. Eliminating or activating the passive oxide layer is a key step for improving the hydrolysis reactivity of aluminum to generate hydrogen. In the present investigation, a gel‐coating method was used to prepare the precursor powder of a composite with alumina (Al/Al2O3) to clarify the effect of the Al2O3 additive on the hydrolysis of Al powder. The results showed that γ‐Al2O3 was formed after the heat treatment of the Al/Al2O3 composite precursor at 550 °C for 4 h, which results in the coating of Al particles with γ‐Al2O3 agglomerates. The XPS analysis of the heat‐treated Al particles indicated that the initial dense oxide layer covered on the surface of Al particles transformed into a loose γ‐Al2O3 layer that increased the hydrolysis reactivity of the Al powder. The Al2O3 additive coated on the surface of the Al particles was found to lower the hydrolysis reactivity of the Al particles. It was concluded that the heat treatment rather than the addition of the γ‐Al2O3 additive is the predominant factor in determining the hydrolysis reactivity of the Al particles. However, it was observed that coating the Al particles with Al2O3 did hinder the degradation of the Al hydrolysis reactivity upon exposure in air for several days.

Mechanism of Reduced Sintering Temperature of Al2O3–ZrO2 Nanocomposites Obtained by Microwave Hydrothermal Synthesis

“…Pure ZrO 2 , boehmite (AlO(OH)), and Al 2 O 3 were added as references. The bands observed for the as-synthesized samples were identified; they are listed in Table 1 [10,36,37,46,47,48,49,50,51,52]. …”

Preparation of graphene oxide/semiconductor oxide composites by using atomic layer deposition

“…Al-O stretching bands are between 900-400 cm -1 , i.e. the 900-700 cm -l region is assigned to tetrahedral AlO 4 , and the proposed characteristic frequencies of octahedral AlO 6 are between 750-400 cm -1 [46][47][48]. The Zn-O stretching vibration is at around 400 cm -1 [49,50].…”

Ordered Mesoporous Co3O4−Al2O3Binary Metal Oxides for CO Hydrogenation to Hydrocarbons: Synergy Effects of Phosphorus Modifier for an Enhanced Catalytic Activity and Stability

“…The second absorption band at 662 cm À 1 can be assigned to the ABO 3 vibration modes in tetrahedral sites, where A site can be assigned to Co 2 + cations in the mixed metal oxide matrices of Co 3 O 4 À CoAl 2 O 4 À Al 2 O 3 . There are no clear observations of Al 2 O 3 absorption bands located at 750-770 cm À 1 due to the possible formation of spinel-type metal oxides, [32,33] which were not clearly detected from XRD analysis as well. This observation suggests that the Al species seems to be substituted in the matrix of the spinel-type Co 3 O 4 to partially form the cobalt aluminate (CoAl 2 O 4 ) [5,34,35] or aluminum phosphates.…”