Characterization and evaluation of Fe2O3/Al2O3 oxygen carrier prepared by sol–gel combustion synthesis
✍ Scribed by Baowen Wang; Rong Yan; Dong Ho Lee; Ying Zheng; Haibo Zhao; Chuguang Zheng
- Publisher
- Elsevier Science
- Year
- 2011
- Tongue
- English
- Weight
- 655 KB
- Volume
- 91
- Category
- Article
- ISSN
- 0165-2370
No coin nor oath required. For personal study only.
✦ Synopsis
The sol-gel combustion synthesis (SGCS) for oxygen carrier (OC) to be used in chemical looping combustion (CLC) was first designed and experimented in this work, which is a new method of OC synthesis by combining sol-gel technique and solution combustion synthesis. Cheap hydrated metal nitrates and urea were adopted as precursors to prepare Fe 2 O 3 /Al 2 O 3 OC at the molar ratio to unity (Fe1Al1), which was characterized through various means, including Fourier transforms infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), differential thermal analysis (DTA), X-ray diffractor (XRD), and N 2 isothermal adsorption/desorption method. FTIR analysis on the chemical structure of the dried gel of Fe1Al1 indicated that urea was partly hydrolyzed and the hydrated basic carbonate was formed by the combination of groups such as (Fe( 1-y Al y ) 1-x O 1-3x , CO 3 2-and -OH-. By analyzing the staged products during SGCS, calcination was found as a necessary step to produce Fe 2 O 3 /Al 2 O 3 OC with separate phases of ␣-Fe 2 O 3 and ␣-Al 2 O 3 . Through TGA-DTA, the decomposition of the dried gel was found to undergo five stages. The analysis of the evolved gases from the gel decomposition using FTIR partially confirmed the staged decomposition and assisted a better understanding of the mechanism of SGCS. XRD identification further substantiated the necessity of calcination to synthesize Fe 2 O 3 /Al 2 O 3 OC with separate phases of ␣-Fe 2 O 3 and ␣-Al 2 O 3 , though it was not necessary for the synthesis of single phase ␣-Fe 2 O 3 and ␣-Al 2 O 3 . Structural characterization performed on N 2 adsorption analyzer displayed that the pore shape of Fe1Al1 particles was heterogeneous. Finally, H 2 temperature-programmed reduction (TPR) of Fe1Al1 products in TGA indicated that the reduction reaction of Fe1Al1 OC after calcination was a single step reaction from ␣-Fe 2 O 3 to Fe, and calcination benefited to improve the transfer rate of the lattice oxygen from the OC to fuel H 2 . Furthermore, four times of reduction and oxidization (redox) reaction by alternating with H 2 and air demonstrated the synthesized OC had good reactivity and sintering-resistance, much suitable to be used in the realistic CLC. Overall, the SGCS method was found superior to other existent methods to prepare Fe 2 O 3 /Al 2 O 3 OC for CLC application.
📜 SIMILAR VOLUMES
A series of Pt/Al 2 O 3 catalysts were prepared using a sol-gel method. The influence of several parameters used in the synthesis including: metal content, identity of the metal precursor, and the water/alkoxide ratio on the structural properties of the fresh (dried) and calcined samples were studie