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- Title
Structural, textural, and acid-base properties of layered Mg-Al oxides modified with a tungstate or phosphate and their activity and selectivity in gas-phase glycerol dehydration.
- Authors
Korneeva, E.; Ivanova, A.; Bondareva, V.; Plyasova, L.; Glazneva, T.
- Abstract
The effect of the nature of the anion (WO, [HWO], HPO) introduced into the interlayer space of Mg-Al hydroxides with Mg/Al = 3 on their structural, textural, acid-base, and catalytic properties has been investigated. The synthesized materials are layered Mg-Al hydroxides with a hydrotalcite-like structure. Heat treatment of these hydroxides at 450-600°C yields a MgO-based solid solution, which turns into a mixture of MgO and MgAlO phases on being heat-treated at 900°C. The samples modified with the [HWO] and HPO anions additionally contain MgWO and Mg(PO) phases, respectively. The OH groups of the materials examined do not show pronounced Brønsted acidity. (NH)HPO introduced into the interlayer space of the Mg-Al hydroxide is the most effective modifier enhancing the surface acidity, while the highest basicity is attained by introducing the NaWO modifier. Glycerol dehydration at 275-350°C, involving acid sites of the surface, yields a wide variety of products containing 2 to 12 carbon atoms per molecule. A correlation has been established between the amount of glycerol dehydration products (acrolein + acetol) and the number of strong Lewis acid sites (ν = 2177-2195 cm). The presence of basic sites varying in strength and concentration on the catalyst surface is favorable for condensation, cyclization, and oligomerization reactions yielding a wide range of C products.
- Subjects
SPINEL; TUNGSTATES; GLYCERIN; DEHYDRATION; OLIGOMERIZATION
- Publication
Kinetics & Catalysis, 2015, Vol 56, Issue 5, p605
- ISSN
0023-1584
- Publication type
Article
- DOI
10.1134/S0023158415050109