Oxidative Dehydrogenation of Ethanol over Vanadium- and Molybdenum-modified Mg-Al Mixed Oxide Derived from Hydrotalcite

Abstract

Hydrotalcite or Mg-Al LDHs were synthesized by co-precipitation method. The Mg-Al mixed oxide was then derived by calcination of hydrotalcite at 450℃. The metal modified catalysts (Mo/Mg-Al and V/Mg-Al) were prepared by incipient wetness impregnation method. The obtained catalysts were characterized by several useful techniques and tested the reactivity for dehydrogenation and oxidative dehydrogenation of ethanol (gas-phase) to produce acetaldehyde. The catalytic reactions were performed at temperature range from 200 to 400℃ for both non-oxidative and oxidative atmospheres. The results showed that the vanadium-modified hydrotalcite (V/Mg-Al) exhibited the highest ethanol conversion (34.3%) and acetaldehyde yield (15.5%) at 400℃ in the non-oxidative atmosphere. For the oxidative dehydrogenation of ethanol, the V/Mg-Al catalyst showed the highest activity at 400℃ giving the ethanol conversion and acetaldehyde yield of 73.7% and 29.5%, respectively. This result probably related to the highest base density of V/Mg-Al catalyst (6.13 µmol CO 2 /m 2) measured by CO 2-TPD. The catalytic activity of Mg-Al catalyst and metal modified catalyst slightly decreased upon time-on-stream test for 10 h on oxidative dehydrogenation of ethanol due to carbon deposition.

Ethanol Dehydrogenation: A Reaction Path Study by Means of Temporal Analysis of Products

“…An important topic with respect to catalysts for ethanol dehydrogenation is the significant deactivation that occurs due to coke formation on the catalyst surface and the sintering of the active catalyst particles. This was found in the case of PdZn nanoparticles [28], monometallic Cu [29,30], bi-or tri-metallic Cu alloys [29,[31][32][33], SiO 2 − supported Cu catalysts [34] and V/Mg − Al catalysts [35,36]. There is a considerable number of papers that use computational methods such as density functional theory or a combination of experimental methods and modelling tools to investigate correlations between catalyst activity and selectivity on the one hand and material characteristics such as crystal faces, monolayer coverages, etc., on the other [37][38][39][40][41].…”

Optimal Conditions for Butanol Production from Ethanol over MgAlO Catalyst Derived from Mg-Al Layer Double Hydroxides

“…Figure 2 shows the adsorption-desorption isotherms for MgAl-LDH and MgAlO catalysts. For both catalysts, their isotherms exhibited the hysteresis loop at high relative pressure (P/P 0 ＞0.7) indicating that both catalysts have the mesoporous structure of type IV (IUPAC) 27,28) . The BET surface area, pore volume and pore size of catalyst are listed in Table 1.…”

Comparative Study of Physicochemical Characteristics and Catalytic Activity of Copper Oxide over Synthetic Silicon Oxide and Silicon Oxide from Rice Husk in Non-Oxidative Dehydrogenation of Ethanol

“…It should be noted that since biomass absorbs carbon dioxide from the atmosphere for its growth, the processing of ethanol obtained from biomass does not contribute to global warming. Two gas-phase processes of ethanol conversion to acetaldehyde are known [12,13]: selective catalytic oxidation with oxygen or air and non-oxidative catalytic dehydrogenation. The non-oxidative dehydrogenation of ethanol to acetaldehyde in comparison with the oxidative dehydrogenation method has obvious advantages such as no oxidant, its partial oxidation to acetic acid and carbon dioxide, and that the resulting acetaldehyde is easily separated from the reaction by-products.…”