Oxidative dehydrogenation of ethanol

The same samples, after a pretreatment in flowing oxygen (10%) at 625 K, were used as catalysts for the oxidative dehydrogenation of ethanol and methanol in the same reactor. The reaction mixture consisted of O2 (3 or 5%), methanol vapor (3%) or ethanol vapor (5%) and He (balance), all delivered by Tylan mass flow controllers or vaporizer flow controllers. Products were analyzed by gas chromatography. The catalysts exhibited no induction period and their activities were stable over many days and over repeated temperature cycles. 

Catalysts were prepared by the incipient wetness impregnation. PdZn-alloy formation favors the oxidative dehydrogenation of ethanol to acetaldehyde rather than CH4 thereby producing H2 with high yield in the OSR at low temperatures... 

Oxidative Dehydrogenation of Ethanol to Acetaldehyde Nonporous Ag membranes... 

Fig. 15. Deactivation of Fe2(MoQ4)3 and a mechanical mixture (50 50) of Fe2(Mo04>3 + a-Sb2C>4 during the oxidative dehydrogenation of ethanol to acetaldehyde. The amount of Fe2(MoC>4)3 is identical (200 mg) in both experiments. T = 350°C ethanol/02/N2 2/1/20. Gas flow rate 50 ml/min.

Oxidative dehydrogenation of ethanol over binary oxides of Sn and Mo... 

Gataluminescence (GTL) is the chemiluminescence produced during catalytic oxidation reactions. Ye et al studied GTL and the catalytic oxidation reactions of ethanol on nanosized Gei r,02 materials. The ceria-rich solid solutions (x= 0.05-0.25) showed high GTL activity at 220°G and were considered to be efficient low-temperature GTL sensors for ethanol. The GTL intensity of ethanol oxidation was closely related to the steady-state activity of the Gei jZr 02 catalysts in the oxidative dehydrogenation of ethanol. Xuan et al studied the GTL of GS2 on the surface of ceria nanorods, nanocubes, and... 

Acetaldehyde, first used extensively during World War I as a starting material for making acetone [67-64-1] from acetic acid [64-19-7] is currendy an important intermediate in the production of acetic acid, acetic anhydride [108-24-7] ethyl acetate [141-78-6] peracetic acid [79-21 -0] pentaerythritol [115-77-5] chloral [302-17-0], glyoxal [107-22-2], aLkylamines, and pyridines. Commercial processes for acetaldehyde production include the oxidation or dehydrogenation of ethanol, the addition of water to acetylene, the partial oxidation of hydrocarbons, and the direct oxidation of ethylene [74-85-1]. In 1989, it was estimated that 28 companies having more than 98% of the wodd s 2.5 megaton per year plant capacity used the Wacker-Hoechst processes for the direct oxidation of ethylene. 

The reaction kinetics for the dehydrogenation of ethanol are also weU documented (309—312). The vapor-phase dehydrogenation of ethanol ia the presence of a chromium-activated copper catalyst at 280—340°C produces acetaldehyde ia a yield of 89% and a conversion of 75% per pass (313). Other catalysts used iaclude neodymium oxide and samarium hydroxide (314). 

There are many ways to produce acetaldehyde. Historically, it was produced either hy the silver-catalyzed oxidation or hy the chromium activated copper-catalyzed dehydrogenation of ethanol. Currently, acetaldehyde is obtained from ethylene hy using a homogeneous catalyst (Wacker catalyst). The catalyst allows the reaction to occur at much lower temperatures (typically 130°) than those used for the oxidation or the dehydrogenation of ethanol (approximately 500°C for the oxidation and 250°C for the dehydrogenation). 

Normalization by Oxygen Uptake of the Rates of Oxidative Dehydrogenation of Methanol and Ethanol... 

In acidic media, the reactivity of ethanol on Au electrodes is much lower than in alkaline media. The main product of the oxidation of ethanol on Au in an acidic electrolyte was found to be acetaldehyde, with small amounts of acetic acid [Tremiliosi-FiUio et al., 1998]. The different reactivities and the product distributions in different media were explained by considering the interactions between the active sites on Au, ethanol, and active oxygen species absorbed on or near the electrode surface. In acidic media, surface hydroxide concentrations are low, leading to relatively slow dehydrogenation of ethanol to form acetaldehyde as the main oxidation pathway. In contrast, in alkaline media, ethanol, adsorbed as an ethoxy species, reacts with a surface hydroxide, forming adsorbed acetate, leading to acetate (acetic acid) as the main reaction product. 

Figure 1. First order plots based on hydrogen evolution for the oxidative dehydrogenation of ethanolamine (EA), 2-(2-aminoethylamino)ethanol (AEAE), 3-amino-1-propanol (AP), 2-(methylamino)ethanol (MAE) and benzyl alcohol (BA) over chromia-promoted copper.

Acetaldehyde. The industrial production of acetaldehyde by the hydration of acetylene has lost its importance with the introduction of more economical petrochemical processes (dehydrogenation of ethanol, oxidation of ethylene see Section 9.5.2). At present it is practiced only in a few European countries where relatively cheap acetylene is still available.86-88... 

It is assumed that also the oxidative dehydrogenation of alcohols like methanol, ethanol and isopropanol with the polyPc goes through hydrogen abstraction at the oxygen bond. The polymers prepared from TCB and CU2CI2 in bulk were treated at 393 K... 

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