Ethanol adsorbate

The variation of amount of VOC adsorbed and the variation of BET surface area with modified contents were shown in Fig. 1. The optimum modified content was lwt% for benzene, toluene, p-xylene, methanol, ethanol and iso-propanol, but the amount of o-xylene, m-xylene, and MEK adsorbed were decreased with increasing modified contents. Interestingly, the amount of benzene, p-xylene, and ethanol adsorbed on lwt%-PA/AC was 1.5 to 2 times that on purified AC. The BET surface area of lwt%-PA/AC (1109m /g) took the maximum value. 

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. 

On Pt-Sn, assuming that ethanol adsorbs only on platinum sites, the first step can be the same as for platinum alone. However, as was shown by SNIFTIRS experiments [37], the dissociative adsorption of ethanol on a PtSn catalyst to form adsorbed CO species takes place at lower potentials than on a Pt catalyst, between 0.1 and 0.3 V vs RHE, whereas on a Pt catalyst the dissociative adsorption of ethanol takes place at potentials between 0.3 and 0.4 V vs RHE. Hence it can be stated that the same reactions occur at lower potentials and with relatively rapid kinetics. Once intermediate species such as Pt-(COCH3)adsand Pt-(CO)ads are formed, they can be oxidized at potentials close to 0.3 V vs RHE, as confirmed by CO stripping experiments, because OH species are formed on tin at lower potentials [39, 40] ... 

Supercritical COj (SC-CO2) was used to reduce the lipid of meat and the cholesterol of meat and beef tallow. Lipids can be removed quantitatively from dried muscle foods by SC-CO2, but relatively high temperatures are needed. The use of SC-CO2 in conjunction with ethanol, adsorbents and multi-separators also reduced the cholesterol of beef tallow. SC-CO2 was also used to concentrate volatile flavor compounds from beef and pork fat. The volatile components in various extraction fractions were identified and quantitated. 

Fig. 1 SPR angle scans Bare gold (solid line), 1 mM ADP adhesion promoter solution in ethanol adsorbed for 24 h on gold surface (idotted line)...

In this species the C-O bond is tilted awy from the surface normal and the CH2 group becomes a favorable position forythe excitation of both symmetric and asymmetric vibrations. Both vibrations would also be active for the methyl group. This species can therefore explain the spedtrum of ethanol adsorbate. The dipole moment of the C - O bond in the ethoxide may have a negligible component perpendicular to the surface, a situation which is unfavorable to observation of the corresponding mode (expected at c. 1000-1050cm ). 

A species of the form -CO-CH3 was also suggested as one of the constituents of ethanol adsorbate [107]. For an sp hybridization the C-O stretching could have a negligible component perpendicular to the electrode surface. The spectrum in Fig. 30 does not allow a -CO-CH3 species to be either confirmed or discarded. 

Decomposition reactions of larger aliphatic alcohols have been examined in detail on the (Oil [-faceted TiO2(001) surface [80]. Ethanol adsorbed at 300 K exhibited a low temperature desorption peaks for ethanol and water at 365 K and a high temperature desorption state for decomposition products at 588 - 595 K. Half of the ethanol adsorbed on the surface desorbed as ethanol at 365 K. Half of the remaining surface ethoxide groups desorbed as ethanol at 588 K. The... 

Figure 3 shows the XRD patterns of ethanol-adsorbed P20 and pure P20 at 303 K. Though the XRD pattern of P20 has a weak peak of (002) relleetion near. v = 15 nm , the diffraction pattern of ethanol-adsorbed P20 has a broad peak due to the adsorbed ethanol in the (002) relleetion area. The subtraction of I,(.v) - l((.v) leads to the approximated diffraction of adsorbed ethanol in carbon mieropores, where l,(.v) and I((.v) are the total scattering intensity of ethanol-adsorbed P20 and the intensity of pure P20, respectively. Figure 4 shows the corrected XRD patterns of adsorbed ethanol on P5 and P20. 

Figure 3. X-ray diffraction patterns of P20 (line line) and ethanol-adsorbed P20 (bold line) at 303 K.

Another very interesting example of the use of H multiple-quantum spectroscopy under rapid MAS for the purpose of investigating rapid molecular motion concerns the motion of ethanol adsorbed on a silica surface.24 The DQ sideband patterns obtained from DQ SQ correlation experiments using different DQ excitation times are shown in Fig. 17, along with their simulation according to the motion of the OCH2 group of the adsorbed ethanol. 

This reaction (Equation 3.3), which occurs at 250—300 °C with almost total yield (187), might find renewed interest in the future to convert bioethanol produced by fermentation into bioethylene (375,376) in the frame of a new industrial organic chemistry based on renewables. Ethanol dehydration has also been used recently as a test reaction for the investigation of the surface properties of aluminas (187,377—379). At low conversions, ethanol can be converted into diethylether with high selectivitiy. IR spectra show that ethanol adsorbs in the form of ethoxy groups, which are formed either by dissociation on Lewis acid—base pairs or by substitution of hydroxyl groups (187). 

Ethanol Carbon Oxide Ethanol Cyclohexane Ethanol Ethanol, Monodeuterated Ethanol Hydrogen Ethanol Iodine Ethanol, Adsorbed On Graphite Ethanol, Monodeuterated Ethanolamine... 

We also found that water, methanol and ethanol adsorbed on coal. When high-volatile bituminous coal was treated with 3h20, methanol- C, and ethanol-l-l C at room temperature for a period of 24h, the residue retained some radioactivity. The soxlet extraction with non-radio active solvent of these treated samples caused some decrease in the radio-activity. 

A detailed evaluation of the ethanol-generating sachets used in Japan has been made by Labuza and Breene (1989) and the range of generators available has been tabulated (Abe, 1990), while the effectiveness of some of them has been reviewed by Smith et al. (1990). Commercial ethanolgenerating sachets contain from 0.5 to 3.0 g of ethanol adsorbed on silica gel. The sachets are made from ethylene vinyl acetate copolymer, which is permeable to water from the headspace of the food pack. Ethanol desorbs from the silica gel and diffuses through the sachet into the package headspace. 

The complete electrooxidation of ethanol to CO2 releases 12 electrons and two molecules of CO2 per molecule of ethanol. Alas, in aqueous acid medium at room temperature, the partial oxidation of ethanol is the most favorable route, leading to the formation of acetaldehyde and acetic acid releasing of 2 and 4 electrons, respectively (see Figure 3.1). Whereas acetaldehyde can be further oxidized to acetic acid and CO2, acetic acid is a dead-end product of the electrooxidation of ethanol in acid medium. The formation of CO2 implies the scission of the C—C bond, a process which seems to be the bottleneck step for the complete oxidation of ethanol. Many aspects of the electrooxidation of ethanol still remain unclear in particular it not yet understood how the cleaving of the C—C bond proceeds. The nature of the ethanol adsorbate(s) and the intermediate adsorbed species leading to the cleavage of the C—C bond are also still under debate. Some authors propose that C—C scission can happen directly from ethanol whereas others claim that acetaldehyde (or acetyl) species are formed before C—C scission. The nature of the active site for the cleavage of the C—C scission is also under debate. 

ELECTROOXIDATION OF ETHANOL ON POLYCRYSTALLINE PT, PT (HKL) ELECTRODES AND PT/C ELECTRODES. IDENTIFICATION AND OXIDATION OF ETHANOL ADSORBATE(S)... 

Identification of Ethanol Adsorbate and Oxidation Products by EC-FTIR and DEMS on Polycrystalline Pt and Pt/C Electrodes... 

Fig. 12 Simultaneously recorded CVs (a) and MSCVs of CO2 at miz = 44 (b) for the oxidation of ethanol adsorbates formed on Pt/C (E-TEK) at different adsorption potentials. Solid lines — +0.16 V, dashed lines — +0.31 V, dotted lines — +0.46 V. After the adsorption of ethanol, the potential is first scanned in the positive direction. Scan rate 10 mV/s. Electrolyte flow rate 10 pL/s [34]...

The relative coverage of the ethanol adsorbate, compared to that of a saturated CO adlayer on the Pt/C catalyst, calculated simply as the ratio of the mass spectrometric charge of the mIz = 44 peak for ethanol adsorbate oxidation to that for stripping of a saturated CO adlayer, is shown for different adsorption potentials in Fig. 13 (squares). The maximum ethanol adsorbate coverage is achieved at an adsorption potential of around +0.36 V. It is, however, only about 60% of the coverage of a saturated CO adlayer. In the hydrogen adsorption region, Hads... 

Oxidation and Reduction of Ethanol Adsorbate on PtRu, PtRh, and PtaSn Nanoparticle Catalysts... 

Fig. 16 Simultaneously recorded CVs (a) and MSCVs of CO2 at m z = 44 (b), and methane at the reduction and oxidation of ethanol adsorbates formed upon adsorption at...

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