Ethanol combustion

Ethanol combusts when chromyl dichloride (Cl2Cr02) is present. 

If 1501bmol/h of water is produced, at what rate (molar) is the ethanol combusted ... 

Properties Orange-red crystals brownish-yellow powder. Mp 289C, bp 430C (sublimable). Soluble in aromatic solvents, hot methanol, and ether sparingly soluble in water moderately soluble in ethanol. Combustible. 

Properties Tan, waxlike solid free from ammonia odor. Mw 301.58, d 0.89 (22C), pH (3% dispersion) 7.6, mp 73-75C, neutrahzation value 70-80. Soluble in boiling water and hot toluene partly soluble in hot butyl acetate and ethanol. Combustible. 

Properties Colorless liquid. Fp 2.6C, bp 238C, d 8.7 lb/gal, refr index 1.5277, flash p 246F (118.9C). Very soluble in water, benzene, and ethanol. Combustible. 

Properties Almost colorless odorless liquid. Hygroscopic, bp 312C (extrapolated), d 1.184, refr index 1.473, flash p 332F (166C). Miscible with water and ethanol. Combustible. 

Properties Colorless liquid strong musky odor. Congeals to white crystals at room temperature. Minimum congealing p 36C, soluble in equal volume of 90% ethanol. Combustible. 

Properties White, crystalline solid. Mp 132-135C, bp 140C (0.15mm Hg). Insoluble in water, benzene, di-(2-ethylhexyl)phthalate soluble in acetone and ethanol. Combustible. 

The catalysts were tested in a gas stream simulating ethanol combustion at 100% excess air (A,=2). The composition was . 10 vol.% oxygen, 10% steam and 6.5% carbon dioxide with nitrogen as the remainder (73.4%). The concentrations of the reactive gases were 300 ppm carbon monoxide, 600 ppm nitric oxide and either 200 ppm ethanol or 100 ppm acetaldehyde. The experimental conditions were a space velocity of 100,000 h l and temperatures between 75 and 500°C. 

Combustion of fuels in internal combustion engines, causes emissions of aldehydes. Aldehydes are either formed in the cold zones of the combustion chamber, in the exhaust pipe or over the oxidation catalyst by partial oxidation of unbumed alcohol. Acetaldehyde is the principal aldehyde formed in ethanol combustion and it is one of the compounds, which the US Enviromnental Rotection Agency proposes as a future regulated pollutant. Acetic acid, which has a characteristic smell and can be experienced as an irritant far below directly hazardous concentrations, can also appear in the exhaust from ethanol-fuelled vehicles. Consequently, it is important to minimize these emissions. 

Llorca et developed a micro-channel reactor where ethanol steam reforming is performed on one side of the plate while ethanol combustion is performed on the with 14 microchannels. The results revealed that Rh-based catalysts exhibited the highest catalytic activity, when compared to Co and Ni. The Rh-Ni-Ce catalyst was operated for 100 h without any noticeable degradation in activity and selectivity. Full conversion was achieved for the entire period and the Hg selectivity was 86%. The CO content in reformate remained constant ca. 8.2%. 

The ethanol can be tested as suggested previously by burning and by reaction with an acidified solution of potassium dichromate (which turns green in the presence of ethanol). The results can be compared with tests on the distillation mixture. The mixture should not burn (as proved in the earlier demonstration The non-burning 5 note ), but pure ethanol combusts easily with a blue flame. 

The AGr and AH of ethanol combustion into CO2 and H2O under standard conditions are equal to —1325 kJ mol and 1366 kJ mol respectively, so that the following equality is respected ... 

Taylor PH, Cheng Li, Dellinger B. The influence of nitric oxide on the oxidation of methanol and ethanol. Combust Flame 1998 115 561—7. 

Bialobok, B. Trawczynski, J. Mista, W. et al. Ethanol combustion over strontium-and cerium-doped LaCoOs catalysts. Appl. Catal. B Environ. 2007, 72, 395-403. 

Sellden G,Andersson K and Egneus H (1982) Health and environmental effects of synthetic fuels III.Emissions from methanol and ethanol combustion Report to Natl.Swed.Env.Prot.Board... 

Methods exist to simpHfy mechanism development. As described by Westbrook and Dryer," this process can be systematized by acknowledging the hierarchical nature of fuel combustion. For instance, in the combustion of ethanol, several smaller species are involved, such as H2, CO, formaldehyde, methane, ethane, ethene, and acetylene. The combustion mechanisms of these species can thus be used to build the detailed mechanism of ethanol combustion. Sensitivity and reaction path analyses are tools that allow key reactions in a detailed chemical kinetic mechanism to be identified.The former highHghts the reactions most likely to dictate overall fuel reaction rate, whereas the latter identifies key reactions by which a chemical species of interest is formed and consumed. As needed, these analyses are sometimes used to generate skeletal mechanisms, in which species and reactions unlikely to play a major role are removed from consideration, and reduced... 

As representative examples. Tables 1 and 2 provide a small portion of a detailed mechanism for ethanol combustion ethanol is the simplest biofuel species explored in this review. The kinetic parameters for reactions pertaining to the chemistry of ethanol in a flame (the ethanol submechanism) are shovm in Table 1, while the thermochemical quantities for species involved in this submechanism are included in Table 2. As can be seen, accurately describing the chemistry of even a few chemical species requires dozens of elementary reaction steps. Moreover, as described above, a fioU detailed chemical kinetic mechanism for ethanol will also involve hundreds of other reactions for hydrogen/oxygen species Cl, C2, and C3 HC chemistry and oxidative reactions involving Cl, C2, and C3 HCs. 

Leplat N, Dagaut P, Toghe C, Vandooren J. Numerical and experimental study of ethanol combustion and oxidation in laminar premixed flames and in jet-stitred reactor. Combust Flame. April 2011 158 705—725. 

---