Polycyclic aromatic hydrocarbons (PAHs) and soot formation in the pyrolysis of the butanol isomers

Abstract

The formation of polycyclic aromatic hydrocarbons (PAHs) and soot from the pyrolysis of the four butanol isomers: 1-butanol, 2-butanol, iso-butanol and tert-butanol, at three reaction temperatures (1275, 1375 and 1475 K) has been studied. The identification and quantification of the sixteen PAHs, classified by the Environmental Protection Agency (EPA) as priority pollutants, were done using the gas chromatography-mass spectrometry (GC-MS) technique. The soot formed was collected at the reactor outlet. Light gases formed were also quantified. The harmful potential of the PAHs through the benzo[a]pyrene equivalent, B[a]P-eq amount, has been evaluated. The main results show that the highest formation of light gases was obtained from the pyrolysis of isobutanol at 1275 K. The formation of H2 increases significantly as the temperature increases, following the Hydrogen abstraction carbon addition (HACA) route that leads to form PAHs which subsequently form soot. The tendency to soot formation, under the experimental conditions of the present study, is ranked as follows: tert-butanol, 2butanol, 1-butanol and iso-butanol. The highest PAHs amount and the highest toxic potential, expressed as B[a]P-eq amount, were found in the pyrolysis of all butanol isomers at 1275 K.

Gas and soot formed in the dimethoxymethane pyrolysis. Soot characterization

“…However, to our knowledge, there are not works reported in literature on the quantification of soot from DMM conversion. The present work is part of the research carried out in our group on the capacity to form soot, under pyrolytic conditions, of different oxygenated compounds proposed in literature as alternative fuels, such as dimethyl carbonate (DMC) [16], 2,5-dimethylfuran (2,5-DMF) [17], 2-methylfuran (2-MF) [18], ethanol [19], and butanol isomers [20]. The present study includes experiments under well-controlled laboratory conditions in a quartz tubular flow reactor, accompanied by a gas-phase chemical kinetic modelling that helps to interpret and understand the reaction schemes that occur during the pyrolysis process.…”

Theoretical Studies on Isomerization and Decomposition Reactions of 2-Methyl-1-butanol Radicals

“…Ethanol, the recognized prototypical first-generation biofuel, has already been broadly employed as the practical fuel. However, as a result of its obvious drawbacks of low heating, high hygroscopicity, and corrosivity, the research emphasis has transferred into long carbon chain alcohols, in particular, the C 4 and C 5 alcohols. − …”

Measurement of soot mass and PAHs during the pyrolysis of C2C4 alcohols at high temperatures

“…Propanol and butanol have been studied in flow reactors [11,17,19], shock tubes [20][21][22][23][24][25], flames [26][27][28][29][30][31][32][33], and engine [34][35][36][37][38]; these works focus on enhancing the understanding of the gas phase processes during the combustion process. However, some studies have investigated the effect of butanol isomers on the formation of PAHs and soot propensity [13,33,39]. For example, Vikeri et al, 2017 studied the effect of 1-butanol, 2-butanol, iso-butanol, and tert-butanol on the formation of PAHs and soot in a pyrolysis tubular flow reactor at a temperature range of 1273 K -1473 K and found that the soot mass increased with increasing β H-atoms due to the ease of unimolecular decomposition at these sites.…”