Polycyclic aromatic hydrocarbons formed during the pyrolysis of dimethoxymethane (DMM). Comparison with other oxygenated additives

The influence of the temperature (1075 – 1475 K) and inlet concentration of fuel (33,333 and 50,000 ppmv) on the formation of the 16 EPA-priority Polycyclic Aromatic Hydrocarbons (PAH) from the pyrolysis of dimethoxymethane (DMM) was analyzed. PAH were detected in different phases (gas phase, adsorbed on soot, and stuck on the reactor walls) and quantified by gas chromatography-mass spectrometry (GC–MS). Additionally, the toxicity of the PAH samples, expressed as B[a]P-eq, was analyzed in all experiments. A comparison with the results obtained from the pyrolysis of other oxygenated compounds was also performed and similar behaviors were observed. The main results showed that, at low temperatures, the highest concentrations of PAH were found in the gas phase, while at high temperatures were found on soot. For both inlet concentrations of DMM, the light PAH, such as naphthalene and acenaphthylene, were found in major concentrations, in all phases and temperatures. The heavy PAH, such as fluoranthene and pyrene, increased its concentration on soot at highest temperatures. The highest formation of soot was obtained at 1475 K and follows the trend: 2,5DMF < tert-butanol < 2MF < 2butanol < iso-butanol < 1-butanol < ethanol < DMC < DMM. The highest formation of PAH was at 1275 K with the tendency: tert-butanol < 2-butanol < 1-butanol < 2,5DMF < 2MF < iso-butanol < ethanol < DMC < DMM. The highest B[a]P-eq value was found in the pyrolysis of 2,5DMF, and the lowest in the pyrolysis of DMM.