Abstract
We have used a heated 2 cm × 1 mm SiC microtubular (μtubular) reactor to decompose acetaldehyde: CH3CHO → products. Thermal decomposition is followed at pressures of 75-150 Torr and at temperatures up to 1675 K, conditions that correspond to residence times of roughly 50-100 μs in the μtubular reactor. The acetaldehyde decomposition products are identified by two independent techniques: vacuum ultraviolet photoionization mass spectroscopy (PIMS) and infrared (IR) absorption spectroscopy after isolation in a cryogenic matrix. Besides CH3CHO, we have studied three isotopologues, CH3CDO, CD3CHO, and CD3CDO. We have identified the thermal decomposition products CH3 (PIMS), CO (IR, PIMS), H (PIMS), H2 (PIMS), CH2CO (IR, PIMS), CH 2CHOH (IR, PIMS), H2O (IR, PIMS), and HC≡CH (IR, PIMS). Plausible evidence has been found to support the idea that there are at least three different thermal decomposition pathways for CH3CHO; namely, radical decomposition: CH3CHO + Δ → CH3 + [HCO] → CH3 + H CO; elimination: CH3CHO + Δ → H2=CH2=CO; isomerizationelimination: CH 3CHO + Δ → CH2=CH-OH → HC≡CH + H2O. An interesting result is that both PIMS and IR spectroscopy show compelling evidence for the participation of vinylidene, CH2=C:, as an intermediate in the decomposition of vinyl alcohol: CH2=CH-OH + Δ → [CH2=C:] + H2O → HC≡CH + H 2O.
Original language | American English |
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Article number | 014306 |
Number of pages | 5 |
Journal | The Journal of Chemical Physics |
Volume | 135 |
Issue number | 1 |
DOIs | |
State | Published - 7 Jul 2011 |
NREL Publication Number
- NREL/JA-5100-52455
Keywords
- CH3CHO
- thermal cracking
- thermal decomposition