Pyrolysis of Lignocellulosic Biofuel Di‑<i>n</i>‑butyl Ether (DBE): Flow Reactor Experiments and Kinetic Modeling

Di-n-butyl ether (DBE) is considered a promising biofuel and fuel additive. To gain insight into the DBE pyrolysis kinetics, flow reactor experiments were performed at low and atmospheric pressures in this work. About 30 intermediates and products were identified and quantified with photoionization molecular-beam mass spectrometry (PI-MBMS). On the basis of the experimental observations and previous kinetic studies, a new pyrolysis model of DBE was developed. The most important reaction for DBE consumption at both pressures is the H-abstraction reaction by the H atom. Due to the effect of the ether functional group, the H-abstraction at Cα is the most favored. The four-center elimination reaction is the most important reaction among the DBE unimolecular decompositions and accounts for almost all the production of n-butanol. In addition to hydrocarbon species (ethene, propene, and 1-butene), oxygenated species CH2O, n-butanal, and n-butanol are also identified as the primary intermediates. Other C0–C4 intermediates are mainly formed by the subsequent reactions of the C3–C4 primary species. Traces of C5–C7 soot precursors such as 1,3-cyclopentadiene, benzene, and toluene were also detected in the experiments. These species are formed by small-molecule-related reactions instead of fuel-related reactions due to the O atom in the DBE molecule. Besides, the greater aromatic formation tendency of DBE than small ethers such as dimethyl ether and diethyl ether is caused by abundant C3H5-A and 1-butene intermediates formed in DBE pyrolysis. On the basis of ROP analysis, the formation pathways of benzene are also illuminated