DME/LPG混合体系的氧化反应与热稳定性

采用加速量热仪(ARC)分别测定了液化石油气(LPG)及其DME/LPG的氧化反应初始温度(To)和活化能(Ea),考察了添加剂对氧化反应的稳定性效应,用气相色谱-质谱联用仪(GC-MS)分析热分解产物。结果表明,LPG和DME/LPG的To分别为180℃和150℃,反应活化能Ea分别为203.2kJ·mol-1和188.6kJ·mol-1。氧的存在是导致LPG及其DME/LPG热稳定性下降重要因素,特别是有过氧化物存在下,由于自由基的引发,显著降低LPG、DME/LPG氧化反应的初始温度和反应活化能,在氧化反应体系中添加Fe、Al时,To和Ea值减小,稳定性降低,抗氧剂能提高它们的热稳定性。DME/LPG氧化产物主要有HCHO,CH3OH,HCOOCH3,HCOOH,CH3OCH2CH2OCH,H3CH(OH)CH3,CH3C(O)CH3,CH3CH2CH2OH,(CH3)2CHCH2OCH3,CH3CH2CH2CH2OCH3等20种化合物。

Oxidation Reaction of DME/LPG and its Thermal Stability

Using accelerating rate calorimeter (ARC), the initial oxidation temperatures (T_0) and oxidation activation energies (E_a) of liquefied petroleum gas (LPG) and dimethyl ether (DME)/LPG were measured, and the effect of the additives on the stabilities of LPG and DME/LPG was studied. The results indicate that the T0 of LPG and DME/LPG are 180℃ and 150℃, respectively, and their E_a are 203.2 kJ·mol~(-1) and 188.6 kJ·mol~(-1), respectively. It was found that the stabilities of LPG and DME/LPG decrease with the presence of oxygen, especially with the presence of hydrogen peroxide H_2O_2 or other organic peroxides which could easily initiate the formation of free radicals; and the addition of Fe or Al will decrease the T_0 and E_a of LPG and DME/LPG too. The compositions of the thermal decomposition products of LPG and DME/LPG were analyzed by GC-MS, and the results show that the oxidation reaction products of LPG and DME/LPG include about 20 compounds, such as HCHO, CH_3OH, HCOOCH_3, HCOOH, CH_3OCH_2CH_2OCH, H_3CH(OH)CH_3, CH_3C(O)CH_3, CH_3CH_2CH_2OH, (CH_3)_2CHCH_2OCH_3, CH_3CH_2CH_2CH_2OCH_3 et al.