作者:Gao-Feng Shi、Jian Miao、Guo-Ying Wang、Jin-Mei Su、Hai-Xiao Liu
DOI:10.14233/ajchem.2015.17822
日期:——
Polyoxymethylene dimethyl ethers (PODMEn) have been synthesized in moderate yields by the reaction of methylal (PODME1) and paraformaldehyde catalyzed by rare earth compounds. The activities of catalyst in the reaction were investigated and the results show that La3+/SO42- has a high value. The influencing factors of reaction such as catalyst amount, reaction temperature, time, pressure and mole ratio of methylal (PODME1) to paraformaldehyde were also investigated. The appropriate reaction conditions i.e., n(paraformaldehyde)/n(methylal) = 1.60, catalyst amount of 1 %, 130 °C, 6 h and 0.5 MPa. Under the above conditions, methylal conversion rate and selectivity of PODME2-8 is 81.6 and 75.5 %, respectively. In addition to, the combustion and emission characteristics of PODME2-8 added diesel was compared with the diesel, polyoxymethylene dimethyl ethers (PODME2-8) not only improved the combustion characteristics of diesel, but improved the low temperature fluidity.
在稀土化合物的催化下,通过甲缩醛(PODME1)和多聚甲醛的反应,以中等产率合成了聚氧亚甲基二甲醚(PODMEn)。对反应中催化剂的活性进行了研究,结果表明 La3+/SO42- 的活性值较高。此外,还研究了催化剂用量、反应温度、时间、压力和甲缩醛(PODME1)与多聚甲醛的摩尔比等反应影响因素。合适的反应条件为:n(多聚甲醛)/n(甲缩醛) = 1.60、催化剂用量 1%、130 °C、6 小时和 0.5 兆帕。在上述条件下,PODME2-8 的甲缩醛转化率和选择性分别为 81.6% 和 75.5%。此外,将添加 PODME2-8 的柴油的燃烧和排放特性与柴油进行了比较,发现聚氧亚甲基二甲醚(PODME2-8)不仅改善了柴油的燃烧特性,而且提高了低温流动性。