海洋船舶绿色酯类润滑油的分子设计、合成与性能

Marine lubricating oil based on petroleum is facing the dual challenges of dwindling oil reserves and marine environmental pollution, but the development of vegetable-based ester lubricants with being renewable and high-biodegradability is one of important measures responding to the above challenges. Coconut oil fatty acid is the ideal structure factor for synthesis of vegetable-based ester lubricants due to the high content of saturated fatty acids and a wider range of length distribution of fatty acid chains. In this work, both of coconut oil fatty acids and neopentyl polyol are introduced into the molecule of ester lubricants by molecular design in order to improve their thermal-oxidation stability and biodegradation rate by marine microorganism. The green synthesis of the intermediates with different oligomeric degree is carried out in the first esterification of dicarboxylic acid with neopentyl polyol; then the intermediates are esterified with coconut oil fatty acids to prepare a series of coconut oil-based ester lubricants with tunable viscosity. The oligomeric degree can be adjusted by controlling the esterification conditions, accordingly to adjust the viscosity of final products. Characterization of molecular structure of the products prepared will be performed on FT-IR, ¹HNMR, GC-MS and so on, and then their lubricating properties are evaluated. The relationships between the molecular structure of coconut oil-based ester lubricants and lubricating properties, such as viscosity, viscosity-temperature performance,thermal-oxidation stability, tribological properties and degradation rate by marine microorganisms are studied as well. The findings in this work are expected to provide the basic theoretical support for developing marine lubricating oils based on vegetable oils with wider viscosity range, excellent lubricating properties and marine environment compatibility. A series of green marine lubricating oil products with excellent lubricating properties will be provided by our work.

海洋船舶矿物润滑油正面临资源日益枯竭和污染大洋环境的双重挑战，制备可再生、易生物降解的植物油基酯类润滑油是重要的应对措施之一。椰子油脂肪酸具有饱和度高、碳链长度分布宽等特点，是绿色酯类润滑油分子理想的结构因子。通过分子设计，将椰子油脂肪酸与新戊基多元醇同时引入酯类油分子中，以提高其热-氧稳定性和生物降解率。先以新戊基多元醇与二元羧酸反应，绿色合成不同低聚度的中间体，然后中间体再与椰子油脂肪酸反应，制备一系列粘度可调变的椰子油基酯类润滑油。通过控制酯化反应条件，调节中间体的低聚度，从而调节产物的粘度。采用红外光谱, 核磁共振, 气质联用等方法表征产物的分子结构，并检测产物的润滑性能。研究产物分子结构与粘度、粘温性能、热-氧稳定性、摩擦学性能和海洋微生物降解率的关系，为研发宽粘度范围、润滑性能优异、海洋环境友好型植物油基酯类润滑油提供新的基础理论支持，并提供一系列高性能的绿色船用润滑油新品种。

海洋船舶矿物润滑油面临石油资源枯竭、污染大洋环境、长期接触危害人类健康等多重严峻挑战。植物油基新戊基多元醇酯可再生、环境友好是海洋船舶矿物润滑油最具前景的替代品之一。椰子油脂肪酸含91%以上的C6～C18饱和脂肪酸，新戊基多元醇分子不含β-H，本项目将两者合成椰子油脂肪酸新戊基多元醇酯（椰油酯），它有类似植物油的分子结构，却能弥补植物油作为润滑油的分子结构缺陷（即脂肪酸不饱和度高引起氧化稳定性低、β-H导致热稳定性不高）。此外，为了拓宽椰油酯的黏度范围，本项目将二元羧酸（如己二酸）引入椰油酯，先由己二酸与新戊基多元醇合成低聚中间体，再与椰子油脂肪酸反应制备一系列黏度可调控的椰子油脂肪酸己二酸新戊基多元醇低聚酯（低聚酯）。筛选8种酯化催化剂；优化椰油酯、中间体和低聚酯的制备工艺条件；建立中间体聚合度的测定方法；研究反应条件对聚合度的影响。检测椰油酯、低聚酯的理化性能、摩擦学性能及海洋微生物降解性能等；探索低聚酯的黏度调控因子；研究椰油酯、低聚酯的分子结构与润滑性能的关系。通过本项目研究，制备了一系列椰油酯（6种）与黏度可调控的低聚酯（10种），并获得其优化制备工艺条件与高酯化催化活性的固体酸催化剂Zr(SO4)2-Ti(SO4)2/SiO2（酯化率>98%）；建立了气相色谱法与黏度法测定中间体聚合度的方法，获得了低聚酯较理想的黏度调控因子，如反应物新戊二醇与己二酸的物质的量比；通过调变两者的物质的量比(3.5～1.2)，可调节中间体聚合度(1.63～6.85)，从而调控低聚酯的黏度(54.6～378.2 mm2·s-1/40℃，8.8～56.5 mm2·s-1/100℃；黏度指数139～219)，拓宽了椰子油基酯类油的应用范围。椰油酯、低聚酯的流变学性能、热-氧稳定性、摩擦学性能普遍优于椰子油、菜籽油等植物油，海洋微生物降解性能（14天降解率>80%）与之相当，并远大于矿物油（22%）。所制椰油酯、低聚酯的黏度指数>110，属于特高级黏度指数油；三羟甲基丙烷系列低聚酯的热分解起始温度大于300 ℃，新戊二醇系列椰油酯的倾点低于-40℃，能满足较苛刻的机械工况要求。