| As lubricant metal detengents, possessing fairly good performance, calcium salts have been widely used at present. With higher total base number, lower ash content, stronger neutralization capability, magnesium salt detergents have been developing quickly in recent years. Because these two kinds of detengents have good synergistic effect, they are usually taken in a compound form in practical application. Presently, the most widely used lubricant detengents are sulfonates, while the sulfur-free lubricant detengents are salicylates. These two kinds of detengents are also taken in a compound form in practice. The sedimentation phenomena sometimes occur when detengents are compounded with each other. In view of the above circumstance, studies on direct synthesis of calcium-magnesium sulfonate composite detergents and calcium-magnesium sulfonate/salicylate composite detergents are carried out. Using the ammonium sulfonate(light and heavy) from Yumen petrochemical factory and the salicylic acid from Lanzhou petrochemical company as raw materials, the synthesis process conditions of the calcium-magnesium sulfonate(light and heavy) composite detergents and the calcium-magnesium sulfonate/salicylate composite detergents are optimized by single-factor and orthogonal experiments. The influence of composition and structre of calcium-magnesium composite detergents on their performance is studied. Finally, the synthesis mechanism of calcium-magnesium sulfonate composite detergents is investigated. The main contents and conclusions are summarized as follow:(1) The analytical results of chemical composition and properties of ammonium light sulfonate and ammonium heavy sulfonate indicated that they can be used to synthesize lubricant detengents. The ammonium heavy sulfonate is a good raw material for synthesis lubricant detengents.(2)The optimum conditions of synthesis calcium-magnesium light sulfonate composite detergents should be:ammonium light sulfonate 65g, magnesium oxide 22g, water 10ml, methanol 16ml, carbonation temperature 42℃, carbonation time 4 hours, carbon dioxide 120ml·min-1. The base number of product synthesized by the optimum conditions is higher than 320mgKOH·g-1, and its viscosity is lower than 140mm2·s-1. The distribution of colloidal particles in product is homogeneous. The average diameter of colloidal particles is about 50nm. The product can effectively improve the properties of the lubricating oil.(3) The optimum conditions of synthesis calcium-magnesium heavy sulfonate composite detergents is determined as follow:ammonium heavy sulfonate 80g, magnesium oxide 24g, water 12ml, methanol 18ml, urea 4g, ammonium carbonate 4g, carbonation temperature 45℃, carbonation time 3 hours, carbon dioxide 120ml·min-1. The base number of product synthesized by the optimum conditions is higher than 410mgKOH-g"1, and its viscosity is lower than 150mm2·s-1. The distribution of colloidal particles in product is homogeneous. The average diameter of colloidal particles is about 40nm. The properties of the lubricating oil can be improved obviously after addding this product. The composition and structure of the product are characterized. It is proved that the neutral salt is neutral calcium sulfonate and the overbasic components is mainly magnesium carbonate.(4) The optimal dosage of main materials in synthesis calcium-magnesium heavy sulfonate/salicylate composite detergents is determined as follow:magnesium oxide 24g, water 10ml, methanol 18ml, ammonium heavy sulfonate 60g, salicylic acid 20g. The base number of product synthesized by the optimum conditions is higher than 400mgKOH·g-1, and its viscosity is lower than 140mm2·s-1. The colloidal particles in product have even distribution of particle size and they are about 30nm of average diameter. The properties of the lubricating oil can be improved obviously after adding this product.(5) The influence of composition and structure on performance of calcium-magnesium composite nanodetergents is researched. The results show:①By using the neutral calcium sulfonate as neutral salt, appropriately increasing the content of calcium, decreasing the content of hydroxide in the basic component, enhancing the base number and using large molecular sulfonate, the comprehensive properties of calcium-magnesium sulfonate composite detergents can be improved.②Taking suitable ratio of sulfonate and salicylate in the calcium-magnesium sulfonate/salicylate composite detergents, the performance of products will be greatly improved.③Comparing with the same type of lubricant detergents, the calcium-magnesium light sulfonate composite detergents has equivalent performance except the base number, the calcium-magnesium heavy sulfonate composite detergents has better performance and the calcium-magnesium sulfonate/salicylate composite detergents has superior performance.④The comprehensive property of calcium-magnesium sulfonate composite detergents is superior to that of magnesium sulfonate detergents, while the comprehensive property of calcium-magnesium sulfonate/salicylate composite detergents is superior to that of calcium-magnesium sulfonate composite detergents. This indicates that calcium-magnesium composite detergents can improve the performance of magnesium salt detergents and the mixed substrate detergents can further improve the performance of single substrate detergents.(6) By researching and analyzing the changes of chemical structure, conductivity and the base number of the reaction solution, the reaction mechanism of synthesis calcium-magnesium composite detergents is definited. The studies of carbonation kinetics show that the diffusion was the control step of the carbonation process. The methanol, used as promoter, can increase the carbonation rate and improve the base number of product by lowering the interfacial film strength of reverse micelles and the criticalmicellar concentration of the calcium sulfonate. The urea and ammonia, used as co-promoters, can accelerate the carbonation rate by increasing the solubility of magnesium hydroxide in water. The fitting amount of water and the feasible flow rate of carbon dioxide are beneficial to carbonation process and to improving the base number of products. |
PDF Full Text Request