Lubricant hydrogenation issue
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I have two questions for the experts in lubricant hydrogenation. First, why is isomerization carried out before refining? Second, the high-pressure hydrogenation of lubricating oil uses a cold high-pressure separation process; why is no water injection employed, and what is the reason for that?
1. Homogenization is first carried out to lower the freezing point of the oil, while refining is done later to remove impurities from the oil and improve its stability. 2. A cold high-pressure separator is used to improve the separation of three components (mainly: oil, recycled hydrogen, and water). The purpose of adding water is to prevent the formation of amine salts in low-temperature areas. The decision not to add water may be related to the raw materials; it’s possible that their nitrogen content is not low enough to prevent the formation of amine salts. I think this is the main reason for not adding water.
1. Pre-refining is available, resulting in less filler used； Heterogeneous processes tend to produce small amounts of alkenes and unsaturated intermediates, requiring subsequent purification to saturate them and thorough dearomatization. 2. Heterogeneous noble metal catalysts have strict requirements regarding the raw materials; these materials contain very low levels of sulfur and nitrogen. As a result, little hydrogen sulfide and ammonia are produced after the reaction, and thus there is a small amount of hydrogen sulfide-ammonium formed, eliminating the need for water washes to remove this compound