Why It Is Difficult To Promote The Recycling Of Waste Lubricating Oil In Hydrorefining Process?

The hydrofining process was first applied to the processing of natural lubricating oils, and the products obtained were excellent in performance and rich in variety. In recent years, it has also been widely used in the regeneration of waste lubricating oil. Since waste lubricating oil contains solid impurities such as water, metal scraps and asphaltenes, and light components such as gasoline and diesel, it is necessary to waste before hydrorefining. The lubricating oil is pretreated by precipitation, distillation under reduced pressure, and the like. The waste lubricating oil obtained after pretreatment still contains a variety of oxides, mainly carboxylic acid, hydroxy acid, carboxylic acid esters, aldehydes and ketones. Such oxygenates are the least difficult to hydrogenate, and undergo hydrogenation reaction accompanied by condensation ring opening, dealkylation isomerization and the like, and finally form corresponding hydrocarbons. The saturated hydrocarbons and aromatic hydrocarbons with higher content in the waste lubricating oil generally do not react under hydrogenation conditions; while the small amount of olefins present in the waste lubricating oil will undergo an addition reaction in the hydrogenation process to form corresponding saturated hydrocarbons. . Due to the type of lubricating base oil and the additives, the waste lubricating oil may contain other compounds such as sulfur compounds, nitrogen compounds, and chlorocarbons. After hydrogenation, these compounds form corresponding hydrocarbons, sulfides, nitrides and hydrogen chloride. Under the same hydrogenation conditions, the hydrogenation of sulfur compounds is equivalent to that of chlorocarbons, while the hydrogenation of nitrogenous compounds is It is relatively difficult and can only be completely removed under the more severe hydrogenation conditions.

In the early 20th century, developed countries in the West conducted in-depth research on the refining waste lubricating oil of hydrorefining process, and developed various hydrogenation processes suitable for large-scale production. The Kleen process, which is widely used in Europe, combines a distillation process with a hydrogenation process and uses a Ni/Mo catalyst as a hydrogenation catalyst to regenerate the waste lubricating oil. The process can significantly remove polycyclic aromatic hydrocarbons from waste lubricating oils to obtain base oils, fuel oils and bituminous oils of desirable quality, as well as high-boiling chlorinated paraffins. The Hylube process developed by IWC is used to regenerate waste lubricating oil by flash-distillation and two-step catalytic hydrogenation process. The obtained base oil can reach the class II base oil standard, and the recovery rate of lubricating oil can reach 70%. This process not only provides a good quality base oil, but also a diesel with very low sulfur content. The REVIVOIL process independently developed by Viscolube of Italy can remove all kinds of deterioration products in waste lubricating oil well, and has good decolorization effect on waste lubricating oil. The residue obtained after reaction can also be used as asphalt blending component. Or heavy fuel, the whole process engineering has no secondary pollutant discharge, no pollution to the environment, and the recovery rate of lubricating oil of the process can reach 72.63%, and the asphalt yield can reach 12%. Sinopec Fushun Petrochemical Research Institute uses the hydrorefining-adsorption refining process to regenerate waste lubricating oil, which can obtain high quality base oil lubricating oil, and the base oil recovery rate can reach more than 80%. Feng Quan et al. used the FDS-1 hydrogenation catalyst prepared by using Ni-MO as the active component and Al2O3 as the carrier to hydrotreat the components obtained from the distillation of waste lubricating oil. The experiment showed that the reaction temperature was 320 ° C. Under the ideal conditions of pressure 5MPa, hydrogen/oil volume ratio of 400:1 and space velocity 1.2h-1, the flash point is 210°C, the viscosity (40°C) is 48.2mm2/s, and the viscosity index is 117, a pale yellow regenerated base oil having a sulfur concentration of 103 mg/L. Yao Guangming uses the self-developed hydrogenation catalyst to regenerate the waste lubricating oil. For the waste lubricating oil with different degrees of deterioration, the base oil or base oil blending component can be obtained. The recycling rate of waste lubricating oil is as high as 90%.

The hydrorefining method is a recycling lubricating oil base oil which is excellent in regenerative efficiency and environmentally friendly by changing the composition of the waste lubricating oil and then obtaining a regenerated oil base oil having excellent quality. However, the hydrogenation catalyst as the core of the hydrofining has extremely strong selectivity, and different hydrogenation catalysts are often required for waste lubricating oils of different properties. However, the preparation process of the hydrogenation catalyst is complicated, and the research and development cost is high, and it is difficult for the general enterprise to independently research and develop. Moreover, the equipment investment in the early stage of the hydrorefining process is relatively large, and the requirements for operators are high. If it is not large-scale continuous production, it will be difficult for enterprises to make profits. If there is no government support, the hydrofining process is difficult to promote.