| SZ36-1 crude oil is scare heavy crude oil with low freezing point in our country, the distillation products of this oil under atmospheric or low pressure can be used as good raw materials for cyclo-alkyl lubricant. At present, the CNOOC Asphaltum Limited Stock Company has successfully used the cyclo-alkyl distillates to produce environment friendly oils for transformers and rubber by using the technology of furfural extraction. SZ36-1 crude oil contains high contents of carboxylic acids, which can not only seriously corrupt the setups, but also increase the acidity value of products. To decrease the acidity value of these products, deep refinery must be adopted; however, it will reduce the yield of products and the economic benefit. In order to fully utilize the cyclo-alkyl crude oil resources and produce top grade cyclo-alkyl products, the CNOOC Asphaltum Limited Stock Company has developed hydro-decarboxylic acids technique to increase the quality of products so as to eliminate the environmental pollution.This thesis focuses on the study of hydro-decarboxylic acids of SZ36-1 low pressure three-line distillates of lubricants. We obtained following results.(1) Selection of the catalyst support used for hydro-decarboxylic acids A series of supports were prepared by using pseudoboehmite as raw powder, nitric acid as bonding agent, and sesbania powder as extrusion agent. The results are as follows. 1. The support has high strength, proper pore structure and big surface area when Wenzhou pseudoboehmite and Shandong alumina mixed in the ratio of 2:1; 2. With the increase of calcination temperature of the support, the strength and average pore diameter increase a little, but the surface area decreases; 3. The addition of citric acid can increase the pore volume of the support; when this support is used for the catalyst, the activity for hydro-decarboxylic acids is enhanced.(2) Ni-Mo is used as the main active components, and P is used as promoter. The activity evaluation results show that the addition of promoter P obviously increases the the activity for hydro-decarboxylic acids of the catalysts.(3) The impregnation order for different active components can remarkably influence the catalytic activity of the catalysts. For the catalysts containing Ni, Mo and P, there are several impregnation order, such as (a) P-Mo first, then Ni; (b) Ni first, then P-Mo; (c) Ni, Mo, P co-impregnation. Among them, the co-impregnation possesses very preparation procedures, and the catalyst prepared this method shows higher catalytic activity than others. (4) The operating reaction conditions can also influence the activity. Decrease of space velocity and increase of reaction temperature are favorable to the reaction of hydro-decarboxylic acids. However, too high reaction temperature and too low space velocity can lead to thermal cracking of fraction oil, unfavorable to the next manufacturing. When volume space velocity of 1.5 h-1, H2/oil ratio of 300, reaction temperature of 315 oC, and reaction pressure of 3.2 MPa are used, the acidity value of the products after hydro-decarboxylic acids over NiMoP is less than 0.03 mg KOH/g, better than the domestic reference catalyst.(5) On the basis of micro-reaction system of 20 mL, the pilot scale measurement was performed using 200 mL catalyst. The results of pilot scale is consistent with those obtain in lab over micro-reaction system. After 1500 h continuous operation, the catalyst is still stable, and the acdity value of the products is less than 0.03mg KOH/g. |
