减四线馏分油的酯化脱酸反应

Deacidification of 4th Vacuum Gas Oil by Catalytic Esterification

摘要:

采用浸渍法制备ZnO/Al2O3催化剂，并用于减四线馏分油与乙二醇的酯化脱酸反应。通过X射线衍射（XRD）对不同灼烧时间制备的催化剂的物相进行分析，结果表明，较短灼烧时间更有利于活性组分ZnO晶体的存在；催化剂的NH3-TPD分析表明，灼烧时间为1h的催化剂表面的酸量为0.415 mmol/g，高于更长灼烧时间催化剂的表面酸量；考察了催化剂灼烧时间、催化剂用量、乙二醇用量、反应温度和反应时间对脱酸的影响，并对脱酸前后的馏分油进行FTIR表征。结果表明，灼烧时间1h的ZnO/Al2O3催化剂具有良好的减压馏分油催化酯化脱酸活性。优选的实验条件为：减四线馏分油用量40g，催化剂用量为馏分油质量的2.5%，乙二醇用量为馏分油质量的4%，反应温度250 ℃，反应时间1.0 h，在该条件下，脱酸率达到92.43%。催化剂重复使用5次脱酸率仍可达到92%，显示出良好的催化活性与稳定性。FTIR结果显示，减四线馏分油中环烷酸与乙二醇反应转化成为酯类，达到了脱酸目的，这也由13CNMR谱图证实。酯化脱酸后馏分油的酸值大幅度降低,从2.51降低到0.19 mgKOH/g，而其他部分主要理化性质变化不大。

Abstract:

ZnO/Al2O3 catalyst was prepared by an impregnation method and applied in the deacidification of 4th vacuum gas oil through the esterification with glycol. The catalyst phases were identified by XRD and it indicated that less calcining time was more benefit for the active component ZnO. The surface acid amount of the catalysts was analyzed by NH3-TPD, the catalyst calcined in 1.0 h had more surface acid amount which reached up to 0.415 mmol/g. The effects of the catalyst calcining time、catalyst dosage，glycol dosage，reaction temperature and reaction time on the deacidification were investigated. The vacuum gas oils before and after the deacidification were characterized by means of FTIR. The results showed that the ZnO/Al2O3 which was incandesced 1hour exhibited excellent catalytic activity for the esterification. Under the selected reaction conditions of vacuum gas oil dosage 40 g，the catalyst dosage 2.5% (w)(based on the vacuum gas oil，the same below), glycol dosage 4.0% (w)，reaction temperature 250 ℃ and reaction time 1.0 h，the acid removal rate reached 92.43%.The catalyst used five times and the deacidification rate reached to 92% which appeared good catalytic activity and stability. The FTIR results showed that naphthenic acids in the vacuum gas oil reacted with glycol into corresponding esters，which was also proved by 13C NMR，so the acids were mostly eliminated. Comparison of the part physicochemical indexes before and after the deacidification indicated that，the acids in the vacuum gas oil was greatly decreased after the catalytic esterification which drop from 2.51 to 0.19 KOH/g, and the other main physicochemical properties after the deacidification varied a little.