脂肪酸甲酯加氢脱氧和加氢脱氮制备生物烷烃

Production of Bio-paraffin via Catalytic Hydrodeoxygenation of Fatty Acid Methyl Esters and Subsequent Hydrodenitrogenation

摘要:

以源于废弃油脂的脂肪酸甲酯 (FAMEs) 为原料，以NiMo/Al2O3为催化剂，采用加氢脱氧和加氢脱氮两步法制备生物烷烃并对反应工艺进行了优化。结果表明，加氢脱氧的最佳反应条件：反应温度为380 ℃、氢气压力为2 MPa、氢气和FAMEs体积比为1000，以及空速为1 h-1；加氢脱氮的最佳反应条件：反应温度为310 ℃、氢气压力为2 MPa、氢气和烷烃体积比为2000，以及空速为0.25 h-1。在此优化反应条件下，硫化后的NiMo/Al2O3催化FAMEs加氢脱氧能够获得正构烷烃质量分数高于97% 的生物烷烃，所得产品采用NiMo/Al2O3催化剂进行二次加氢脱氮能够进一步移除超过90% 的含氮化合物，显著降低产品的荧光现象。此外，硫化后的NiMo/Al2O3催化剂在FAMEs加氢脱氧反应中具有良好的结构稳定性和抗积碳性能，使用1000 h后其晶相结构无明显改变且表面积碳量仅为3.18%。

Abstract:

Reaction conditions for the NiMo/Al2O3-catalyzed production of bio-paraffins through an integrated process combining hydrodeoxygenation (HDO) of fatty acid methyl esters (FAMEs) derived from waste cooking oils and the subsequent hydrodenitrogenation (HDN) have been optimized in the following work. Under the optimal HDO conditions containing a temperature of 380 ℃, a hydrogen pressure of 2 MPa, a H2/FAMEs volume ratio of 1000, and a space velocity of 1 h-1, the presulfided NiMo/Al2O3 catalysts converted FAMEs to bio-paraffins with an overall selectivity of normal alkanes above 97%. The employed catalysts showed enough structural stability and high resistance to coke in the HDO of FAMEs, with an identical structure to the fresh catalysts observed and an amount of deposited carbonaceous species at 3.18% measured after reaction for 1000 h. However, the deoxygenated products appeared to be colored, especially after an exposure to sunlight, due to the undecomposed residual fragments of chlorophyll. The following HDN reaction over NiMo/Al2O3 catalysts reduced significantly their fluorescence and removed more than 90% nitrogen-containing impurities in the bio-paraffins under conditions of a temperature of 310 ℃, a hydrogen pressure of 2 MPa, a H2/paraffin volume ratio of 2000, and a space velocity of 0.25 h-1.