催化裂化待生剂积炭结构组成的多重表征

Characterization of Coke on Spent Catalytic Cracking Catalysts by Integrated Techniques

了解催化裂化待生剂上焦炭的结构成分和结焦位置对深入认识催化裂化反应机理和指导催化剂研发具有重要意义。以加工减压渣油和减压瓦斯油混合原料的催化裂化工业待生剂为例,通过萃取、溶解催化剂骨架等手段将焦炭分离,同时结合元素分析、热重分析、红外光谱、色-质联用、核磁共振、N2吸附等多种表征手段,对催化裂化待生剂上的焦炭含量、结构成分和结焦位置进行综合分析。结果表明,该催化裂化待生剂上焦炭质量分数约为1.9%,包含可溶于二氯甲烷等有机溶剂的轻质组分和不溶于有机溶剂的重质组分。轻质组分主要由饱和烷烃和轻度聚合的芳香烃组成,质量分数约为27%;重质组分主要为稠环芳烃,质量分数约为73%。焦炭主要存在于待生剂的中孔和大孔中。此结果说明,在工业催化裂化装置中存在通过调整汽提工艺参数进一步降低焦炭产量,从而提高汽油/柴油产率的可能性。

The quantity,composition and location of the coke on spent fluidized catalytic cracking（FCC） catalysts are of critical importance for knowledge on the FCC mechanism and provide insights into development of new FCC catalysts.Illustrated with a spent FCC catalyst from a refinery,the coke was separated by extraction and demineralization.The quantity,composition and location of the coke were comprehensively characterized by multiple diagnostic techniques,including elemental analysis,thermal gravity analysis,infrared spectroscopy,gas chromatography-mass spectroscopy,nuclear magnetic resonance and N2 adsorption.The coke accounted for 1.9% mass fraction of the spent catalyst,which was composed of a dichloromethane soluble light component and an insoluble heavy component.The light component accounted for 27% of the total coke,which was mainly composed of saturated hydrocarbons and aromatic hydrocarbons with low degree of condensation.The heavy component accounted for 73% of the total coke,which was mainly composed of aromatic hydrocarbons with high degree of condensation.The coke mainly deposited in the macro-and meso-pores of the catalysts.The analysis results suggested that it was possible to lower the coke yield and enhance the gasoline and diesel yield by adjusting the operation parameters of stripping in the industrial FCC setups.