FCC硫转移复合助剂的研究

FCC硫转移复合助剂的研究

  • 摘要: 以Mg-Al元素为基础,引入Fe、稀土等元素,制备了一系列FCC(流化催化裂化)液体硫转移复合助剂,负载于FCC平衡剂上,得待评价的催化剂。利用工业模拟装置考察了复合助剂降低FCC烟道气和FCC产品油总硫质量分数的效果。结果表明,同时加入稀土、Fe元素的复合助剂在烟道气和汽油中的降硫效果都较好,经热重仪分析发现,稀土,Fe元素的加入加强了复合助剂吸附氧并转化为结晶氧的能力,使SO2更易被氧化吸收,达到脱硫目的。此复合助剂在烟道气中最高脱硫率可达85.7%,FCC产品油的最高降硫量达到15.8%。通过酸性数据分析和产品油分布对比实验,发现加入少量复合助剂,对FCC催化剂活性和选择性均无不良影响。

     

    Abstract: Environmental concerns have resulted in legislation which places limits on the sulfur content of gasoline. However, the major source of sulfur in the gasoline pool is fluidized catalytic cracking (FCC) naphtha which usually contributes 90% of the total in China. Most economic solutions would be to use an FCC catalyst additive which could reduce the sulfur content in the FCC naphtha in situ in the cracker itself. Here a group of additives have been studied. Based on support materials as alumina and magnesium oxide, cerium and iron were added by co-gel method. The additives were blended to 8 000×10-6 with a reference FCC-catalyst. By TG analysis, it was revealed that the additive with cerium and iron would strengthen the absorption of oxygen and turn it into the oxygen in the lattice and thus make SO2 easier to be oxidized and absorbed. The results show that the extent of sulfur removal of the additive with iron for the FCC flue gas can reach up to 85.7% in a simulating device while that the reduction of sulfur for the FCC product will reach 15.8% on the base of FCC-catalyst in fixed fluidizing bed (FFB) unit. It has also been shown that the additive has no effect on the catalyst activity and the FCC product distributions.

     

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