改性壳聚糖用于平衡剂脱钒的再生工艺研究

MODIFIED CHITOSAN FOR VANADIUM REMOVAL FROM SPENT FCC CATALYST

催化裂化(FCC)催化剂在使用过程中会因金属沉积等因素作用而中毒失活,传统的废催化剂填埋处理不仅会引起生态污染,还会增加生产成本,寻找一种有效的FCC催化剂再生方法已成为业界所关注的热点问题。本研究采用壳聚糖与CS 2为原料,通过亲核加成反应合成了改性壳聚糖-二硫代氨基甲酸盐(DTC-CTS)并将其用于脱除FCC平衡剂上的金属钒,从而达到平衡剂再生的目的。探究了工艺条件对DTC-CTS脱钒效果的影响,结果表明,当反应温度为125℃、反应时间为4.5 h时,钒的脱除率达到54.9%,DTC-CTS对平衡剂表现出良好的脱钒效果。采用XRD,BET,SEM等表征方法对再生前后平衡剂的结构进行表征,并采用ACE评价装置考察其微反活性,结果表明,再生后的催化剂保留了Y型分子筛的晶体结构,比表面积和孔体积增大,微反活性提高5百分点。

Fluid catalytic cracking(FCC)catalysts are poisoned and deactivated due to metal deposition during operation.Traditional landfill treatment not only causes ecological pollution,but also increases production costs.Therefore,finding an effective regeneration method has become a hot issue in the industry.Dithiocarbamates(DTC-CTS)was synthesized by modified chitosan made by nucleophilic addition reaction using chitosan and CS2 as raw materials.The DTC-CTS was used to remove vanadium from spent FCC catalyst to achieve the purpose of regeneration.The technological conditions of vanadium removal using DTC-CTS were further investigated.It was found that at 125℃and the reaction time of 4.5h,the vanadium removal ratio reached the maximum(54.9%),which indicates that DTC-CTS has a good removal efficiency on vanadium from the equilibrium catalyst.The structure of FCC equilibrium catalyst before and after regeneration was determined by XRD,BET and SEM techniques.The results showed that the crystal structure of Y zeolite was retained in the regenerated catalyst,and the specific surface area and pore volume of the catalyst were increased.The MAT activity was increased by 5 percentage points.