变色硅胶对模拟柴油中喹啉或吡啶的吸附行为研究

ADSORPTION BEHAVIOR OF QUINOLINE OR PYRIDIINE IN MODEL DIESEL OVER ALLOCHROIC SILICA GEL

采用XRD、FT-IR、低温N_2吸附-脱附和NH_3-TPD等方法对硅胶和变色硅胶进行了较详细的表征。XRD和FT-IR表征结果表明硅胶和变色硅胶都具有非晶态结构。硅胶和变色硅胶的平均孔径分别为18.46nm和1.80nm,BET比表面积分别为437.86m^2/g和623.39m^2/g,孔体积分别为0.972 4cm^3/g和0.344 2cm^3/g。NH_3-TPD表征结果表明变色硅胶的酸性要远大于硅胶的酸性。研究了氧化铝、硅藻土、硅胶及变色硅胶对模拟柴油中喹啉的吸附脱除效果,结果表明,变色硅胶吸附脱除喹啉的效果远好于其它吸附剂,较强的酸性大大增强了变色硅胶吸附脱除碱性氮化物喹啉的能力。进一步研究了变色硅胶吸附脱除模拟柴油中的喹啉或吡啶的动力学,结果表明:喹啉和吡啶在变色硅胶上的吸附等温线均属于S型;采用Freundlich(F型)和Langmuir(L型)方程对喹啉吸附数据拟合所得到的R值几乎相同,说明变色硅胶吸附喹啉的动力学符合L型和F型混合模型;对吡啶数据拟合所得Freundlich方程的R值远大于Langmuir方程的R值,说明变色硅胶吸附吡啶更接近于F型模型。

The silica gel and allochroic silica gel were c characterized by X-ray diffraction（XRD）,Fourier transform infrared spectrum（FT-IR）,nitrogen adsorption and NH3-TPD.The results of XRD and FT-IR indicated that the two samples are amorphous structure.The average pore diameter of silica gel and allochroic silica gel are18.46nm and 1.80nm,the surface areas are 437.86m^2/g and 623.39m^2/g,the pore volumes are 0.972 4cm^3/g and0.344 2cm^3/g,respectively.The results of TPD showed that the acidity of allochroic silica gel is far stronger than that of silica gel.The adsorption removals of quinoline in model diesel over alumina,diatomite,silica gel and allochroic silica gel were investigated.The experiment results indicated that the adsorption denitrification performance of allochroic silica gel is much superior to that of other three adsorbents.The stronger acidity of allochroic silica gel is helpful to enhance its removal quinoline by adsorption.Moreover,the adsorption thermodynamics for removal of quinoline or pyridine over the allochroic silica gel from model diesel were further investigated.The adsorption isotherms of quinoline and pyridine belong to S type.Experiment data was fitted Langmuir and Freundlich equations with the Rof two regression equations is much the same.But the adsorption of pyridine over allochroic silica gel belongs to Freundlich adsorption model;the Rof Freundlich regression equation is far more than that of Langmuir.