氧化铝和磷改性对非负载型催化剂结构和加氢脱硫性能的影响

Effect of Aluminium Oxide and Phosphorus Modification on Structure and Hydrodesulfurization Performance of Unsupported Catalysts

采用共沉淀法制备了Ni-Mo非负载型加氢脱硫催化剂,利用X射线粉末衍射分析(XRD)、低温N2吸附分析(BET)、红外光谱分析(Py-IR、FT-IR)、氢气程序升温还原(H_2-TPR)、程序升温脱附分析(NH_3-TPD)、拉曼光谱分析(LRS)和气相色谱分析(GC-PFPD)等技术手段,考察了Al_2O_3和磷对催化剂结构性能的影响。研究结果表明,Al_2O_3能够增加催化剂的孔容、孔径、比表面积,增加Lewis(L)酸酸量的同时形成了Bronsted(B)酸位。在含有Al_2O_3的催化剂中加入磷会形成Al-P-O结构,阻止NiAl_2O_4尖晶石结构的形成,减小活性组分与Al_2O_3之间的作用;同时磷能够减少四面体配位Mo物种数量,增加八面体配位Mo物种数量。催化剂具有较长的使用寿命;磷的加入使催化剂酸性由强酸性变成弱酸性,加氢脱硫活性由94%增加到99.8%。在温度280℃,压力4.0 MPa、液时空速2.0 h-1和氢油体积比500条件下,可将催化裂化柴油中的4-甲基二苯并噻吩(4-MDBT)、4,6-二甲基二苯并噻吩(4,6-DMDBT)和2,4,6-三甲基二苯并噻吩(2,4,6-TMDBT)深度脱除,硫含量由3950μg/g降至7.9μg/g。

Unsupported Ni-Mo hydrodesulfufization catalysts were prepared by a coprecipitation method and characterized by X-ray diffraction （XRD）, nitrogen physisorption measurement（ BET）, infrared （ Py-IR, FI-IR ）, H2-temperaure programmed reduction （ H2-TPR ）, temperature-programmed spectroscopy desorption of NH3 （ NH3-TPD） , Laser Raman spectroscopy （LRS） and gas chromatography analysis （GC-PFPD） tests. The effects ofAl2O3 and phosphorus addition on the structure of the catalysts were studied. The results indicate that the addition of Al2O3 greatly increases the pore diameter, specific surface area, the amount of the L acid sites and also promotes the formation of B acid sites. Addition of phosphorus leads to the formation of the A1-P-O structure instead of the NiAAl2O4 structure, and weakens the interaction between active phase and Al2O3. The amount of tetrahedral Mo species decreases while the anount of octahedral Mo species increases. The catalysts has a longer service life. The catalyst acidity is changed from strong to weak by adding phosphorus. The hydrodesulfurization rate is increased from 94% to 99.8%. At 280℃, hydrogen pressure of 4 MPa, liquid hourly space velocity （LHSV） of 1.5 h-1 and hydrogen-to-oil volume ratio of 500, 4-methyldibenzothiophene, 4,6-dimethyldibenzothiophene and 2,4,6-trimethyldibenzothiophene catalytic cracking are depthly removed in fluid catalytic cracking diesel oil; the sulphur concentration is decreased from 3950μg/g to 7.9μg/g.