【作者】 魏妮；

【导师】 季生福；

【作者基本信息】 北京化工大学 ， 化学工程与技术， 2011， 博士

【摘要】 近年来,各国制定越来越严厉的环境法规限制轻质油品中硫的含量,这激发了石油炼制行业对高活性加氢脱硫催化剂的探索和研究。一些研究表明过渡金属磷化物在许多反应中都表现出好的催化性能,特别是在加氢脱硫反应中显示了优异的催化活性,被认为是新一代的加氢脱硫催化剂；整体式催化剂作为一种新型催化剂,它与传统的颗粒状催化剂相比具有压降低、反应物径向分布均匀,良好的传递能力等优点。正由于这些优点,整体式催化剂已经成功地应用在环境污染控制领域,但在石油脱硫方面的应用有较少的报道。经过我们前期的研究,发现Ni2P/SBA-15催化剂具有很好的噻吩和二苯并噻吩加氢脱硫反应活性,而对于Ni2P/SBA-15前躯体负载到堇青石上的整体式催化剂的加氢脱硫性能还没有进行系统的考察。本文的研究是将前躯体Ni2P引入到介孔分子SBA-15中,再将助剂Co、La、W、Ce引入到Ni2P/SBA-15前躯体中,采用程序升温还原的方法制备了Co-Ni2P/SBA-15、La-Ni2P/SBA-15、W-Ni2P/SBA-15、Ce-Ni2P/SBA-15等催化剂体系。同时以堇青石为载体,将NixP/SBA-15前躯体涂覆到预处理后的堇青石上,采用程序升温还原方法制备了不同NixP质量含量(NixP=6%-31%)和P/Ni比(P/Ni=1/3,1,2,3)的NixP/SBA-15/堇青石整体式催化剂；以Co-Ni2P/SBA-15和La-Ni2P/SBA-15为活性涂层,制备了Co-Ni2P/SBA-15/堇青石和La-Ni2P/SBA-15/堇青石整体式催化剂。通过XRD、N2吸脱附等温线、HRTEM、SEM、TEM. NH3-TPD和XPS等分析手段对所得催化剂进行结构表征,采用二苯并噻吩的加氢脱硫模型反应评价了催化剂的性能。对于不同NixP含量的NixP/SBA-15/堇青石整体式催化剂(P/Ni=1/2),所制备的样品中Ni2P和Ni12P5为活性相,NixP/SBA-15活性涂层能够大幅度提高整体式催化剂的比表面积。其中31%NixP/SBA-15/堇青石整体式催化剂有最好的加氢脱硫性能,在360℃C时DBT转化率能够达到93%。对于不同P/Ni比的NixP/SBA-15/堇青石整体式催化剂,当P/Ni=1/3时,活性相是Ni3P；P/Ni=1,2,3时,活性相是Ni2P。随着P/Ni比的增加,NixP/SBA-15/堇青石整体式催化剂的比表面积和孔体积降低。P/Ni=1的NixP/SBA-15/堇青石整体式催化剂有最好的加氢脱硫活性,在360℃C时DBT转化率能够达到99%。对于不同Co含量的Co-Ni2P/SBA-15催化剂,所制备的样品中都形成了Ni2P,样品中仍然保留很好的介孔结构,在360℃时,4% Co-Ni2P/SBA-15催化剂有最高的DBT加氢脱硫活性,DBT转化率为99%,Co的加入能够提高加氢脱硫反应产物BP的选择性,在360℃时,4%Co-Ni2P/SBA-15催化剂的BP选择性比Ni2P/SBA-15催化剂提高了9%。对于不同Co含量的Co-Ni2P/SBA-15/堇青石整体式催化剂,Ni2P是活性相,Co能够提高整体式催化剂的比表面积和孔体积,0.55%Co的加入能够提高催化剂表面Niδ+的相对浓度,Co的加入使得催化剂表面富磷。0.55%Co-Ni2P/SBA-15/堇青石整体式催化剂有最高的加氢脱硫活性,在360℃时DBT转化率为95%。对于不同La含量的La-Ni2P/SBA-15催化剂,Ni2P是活性相,La的加入能够降低Ni2P颗粒尺寸,La以La3+的形成存在于催化剂表面,Ni以Niδ+和Ni2+形式存在于催化剂表面,P以P6-和P5+形式存在于催化剂表面。在340℃时,4% La-Ni2P/SBA-15催化剂有高的加氢脱硫活性,DBT转化率为94%。在不同La含量的La-Ni2P/SBA-15/堇青石整体式催化剂体系中,随着La含量的增加,催化剂比表面积和孔体积先增加后减少。1.5%La-Ni2P/SBA-15/堇青石整体式催化有最高的活性,在360℃时,DBT转化率为94%。对于不同W含量的W-Ni2P/SBA-15催化剂,W添加到Ni2P/SBA-15催化剂中提高了催化剂的比表面积和孔体积,当W加入到Ni2P/SBA-15中,催化剂表面酸性发生改变,随着W含量的增加,催化剂的酸强度和总酸量增加,W的加入抑制了Ni2P的生成。在360-380℃, W-Ni2P/SBA-15催化剂的BP选择性比Ni2P/SBA-15催化剂高18%左右。对于不同Ce含量的Ce-Ni2P/SBA-15催化剂,当Ce=7%时,催化剂中形成了Ni2P和Ni12P5混合物相,当Ce<5%时,催化剂中形成了纯的Ni2P相,Ce添加到Ni2P/SBA-15催化剂中提高了催化剂的比表面积和孔体积,随着Ce含量的增加,催化剂的酸强度和总酸量增加。在360-380℃,Ce-Ni2P/SBA-15催化剂的BP选择性比Ni2P/SBA-15催化剂高13%左右。更多还原

【Abstract】 Recently, many countries enact severe regulations to limit the sulfur contents in fuel. It has stimulated the investigation and development of high performance hydrodesulfurization (HDS) catalysts. Transition metal phosphides exhibit very good catalytic performance in some catalytic reactions, especially for HDS reaction. Transition metal phosphides are considered as new generation of HDS catalysts due to excellent desulfurization performance. Monolithic catalysts have obvious advantages, such as low-pressure drop over the catalyst bed, favorable heat and mass transfer properties, and uniform profiles of concentration and temperature in comparison with the conventional fixed-bed catalytic reactors. Therefore, monolithic catalysts have been extensively applied to the control of emissions. However, the applications of monolithic catalysts in petroleum and chemical industry are being explored.In previous research work, Ni2P/SBA-15 catalysts had showed good activity for HDS of thiophene and dibenzothiophene. The activity for HDS of DBT over Ni2P/SBA-15/cordierite monolithic catalyst is not investigated. In this paper, Ni2P was introduced into SBA-15 by impregnation method, and then promoters (Co, W, La, and Ce) were introduced into Ni2P/SBA-15 precursor. A series of Co-Ni2P/SBA-15、W-Ni2P/SBA-15、La-Ni2P/SBA-15、Ce-Ni2P/SBA-15 catalysts were prepared by TPR. Addition, NixP/SBA-15 precursors were coated onto the pretreated cordierite and NixP/SBA-15/cordierite monolithic catalysts with different NixP content (NixP=6%-31%) and P/Ni ratio (P/Ni= 1/3,1,2,3) were obtained by TPR. Co-Ni2P/SBA-15/cordierite and La-Ni2P/SBA-15/cordierite catalysts were also prepared using cordierite as support and Co-Ni2P/SBA-15 and La-Ni2P/SBA-15 precursors as active washcoat. Then, the prepared catalysts were characterized by XRD, N2 adsorption-desorption isotherms, HRTEM, SEM, TEM, NH3-TPD, and XPS. The catalytic performances of the catalysts were evaluated by HDS of dibenzothiophene (DBT).For NixP/SBA-15/cordierite monolithic catalysts with different NixP content and P/Ni=0.5, Ni2P and Ni12P5 were the active phases. Surface area of cordierite increased when NixP/SBA-15 was coated onto cordierite and the thickness of washcoat was about 90μm. The 31%NixP/SBA-15/cordierite monolithic catalyst had the highest HDS activity, which DBT conversion can reach 99% at 360℃. For NixP/SBA-15/cordieritemonolithic catalysts with different P/Ni ratio, the active phase is Ni3P for NixP/SBA-15/cordierite (P/Ni=1/3), whereas the active phase is Ni2P for the catalysts with P/Ni of 1,2, 3. The surface area and pore volume of NixP/SBA-15/cordierite decreased with increasing P/Ni ratio. The catalytic activity over Ni2P for HDS of DBT was higher than that of Ni12P5 and Ni3P. NixP/SBA-15/cordierite with P/Ni of 1 had the highest HDS activity, which DBT conversion can be reach 95% at 360℃.For Co-Ni2P/SBA-15 catalysts with different Co content, Ni2P existed in Co-Ni2P/SBA-15 catalysts. All obtained samples have mesoporous structure. The addition of Co to Ni2P/SBA-15 catalyst can increase surface area and pore volume of samples; 4%Co-Ni2P/SBA-15 catalysts had the best HDS activity, which DBT conversion can reach 99% at 360℃. The addition of Co can improve BP selectivity. Compared to N2P/SBA-15 catalyst, BP selectivity over Co-N2P/SBA-15 catalysts was increased by 9%. In case of Co-N2P/SBA-15/cordierite monolithic catalyst, the active phase was Ni2P. The surface area and pore volume increased due to the addition of Co. The additions of 0.55%Co to Ni2P/SBA-15/cordierite monolithic catalysts can promote Niδ+ relative concentration. Excess P existed on the surface of monolithic catalyst.0.55%Co-Ni2P/SBA-15/cordierite monolithic catalyst had the best HDS activity, which DBT conversion can reach 95%.For La-Ni2P/SBA-15 catalysts with different La content, Ni2P was active phase. The size of Ni2P particles decreased when La was introduced into Ni2P/SBA-15 catalyst. La, Ni and P existed as the form of La3+, Niδ+and Ni2+, Pδ+ and P5+ respectively on the surface of catalysts. The 4%La-Ni2P/SBA-15 catalyst had the best HDS activity, which DBT can reach 94% at 340℃. In case of La-Ni2P/SBA-15/cordierite monolithic catalysts with different La content, the value of the surface area and pore volume of samples first increased, and then decreased with increasing La content. The 1.5%La-Ni2P/SBA-15 catalyst had the best HDS activity, which DBT conversion can reach 94%.In case of W-Ni2P/SBA-15 catalysts with different W content, the values of the surface area and pore volume of W-Ni2P/SBA-15 catalysts increased when W was added to Ni2P/SBA-15 catalysts. The acid properties of the samples were affected when W was added to Ni2P/SBA-15 catalyst. The strength of acid and the amount of total acid increased with increasing W content. The addition of W to Ni2P/SBA-15 catalyst decreased the Niδ+ concentration in Ni2P. BP selectivity over W-Ni2P/SBA-15 catalyst was increased by 18% at 360℃-380℃.For Ce-Ni2P/SBA-15 catalysts with different Ce content, Only Ni2P phase was formed in Ce-Ni2P/SAB-15 catalysts with Ce≤5%. Ni2P and Ni12P5 phases existed in 7%Ce-Ni2P/SBA-15 catalyst. The surface area and pore volume increased when Ce was added to Ni2P/SBA-15 catalyst. Ce-Ni2P/SBA-15 gave a higher the strength of the acid sites and total acid amount. The addition of Ce to the Ni2P/SBA-15 catalyst decreased the amount of active sites in Ni2P/SBA-15. BP selectivity over Ce-Ni2P/SBA-15 catalyst was increased by 13%.更多还原