摘要
固相研磨法是将不同量的活性组分掺入到介孔材料上的一种简单有效的方法.采用该法以焙烧脱模前后的SBA-15为载体分别制备了不同负载量的CuO-SBA-15吸附剂.利用X射线衍射(XRD)、N2物理吸附、傅里叶变换红外(FTIR)等方法表征了吸附剂的物理性质.通过原位红外技术考察了改性前后介孔材料表面羟基的变化.借助吡啶-原位傅里叶变换红外(py-FTIR)技术考察了吸附剂表面的酸类型及相对酸量.采用静态吸附实验评价了吸附剂对催化裂化(FCC)燃料油的吸附脱硫性能.结果表明:CuO是与SBA-15表面的Si―OH结合形成[Si-O-Cu-O-Si]交联从而达到分散的目的;以SBA-15介孔材料(APS)为载体能够有效抑制在焙烧过程中介孔材料表面羟基的缩合,且CuO负载量达到3mmo·lg-1时仍能够均匀分散在载体SBA-15上,而采用焙烧脱模的SBA-15(CS)为载体制备的CuO-SBA-15吸附剂却出现了活性组分团聚现象;吸附剂的酸性与脱硫性能均随着CuO的增加出现先增加后降低的趋势,当CuO负载量达到3mmo·lg-1时吸附剂具有最高的Lewis酸(L酸)酸量及最佳的脱硫性能;吸附剂的L酸酸量与其脱硫性能成正相关关系;另外吸附剂的L酸的形成是由于改性后Cu周围的电荷密度降低引起的.
Solid-state grinding is a simple and effective technique to incorporate active species into the channels of mesoporous materials with different degrees of filling.Using this method,different concentrations of CuO were loaded into the mesochannels of as-prepared mesoporous silica（APS） and calcined SBA-15（CS）.The samples were prepared and characterized using X-ray diffraction（XRD）,N2 physisorption,and Fourier transform infrared（FTIR） spectroscopy.The relative number of hydroxyl groups was studied by in situ FTIR spectroscopy,and the total surface acidity of the adsorbents was monitored by FTIR spectroscopy at 423 K using pyridine as a probe.Desulfurization of fluid catalytic cracking（FCC） fuel oils using these materials was investigated.The results suggest that CuO interacts directly with support hydroxyl groups to form [Si-O-Cu-O-Si] linkages in the mixtures,which can effectively constrain the condensation of hydroxyl groups in SBA-15 to improve the mesostructure of the adsorbents during calcination.Saturated coverage of the surface of APS is reached using 3 mmol·g-1 CuO.However,using CS,aggregation of CuO is observed in the material containing 3 mmol·g-1 of CuO.Both the surface acidity and desulfurization performance significantly increase upon modification of SBA-15 with CuO,and then decrease slowly as the concentration of CuO is increased.The sample containing 3 mmol·g-1 CuO shows the highest Lewis acidity and desulfurization performance.The Lewis acidity of the adsorbents matches the adsorptive desulfurization performance.It is also demonstrated that reduction of charge density around copper atoms helps to form Lewis acid sites.
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
2012年第6期1467-1473,共7页
Acta Physico-Chimica Sinica
基金
supported by the National Natural Science Foundation of China(20976077,21076100)
National Key Basic Research Program of China(973)(2007CB216403)
Innovation Team of Liaoning Province Colleges,China~~
