L/W复合分子筛的合成及在催化裂化汽油加氢改质催化剂中的应用

Synthesis of L/W Composite Zeolite and Its Application in FCC Gasoline Hydro-upgrading Catalyst

报道了一种新型复合分子筛L/W的制备、表征及应用.采用X射线衍射(XRD)、扫描电子显微镜(SEM)、红外光谱(IR)、氮气吸附-脱附、吡啶红外光谱(Py-IR)、氢气程序升温还原(H2-TPR)及拉曼光谱(Raman)等手段系统地比较了复合分子筛与机械混合分子筛的差异.结果表明,机械混合分子筛中的L和W分子筛均以独立相存在,而复合分子筛中L分子筛是部分生长在W分子筛之上的;并且复合分子筛表现出了更大的比表面积和孔径以及更适宜的酸性分布,这有利于反应物的扩散,增强了B酸与L酸的协同效应.在催化裂化反应中,复合分子筛催化剂比机械混合分子筛催化剂具有更高的脱硫活性(脱硫率93.3%)以及更低的辛烷值损失(ΔRON=-1.15).

A novel L/W composite zeolite was synthesized via the in situ overgrowth of L zeolite on W zeolite and the corresponding physical-chemical property was characterized by means of X-ray diffraction （ XRD ）, scanning electron microscopy（ SEM）, Fourier transformed infrared（ FTIR） spectrometry, N2 adsorption, infra-red spectroscopy of adsorbed pyridine, Raman and H2-TPR. The results were compared with those of the me-chanical mixture composed of the individual L zeolite and W zeolite. In the mechanical mixture, the L zeolite phase was morphologically separated from the W zeolite phase, while the L/W composite zeolite existed in a form of a epitaxial growth structure, with the W zeolite phase as the core and the L zeolite phase as the shell. Compared with the mechanical mixture, the composite had more appropriate pore structure and moderate aci-dity distribution, which could accelerate the diffusion of reactants and enhance the synergetic effect between Br？nsted and Lewis acids. The comparison of the catalytic performances of the mechanical mixture and the composite-based Co-Mo catalysts for fluid catalytic cracking（ FCC） gasoline hydro-upgrading showed that, due to the above advantages of the composite, the corresponding catalyst exhibited a lower octane number（ RON） loss（△RON=-1.15） and higher desulfurization efficiency（HDS=93.3%）.