以催化油浆为增孔剂的MCM-41介孔分子筛的合成

SYNTHESIS OF MCM-41 MESOPOROUS MOLECULAR SIEVES WITH FCC DECANT OIL AS SWELLING AGENT

采用阳离子表面活性剂十六烷基三甲基溴化铵为模板剂、正硅酸乙酯为硅源、硫酸铝为铝源,水热合成了以甲苯溶解的催化油浆为添加剂的MCM 41介孔分子筛,通过XRD、N2吸附脱附、TG DTA、SEM等测试手段对合成样品进行了表征,重点研究了在甲苯 催化油浆=1∶1和2∶1(质量比)两个剂油比下分子筛结晶度、晶胞参数、BET表面积、平均孔径以及孔容等结构性质随催化油浆添加量的变化规律,并对合成机理进行了解释。结果表明,当剂油比为1∶1时,分子筛的结晶度和晶胞参数随催化油浆添加量的变化呈现先增加后减小趋势,当noil nCTMAB=0.34时,其晶胞参数最大可以达到5.95nm;当剂油比为2:1时,随添加剂量的增加,分子筛结晶度降低,BET表面积成先增大后减小,而孔容和平均孔径呈逐渐增加趋势。当noil nCTMAB=0.15时,MCM 41的BET表面积可达1163.7m2·g-1,孔容可达到1.34cm3·g-1,平均孔径为4.34nm。

AlMCM41 mesoporous molecular sieves with high specific surface area have been hydrothermally synthesized with Shenghua Refinery's FCC decant oil dissolved in toluene as additive, using cationic surfactant of cetyl trimethyl ammonium bromide as template, tetraethyl orthosilicate as silica source and aluminum sulfate as aluminum source in this article XRD, SEM, nitrogen adsorption and TGDTA have been used to characterize pore structures of these synthesized samples Effects of additive on synthetic conditions have been investigated and longer time for blending colloidal solution has been taken Emphasis has been put on changes of structure properties such as crystallization, crystal cell parameter, BET surface area, average pore diameter and pore volume with addition amount of FCC decant oil under conditions that the ratios of toluene to FCC decant oil are 1∶1 and 2∶1 respectively Explanations of these varieties have been supported from synthetic mechanism Results of N2 adsorption reveal that BET surface area and pore volume of molecular sieves synthesized are respectively up to 1?1637?m2·g-1 and 134?cm3·g-1, and average pore diameter is 434?nm TGDTA profiles show that for the molecular sieves added by FCC decant oil there existed two clear exothermic phases, which are respectively resulted from the removals of surfactant and FCC decant oil from pores In addition, DTA profile shows that exothermic peak for removal of the template of the sample added by FCC decant oil is inclined to shift to higher temperature, which explains that decomposition temperature of template molecules bonded with SiOAl group is increased with addition of SC SEM photos show that crystal particles become smaller, more disperse and still look like the shape of bars