介孔SO42-/ZrO2的制备、表征及其催化煎炸废油合成生物柴油

Preparation and characterization of mesoporous SO42-/ZrO2 and its catalytic synthesis of biodiesel from waste cooking oil

采用溶胶凝胶法,使用十六烷基三甲基溴化氨(CTAB)为模板剂,正丙醇锆为锆源,(NH4)2SO4为硫化剂,经不同温度(400~600℃)煅烧制备介孔SO42-/ZrO2固体超强酸。并利用氨程序升温脱附(NH3-TPD)、傅里叶红外光谱(FT-IR)、N2物理吸脱附(BET)、X射线衍射(XRD)和透射电子显微镜(TEM)对样品结构进行表征。结果显示:当煅烧温度为500℃时制备的催化剂出现明显的四方晶相,随着煅烧温度的升高,催化剂的比表面积先增加后减小,500℃时最大,比表面积为130 m2/g,孔径为3.3 nm;TEM显示所制备的催化剂均具有蠕虫状介孔结构;NH3-TPD曲线显示所制备的催化剂均具有超强酸性,500℃时酸量最大,为22 cm3/g STP。将该催化剂用于煎炸废油和甲醇酯交换制备生物柴油试验,发现500℃煅烧的催化剂具有较高的催化活性,于190℃下反应8 h生物柴油收率达到92.3%。催化剂重复利用5次后,生物柴油收率仍能达到76.3%。

Using sol-gel method,with hexadecyl trimethyl ammonia bromide(CTAB) as template, zirconium n-propanol as zirconium source and(NH4)2SO4 as sulfide agent,mesoporous SO42-/ZrO2 solid superacid was prepared by calcination at different temperatures(400-600℃).The structure of the catalyst was characterized by ammonia temperature programmed desorption(NH3-TPD), Fourier transform infrared spectroscopy(FT-IR), physical adsorption and desorption of N2(BET), X-ray diffraction(XRD) and transmission electron microscopy(TEM).The results showed that when calcination temperature was 500℃, the catalyst showed obvious tetragonal phase. With the increase of calcination temperature, the specific surface area of the catalyst increased first and then decreased.When the calcination temperature was 500℃, the specific surface area was the highest with 130 m2/g and and the pore size was 3.3 nm. TEM showed that the catalyst had worm-like mesoporous structure. NH3-TPD curves showed that the prepared catalyst had super acidity, and the maximum acidity was 22 cm3/g STP at 500℃. The catalyst was used to prepare biodiesel by transesterification of waste cooking oil with methanol. It was found that the catalyst calcinated at 500℃ had high catalytic activity and the yield of biodiesel reached 92.3% at 190℃ for 8 h. The yield of biodiesel still could reach 76.3% after the catalyst calcinated at 500℃ was reused for five times.