In2O3/SSZ-13催化CO2加氢高选择性合成液化石油气

Highly selective synthesis of LPG from CO2 hydrogenation over In2O3/SSZ-13 binfunctional catalyst

  • 摘要: 通过In2O3/SSZ-13双功能催化剂实现了二氧化碳(CO2)加氢高选择性合成液化石油气(LPG,\rmC_3^0 \rmC_4^0 )。利用X射线衍射(XRD)、N2吸附-脱附、扫描电镜(SEM)、透射电镜(TEM)、NH3程序升温脱附(NH3-TPD)等表征手段对双功能催化剂的物化性质进行了表征。在固定床反应器上研究了氧化铟的晶粒尺寸、反应条件对In2O3/SSZ-13催化二氧化碳加氢制液化石油气性能的影响。结果表明,SSZ-13分子筛的八元环结构和强酸性位点有利于丙烷的选择性生成,初始晶粒尺寸为5 nm的氧化铟具有最高的CO2转化率(11.7%)和CO选择性(61.0%),而烃类产物分布受In2O3晶粒尺寸影响较小,其中,烃类产物中LPG的选择性基本维持在90%左右,丙烷选择性约为75%。增加反应压力、降低反应空速均有利于LPG收率的提高,在350 ℃,3 MPa,9000 mL/(gcat·h)的反应条件下,In2O3/SSZ-13双功能催化剂反应100 h未观察到显著失活现象。本研究为CO2加氢高选择合成液化石油气提供了新的探索途径。

     

    Abstract: Highly selective synthesis of liquefied petroleum gas (LPG, \rmC_3^0 and \rmC_4^0 ) from CO2 hydrogenation have realized over the In2O3/SSZ-13 bifunctional catalyst. The physicochemical properties of the bifunctional catalyst were characterized by X-ray diffraction spectroscopy (XRD), N2 physical adsorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and NH3 temperature-programmed desorption (NH3-TPD). The particle size effect of In2O3 and reaction conditions were investigated for CO2 hydrogenation to LPG over the In2O3/SSZ-13 bifunctional catalyst. Results indicate that CO2 conversion and CO selectivity are related to the particle size of In2O3, and fresh 5 nm In2O3 shows the highest CO2 conversion (11.7%) and the highest CO selectivity (61.0%), since it is more prone to reverse water gas reaction (RWGS). However, the hydrocarbon distribution does not exhibit a dependence of In2O3 size changes, and the selectivity of LPG maintains at 90% and the selectivity of propane reaches up to 76.8% due to the 8-MR micropores and strong acid sites of SSZ-13 zeolite. Additionally, the yield of LPG shows a volcano type with increasing reaction temperature, and the optimal reaction temperature is 370 ℃. Low space velocity is more favorable to the CO2 conversion, and LPG selectivity in hydrocarbon products still maintains about 90%. High reaction pressure is beneficial to improving the yield of LPG via promoting the secondary hydrogenation reaction over the SSZ-13 zeolite and inhibiting CO formation. Furthermore, no obvious deactivation is observed after a time on stream (TOS) of 100 h over the In2O3/SSZ-13 bifunctional catalyst at 350 ℃, 3 MPa and 9000 mL/(gcat·h). The research provides a new strategy for highly selective synthesis of LPG from CO2 hydrogenation.

     

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