Highly hydrothermal stable mesoporous molecular sieves (TZM) prepared by the self assembly of zeolitic subunits from ZSM-5 desilication and their catalytic performance for CO2 reforming of CH4†,New Journal of Chemistry

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Highly hydrothermal stable mesoporous molecular sieves (TZM) prepared by the self assembly of zeolitic subunits from ZSM-5 desilication and their catalytic performance for CO2 reforming of CH4†
New Journal of Chemistry ( IF 2.7 ) Pub Date : 2018-11-05 00:00:00 , DOI: 10.1039/c8nj03861a
Junqiang Xu _{1,

2,

3,

4} , Qiang Zhang _{1,

4,

5,

6} , Fang Guo _{1,

2,

3,

4} , Yaoqiong Wang _{1,

2,

3,

4} , Jiaqing Xie _{4,

7,

8,

9}

Affiliation

We demonstrated a new strategy for the preparation of highly stable mesoporous molecular sieves (TZM) by the desilication of ZSM-5 zeolite and self-assembly of the zeolite subunits in a Na₂O·(3.3–3.4) SiO₂ aqueous solution. Na₂O·(3.3–3.4) SiO₂ in the aqueous solution plays two roles in the synthesis, one is providing a moderate alkaline medium with a buffering effect for the desilication of ZSM-5 zeolite, and the other one is supplementing the silica source. The desilication of ZSM-5 zeolite was optimized by the adjustment of reaction temperature and time, and pH of the solution. TZM were characterized by X-ray diffraction (XRD), N₂ adsorption/desorption (BET), Fourier transform infrared (FT-IR) spectroscopy and transmission electron microscopy (TEM). The characterization results show that the characteristics of ZSM-5 zeolite, such as double six-membered or five-membered ring subunits, were still preserved in TZM, and TZM possessed the well-ordered mesostructure of ZSM-5 zeolite crystals. Compared with the pure silica mesoporous molecular sieve (Si-MCM-41, 4 days), the hydrothermal stability of TZM (8 days) was increased by 100% in refluxed water. The significant improvement of TZM hydrothermal stability was due to an increase of the surface hydrophobicity and the ratio of 5-rings or 6-rings, and a remarkable decrease in the number of hydrophilic silanol groups. After hydrothermal treatment for 8 days, TZM also exhibited a more efficient catalytic activation than Si-MCM-41 treated for 4 days in the CO₂ reforming of methane reaction at 1023 K (750 °C). The 5% Ni/TZM-8-Glu (5 wt% Ni, loading) catalyst prepared by a glucose modified impregnation method exhibited excellent catalytic activity, which provided 73% CH₄ and 72.5% CO₂ conversion at 1023 K (750 °C).

中文翻译：

由ZSM-5脱硅作用的沸石亚基的自组装制备的高度水热稳定的介孔分子筛及其对CH ₄†的CO ₂重整的催化性能

我们展示了通过ZSM-5沸石的脱硅和Na ₂ O·（3.3-3.4）SiO ₂水溶液中沸石亚基的自组装来制备高度稳定的介孔分子筛（TZM）的新策略。水溶液中的Na ₂ O·（3.3–3.4）SiO ₂在合成中起两个作用，一种是为ZSM-5沸石的脱硅提供适度的碱性介质，具有缓冲作用，另一种是补充二氧化硅资源。通过调节反应温度和时间以及溶液的pH值，可以优化ZSM-5沸石的脱硅作用。TZM通过X射线衍射（XRD），N _2进行表征吸附/解吸（BET），傅立叶变换红外（FT-IR）光谱和透射电子显微镜（TEM）。表征结果表明，TZM中仍然保留了ZSM-5分子筛的特征，如双六元或五元环亚基，并且TZM具有ZSM-5分子筛的良好的介孔结构。与纯二氧化硅介孔分子筛（Si-MCM-41，4天）相比，TZM（8天）在回流水中的水热稳定性提高了100％。TZM水热稳定性的显着改善是由于表面疏水性和5环或6环比例的增加，以及亲水硅烷醇基团数量的显着减少。经过水热处理8天后，₂在1023 K（750°C）下甲烷反应的重整。通过葡萄糖改性浸渍法制得的5％Ni / TZM-8-Glu（5 wt％Ni，负载）催化剂表现出优异的催化活性，在1023 K（750°C）下可提供73％的CH₄和72.5％的CO₂转化率。）。

更新日期：2018-11-05

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