Selective Synthesis of Benzene, Toluene, and Xylenes from Syngas,ACS Catalysis

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Selective Synthesis of Benzene, Toluene, and Xylenes from Syngas
ACS Catalysis ( IF 11.3 ) Pub Date : 2020-05-28 , DOI: 10.1021/acscatal.9b05200
Dengyun Miao ₁ , Yi Ding _{1,

2} , Tie Yu ₁ , Jian Li ₁ , Xiulian Pan ₁ , Xinhe Bao ₁

Affiliation

Although direct synthesis of aromatics from synthesis gas (syngas) using a bifunctional catalyst composed of metal oxide and zeolite (OX–ZEO) has attracted extensive attention, the selectivity of benzene, toluene, and xylenes (BTX) remains a challenge. Herein, we show that a hybrid dual bed by packing a zeolite bed below the MnCr–ZSM-5 composite significantly enhances BTX formation. For instance, the BTX fraction in aromatics reaches over 80% when the second bed is beta zeolite and rises to 88% if an ultrastable Y zeolite (USY) is used. Studies show that the zeolite structure of three-dimensional (3D) channels of the 12-membered ring plays an important role in facilitating the BTX formation. Passivation of the external acid sites of zeolites further enhances the BTX selectivity. However, too much silica on the surface of ZSM-5 could narrow the pore opening and is detrimental for the diffusion of BTX, resulting in a lowered BTX selectivity. This hybrid catalyst system provides a promising strategy for direct production of BTX from syngas.

中文翻译：

由合成气选择性合成苯，甲苯和二甲苯

尽管使用由金属氧化物和沸石（OX-ZEO）组成的双功能催化剂从合成气（合成气）直接合成芳烃引起了广泛关注，但苯，甲苯和二甲苯（BTX）的选择性仍然是一个挑战。在本文中，我们表明，通过在MnCr–ZSM-5复合材料下方填充沸石床的混合双层床显着增强了BTX的形成。例如，当第二层床是β沸石时，芳烃中的BTX比例达到80％以上，如果使用超稳定Y沸石（USY），则上升到88％。研究表明，该12元环的三维（3D）通道的沸石结构在促进BTX形成中起着重要作用。沸石外部酸位的钝化进一步提高了BTX的选择性。然而，ZSM-5表面的二氧化硅过多会缩小孔的开口，并且不利于BTX的扩散，从而降低BTX的选择性。这种杂化催化剂系统为从合成气直接生产BTX提供了有希望的策略。

更新日期：2020-07-02

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