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Surface-Protection-Induced Controllable Restructuring of Pores and Acid Sites of the Nano-ZSM-5 Catalyst and Its Influence on the Catalytic Conversion of Methanol to Hydrocarbons
Langmuir ( IF 3.9 ) Pub Date : 2020-04-02 , DOI: 10.1021/acs.langmuir.0c00214
Tingjun Fu 1 , Yujie Wang 1 , Zhong Li 1
Affiliation  

Creating mesopores for the nano-ZSM-5 catalyst could further promote the diffusion of molecules in its micropores and improve the catalytic activity and stability. Inorganic alkali treatment of ZSM-5 usually removes internal silica for the existence of an aluminum distribution gradient and leads to a hollow structure. Herein, surface TPA+ adsorption-induced protective desilication and recrystallization successively occurred during hydrothermal treatment, and controllable mesopore fabrication was achieved. The evolution of mesopores and acid sites was characterized by N2 physisorption, XRD, XRF, TEM, NH3-TPD, Py-IR, 27Al MAS NMR, 29Si MAS NMR, and TG techniques. It was found that the TPAOH concentration influenced the formation of internal cavity and mesopores in the shell. Introducing TPABr into TPAOH solution increased the surface protection because of the increased TPA+ adsorption, and coated hollow ZSM-5 was obtained. The acidity was restructured during the above mesopore fabrication. High-concentration TPAOH solution promoted the insertion of destructive Al into the skeleton structure to form strong acid sites, and the catalytic lifetime was recovered and even obviously prolonged. This reflected the key role of strong acid sites on the catalytic performance. Applying hollow nano-ZSM-5 with a mesoporous shell and strong acidity increased the lifetime by 50% and the conversion capacity for liquid hydrocarbon by 20% compared to the parent sample.

中文翻译:

表面保护诱导的纳米ZSM-5催化剂的孔和酸位的可控重组及其对甲醇催化转化为烃的影响

为纳米ZSM-5催化剂创造中孔可以进一步促进分子在其微孔中的扩散,并提高催化活性和稳定性。ZSM-5的无机碱处理通常会由于铝分布梯度的存在而除去内部二氧化硅,并导致形成空心结构。此处,在水热处理期间,表面TPA +吸附引起的保护性脱硅和重结晶相继发生,并且实现了可控的中孔制造。N 2物理吸附,XRD,XRF,TEM,NH 3 -TPD,Py-IR,27 Al MAS NMR,29表征了中孔和酸位的演变Si MAS NMR和TG技术。发现TPAOH浓度影响壳内腔和中孔的形成。将TPABr引入TPAOH溶液可提高表面保护性,因为TPA +吸附,得到涂覆的空心ZSM-5。在上述中孔的制备过程中,酸度得到了重构。高浓度的TPAOH溶液促进了破坏性Al向骨架结构的插入,形成强酸位,催化寿命得以恢复,甚至明显延长。这反映出强酸​​位点对催化性能的关键作用。与母体样品相比,使用具有中孔壳和强酸性的中空纳米ZSM-5可以将寿命延长50%,将液态烃的转化能力提高20%。
更新日期:2020-04-03
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