In situ solid state NMR observation of the methanol-to-hydrocarbons (MTH) process over nanosized and microsized HZSM-5 zeolites
In situ solid state NMR observation of the methanol-to-hydrocarbons (MTH) process over nanosized and microsized HZSM-5 zeolites
复制标题
纳米级和微米级 HZSM-5 沸石上甲醇制烃 (MTH) 过程的原位固态核磁共振观察
DOI：
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发表时间：
2002
期刊：
影响因子：
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通讯作者：
X. Bao
中科院分区：
文献类型：
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作者：
Zhimin Yan;Dinghan Ma;Jianqin Zhuang;Xianchun Liu;Xiumei Liu;Xiuwen Han;X. Bao
用原位固体核磁共振研究了纳米HZSM-5和微米HZSM-5在甲醇中转化为烯烃后表面烷氧基物种的形成。与微米HZSM-5沸石相比，纳米HZSM-5沸石对甲醇物种具有更高的亲和力。吸附的甲醇物种的活化导致了不同刚性的表面烷氧基物种的形成，包括类羧酸盐表面物种，相关光谱的去卷积证明了这一点。这些结果支持在甲醇转化过程中存在所谓的碳池，它不仅是物种偶联生成烯烃的反应前驱，也是失控聚合在表面生成焦炭的前驱。纳米HZSM-5对表面碳质沉积物的形成有明显的阻挡作用。
The formation of surface alkoxy species on nanosized HZSM-5 and microsized HZSM-5, after exposure to methanol and subsequent conversion to olefins, has been investigated by in situ solid state NMR. Compared to microsized HZSM-5 zeolite, the nanosized HZSM-5 zeolite was found to exhibit a higher affinity for trapping methanol species. Activation of the adsorbed methanol species resulted in the formation of various surface alkoxy species with different rigid characters, including the carboxylate-like surface species, as evidenced by deconvolution of the related spectra. The present results support the existence of the so-called carbon-pool in the conversion of methanol, which serves as the reaction precursor not only for the coupling of the species to form olefins, but also for uncontrolled polymerization to give coke on the surface. The nanosized HZSM-5 shows a distinct resistance to the formation of carbonaceous deposits on the surface.