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首页> 外文期刊>Catalysis science & technology >The effect of MFI zeolite lamellar and related mesostructures on toluene disproportionate and alkylation
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The effect of MFI zeolite lamellar and related mesostructures on toluene disproportionate and alkylation

机译：MFI沸石层层和相关介质结构对甲苯的影响不成比例和烷基化的影响

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摘要

The effect of MFI zeolite nanosheet morphology and related mesostructures on the accessibility of acid sites evaluated from FTIR spectra of different adsorbed probe molecules and conversions and selectivities in toluene disproportionation and alkylation with isopropyl alcohol was investigated. Two-dimensional MFI lamellar zeolite (1.5 nm thickness of layers) and related mesoporous sponge morphologies, most probably with 10-ring channel system not yet structurally fully determined, were synthesized and characterized by XRD, SEM, TEM, and adsorption measurements. FTIR spectroscopy using pyridine, deuterated acetonitrile and 2,6-di-tert-butyl pyridine evidenced high concentrations of accessible Lewis acid sites at the expense of Bronsted acid sites. Ordered mesoporous zeolites exhibited slightly higher toluene conversion in its alkylation with isopropyl alcohol than lamellar MFI or conventional MFI due to easy access to active sites. The lamellar zeolite consisting of less than a unit cell layer was slightly more active than MFI but still exhibited high selectivity to p-cymene. It evidences that alkylation of toluene with isopropyl alcohol proceeds mainly in the 10-ring channel system of MFI zeolite, although the effect of large external surface cannot be neglected. Increased para-selectivity compared with thermodynamic value is achieved even in the case of extremely thin zeolite nanosheets.
机译：研究了MFI沸石纳米片形态和相关介质结构对从不同吸附的探针分子的FTIR光谱评估的酸位点的可及性的影响，并研究了与异丙醇的甲苯相比化和烷基化中的转化和选择性。二维MFI层状沸石（层的厚度为1.5 nm）和相关的介孔海绵形态，很可能具有尚未完全确定的10环通道系统，由XRD，SEM，TEM和吸附测量值合成和表征。 FTIR光谱法使用吡啶，氘代乙腈和2,6-二丁基吡啶吡啶证明了高浓度的可访问的路易斯酸位点，其费用为布朗斯特酸位点。有序的介孔沸石在用异丙醇烷基化中表现出比层状MFI或常规MFI的甲苯转化略高，这是由于容易进入活性位点。由小于单位细胞层组成的层状沸石比MFI稍有活性，但对P-甲烷的选择性仍然很高。它证明，甲苯用异丙醇的烷基化主要在MFI沸石的10环通道系统中进行，尽管不能忽略大型外表面的作用。即使在极其薄的沸石纳米片的情况下，与热力学值相比，与热力学值相比，PARA选择性的增加。

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