Abstract

P-xylene is one of petrochemical products eagerly in demand. Until recently, the process for preparing of p-xylene was done via gas-phase toluene methylation reaction at high temperature using a strong acid catalyst. In this work, high surface area, shape-selective and single-site MIL-101(Cr) was used as a catalyst to perform toluene methylation reaction in a liquid phase at low reaction temperature (60-120 °C). Toluene conversion and p-xylene selectivity are up to 50% and 90%, respectively. Under the optimum operating conditions; 1:1 toluene: methanol molar ratio, the reaction temperature is 120 °C. The catalyst was synthesized via the hydrothermal method and the MIL-101 structure was confirmed by different analytical techniques: TGA, XRD, FTIR and BET surface area. The remarkably high toluene conversion and xylene selectivity at a low reaction temperature, in comparison to previous research, was attributed to the suppression of side reactions that could convert methanol to linear hydrocarbons, and to the inhibition of p-xylene isomerization. This suppression can be attributed to the single site properties and to the uniform pore size distribution of the prepared MIL 101 catalyst.

Graphic abstract

Synthesis and characterization of single-site MIL-101(Cr) were used as a catalyst for toluene methylation reaction in a liquid phase at low reaction temperature (60–120 °C). The results suggest that toluene conversion and p-xylene selectivity are up to 50% and 90%, respectively, under the optimum operating conditions; 1:1 toluene: methanol molar ratio, the reaction temperature is 120 °C.

中文翻译：

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单点MIL-101用于新型低温液相甲苯甲基化

摘要

对二甲苯是迫切需要的石化产品之一。直到最近，通过使用强酸催化剂在高温下通过气相甲苯甲基化反应完成对二甲苯的制备方法。在这项工作中，使用高表面积，形状选择性和单中心的MIL-101（Cr）作为催化剂在较低的反应温度（60-120°C）下在液相中进行甲苯甲基化反应。甲苯转化率和对二甲苯选择性分别高达50％和90％。在最佳操作条件下；甲苯：甲醇的摩尔比为1：1，反应温度为120°C。该催化剂是通过通过不同的分析技术（TGA，XRD，FTIR和BET表面积）确定了水热法和MIL-101结构。与以前的研究相比，在较低的反应温度下甲苯转化率和二甲苯选择性显着提高，这归因于抑制了副反应，该副反应可将甲醇转化为线性烃，并抑制了对二甲苯异构化。这种抑制可归因于所制备的MIL 101催化剂的单位性质和均匀的孔径分布。

图形摘要

单中心MIL-101（Cr）的合成和表征被用作液相低温度（60-120°C）下甲苯甲基化反应的催化剂。结果表明，在最佳操作条件下，甲苯转化率和对二甲苯选择性分别高达50％和90％。甲苯：甲醇的摩尔比为1：1，反应温度为120°C。