Trioxane (TOX), which is usually produced from formaldehyde catalyzed by acid-catalysts, is an important polymerizing monomer to produce high-performance plastics polyoxymethylene polymers (POMs). In order to reduce the separation cost and increase the catalytic activity, hierarchical Beta zeolites with different pore size were synthesized by PDDA and used for TOX produce from formaldehyde in this work. Hierarchical Beta zeolites’ average pore size increased with the increasing of PDDAs’ molecular weight. Compare to conventional Beta zeolite, it exhibited a higher catalytic performance with 95.13% selectivity and 2118 g/kg/h space–time yield of TOX due to its excellent diffusion performance from extra mesopore. The HCHO conversion and space–time yield of TOX increase first and then decrease with the pore size increasing. Further research showed that the decrease of catalytic activity is mainly due to the increase of extra-framework Al percent. This work illustrates the influence of both pore size and extra-framework Al content in hierarchical Beta zeolites for TOX produce from formaldehyde reaction.

Graphical Abstract

中文翻译：

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阳离子聚合物合成多级β沸石甲醛制三氧杂环己烷

三氧杂环己烷 (TOX) 通常由酸催化剂催化甲醛产生，是生产高性能塑料聚甲醛聚合物 (POM) 的重要聚合单体。为了降低分离成本并提高催化活性，本工作采用 PDDA 合成了不同孔径的多级 Beta 沸石，并将其用于甲醛的 TOX 生产。多级β沸石的平均孔径随着PDDAs分子量的增加而增加。与传统的 Beta 沸石相比，由于其出色的超中孔扩散性能，它表现出更高的催化性能，选择性为 95.13%，TOX 时空产率为 2118 g/kg/h。随着孔径的增大，TOX的HCHO转化率和时空产率先升高后降低。进一步研究表明，催化活性的降低主要是由于骨架外Al百分比的增加。这项工作说明了分级 β 沸石中的孔径和骨架外铝含量对甲醛反应产生的 TOX 的影响。

图形概要