Interaction between phosphorus and zeolite/binder: A realumination study on beta zeolites

Zeolite/binder (beta/Al2O3) was treated with different concentrations of phosphoric acid, and the samples pre- and post-treatment were characterized by several methods. It was found that the content of tetrahedral framework Al species in the beta zeolite increased after the sample was impregnated with phosphoric acid, and the generated aluminophosphate reduced the external surface area of the catalyst but had no effects on the catalytic ability of the beta zeolite. The realumination behavior of beta zeolite is proposed in this work. Polyphosphate reacted with hexa-coordinated aluminum, resulting in the formation of amorphous aluminophosphate species, which were then transferred to the silicon hydroxyl structure cavity on the zeolite to complete realumination. The influence of the sample before and after phosphoric acid modification on the activity of synthesized polyoxymethylene dimethyl ethers was discussed. When the phosphoric acid concentration was 0.5 M, the time to reach the same conversion of trioxane (about 94%) was shortened by 60 min compared to the parent sample.

Automated summary

In this study, it was found that phosphoric acid treatment increased the content of tetrahedral framework Al species in beta zeolite and generated aluminophosphate that reduced the catalyst's external surface area without affecting its catalytic ability. The realumination behavior of beta zeolite was proposed, where polyphosphate reacted with hexa-coordinated aluminum to form amorphous aluminophosphate species transferred to the zeolite structure cavity for realumination. The impact of phosphoric acid modification on the activity of synthesized polyoxymethylene dimethyl ethers was discussed, showing a notable reduction in the time required for conversion.