Biomimetic supported polyoxometalate structures designed and its applications for the ultra-deep oxidative desulfurization of fuels

Abstract

Inspired by the fact that human nose cilia can effectively contact with particles to prevent their entry into our body, this kind novel biomimetic structures are designed and synthesized to enable the loading efficiency between the polyoxometalate catalytic species (POMs) and the carrier, thereby improving their loading rate and promoting their catalytic performance. The mullite whiskers-uniformed cordierite (CMW) is used as a carrier to support POMs, in which mullite whiskers regarding as the cilia in our nose, this kind catalyst could not only overcome the shortcomings of simple POMs with low specific surface and easy to self-agglomerate, but also could greatly increase their contact probability with the carrier. At the same time, the advantage of the cordierite block structure also greatly conducive to their actual application value on the reusing operation. A series of Keggin-type POM-loaded bulk materials, POM@CMW, [VimAm]Br@POM@CMW, [DVim]Br@POM@CMW, have been developed with various ionic liquid-based POMs (ionic liquid = ILs, chosen these two kinds of [VimAm]Br and [DVim]Br) to a comparative study. The oxidative desulfurization reaction (ODS) for fuels was performed using the obtained materials as catalysts and H2O2 as oxidant, without the additional extractants for the existing of ILs in catalyst. Through experimental evaluations, [DVim]Br@POM@CMW was found the excellent efficiency on the Sulfur removal, with an DBT removal of 96.34 % at 70 °C for 120 min. According to the FT-IR and SEM results after the reaction, the catalyst could retain their original structure and the dibenzothiophene (DBT) removal could still be maintained above 95 % after 7 reuses. Furthermore, the oxidation reactivity of different substrates was in the following order: DBT > 4,6-dimethyldibenzothiophene (4,6-DMDBT) > thiophene (BT) and the high activity in actual diesel oil could be also exhibited. The enhanced reaction activity, excellent structural stability, and recyclability can be attributed to the abundance of active sites and outstanding mechanical properties provided by cordierite/mullite whiskers as a carrier, indicating their potential in the novel biomimetic-structured POMs-loaded catalysts.