High-yield synthesis of BTEX over Na-FeAlOx/Zn-HZSM-5@SiO2 by direct CO2 conversion and identification of surface intermediates

We present a tandem catalyst consisting of Na-promoted bifunctional FeAlOx (Na-FeAlOx) and Zn-doped HZSM-5, the outer surface of which was coated with a SiO2 layer (Zn-HZSM-5@SiO2). This tandem catalyst afforded a high BTEX space-time yield of 4.0 mmol g-1h-1 with a CO2 conversion of 45.2%. The selectivities toward BTEX were tuned by controlling the nature, density, and distribution of the Bronsted acid sites of the zeolites, in addition to adjusting the proximity between the Fe-based and zeolitic active sites. In situ operando experiments revealed the role of Zn-HZSM-5@SiO2 not only in dehydroaromatization, but also in CO2 adsorption, reverse water-gas shift reactions, and C-C coupling reactions. The findings of this study are promising for designing a tandem catalyst to directly convert CO2 to BTEX in high yields, and also provide novel insights into the reaction intermediates for this tandem catalyst.

Automated summary

This study presents a tandem catalyst that can efficiently convert CO2 to BTEX. The selectivity of the catalyst towards the desired products was controlled by adjusting the nature of the acid sites in the zeolite and the proximity between the Fe-based and zeolitic active sites. In situ operando experiments revealed the role of the catalyst in multiple reaction steps.