Selective Conversion of CO2 into Propene and Butene

Selective conversion of CO2 into light olefins (C2=–C4=) has attracted considerable research interests. However, effective regulation of C2=–C4= distribution or selective production of specific olefins is still challenging. Herein, we report a new catalyst system composed of Zn0.5Ce0.2Zr1.8O4 solid solution and H-RUB-13 zeolite, which shows C2=–C4= yield as high as 16.1%, being 2.3–3.3 times of those reported in literature, but CO selectivity of only 26.5% at 350°C and 3.5 MPa. More strikingly, propene and butene account for about 90% of C2=–C4=. In situ spectroscopy, isotopic-labeling experiments, and DFT calculations indicate that formate and methoxyl are the dominant intermediates for CO2 hydrogenation to methanol on Zn0.5Ce0.2Zr1.8O4, whereas CO formation via RWGS reaction is substantially suppressed. By tuning the acid site content, strength, and distribution in H-RUB-13, the alkene-based cycle in MTO is significantly enhanced, and consequently, leads to the formation of more propene and butene.