A MoO₃–Metal–Organic Framework Composite as a Simultaneous Photocatalyst and Catalyst in the PODS Process of Light Oil

Abstract

Photo-oxidative desulfurization (PODS) properties of MoO3–metal–organic framework composite photocatalysts were investigated by introducing the proper weight percent of MoO3 into a Zn(II)-based MOF, [Zn(oba)(4-bpdh)0.5]n·1.5DMF (TMU-5), for the mineralization of dibenzothiophene from model oil. The addition of 3 wt % of MoO3 into a TMU-5 host acting as a crystal growth inhibitor was confirmed by PXRD and BET results. For the first time, under mild and green reaction conditions, 5 wt % MoO3–TMU-5 composite (MT-5) exhibited good photocatalytic activity in the model oil PODS reaction, which has no limitations in the current oxidative desulfurization catalytic systems. Only 3% of the total amount of MoO3 content in the MT catalyst is leached during the reaction. In addition, the rate of PODS of MT-5 obeys a pseudo-first-order equation with an apparent rate constant of 0.0305 min–1 and half-life t1/2 of 22.7 min. Radical scavenger experiments and terephthalic acid fluorescence techniques confirmed that OH• and O2•– are the main reactive species in the dibenzothiophene photocatalytic degradation. The synergic effects of the active surface of TMU-5 (organic linkers as antennas) together with the active sites of MoO3 may lead to the further enhancement of the PODS activity of the MT-5 photocatalyst. Moreover, a possible photocatalytic desulfurization mechanism was proposed in the presence of MoO3–TMU-5 composites.