Synthesis of Hydrocarbons over a Bifunctional Oxide/Zeolite catalyst

The direct conversion of syngas into hydrocarbons, catalyzed by a combination of metal oxide and acidic zeolite, has garnered increasing attention in the scientific community. The remarkable hydrocarbon selectivity achieved in the OX-ZEO process is a key factor in this growing interest. This process involves two distinct steps: CO activation over the oxide and subsequent C-C coupling within the zeolite pores, connected by an unidentified oxygenate intermediate. In this study, we explored three proposed oxygenates as potential intermediates and compared their conversion within the OX-ZEO process. Using a bifunctional ZnCr2O4/H-MOR catalyst in a syngas-fed batch reactor, we found that methanol (MeOH) and dimethyl ether (DME) produced a hydrocarbon distribution similar to syngas conversion. However, the conversion of acetic acid (AcOH) resulted in a notably distinct range of hydrocarbons, including short olefins not detected with other reagents. Our findings suggest that methanol/DME might serve as active intermediates in the OX-ZEO process over the ZnCr2O4/H-MOR catalyst. This study provides a deeper insight into the transformation of proposed intermediates, contributing to the identification of the bridging intermediate that links the two catalytic functions.