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Direct conversion of syngas to aromatics over metal oxide‐zeolite (OX‐ZEO) composite catalysts is a novel route for efficient utilization of carbon resources. To realize a high activity with considerable selectivity to aromatics and stability, the design of synergetic OX‐ZEO catalyst to meet complex kinetics still remains a great challenge. In this work, a synergetic dual‐oxide/zeolite catalyst was developed to tune the coupling between CO and H2 activation through active H species migration, by adopting ZnZrOx oxide with stable single‐layer Zn−O structure for H2 activation and CeZrOx oxide with abundant oxygen vacancies as the CO activation component. The ratio and the proximity of CeZrOx and ZnZrOx is essential for the catalyst activity and stability. The optimal catalyst 1CeZrOx‐2ZnZrOx/Z5@Si shows a superior catalytic performance with 75.6 % aromatics selectivity at a CO conversion as high as 57.5 %. After induction period, the catalyst exhibits excellent stability for 1100 h, keeping the high selectivity above 75 % with an average conversion of 43 %. This work will provide a new perspective to design a high performance and long‐life OX‐ZEO composite catalyst for direct conversion of syngas to high value chemicals. [ABSTRACT FROM AUTHOR]

Ceria‐zirconia solid solutions with tunable surface oxygen vacancy have been used in the direct conversion of syngas into aromatics after coupling with ZSM‐5 zeolite. A high selectivity of 83.1 % to aromatics has been achieved from syngas with low H2/CO ratio over Ce0.2Zr0.8O2/ZSM‐5 bifunctional catalyst. The surface oxygen vacancy of Ce0.2Zr0.8O2 is supposed to facilitate the formation of oxygenates which act as intermediates for C−C coupling and aromatization on ZSM‐5, and thus contribute to the well kinetic matching between C−O activation and C−C coupling over these two components of catalyst. The ceria‐zirconia with abundant surface oxygen vacancies and enhanced lattice oxygen mobility intimately mixed with ZSM‐5 zeolite with moderate acidity and crystal size play an important role in the catalytic performance. O‐pen vacancy: By tuning the surface oxygen vacancy of ceria‐zirconia solid solutions, a well kinetic matching between C−O activation and C−C coupling can be achieved, and syngas with low H2/CO ratio is directly converted into aromatics with a high selectivity over a ceria‐zirconia/HZSM‐5 bifunctional catalyst. [ABSTRACT FROM AUTHOR]

Zirconia has recently been used as an efficient catalyst in the conversion of syngas. The crystalline phases of ZrO2 in ZrO2/HZSM-5 bi-functional catalysts have important effects on C–O activation and C–C coupling in converting syngas into aromatics and been investigated in this work. Monoclinic ZrO2 (m-ZrO2) and tetragonal ZrO2 (t-ZrO2) were synthesized by hydrothermal and chemical precipitation methods, respectively. The results of in situ diffuse reflection infrared Fourier transform spectroscopy (DRIFTs) revealed that there were more active hydroxyl groups existing on the surface of m-ZrO2, and CO temperature programmed desorption (CO-TPD) results indicated that the CO adsorption capacity of m-ZrO2 was higher than that of t-ZrO2, which can facilitate the C–O activation of m-ZrO2 for syngas conversion compared to that of t-ZrO2. And the CO conversion on the m-ZrO2 catalyst was about 50% more than that on the t-ZrO2 catalyst. 31P and 13C magic angle spinning nuclear magnetic resonance (MAS NMR) analysis revealed a higher acid and base density of m-ZrO2 than that of t-ZrO2, which enhanced the C–C coupling. The selectivity to CH4 on the m-ZrO2 catalyst was about 1/5 of that on the t-ZrO2 catalyst in syngas conversion. The selectivity to C2+ hydrocarbons over m-ZrO2 or t-ZrO2 as well as the proximity of the ZrO2 sample and HZSM-5 greatly affected the further aromatization in converting syngas into aromatics. [ABSTRACT FROM AUTHOR]