Yuhua Zhang

Tuning the particle size of Co ₃ O ₄ modulates' reducibility and the evolved active-phase components, which ultimately dictate the catalytic behaviour of cobalt species toward CO ₂ hydrogenation.

In2O3-based catalysts have emerged as promising candidates for CO2 hydrogenation to methanol, yet their practical application is hindered by low CO2 conversion due to weak H2 dissociation capability. Herein, we report a WO3-promoted In2O3 catalyst that significantly enhances methanol production via a distinct interfacial promotion mechanism. A series of WO3/In2O3 catalysts with varying WO3 loadings (3–15 wt%) were prepared by incipient wetness impregnation. The 5% WO3/In2O3 catalyst achieves a methanol space-time yield of 8.1 mmol·g1·h-1 at 300 °C and 2.0 MPa, which is 2.2 times that of pristine In2O3. A combination of characterization techniques including XPS, XAS, H2-TPR, and CO2-TPD reveals that the enhanced activity originates from W–O–In interfacial electron transfer and the partial reduction of WO3 to WO3-x, which collectively promote H2 activation and enhance the overall hydrogenation activity toward methanol. This work demonstrates that WO3, an acidic oxide with redox properties, offers a distinct promotion pathway for In2O3-based catalysts, providing a new perspective for designing oxide promoters for CO2 hydrogenation.

Pt–N–CeO ₂ cluster catalyst was constructed via nitridation of Pt–CeO ₂ single-atom catalyst, delivering highly active and stable performance in dry reforming of methane.

In this work, carbon nanotubes (CNTs) were employed as supports, and CoO particles with hexagonal close-packed (hcp) or face-centered cubic (fcc) structures were deposited via ultrasonic impregnation. The influence of CoO crystal structure and potassium promotion on the catalytic performance of the supported catalysts was systematically investigated. Compared with hcp-CoO, fcc-CoO was more uniformly dispersed on CNTs, and potassium addition further stabilized cobalt dispersion. The CNTs supports effectively stabilized the CoO oxidation state, with a significant fraction of CoO retained after reaction at 400 °C. hcp-CoO/CNTs displayed markedly higher activity than fcc-CoO/CNTs, and product selectivity evolved very differently between the two catalysts. The synergy between potassium promotion and CoO phase control significantly enhanced CO and C ₂₊ hydrocarbon selectivity. Reduction of CoO to Co⁰ at elevated temperatures substantially increased CO₂ hydrogenation activity, albeit with a pronounced rise in CH ₄ selectivity.

Fischer-Tropsch synthesis represents a key endeavor aimed at converting nonpetroleum carbon resources into clean fuels and valuable chemicals. However, the current state-of-the-art industrial FTS employing Fe-based catalysts is still challenged by the low carbon efficiency (2 and CH ₄ resulting from the nonregulated side water gas shift reaction. Herein, we describe a shielding strategy involving the encapsulation of the active Hägg carbide (χ-Fe ₅ C ₂ ) by a graphene layer, exhibiting excellent resilience under reaction conditions and exposure to air, thereby eliminating the need for reduction or activation before the Fischer-Tropsch synthesis reaction. The graphene layer helps to stabilize the Hägg carbide active phase, and more importantly, greatly suppresses the side water gas shift reaction. Theoretical calculations suggest that graphene shielding inhibits the water gas shift reaction by reducing the absorption strength of OH _x species. Remarkably, the optimum χ-Fe ₅ C ₂ @Graphene catalyst demonstrates a minimized CO ₂ and CH ₄ formation of only 4.6% and 5.9%, resulting in a high carbon efficiency (ca. 90%) for value-added products. These results are expected to inspire unique designs of Fe-based nanocomposite for highly efficient FTS with regulated carbon transfer pathways.

The synthesis of a specific product via the Fischer-Tropsch synthesis remains challenging due to the uncontrollable coupling of CHx on active sites. Isoparaffins, essential high-quality petroleum additives for improving octane numbers, are primarily derived from petroleum or natural gas. With petroleum reserves dwindling and the associated low selectivity, the direct conversion of syngas to isoparaffins has emerged as a promising alternative. This study presents a tandem catalyst comprising CoxMn1-xO and zeolites for catalyzing the direct conversion of syngas to C-4-C-5 isoparaffins. The relay catalyst exhibited an impressive selectivity of 55.6% toward the desired products while maintaining a low CO2 selectivity of approximately 20%. Notably, the selectivity of isobutane reached 43.5%, exceeding predictions based on the Anderson-Schulz-Flory distribution. Syngas undergoes conversion into olefins on CoxMn1-xO nanocomposites, diffuses into microporous zeolites, and interacts with Br & oslash;nsted acids to produce isoparaffins. The stability of the relay catalyst relied significantly on the pore characteristics and acidic density of the zeolites.