Direct synthesis of light olefins from syngas (STO) using a bifunctional catalyst composed of oxide and zeolite has attracted extensive attention in both academia and industry. It is highly desirable to develop robust catalysts that could enhance the CO conversion while simultaneously maintain high selectivity to C2-C4 olefins. Herein, we report a bifunctional catalyst consisting of ZnCr binary oxide (ZnCrOx) and low-Si AlPO-18 zeolite, showing both satisfying selectivity to C2-C4 olefins of 45.0% (86.7%, CO2 free) and high olefin/paraffin ratio of 29.9 at the CO conversion of 25.2% under mild reaction conditions (4.0 MPa, 390 °C). By optimizing the reaction conditions, the CO conversion could be markedly increased to 49.3% with a slight drop in selectivity. CD3CN/CO-FTIR characterizations and theoretical calculations demonstrate that low-Si AlPO-18 zeolite has lower acid strength, and is therefore less reactive toward the hydride transfer in the STO reaction, leading to a higher olefin/paraffin ratio.

Operando and kinetic studies of lean-burn methane combustion were preformed on a Pd­(3.3 wt %)/γ-Al2O3 catalyst in a low temperature range of 473–673 K. The reaction order with respect to oxygen decreased with temperature, and the order with respect to methane remained constant. The working catalyst is characterized using operando Raman spectroscopy and in situ diffuse reflectance infrared Fourier transform spectroscopy of CO adsorption (DRIFTS), and the Pd chemical states were measured with X-ray photoelectron spectroscopy (XPS). Partial oxidation of Pd atoms during reaction was identified by Raman and XPS spectroscopies. In particular, the DRIFT spectra revealed that ∼45% of Pd atoms at the top layers were transferred into PdO x species above 523 K. The reaction was assumed to occur primarily on the metallic Pd sites below 673 K, proceeding through the Langmuir–Hinshelwood mechanism, and Pd oxide may affect the adsorption and activation of reactants.

The direct synthesis of light olefins from syngas over a bifunctional catalyst containing an oxide and zeolite has been proven to be a promising strategy. Nevertheless, an unclear reaction network hinders any further enhancement in catalytic performance, such as increasing the conversion of CO. We herein report a novel bifunctional catalyst composed of a InZr binary oxide and SAPO‐34 zeolite displaying superior CO conversion (27.7 %) with selectivity to light olefins (73.6 %) at 400 °C, 2.0 MPa. We demonstrate that the Zr‐doped body‐centered cubic In2O3 phase, exhibiting higher stability than pure In2O3 under a reducing atmosphere, is the active oxide component for the initial activation of CO. A complete reaction network is proposed by DFT calculations and model reactions, revealing that CO activation over Zr‐In2O3 follows a quasi‐CO2 hydrogenation pathway and methanol is the key intermediate to be transformed into light olefins in zeolites. Moreover, inhibiting excessive hydrogenation is an effective strategy to achieve higher performance.

Higher alcohol synthesis (HAS) directly from syngas is one of the most promising approaches for utilizing nonoil resources cleanly and efficiently. A series of bimetallic CoCu catalysts with different Co/Cu ratios were prepared using a SiO2 support. The structure of Cu modified Co catalysts was characterized using HRTEM, in/ex situ X‐ray diffraction, and temperature‐programmed reduction. It was evidenced that nanoscale metal particles were formed and the reduction of Co oxide at above 673 K. Meanwhile, the interaction between Co and Cu on the surface was assumed to be responsible for the enhanced selectivity to HAS. The intrinsic kinetics for this reaction was performed over a CoCu/SiO2 catalyst under realistic conditions. The kinetic parameters, including apparent activation energies and reaction orders, were calculated through power‐law models. With the combination of chain growth probability and kinetics, the effect of temperatures on the reaction mechanism and the Cu promotional effects on Co catalysts were elaborated. © 2014 American Institute of Chemical Engineers AIChE J, 60: 1797–1809, 2014