The decomposition of cobalt carbide (Co 2 C) to metallic cobalt in CO 2 hydrogenation results in a notable drop in the selectivity of valued C 2+ products, and the stabilization of Co 2 C remains a grand challenge. Here, we report an in situ synthesized K-Co 2 C catalyst, and the selectivity of C 2+ hydrocarbons in CO 2 hydrogenation achieves 67.3% at 300°C, 3.0 MPa. Experimental and theoretical results elucidate that CoO transforms to Co 2 C in the reaction, while the stabilization of Co 2 C is dependent on the reaction atmosphere and the K promoter. During the carburization, the K promoter and H 2 O jointly assist in the formation of surface C * species via the carboxylate intermediate, while the adsorption of C * on CoO is enhanced by the K promoter. The lifetime of the K-Co 2 C is further prolonged from 35 hours to over 200 hours by co-feeding H 2 O. This work provides a fundamental understanding toward the role of H 2 O in Co 2 C chemistry, as well as the potential of extending its application in other reactions.

A simple method was applied to fabricate phase-pure hollow CuS microspheres. The obtained product was characterized by X-ray diffraction, scanning electron microscopy, photoluminescence spectra and UV-Vis absorption spectroscopy. Further, the catalytic activity of CuS spheres was evaluated by the decolorization of Rhodamine B in the presence of hydrogen peroxide solution at room temperature. The results indicated that the product showed a good optical propertie, and the hollow sphere CuS could be an effective catalytic material.

The reed cellulose was extracted from the wild reed in the hot 12% sodium hydroxide (NaOH) aqueous solution. Then, the cellulose membrane was successfully prepared by using the reed cellulose as the raw materials dissolved in the solvent of N-methylmorpholine-N-oxide (NMMO). The characterization of the reed cellulose film was studied by the digital camera, optical microscope and scanning electron microscope (SEM). The results revealed that the reed cellulose membrane is a smooth appearance and good quality film, which could have many applications in the practical filed.

Conjugate heat transfer (CHT) has been widely used in the analysis on flow field and heat transfer of turbine blades. In this paper, a baseline design of turbine rotor blade is selected. By improving the arrangement of film holes, turning cylindrical holes into laid back fan-shaped holes in the pressure surface (PS) and suction surface (SS), and reducing the radially inclined angle of film holes on the leading edge (LE), an optimized design (OPT) is created. Grid independence validation is conducted by comparing the pressure and temperature distributions adopting three different numbers of grids. In order to select a suitable turbulence model, experiment is performed and its values are compared with the calculation results of three different turbulence models. The distributions of static pressure, static temperature, overall cooling effectiveness and streamlines of cooling flow are compared between the OPT and baseline design by the numerical calculation results of CHT. Furthermore, the adiabatic film cooling effectiveness is calculated and the cooling performances between cylindrical holes and laid-back fan-shaped holes are compared. At last, the flow and heat transfer mechanisms are analyzed and the forming causes of low or high temperature regions on the blade are explained. Calculation results show that compared with the baseline design, the area average temperature drops by 2.6% on the PS and by 3.7% on the SS. The area average overall cooling effectiveness increases by 9.3% on the PS and by 14.1% on the SS. The cooling performances are promoted greatly on the PS and SS but change little on the LE and TE. Obviously, the improvements are successful.

To investigate the superposition effect of the leading edge film on the downstream film cooling under swirling inflow, numerical simulations with three vane models (vane with films on the leading edge only, vane with films on the pressure side and suction side only, full-film cooling vane), two inlet conditions (axial inlet and swirling inlet) are conducted. The results indicate that the leading edge is the area where the film is most affected by the swirling inflow. For full-film cooling vane, the film on the leading edge does not always improve or even reduce the downstream film cooling. Flow mechanism analysis shows that the velocity direction near the downstream wall is governed by the interaction between the direction of swirling inflow and the direction of film hole incidence on the leading edge. A new type of leading edge film proposed by the author is also investigated, with the dividing line of the counter-inclined film-hole row coinciding with the twisted stagnant line to ensure that all films are incident at angles inverse to the direction of the swirling inflow. The new leading edge film successfully changes the velocity direction near the downstream wall and suppresses the deflecting effect on the downstream film. The new leading edge film can increase the overall area averaged cooling effectiveness of the full-film cooling vane by 10%, 15%, 18% and reduce the inhomogeneity by 13%, 19%, 27% over the traditional design, as the coolant mass flow increases.