摘要: The laminar MgO with high specific area and the organometallic precursor Cu (acac)2 were used for the successful synthesis of Cu/MgO catalysts by metal-organic chemical vapor deposition (MOCVD) method. The copper supported on MgO catalysts were characterized by means of X-ray diffraction, Fourier-transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and N2-physisorption. Characterization results indicated that the organic precursor was successfully deposited onto MgO and the crystal structure of MgO remained intact after deposition. The hydrogenation of γ-valerolactone (γ-GVL) was employed to evaluate the catalytic performance of the Cu/MgO catalysts. It was found that the 18% Cu/MgO catalyst exhibited excellent catalytic activity (90.5%) and selectivity (94.4%) for 1, 4-PDO at 473 K and 10 MPa, and the catalytic activity of Cu/MgO did not diminish significantly after cycling for three times.
摘要: The effect of various promoting additives (Mn, Zn, Co) on the performance of CuFeZr catalyst in the synthesis of higher alcohol from syngas was investigated. The results of nitrogen physisorption, XRD and H2-TPR characterization show that these additives can reduce the particle size and enhance the surface basicity and the adsorption capacity towards CO. Especially, the doping of Zn in the CuFeZr catalyst can effectively enhance the interaction between Cu and Fe, strengthen the surface basicity, and improve the reducibility and CO adsorption ability. For the synthesis of higher alcohol from syngas over the CuFeZr catalyst, the catalytic evaluation results in a fixed bed reactor illustrate that the activity and selectivity to alcohols are greatly enhanced by the addition of Zn promoter; the space time yield (STY) of ROH is increased from 0.026 to 0.071 g/(gcat·h). Meanwhile, it was found that CO2 in the feed can improve the CO conversion as well as the STY to alcohols and hydrocarbons, but suppress the chain growth and decrease the ratio of olefin to paraffin; proper amount of CO2 (2.5%) is beneficial to the formation of alcohols and hydrocarbons of short chains.
摘要: A series of as-synthesized HZSM-5 zeolites with different Si/Al ratios (25, 90, 120, 240 and 400) were post-treated by ultrasonication for an optimum time of 60 min. The morphology, acidity and textural properties of HZSM-5 were characterized with XRD, SEM, N2 adsorption and NH3-TPD techniques. The catalytic performance was evaluated by dehydration of methanol to dimethyl ether (DME), which is a promising gaseous automotive fuel in future. It was found that the Si/Al ratio of HZSM-5 had considerable impacts on its catalytic performance for dehydration of methanol to DME. Its activity increased with decreasing Si/Al ratio from 400 to 25. Ultrasonication of HZSM-5 could significantly improve its catalytic performance.
摘要: The ternary catalyst Pt75Ru5Ni20 was conducted on various types of carbon supports including functionalized Vulcan XC-72R (f-CB), functionalized multi-walled carbon nanotubes (f-MWCNT), and mesoporous carbon (PC-Zn-succinic) by sodium borohydride chemical reduction method to improve the ethanol electrooxidation reaction (EOR) for direct ethanol fuel cell (DEFC). It was found that the particle size of the metals on f-MWCNT was 5.20 nm with good particle dispersion. The alloy formation of ternary catalyst was confirmed by XRD and more clearly described by SEM element mapping, which was relevant to the efficiency of the catalysts. Moreover, the mechanism of ethanol electrooxidation reaction based on the surface reaction was more understanding. The activity and stability for ethanol electrooxidation reaction (EOR) were investigated using cyclic voltammetry and chronoamperometry, respectively. The highest activity and stability for EOR were observed from Pt75Ru5Ni20/f-MWCNT due to a good metal-carbon interaction. Ru and Ni presented in Pt-Ru-Ni alloy improved the activity and stability of ternary catalysts for EOR. Moreover, the reduction of Pt content in ternary catalyst led to the catalyst cost deduction in DEFC.
