Yizan Zuo

Methanol Synthesis from CO2 Hydrogenation with a Cu/Zn/Al/Zr Fibrous Catalyst

A highly active Cu/Zn/Al/Zr fibrous catalyst was developed for methanol synthesis from CO2 hydrogenation. Various factors that affect the activity of the catalyst, including the reaction temperature, pressure and space velocity, were investigated. The kinetic parameters in Graafs kinetic model for methanol synthesis were obtained. A quasi-stable economical process for CO2 hydrogenation through CO circulation was simulated and higher methanol yield was obtained.

Steam Reforming of Dimethyl Ether over Coupled ZSM-5 and Cu-Zn-Based Catalysts

Abstract Dimethyl ether (DME) steam reforming (SR) is one possible source of hydrogen for fuel cells. The synergistic effect of catalyst coupling for the DME SR process and the coupling of reaction-heat transfer was studied. A DME hydrolysis catalyst comprising ZSM-5 (Si/Al = 25) and a series of methanol steam reforming catalysts (a series of Cu-Zn-based catalysts and a commercial Cu-Zn-Al catalyst) were used for DME SR. The evaluation of catalytic activity was conducted in a fixed-bed reactor. The catalysts were characterized by scanning electron microscopy, X-ray diffraction, and N 2 adsorption. The activity and selectivity were influenced by the catalyst composition and copper content, and also the content of Al and Zr. A Cu:Zn molar ratio of 60:30 together with Al and Zr gave the best dispersion of Cu crystals and the highest low-temperature catalytic activity, with a DME conversion of 72% at 260 °C and a space velocity of 4 922 ml/(g·h).

Steam Reforming of Dimethyl Ether over Coupled Catalysts of CuO-ZnO-Al2O3-ZrO2 and Solid-acid Catalyst

Steam reforming (SR) of dimethyl ether (DME) was investigated for the production of hydrogen for fuel cells. The activity of a series of solid acids for DME hydrolysis was investigated. The solid acid catalysts were ZSM-5 [Si/A1 25, 38 and 50: denoted Z(Si/A1)] and acidic alumina (γ-A12O3) with an acid strength order that was Z(25) ＞Z(38)＞Z(50)＞γ-A12O3. Stronger acidity gave higher DME hydrolysis conversion. Physical mixtures containing a CuO-ZnO-A12O3-ZrO2 catalyst and solid acid catalyst to couple DME hydrolysis and methanol SR were used to examine the acidity effects on DME SR. DME SR activity strongly depended on the activity for DME hydrolysis. Z(25) was the best solid acid catalyst for DME SR and gave a DME conversion＞90% [T=240℃, n(H2O)/n(DME)=3.5, space velocity=1179 ml•(g cat)^(-1)•h^(-1), and P=0.1MPa]. The influences of the reaction temperature, space velocity and feed molar ratio were studied. Hydrogen production significantly depended on temperature and space velocity. A bifunctional catalyst of CuO-ZnO-A12O3-ZrO2 catalyst and ZSM-5 gave a high H2 production rate and CO2 selectivity.

Stability improvement of the Nieuwland catalyst in the dimerization of acetylene to monovinylacetylene

Abstract In the process of dimerization of acetylene to produce monovinylacetylene (MVA), the loss of active component CuCl in the Nieuwland catalyst due to the formation of a dark red precipitate was investigated. The formula of the precipitate was CuCl·2C 2 H 2 ·1/5NH 3 , and it was presumed to be formed by the combination of NH 3 , C 2 H 2 and [Cu]-acetylene p -complex, which was an intermediate in the dimerization reaction. The addition of hydrochloric acid into the catalyst can reduce the formation of precipitate, whereas excessive H + is unfavorable to the dimerization reaction of acetylene. To balance between high acetylene conversion and low loss rate of CuCl, the optimum mass percentage of HCl in the added hydrochloric acid was determined. The result showed the optimum mass percentage of HCl decreased from 5.0% to 3.2% when the space velocity of acetylene was from 140 h −1 to 360 h −1 . The result in this work also indicated the pH of the Nieuwland catalyst should be kept in the range of 5.80–5.97 during the reaction process, which was good for both catalyst life and acetylene conversion.