Effect of copper loading on texture,structure and catalytic performance of Cu/SiO_2 catalyst for hydrogenation of dimethyl oxalate to ethylene glycol

Cu/SiO2 catalysts prepared by a convenient and efficient method using the urea hydrolysis deposition-precipitation （UHDP） technique have been proposed focusing on the effect of copper loading.The texture,structure and composition are systematically characterized by ICP,FTIR,N 2-physisorption,N2O chemisorption,TPR,XRD and XPS.The formation of copper phyllosilicate is observed in Cu/SiO2 catalyst by adopting UHDP method,and the amount of copper phyllosilicate is related to copper loading.It is found the structure properties and catalytic performance is profoundly affected by the amount of copper phyllosilicate.The excellent catalytic activity is attributed to the synergetic effect between Cu0 and Cu ＋.DMO conversion and EG selectivity are determined by the amount of Cu0 and Cu＋,respectively.The proper copper loading （30 wt%） provides with the highest ratio of Cu ＋ /Cu0,giving rise to the highest EG yield of 95% under the reaction conditions of p=2.0 MPa,T=473 K,H2/DMO=80 and LHSV=1.0h-1.

Ni/Al_2O_3 catalysts for syngas methanation: Effect of Mn promoter

Ni/Al2O3 catalysts with different amounts of manganese ranging from 1 to 3 wt% as promoter were prepared by co-impregnation method. The catalysts were characterized by N2 physisorption, XRD, TPR, SEM and TEM. Their catalytic activity towards syngas methanation reaction was also investigated using a fixed-bed integral reactor. It was demonstrated that the addition of manganese to Ni/Al2O3 catalysts can increase the catalyst surface area and average pore volume, but decrease NiO crystallite size, leading to higher activity and stability. The effects of reaction temperature, pressure and weight hourly space velocity （WHSV） on carbon oxides conversion and CH4 formation rate were also studied. High carbon oxides conversion, CH4 selectivity and formation rate were achieved at the reaction temperature range of 280 300℃.

Reaction and deactivation kinetics of methanol-to-olefins process based on a special TGA reactor

Thermax 700 thermo gravimetric analysis （TGA） instrument is introduced for the investigation of the reaction and deactivation kinetics of Methanol-to-Olefins （MTO） process with SAPO-34 catalyst.By the use of a special sample basket,the TGA instrument can be viewed as a plug flow fixed-bed reactor,while the weight change of SAPO-34 during reaction can be recorded online.Kinetic data are acquired in the temperature range of 648.2？748.2 K and space velocities of 7.08？35.91 h^-1 （WHSV）.Catalyst activity is expressed with average coke content,and selectivity for different products is related as a function of coke content and temperature.Methane is also introduced into the lumping kinetic model,and power exponent function with first-order reaction is adopted for model deduction.Exponential function is tested to give the best fit for catalyst activity and product selectivity with the highest correlation coefficient.The nicely agreed results between experimental and calculated data suggest that the overall kinetic model would be meaningful in both product distribution prediction and reactor simulation.

Effects of the Different Supports on the Activity and Selectivity of Iron-Cobalt Bimetallic Catalyst for Fischer-Tropsch Synthesis

Silica, alumina, and activated carbon supported iron-cobalt catalysts were prepared by incipient wetness impregnation. These catalysts have been characterized by BET, X-ray diffraction （XRD）, and temperature-programmed reduction （TPR）. Activity and selectivity of iron-cobalt supported on different carriers for CO hydrogenation were studied under the conditions of 1.5 MPa, 493 K, 630 h^-1, and H2/CO ratio of 1.6. The results indicate that the activity, C4 olefin/（C4 olefin＋C4 paraffin） ratio, and C5 olefin/（C5 olefin＋C5 paraffin） decrease in the order of Fe-Co/SiO2, Fe-Co/AC1, Fe-Co/Al2O3 and Fe- Co/AC2. The activity of Fe-Co/SiO2 reached a maximum. The results of TPR show that the Fe-Co/SiO2 catalyst is to some extent different. XRD patterns show that the Fe-Co/SiO2 catalyst differs significantly from the others; it has two diffraction peaks. The active spinel phase is correlated with the supports.

Simulation and model design of pipe-shell reactor for the direct synthesis of dimethyl ether from syngas

The simulation was made based on the model of pipe-shell reactor that was established by the model of global kinetics of synthesis of dimethyl ether from syngas over a bifunctional catalyst. The results of simulation showed that the selectivity for dimethyl ether （DME） and the conversion of CO were higher but the hot spot was kept below the temperature limit of the pipe-shell reactor. The suitable diameter of the pipe was φ38×2 mm, and the length of the pipe was 5.8 m. The optimal process conditions of the reactor were that the pressure was 5 MPa, the temperature of the cooling water was 240 ℃, and the temperature of the raw gas at inlet of the reactor was 220 ℃. The production of this reactor was 102800 t/y （ton per year） under these conditions.

Effects of promoters on catalytic performance of Fe-Co/SiO_2 catalyst for Fischer-Tropsch synthesis

2%Fe-10%Co/SiO2 catalysts with different potassium or zirconium loadings were prepared by aqueous incipient wetness impregnation and tested for Fischer-Tropsch synthesis in a flow reactor, using H2/CO = 1.6 （molar ratio） in the feed, under the condition of an overall pressure of 1 MPa, GHSV of 600 h^-1 and temperature of 503 K. The zirconium and potassium promoters remarkably influenced hydrocarbon distribution of the products. CO conversion increased on the catalysts with the increase of zirconium loadings, which indicated that zirconium enhanced the activity of iron-cobalt catalysts. Low potassium loadings also enhanced the activity of the catalysts. However, high potassium loading made CO conversion on the catalysts decrease and weakened the secondary hydrogenations. The catalyst was characterized by BET, XRD and TPR. The catalyst characterization revealed that the Co3O4 phase was presented on the fresh catalyst, whereas the spinel phase of Fe-Co alloy and CoO existed on the used catalyst.

Pretreatment of Alumina and Its Influence on the Properties of Co/Alumina Catalysts for Fischer-Tropsch Synthesis

16.6%Co/γ-Al2O3 catalysts prepared by incipient wetness impregnation method were used for Fischer-Tropsch synthesis. The support was pre-treated with different concentration of NH4NO3 aqueous solution. The effect of support pre-treatment on the properties of support and performance of supportedcobalt-based catalysts was investigated. To treat the support with NH4NO3 aqueous solution enlarged the pore of γ-Al2O3, decreased the impurity Na2O content, and weakened the surface acidity of γ-Al2O3. The change in the properties of the support decreased the interaction between cobalt species and support, enhanced the CO hydrogenation rate and the C5＋ selectivity. For all catalysts, increasing the reaction temperature increased the CO hydrogenation rate or the CO conversion, slightly decreased the total hydrocarbon selectivity, and favored the formation of methane and light hydrocarbons, while the chain growth probability decreased. For 16.6%Co/γ-Al2O3 catalysts, prepared with the support treated with 100 g/L NH4NO3 aqueous solution, the CO conversion, the CH4 selectivity, and the C5＋ selectivity were 83.13%, 6.86% and 82.75% respectively, and the chain growth probability was 0.83 under the condition of 493 K, 1.5 MPa, 500 h-1 and the molar ratio of H2 to CO being 2.0 in feed.

Synthesis of ethylidene diacetate from dimethyl ether,CO and H_2

Ethylidene diacetate was prepared by reacting dimethyl ether,acetic acid and syngas in the presence of a catalytic system comprising RhI3,PPh3 and CH3I.The effects of reaction temperature,pressure,time and the CO/H2 molar ratio on the conversion of dimethyl ether and the product selectivity were investigated under the same catalyst formulation.Results showed that a maximum conversion of dimethyl ether was obtained when a mixture consisting of 0.3 mol dimethyl ether and 120 ml acetic acid was reacted at 180 ℃ and 3.0 MPa for 10 h at a stirring speed of 600 rpm under a syngas flow with a CO/H2 molar ratio of 2.5,which was catalyzed by a catalyst mixture comprising 0.3 g RhI3,6 g PPh3 and 1.3 g CH3I.The selectivity of ethylidene diacetate increased with temperature,decreased with the CO/H2 molar ratio and exhibited a maximum with pressure.

Effects of the ratio of Fe to Co over Fe-Co/SiO_2 bimetallic catalysts on their catalytic performance for Fischer-Tropsch synthesis

The Fe-Co/SiO2 bimetallic catalysts with different ratios of Fe to Co were prepared by aqueous incipient wetness impregnation. The catalysts of 10%Fe：0%Co/SiO2, 10%Fe：6%Co/SiO2, 10%Fe：2%Co/SiO2, 10%Fe：10%Co/SiO2, 6%Fe：10%Co/SiO2, 2%Fe：10%Co/SiO2 and 0%Fe： 10%Co/SiO2 by mass were tested in a fixed reactor by the Fischer-Tropsch synthesis. Activity and hydrocarbon distribution were found to be determined by the ratio of iron to cobalt of the catalysts. Higher iron content inhibited the activity, whereas higher cobalt content enhanced the activity of the Fe-Co/SiO2 catalysts. On the other hand, for the catalysts of 10%Fe：6%Co/SiO2, 10%Fe：10%Co/SiO2, 6%Fe：10%Co/SiO2, and 2%Fe：10%Co/SiO2, the total C2-C4 fraction increased （from 10.65% to 26.78%） and C5＋ fraction decreased （from 75.75% to 57.63%） at 523 K. Temperature programmed reduction revealed that the addition of cobalt enhanced the reducibility of the Fe-Co/SiO2 catalyst. Metal oxides were present in those catalysts as shown by XRD. The Fe-Co alloy phase was found in the 2%Fe：10%Co/SiO2, 6%Fe：10%Co/SiO2, 10%Fe： 10%Co/SiO2, 10%Fe：6%Co/SiO2 catalysts and their crystals were perfect.

Experimental study on bubble behavior and CFD simulation of large-scale slurry bubble column reactor

Slurry bubble column reactors(SBCR)is a three-phase fluidized reactor with outstanding advantages compared with other reactors and is difficult to scale-up due to lack of information on hydrodynamics and mass transfer over a wide range of operating conditions of commercial interest.In this paper,an experiment was conducted to investigate the bubble behavior in SBCR with a height of 5600 mm and an interior diameter of 480 mm.Bubble rise velocity,bubble diameter,and gas holdup in different radial and axial positions are measured in SBCR using four-channel conductivity probe.Tap water,air,and glass beads(mean diameter 75-150μm)are used as liquid,gas,and solid phases,respectively.It shows that hydrodynamic parameters have good regularity in SBCR.Moreover,a commercial computational fluid dynamics(CFD)package,Fluent,was used to simulate the process in SBCR.The simulations were carried out using axi-symmetric 2-D grids.Data obtained from experiment and CFD simulation are compared,and results show that the tendency of simulation is almost uniform with the experiment,which can help to obtain further understanding about multiphase flow process and establish a model about the synthesis of alcohol ether fuel in SBCR.

Study on direct alcohol/ether fuel synthesis process in bubble column slurry reactor

The recent studies of direct alcohol/ether synthesis process in slurry reactors were reviewed,and the research work in our laboratory was carried out in this paper.a global kinetics model for direct dimethyl ether(DME)synthesis from syngas over a novel Cu-Zn-Al-Zr slurry catalyst was established according to the total of 25 experimental data,and a steady-state one-dimensional mathematical model was further developed in bubble column slurry reactor(BCSR),which was assumed that the bubble phase was plug flow,and the liquid phase was fully mixed flow.The numerical simulations of reactor design of 100000 t/a dimethyl ether pilot plant indicate that higher pressure and lower temperature were favorable to the increase of CO conversion,selectivity of dimethyl ether,product yield and height of slurry bed.The optimal operating conditions for DME synthesis process were obtained:reaction temperature at 240℃,reactor pressure at 5 MPa and reactor diameter of 2.5 m.

Thermodynamic analysis of liquid phase in situ hydrogenation of glycerol for 1,3-propanediol synthesis

Based on the combination of the glycerol aqueous-phase reforming(APR)and catalytic hydrogenation of glycerol,a novel reaction system of liquid phase in situ hydrogenation of glycerol for the synthesis of 1,3-propanediol is proposed,in which hydrogen is produced from glycerol aqueous-phase reforming in the same reactor.In this new system,the glycerol is the raw material of the aqueous-phase reforming reaction;the hydrogen generated from the APR of glycerol can be quickly transformed to the in situ hydrogenation of glycerol to produce 1,3-propanediol,which can improve the selectivity of hydrogen for the APR process of glycerol.Moreover,thermodynamic calculation of the coupling processes was carried out,and standard molar enthalpies and equilibrium constants of foregoing reactions were obtained.The above calculation results indicate that the combination process is feasible for 1,3-propanediol synthesis.