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Comparative study between gas phase and liquid phase for the production of DMC from methanol and CO2
Direct synthesis of dimethyl carbonate (DMC) from methanol and carbon dioxide over Co1.5PW12O40 in liquid and in gas phase is investigated. The synthesized catalyst has been characterized by means of FTIR and XRD. Liquid phase experiment results showed that high pressures are favorable for the synthesis of DMC. However, DMC formation is limited by the reaction with co-produced water. DMC selectivity is more strongly dependent on the temperature than on the pressure of CO2. As for the reactions in gas phase, it has been found that both CH3OH conversion and DMC selectivity decreased with increasing temperature, owing to the decomposition of DMC at high temperatures. High temperatures and more amount of Co1.5PW12O40 catalyst favor the formation of dimethoxymethane (DMM) and methyl formate (MF). 相似文献
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Aouissi S. Mayer D. C. Ismaili M. C. Talbi M. Azizi A. 《Periodica Mathematica Hungarica》2020,81(2):250-274
Periodica Mathematica Hungarica - Let $$k=k_0(\root 3 \of {d})$$ be a cubic Kummer extension of $$k_0=\mathbb {Q}(\zeta _3)$$ with $$d>1$$ a cube-free integer and $$\zeta _3$$ a primitive... 相似文献
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Traditional turbulence models using constant turbulent Prandtl number fail to predict the experimentally observed anisotropies
in the thermal eddy diffusivity and thermal turbulent intensity fields. Accurate predictions depend strongly on the turbulence
model employed. Consequently, the objective of this paper is to assess the performance of turbulence model with variable turbulent
Prandtl number in predicting of thermal and scalar fields quantities. The model is applied to axisymmetric turbulent round
jet with variable density and in turbulent hydrogen diffusion flames using the flamelet concept. The k − ɛ turbulence model is used in conjunction with thermal field; the model involves solving supplemental scalar equations
for the temperature variance and its dissipation rate. The model predictions are compared with available experimental data
for the purpose of validating model. In reacting cases, velocity and scalar (including temperature and mass fractions) predictions
agree relatively well in the near field of the investigated diluted hydrogen flames. 相似文献
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<正>Three Keggin-type heteropolyanions,namely H_3PMo_(12)O_(40)·13H_2O,(NH_4)_3PMo_(12)O_(40)·4H_2O and H_3PW_(12)O_(40)·13H_2O were prepared and tested in the ring-opening polymerization reaction of tetrahydrofuran.The effects of the counter-cation (H~+,NH_4~+) and the peripheral atoms(Mo,W) on the polymerization were investigated.It has been found that when the protons of H_3PMo_(12)O_(40)·13H_2O were replaced by the ammonium cations the polymerization rate decreased dramatically. Whereas,when the peripheral atoms(Mo) were replaced by their homologous(W),the polymerization rate increased twofold.As for the viscosity average molecular weight(M_v) of polymer products,it was found that the high molecular weight(7930) was obtained by using H_3PW_(12)O_(40)·13H_2O.The molecular weight(M_v) obtained by H_3PMo_(12)O_(40)·13H_2O and (NH_4)_3PMo_(12)O_(40)·4H_2O was 6470 and 6810,respectively. 相似文献
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Ahmed Aouissi Allen W. Apblett Zeid A. AL-Othman Amro Al-Amro 《Transition Metal Chemistry》2010,35(8):927-931
The direct synthesis of dimethyl carbonate (DMC) from methanol and carbon dioxide over a series of Keggin-type heteropolyoxometalates has been investigated. The effects of the cations and the addenda atoms of the heteropolyoxometalate on the conversion and the product selectivities were investigated. The results showed that Co1.5PW12O40 was the best catalyst of the series. The effect of reaction temperature and CO2 pressure on the direct synthesis of DMC demonstrated that lower temperatures and higher pressures are favorable for the synthesis of DMC. Higher temperatures favor the formation of dimethoxymethane (DMM) and methyl formate (MF). 相似文献
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