| In recent years, our research group has been working on the dimethyl ether(DME) synthesis from syngas(CO and H2) and acetic acid synthesis from CH4 and CO2 based on the coal gasification. In the process of DME synthesis, the conventional catalysts are easily deactive. Therefore, the complete liquid phase method had been put forward according to the properties of slurry reactor, and the catalysts have excellent stability; In the acetic acid synthesis, it is found that the catalytic activity of the sol-gel is better than that of the impregnation, and XRD results show that the sol-gel catalysts have anatase to rutile phase transition after reaction, the impregnation do not.The aim of this work is to study the catalytic performance due to different catalyst preparation methods of DME and acetic acid synthesis, and study the influence of solvent in catalyst preparation process, adsorption, reaction and desorption of DME synthesis are investigated. The CoPd/TiO2 catalysts of acetic acid synthesis prepared by sol-gel and impregnation methods were characterized by XRD and XPS, and the reason of phase transition are studied by DFT; the main conclusions are as follows:Solvent effects can influence the surface relaxation of CuZnAl catalysts, and then the surface energies of catalysts change. As a result, the structure and morphology of CuZnAl catalyst prepared by complete liquid-phase technology are different that of conventional methods.The Mulliken charges of metal or metal oxide shift due to solvent effects, and then influence the adsorption and desorption performance of CO hydrogenation process. For example, solvent effects improve the extent of CO activation and H-H bond is broken which is in favor of CO hydrogenation. The adsorption ability of CH3OH onγ-Al2O3 and AlOOH surfaces decrease due to the the acid intensity decrease, however, the desorption ability of DME increase.Solvent effects reduce the rate limiting step activation energy(HCO* +H*→H2CO) of CO hydrogenation over Cu/ZnO(1010), thus, the process of CO hydrogenation in liquid phase is easier than that of in gas phase.Overγ-Al2O3, DME synthesis occurs by the reaction of two adsorbed CH3O groups in the gas phase and in liquid phase. The liquid phase can reduce the activation energy. However, liquid paraffin cannot influence the reaction path of DME synthesis. Over AlOOH, DME synthesis in the gas phase involves adsorbed CH3OH reacting with another adsorbed CH3OH or CH3O group; DME synthesis mainly occurs through simultaneous adsorption of two CH3OH molecules in liquid phase. The result indicates liquid phase environment not only influence the activation energies but also alter the reactive path. Phase transition is due to the increase of the energy system, in addition to providing energy by heating, promotion and inhibition phase transition can add a second substance or change the preparation methods. The presence form of additives is the main reason of inhibition or promotion phase transition. Doping form will promote the phase transition, the greater the doping contents, the faster the phase transition and the more narrow completion the phase transition temperature. Adsorption form can inhibit the phase transition, which forms the second phase on the surface, and inhibits the lattice change. In addition, the increase of heat treatment temperature can cause the solid reaction promoting complex formation, and promote the phase transition. Different preparation methods lead to the different forms of additives in the carrier, and affect the phase transition. The species of the impregnation method can only cover with the carrier surface. The species can form the doping which the ionic radius is similar with the carrier and species. As a result, the impregnation method inhibits the phase transition, and the sol-gel method is easy to promote phase transition.
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