The Study Of γ-Al₂O₃ And Its Modified Catalyst For Manufacture Of Dimthyl Ether From Methanol

Base on the analysis of existing techniques for DME synthesis, this paper makes a comparison on the advantages and disadvantages of the universal catalyst for DME synthesis. Catalystγ-Al2O3 is selected as the research object, which is often used in producing DME from methyl alcohol. And base on the research on preparation method, attribute and performance of normalγ-Al2O3, this paper also makes a study of composite catalystγ-Al2O3 which is prepared by dipping technique. And the study focuses on presenting the characteristic and determination on activity and selectivity of this reformative catalyst by technologies of elementary analysis, infrared spectrum, powder diffraction, electron spectroscopy and energy scattering.1. Using dipping technique to dissolve phosphoric acid in water according to certain proportion, then soak certainγ-Al2O3 into the solution. After desiccation and baking, the reformative composite catalystγ-Al2O3 is prepared.2. To present the characteristic of unmodifiedγ-Al2O3 by X-ray powder diffraction test, infrared spectrum test and electron microscope. And determine its conversion rate and selectivity in methyl alcohol dehydration for preparation of DME.3. According to the EDX spectrograms of catalyst which before and after the reaction, we know that it is possible to prepare modified catalystγ-Al2O3 with dipping technique.4. Through changing the mass fraction of additive, we can determine its conversion rate and selectivity at same temperature, quality and airspeed. When the mass fraction of additive is between 0% and 8%, the conversion rate of methyl alcohol has considerable increase. Within this interval, the conversion rate of methyl alcohol are considered raise steadily. However, when the mass fraction of additive is more the 15%, the conversion rate of methyl alcohol will show a trend of decreasing.5. Under the constant temperature and pressure, to change quality airspeed, the conversion rate of methyl alcohol decrease along with the raise of quality airspeed.6. Under the constant pressure and quality airspeed, changing the temperature to determine the conversion rate and selectivity. From 260℃to 320℃, the conversion rate of methyl alcohol is more than 99%. And this shows that using modifiedγ-Al2O3 in methyl alcohol dehydration for preparation of DME causes the selectivity of DME maintain at a high level, and this catalyst has high selectivity.