Conversion of Ethanol and Acetaldehyde to Butadiene over MgO–SiO2 Catalysts: Effect of Reaction Parameters and Interaction between MgO and SiO2 on Catalytic Performance
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- 作者：Qiangqiang Zhu ; Bin WangTianwei Tan
- 刊名：ACS Sustainable Chemistry & Engineering
- 出版年：2017
- 出版时间：January 3, 2017
- 年：2017
- 卷：5
- 期：1
- 页码：722-733
- 全文大小：610K
- ISSN：2168-0485
文摘
For the effect of structural features on the catalytic performance of the conversion of ethanol and acetaldehyde to butadiene to be investigated, a series of MgO–SiO<sub>2sub> catalysts with different structural properties were synthesized by tuning the calcination temperature, investigated, and characterized. The best butadiene selectivity of 80.7% appears for the MgO–SiO<sub>2sub> catalyst calcined at 500 °C using a mixture of acetaldehyde/ethanol/water (22.5:67.5:10 wt %) as feed. Addition of the appropriate amount of water (10 wt %) improved butadiene selectivity by inhibiting the formation of 1-butanol and C<sub>6sub> compounds. Results from XRD, FT-IR, and <sup>29sup>Si MAS NMR indicate the generation of a significant amount of amorphous magnesium silicates along with few crystalline magnesium silicates for the catalyst calcined at 500 °C. XPS results indicate that it contains the lowest binding energies of both Si–O and Mg–O from Si–O–Mg bonds. For the catalysts calcined at low temperature (350 and 400 °C), more 1-butanol and C<sub>6sub> compounds formed, which are considered to be related to residual Mg(NO<sub>3sub>)<sub>2sub>. Additionally, more ethylene, diethyl ether, and butylene isomers were produced over the MgO–SiO<sub>2sub> catalyst calcined at 700 °C with the formation of forsterite Mg<sub>2sub>SiO<sub>4sub>. Further results from Fourier transform infrared spectroscopy after pyridine adsorption and CO<sub>2sub> temperature-programmed desorption show that the high catalytic performance is related to the presence of Lewis acidic sites and an intermediate number of basic sites.