Effects of Al doping on CeZr solid solution for oxidative dehydrogenation of ethylbenzene with CO2
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摘要: 为进一步提高铈锆固溶体储放氧性能，增强乙苯二氧化碳氧化脱氢反应性能，采用共沉淀法合成出氧化铝质量比为50%的铈锆铝氧化物催化剂。通过现代仪器分析表征技术，研究了Al加入对铈锆固溶体复合氧化物晶体结构、储放氧能力的影响。结果表明，Al的加入可起到“扩散阻碍”作用，且有效抑制铈锆固溶体晶粒长大，使得铈锆铝氧化物催化剂比表面积较铈锆固溶体增加了51.8 m2/g，储放氧性OSC值提高了69.4 μmol/g，将铈锆铝氧化物催化剂用在乙苯氧化脱氢5 h反应中，发现乙苯转化率提高了10%。Abstract: For improving the oxygen storage/release capacity of ceria-zirconia solid solution, Ce0.5Zr0.5O2-Al2O3 mixed oxides were prepared by a co-precipitation method and applied in the oxidative dehydrogenation of ethylbenzene to styrene with carbon dioxide.Ce0.5Zr0.5O2-Al2O3 mixed oxides were characterized by powder X-ray diffraction, Raman spectroscopy, N2-sorption, H2 temperature-programmed reduction, and X-ray photoelectron spectroscopy.Results show that Al2O3 acts as a diffusion barrier.The addition of Al prevents the growth of Ce0.5Zr0.5O2 crystallite size, increases the specific surface area and oxygen storage capacity of Ce0.5Zr0.5O2-Al2O3 mixed oxides.The specific surface area and oxygen storage capacity of Ce0.5Zr0.5O2-Al2O3 mixed oxides are 51.8 m2/g higher and 69.4 μmol/g more than those of Ce0.5Zr0.5O2 mixed oxides.The ethylbenzene conversion over Ce0.5Zr0.5O2-Al2O3 mixed oxides is about 10% higher than that over Ce0.5Zr0.5O2 mixed oxides after 5 h reaction.
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图 3 CZ和CZA催化剂的N2-吸脱附曲线及孔径分布
Figure 3 N2-sorption curve and the pore distribution of CZ and CZA catalysts
图 4 CZ和CZA催化剂的XPS谱图
Figure 4 XPS spectra of the CZ and CZA catalysts
(a): full scan; (b): Ce 3d
图 6 CZ和CZA催化剂分别用于乙苯CO2脱氢反应的活性对比
Figure 6 Comparison of the activity over CZ or CZA catalysts in the ethylbenzene dehydrogenation with CO2
表 1 CZ和CZA催化剂的物化性质
Table 1 Physical properties of CZ and CZA catalysts
Catalyst Crystallite size d/nm ABET / (m2·g-1) OSC/ (μmol·g-1CeO2) CZ 4.8 80.5 167.8 CZA 4.4 132.3 237.2 
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