水热合成的MoO3-SnO2催化剂催化氧化二甲醚的性能研究

采用无沉淀剂水热法一步合成了MoO₃-SnO₂复合金属氧化物催化剂，通过调变Mo/Sn物质的量比，考察了催化剂上活性组分MoO_x分散程度对二甲醚（DME）低温氧化生成甲酸甲酯（MF）反应性能的影响。当Mo/Sn=1∶2，反应条件为150℃时，催化剂表现出较好的催化性能，DME转化率为22.0%，MF选择性达到77.6%。实验中采用TEM、XRD、Raman、FT-IR、NH₃-TPD及H₂-TPR等表征对催化剂晶体结构及表面性质进行了分析。结果发现，Mo/Sn物质的量比变化会对催化剂晶体结构产生显著影响，钼氧化物在SnO₂表面形成不同分散程度的MoO_x结构，这种钼氧化物结构的变化进一步影响了催化剂表面的酸性及氧化还原性，是造成催化性能差异的主要原因。

MoO3-SnO2 catalyst prepared by hydrothermal synthesis method for dimethyl ether catalytic oxidation

MoO₃-SnO₂ composite metal oxide catalyst was synthesized by one-step hydrothermal synthesis method without precipitant. The effect of MoO_x dispersion state on the catalytic performance of MoO₃-SnO₂ catalysts with different Mo/Sn molar ratios was investigated for dimethyl ether (DME) low-temperature oxidation to methyl formate (MF). MF selectivity reaches 77.6% with DME conversation of 22.0% over Mo₁Sn₂ at 150 ℃. The physiochemical properties of these catalysts were characterized by TEM, XRD, Raman, FT-IR, NH₃-TPD and H₂-TPR. The results showed that the addition of SnO₂ into MoO₃ affected the crystal structure of catalysts, forming MoO_x species with different degree of dispersion on the surface of SnO₂. The special architecture of MoO_x-SnO₂ plays a major role in modifying the acidity and the oxidizability of MoO₃-SnO₂ catalysts, leading to the obvious differences on catalytic activity.