DEHYDROGENATION OF METHANOL TO METHYL FORMATE OVER SUPPORTED COPPER-CATALYSTS
DEHYDROGENATION OF METHANOL TO METHYL FORMATE OVER SUPPORTED COPPER-CATALYSTS
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DOI：
10.1016/0166-9834(91)85033-r
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发表时间：
1991-05-02
期刊：
影响因子：
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通讯作者：
FIERRO, JLG
中科院分区：
文献类型：
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作者：
GUERRERORUIZ, A;RODRIGUEZRAMOS, I;FIERRO, JLG
在固定床微反装置上，在180-260℃温度范围内，考察了铜负载(Cu/Mo(X)，M=Si，Zr，Mg，Zn和石墨)催化剂上甲醇的催化脱氢反应。铜/二氧化硅和铜/氧化锆催化剂对甲酸甲酯(MF)的生成具有很高的活性和选择性。然而，铜/锌氧化物催化剂的活性较低，铜/镁氧化物催化剂的选择性较差。铜/石墨催化剂是个例外，它的性能接近于块状铜。还研究了CuM/SiO_2(M=Na2O、ZnO、Cr2O_3)助剂催化剂上的反应。只有在0.1%钠(铜/钠=11.2原子)促进铜的情况下，比活性才有所提高，而甲苯的选择性保持不变。用X-射线光电子能谱测定了催化剂中铜的状态。除铜镁氧化物催化剂部分氧化为Cu2+外，其他催化剂只显示还原的铜物种。对于使用过的15.1%铜/二氧化硅催化剂，铜L3VVX射线诱导的俄歇转变在913.4 eV处的位置证实了还原Cu0的存在。以二氧化碳为载体原料，在未还原的二氧化硅负载铜催化剂上进行的额外催化实验表明，在达到稳定状态之前需要较长的运行时间，这反过来又是氢反应副产物(Eqn)对催化剂的典型活化。4)。一氧化碳中毒实验表明，金属铜极有可能是该反应中的活性铜物种。此外，甲醇在选择性较差的5.7%铜镁氧化物催化剂上吸附的红外光谱表明，MF产物是通过碱性中心的碳酸盐结构分解的。
The catalytic dehydrogenation of methanol over copper-supported (Cu/MO(x), M = Si, Zr, Mg, Zn and graphite) catalysts has been studied in a fixed bed microreactor in the temperature range of 180-260-degrees-C. The copper/silica and copper/zirconium oxide catalysts were found to be very active and selective toward methyl formate (MF) formation. However, the copper/zinc oxide catalyst was less active and the copper/magnesium oxide one much less selective. The exception was the copper/graphite catalyst whose performance approached that of massive copper. The reaction has also been studied on CuM/SiO2 (M = Na2O, ZnO, Cr2O3) promoted catalysts. Only in the case of copper promotion by 0.1% sodium (copper/sodium = 11.2 atomic) was the specific activity found to increase, while the MF selectivity remained unchanged. The state of copper in the catalysts used in the reaction was determined by X-ray photoelectron spectroscopy. With the sole exception of the copper/magnesium oxide catalyst, which was partially oxidised as Cu2+, the other catalysts showed only reduced copper species. For the used 15.1% copper/silica catalyst the position of the copper L3 VV X-ray induced Auger transition at 913.4 eV confirmed the existence of reduced Cu0. Additional catalytic experiments carried out on unreduced silica-supported copper catalysts, using carbon dioxide as a carrier feed, showed that a longer time on-stream was required before a steady state was achieved, which in turn is typical of catalyst activation by the hydrogen reaction byproduct (eqn. 4). Carbon monoxide poisoning experiments led to the conclusion that metallic copper is very likely the active copper species in this reaction. Furthermore, the infrared spectra of methanol adsorption on the poorly selective 5.7% copper/magnesium oxide catalyst revealed that the MF product undergoes decomposition through carbonate structures at basic sites.