Cu/MgO催化剂中Cu与MgO协同作用对合成气加氢制甲醇性能的影响

新型高效甲醇(CH₃OH)合成铜基催化剂可克服目前商业铜基催化剂反应活性低和反应过程中易失活等缺点,对实现煤炭资源清洁利用目标具有重要意义。通过共沉淀法合成了一系列Cu/MgO催化剂,利用固定床微分反应器系统对催化剂性能进行了评价,并采用X射线衍射(XRD)、程序升温还原(H₂-TPR)、程序升温脱附(H2-TPD和CO-TPD)以及漫反射傅里叶变换红外光谱(DRIFTS)等表征方法分析了催化剂的物理化学性质,研究了Mg含量(物质的量分数)对铜基催化剂表面结构及合成气制甲醇性能的影响。结果表明,MgO不仅可以改变催化剂表面铜物种的分散度和晶粒尺寸,还可调节铜基催化剂的还原性能,Cu与MgO的协同作用提高了铜基催化剂对合成气的吸附和活化速率,从而提高了催化剂的甲醇合成活性;Mg含量为67%时,催化剂表面Cu⁰物种的晶粒尺寸最小为11.5 nm,在催化剂表面分散效果最明显,展现出最佳的甲醇合成性能,合成气制甲醇的转换频率达到5.67×10^-1s^-1。

Effect of synergistic effect of Cu and MgO in Cu/MgO catalyst on performance of syngas hydrogenation to methanol

The new high efficient copper based catalyst for methanol(CH₃OH)synthesis can overcome the shortcomings of low reaction activity and easy deactivation of commercial copper based catalyst which is of great significance to achieve the goal of clean utilization of coal resources.A series of Cu/MgO catalysts were synthesized by coprecipitation method,The performance of the catalysts was evaluated by fixed bed differential reactor system.The physicochemical properties of the catalysts were characterized by X-ray diffraction(XRD),temperature programmed reduction(H₂-TPR),temperature programmed desorption(H₂-TPD and COTPD)and diffuse reflectance Fourier transform infrared spectroscopy(DRIFTS).The influences of Mg content(mole fraction)on the surface structure of copper-based catalyst and the performance of syngas to methanol were studied.The results show that MgO can not only change the dispersion and particle size of copper species on catalyst surface,but also adjust the reduction performance of the copper based catalyst.The synergistic effect of Cu and MgO improves the adsorption and activation rate of the copper based catalyst to syngas,thus improving the methanol synthesis activity of the catalyst.When the Mg content is 67%,the minimum particle size of Cu⁰ active species on the catalyst surface is 11.5 nm,the dispersion effect on the catalyst surface is the most obvious,showing the best catalytic performance of methanol synthesis,and the conversion frequency of syngas to methanol reaches 5.67×10^-1s^-1.