酸性条件下多壁碳纳米管负载铁基催化氧化甲烷性能

寻求绿色、安全且低能耗的转化技术是实现甲烷转化和利用的关键。采用浸渍法制备了多壁碳纳米管负载铁基的复合催化剂(Fe/MWCNTs),通过比表面积测试法(Brunauer-Emmett-Teller, BET)、X射线光电子能谱技术(X-ray photoelectron spectroscopy, XPS)、X射线衍射(X-ray diffraction, XRD)、透射电子显微镜(transmission electron microscope, TEM)和傅里叶变换红外光谱仪(Fourier transform infrared spectrometer, FTIR)等技术表征了Fe/MWCNTs的结构形态,得知Fe/MWCNTs的活性催化组分主要是α-Fe_2O_3,负载后催化剂比表面积明显增大,且在碳纳米管表面形成的是活性较强的110晶面。在冰乙酸体系中建立Fe/MWCNTs催化体系催化氧化甲烷,通过气相液相产物分析计算甲烷转化率和醋酸甲酯生成量,考察反应温度、压力、时间、催化剂投加量和氧化剂浓度对甲烷催化氧化的反应效果的影响,通过正交试验得到冰乙酸体系中催化甲烷的最佳反应条件。实验表明:在反应温度90℃,反应压力为3 MPa, Fe/MWCNTs复合催化剂0.15 g,氧化剂高锰酸钾浓度为0.2 mol/L,反应时间为4 h的最佳反应条件下,甲烷转化率可达24.78%,醋酸甲酯产量为541.72×10~(-6)。

Catalytic performance of Fe-based multi walled carbon nanotubes for methane oxidation under acidic conditions

The key to realize methane conversion and utilization is to seek green, safe and low energy conversion technology. The Fe/MWCNTs supported by multi wall carbon nanotubes are prepared by impregnation method. The structure of Fe/MWCNTs is characterized by BET, XPS, XRD, TEM and FTIR. It is found that the active catalytic components of Fe/MWCNTs are mainly, the surface deposition of the catalyst increases obviously after loading, and the surface of carbon nanotubes is formed with a more active 110 crystal surface. The Fe/MWCNTs catalytic system was established in the ice acetic acid system to catalyze the oxidation of methane. The conversion rate and the formation rate of methyl acetate were calculated by the analysis of the gas-phase liquid phase products, and the effects of reaction pressure and catalyst dosage on the catalytic oxidation of methane were investigated, and the best reaction conditions for catalytic methane in glacial acetic acid system were obtained. The results show that the conversion rate of methane can reach 7.41% and the yield of methyl acetate is 363.55ppm under the optimum reaction conditions, such as 3Mpa, 0.15g of Fe/MWCNTs composite catalyst, 0.2mol/l of potassium permanganate concentration, 3 hours reaction time and 500rpm stirring rate.