Wang Yu, Li Hou-Xing, Li Xue-Gang, Xiao Wen-De, Chen De
Shanghai Jiao Tong University Shanghai China
Norwegian University of Science and Technology 7491 Trondheim Norway.
RSC Adv. 2020 Nov 9;10(67):40815-40829. doi: 10.1039/d0ra08387a.
In the process of CO hydrogenation to olefins by the Fischer-Tropsch synthesis (FTO), the support is a key factor in the activity, selectivity, and thermal and chemical stability of the catalysts, and magnesium aluminate spinel (MgAlO) has recently been reported to be very effective. In this work, three methods, namely, citric acid solution combustion (MAC), EDTA sol-gel (MAG) and NH-coprecipitation (MAP) have been employed to prepare the spinel with detailed characterization of the structure, specific surface area, porosity, and alkalinity properties of both the as-synthesized spinel and the supported catalysts. The results showed that MAC and MAG possessed stronger basicity with more homogeneous particle sizes and narrower distribution of the pore size due to the formation of the metal-nitrate-chelate-complex. This led to a large quantity of gas being released during calcination, however, stronger interactions between the active phase and MAC resulted in lower CO conversion. The catalyst supported on MAP (CMAP) exhibited the highest CO conversion, the highest selectivity of lower olefins, the shortest induction period of reaction, and the lowest AFS chain growth probability; thus, MAP was suggested as an applicable synthetic method. Based on the CMAP catalyst, the effects of the operational conditions were investigated and a 200 hour stability test was carried out with satisfactory performance.
在费托合成（FTO）将CO加氢制烯烃的过程中，载体是影响催化剂活性、选择性以及热稳定性和化学稳定性的关键因素，最近有报道称铝酸镁尖晶石（MgAlO）非常有效。在本工作中，采用了三种方法，即柠檬酸溶液燃烧法（MAC）、乙二胺四乙酸溶胶 - 凝胶法（MAG）和NH共沉淀法（MAP）来制备尖晶石，并对合成的尖晶石以及负载型催化剂的结构、比表面积、孔隙率和碱性性质进行了详细表征。结果表明，由于金属 - 硝酸盐 - 螯合物 - 络合物的形成，MAC和MAG具有更强的碱性，颗粒尺寸更均匀，孔径分布更窄。这导致在煅烧过程中释放大量气体，然而，活性相与MAC之间更强的相互作用导致CO转化率较低。负载在MAP上的催化剂（CMAP）表现出最高的CO转化率、最高的低碳烯烃选择性、最短的反应诱导期以及最低的AFS链增长概率；因此，MAP被认为是一种适用的合成方法。基于CMAP催化剂，研究了操作条件的影响，并进行了200小时的稳定性测试，性能令人满意。
