Nimoc/gamma - Al < Sub > 2 < / Sub > O < Sub > 3 < / Sub > Catalyst Used In The Three Reforming Reaction Of Methane To Syngas

A series of NiMoC/γ-Al₂O₃catalysts were prepared by impregnation method fortri-reforming of methane. Catalysts was evaluated by a fixed-bed reactor to screen one with bestperformance under the conditions of atmospheric pressure, reaction temperature of600℃⁸50℃, GHSV of4600mL/h and M（CH₄）:M（O₂）:M（CO₂）:M（H₂O）=1:0.16:0.39:0.3. Theinvestigation of preparation conditions were carried out as well. Catalysts were characterized byXRD, TPR, SEM, BET techniques and so on, to obtain the relationships between activity,components and structure.The effects of Ni content on the catalysts activities were studied. The results showed thatNi/Mo-0.4catalyst had a best activity, the conversions of CH₄and CO₂reached95.8%,96.7%,and the yields of H₂and CO were99.0%,95.82%respectively. The doping of Ni benefited theformation of Mo2C, enhanced the interaction and increased the alkaline sites. The result ofcharacterization showed that the molybdenum carbides were not oxidized in NiMoC/γ-Al₂O₃catalyst after reaction, and the stability of carbide was better with the increasing of the Ni content,but it was easier to coke with too high Ni loading.The effect of additions K, Co, Mg, La, Ce on the catalyst activity was investigated. Theresults showed that the catalyst activity was enhanced by doping La. At reaction temperature of600℃⁸00℃, the catalyst of LaNiMoC/γ-Al₂O₃showed the best activity, and the conversion ofmethane reached90%at750℃, higher than the NiMoC/γ-Al₂O₃catalyst of29.3%. TheResults of characterization demonstrated that crystal size and average pore were decreased, butthe BET and volume, the dispersibility of carbide were increased after La doped, whichpromoted the reaction between the methane, carbon dioxide, oxygen and water.The effect of preparing condition （impregnation sequence, calcined and carbonizationtemperature） on catalyst activity was studied. The results showed that the catalysts revealedthe highest activities made by co-impregnation method, calcined at500℃and carbonized at700℃. As the calcined and carbonization temperature increased, the diffraction peak ofmolybdenum carbide became sharper. It revealed that the molybdenum oxide was carbonizedin deepper. However, the exess temperature would lead to the bigger crystal size and thesintering of carbide.This paper was supported by the Natural Science Foundation of China （Grant No:20806017） and the Natural Science Foundation of Guangdong Province （Grant No: 10151009101000009）...