Abstract: The Ni-based catalyst used in fluidized bed methane dry reforming reaction needs to have both high abrasion resistance and high activity, which requires the catalyst support itself to have both good abrasion-resistance and high Ni loading capacity. Based on the phase transformation mechanism of Al2O3, this study aims to prepare a type of core-shell @Al2O3 support with its shell in abrasion-resistant α-phase and its core in porous γ- or θ-phase Al2O3 through calcination of γ-Al2O3 at high temperatures. For this purpose, commercially available mesoporous γ-Al2O3 particles with a specific surface area of 325 m2/g and an average particle size of 850 μm were used as precursor material and calcinated in a vertical high temperature furnace at different temperatures for different periods of time. For prepared @Al2O3 samples, X-ray diffraction (XRD) analysis and N2 isothermal adsorption-desorption measurement were performed to characterize their phase transformation degree; electron microscopy (SEM) observation of their particles' cross-sections was conducted to confirm the formation of core-shell structure. And cold- and hot-state fluidized bed abrasion tests were carried out to evaluate their abrasion-resistance. The XRD results obtained have shown that the target core-shell @Al2O3 support can be prepared by calcination of porous γ-Al2O3 particles at 1250, 1300, and 1370℃ for different periods of time. SEM and BET characterization results also confirmed that the core-shell @Al2O3 particles with a shell thickness of 30~50 μm, a specific surface area of 86 m2/g and an average pore size of 22 nm were successfully prepared by calcination at 1300℃ for 6 min. The results of the fluidized-bed abrasion tests further confirmed that this core-shell @Al2O3 had the same excellent abrasion resistance as α-Al2O3, and the rate of its weight loss by abrasion at 800℃ was only 0.003wt%/h. At last, with this core-shell @Al2O3 as support, 10wt%Ni@Al2O3 catalyst was prepared in an impregnation approach and its abrasion resistance was evaluated at 800℃ to confirm that it also had the same resistance as α-Al2O3, which strongly suggests that such @Al2O3 supported catalyst has a good application prospect in fluidized bed reactor systems.

Key words: methane dry reforming, fluidized bed, core-shell alumina, catalyst support, abrasion resistance

摘要： 应用于流化床甲烷干重整反应的Ni基催化剂需要同时具备高耐磨性和高活性，这要求催化剂载体本身须兼具良好的耐磨性和高Ni负载能力。本研究基于Al2O3晶型转变机制，旨在通过高温焙烧γ-Al2O3制备具有一定Ni负载能力的外壳为α相的高耐磨性核壳结构@Al2O3载体。选用商业球形介孔γ-Al2O3颗粒(比表面积325 m2/g，平均粒径850 μm)作为载体前驱体，并利用立式高温炉在不同焙烧温度和时间下得到焙烧程度不同的@Al2O3颗粒试样；利用X射线衍射(XRD)技术以及N2等温吸附脱附方法(BET)对Al2O3晶型转变程度进行表征，以电子显微镜(SEM)观察颗粒断面形貌的方法表征壳核结构的形成进程，利用冷态以及热态流化态磨损试验对其耐磨性进行表征。XRD结果表明，在1250, 1300和1370℃下通过控制焙烧时间可制备α-相和γ-相或θ-相共存的Al2O3载体；SEM以及BET表征结果表明，在1300℃焙烧6 min可得到外壳为30~50 μm、比表面积为86 m2/g、平均孔径为22 nm的壳核@Al2O3载体；流化态磨损试验揭示该载体具有与α-Al2O3同样出色的耐磨性能，在800℃的流化状态下的磨损速率仅为0.003wt%/h。利用该核壳@Al2O3，通过浸渍法制10wt%Ni@Al2O3催化剂，该催化剂在800℃流化状态下也具有与α-Al2O3相同程度的耐磨性，作为流化床催化剂具有良好的实际应用前景。

关键词: 甲烷干重整, 流化床, 核壳氧化铝, 催化剂载体, 耐磨性