In this research, mesoporous high surface area Ni-Al₂O₃ catalysts promoted with different transition metals (Cr, Fe, Mn, Cu, and Co) were synthesized via ultrasound-assisted co-precipitation method and their performance was explored in CO₂ methanation process. The promoters can affect the textural and catalytic properties of the Ni-Al₂O₃ catalysts to some extent. Powder X-ray diffraction (XRD), scanning electron microscopy (SEM), temperature programmed reduction with hydrogen (H₂-TPR), and N₂ adsorption-desorption (BET) were used for the characterization of the prepared samples. From the BET results, it was found that the incorporation of 5 wt% of the promoter into Ni-Al₂O₃ catalysts caused a decrease in the surface area, NiAl₂O₄ crystalline size and an increase in the mean pore diameter and total pore volume. Among the samples, the catalyst modified by Mn, exhibited the higher catalytic activity and selectivity towards CH₄, especially at low temperatures (200–350 °C). These results could be explained by highest Ni active sites dispersion of this catalyst and enhancement of the catalyst reducibility at the low temperatures. The effect of Mn content was also evaluated and the results revealed that the Ni-Al₂O₃ sample modified with 3 wt% Mn with the highest BET surface area and the lowest crystalline size possessed the best catalytic performance. To further investigate the influence of ultrasonic irradiation, the optimal catalyst was prepared with a conventional co-precipitation method and its textural and catalytic properties were compared with those obtained for the catalyst prepared with the ultrasonic assisted coprecipitation method. Also, 25Ni-3Mn-Al₂O₃ catalyst showed a stable performance at 350 °C for 10 h in the CO₂ methanation reaction.

本研究通过超声辅助共沉淀法合成了不同过渡金属（Cr，Fe，Mn，Cu和Co）助催化的介孔高表面积Ni-Al ₂ O ₃催化剂，并探讨了其在CO _2中的性能。甲烷化过程。助催化剂可以在一定程度上影响Ni-Al ₂ O ₃催化剂的质构和催化性能。粉末X射线衍射（XRD），扫描电子显微镜（SEM），氢气程序升温还原（H ₂ -TPR）和N ₂吸附-解吸（BET）用于表征所制备的样品。根据BET结果，发现将5wt％的助催化剂掺入Ni-Al ₂ O ₃催化剂中导致表面积减小，NiAl ₂ O ₄晶体尺寸减小以及平均孔径和总孔直径增大。孔体积。在样品中，Mn修饰的催化剂表现出较高的催化活性和对CH _4的选择性。，尤其是在低温（200–350°C）下。这些结果可以通过该催化剂的最高Ni活性位点分散和在低温下增强催化剂还原性来解释。还评估了Mn含量的影响，结果表明，用3 wt％Mn改性的Ni-Al ₂ O ₃样品具有最高的BET表面积和最低的晶体尺寸，具有最佳的催化性能。为了进一步研究超声辐射的影响，采用常规共沉淀法制备了最佳催化剂，并将其结构和催化性能与采用超声辅助共沉淀法制备的催化剂进行了比较。另外，25Ni-3Mn-Al ₂ O ₃催化剂在CO ₂甲烷化反应中在350°C下保持10 h的稳定性能。