In this work, NiO supported mesostructured silica nanoparticles (MSN) were synthesized via the urea–nitrate combustion method using urea as fuel and nitrate salts as oxidants with the different urea/nitrate ratios and calcination duration. The physicochemical properties of catalysts were investigated by several techniques, including N₂ physisorption measurements, powder X-ray diffraction, N₂-BET isothermal adsorption, hydrogen temperature-programmed reduction, carbon dioxide temperature-programmed desorption, scanning electron microscopy and transmission electron microscopy. The obtained catalysts were employed in the methanation of CO₂-rich gas at a temperature range of 225–400 °C with the CO₂/H₂ ratio of 1/4 and CO₂ concentration of 20 mol%. The results showed that using the urea–nitrate combustion method in synthesizing catalysts led to improved physicochemical properties that increased the activity of NiO/MSN catalysts. The catalyst prepared with the urea/nitrate molar ratio of 3 and calcined at 600 °C for 3 h showed the highest catalytic performance in methanation of CO₂-rich gas, reaching CO₂ conversion of 96% and CH₄ selectivity of 100% at 375 °C. The best catalyst has excellent stability in CO₂ solo-hydrogenation at a reaction temperature of 375 °C during 30 h of reaction thanks to the resistance to coke formation. Besides, adding 1 mol% CO in the feedstock should be simultaneously conducted to surge the effectivity of CO₂ methanation.

中文翻译：

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通过硝化尿素燃烧提高介孔结构二氧化硅纳米颗粒负载的镍催化剂在富CO 2气体甲烷化中的性能

在这项工作中，通过尿素-硝酸盐燃烧方法，使用尿素作为燃料，硝酸盐作为氧化剂，以不同的尿素/硝酸盐比例和煅烧时间合成了NiO负载的介孔结构二氧化硅纳米粒子（MSN）。通过几种技术研究了催化剂的理化性质，包括N ₂物理吸附测量，粉末X射线衍射，N ₂ -BET等温吸附，氢气程序升温还原，二氧化碳程序升温解吸，扫描电子显微镜和透射电子显微镜。 。将所得到的催化剂中的CO甲烷化被雇用₂富含气体的温度范围内的225-400℃下与CO ₂ / H ₂比率为1/4，CO ₂浓度为20摩尔％。结果表明，使用尿素-硝酸盐燃烧方法合成催化剂可改善物理化学性质，从而提高NiO / MSN催化剂的活性。尿素/硝酸盐摩尔比为3并在600°C下煅烧3 h制备的催化剂在富CO ₂气体的甲烷化中表现出最高的催化性能，在90℃下达到96％的CO ₂转化率和100％的CH ₄选择性375℃。最好的催化剂在CO _2中具有出色的稳定性由于对焦炭的形成具有抵抗力，因此在反应30小时的过程中，反应温度为375°C时进行了单氢化。此外，应该同时在原料中添加1mol％的CO以提高CO ₂甲烷化的有效性。