Chen Shumei, Fu Jiacheng, Peng Yonghui, Liang Lixing, Ouyang Jing
Hunan Key Lab of Mineral Materials and Application, Department of Inorganic Materials, School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China.
Engineering Research Center of Ministry of Education for Carbon Emission Reduction in Metal Resource Exploitation and Utilization, Central South University, Changsha 410083, China.
Molecules. 2024 Sep 25;29(19):4550. doi: 10.3390/molecules29194550.
Converting CO into methane is considered a promising and economically viable technology for global transportation and utilization of this greenhouse gas. This study involves the preparation of a Ni-CZ (CeO-ZrO)/ATP (attapulgite) catalyst through the co-precipitation and impregnation methods. XRD, SEM, TEM, N absorption-desorption isotherms, XPS, H-TPR, CO-TPD, TG/DSC, and Raman were adapted to characterize the obtained samples. Real-time GC was used to measure the catalytic performances and to intensively study the impact of Ni loading content and ATP to CZ ratio on the catalytic performance of the products. DRIFTs was used to monitor the interstitial radicals in the catalytic reactions and to deduce the catalytic mechanisms. The results indicate that the composite catalytic matrix composed of CZ assembled on ATP demonstrated higher CO methanation stability and better carbon deposition resistance ability than the single CZ or ATP as the carrier, which should be attributed to the improved specific surface area and pore volume of the ATP assembled matrix and the enhanced dispersibility of the CZ and Ni species. The adoption of CZ solid solutions improves the oxygen storage capability of the catalyst, thereby providing continued mobile O in the matrix and accelerating the molecular exchange rate in the catalytic reactions. The ideal loading quantity of nickel contents on the CZA matrix is 15%, as the CO conversion decreases at elevated temperatures when the Ni loading content reaches 20%. Among the tested samples, the 15Ni-0.8CZA sample showed the best catalytic performance of 75% CO conversion and 100% CH selectivity at 400 °C. After 50 h of stability tests, the CO conversion rate still remained 70.84%, and the CH selectivity obtained 97.46%. No obvious coke was detected according to the Raman spectra of the used catalyst. The in situ DRIFTS experiment showed that formate is the main intermediate of the CO hydrogenation reaction on the 15Ni-0.8CZA catalyst.
将一氧化碳转化为甲烷被认为是一种用于全球运输和利用这种温室气体的有前景且经济可行的技术。本研究涉及通过共沉淀和浸渍法制备Ni-CZ（CeO-ZrO）/ATP（凹凸棒石）催化剂。采用XRD、SEM、TEM、N吸附-脱附等温线、XPS、H-TPR、CO-TPD、TG/DSC和拉曼光谱对所得样品进行表征。使用实时气相色谱仪测量催化性能，并深入研究镍负载量和ATP与CZ的比例对产物催化性能的影响。采用漫反射红外傅里叶变换光谱（DRIFTs）监测催化反应中的间隙自由基，并推断催化机理。结果表明，与以单一CZ或ATP为载体相比，以ATP负载的CZ组成的复合催化基质表现出更高的CO甲烷化稳定性和更好的抗积碳能力，这应归因于ATP负载基质比表面积和孔体积的改善以及CZ和Ni物种分散性的增强。采用CZ固溶体提高了催化剂的储氧能力，从而在基质中提供持续移动的O并加速催化反应中的分子交换速率。CZA基质上镍的理想负载量为15%，当镍负载量达到20%时，在高温下CO转化率会降低。在所测试的样品中，15Ni-0.8CZA样品在400℃时表现出最佳催化性能，CO转化率为75%，CH选择性为100%。经过50小时的稳定性测试后，CO转化率仍保持在70.84%，CH选择性达到97.46%。根据使用过的催化剂的拉曼光谱未检测到明显的焦炭。原位漫反射红外傅里叶变换光谱实验表明，甲酸盐是15Ni-0.8CZA催化剂上CO加氢反应的主要中间体。
