海泡石纳米纤维负载Ni-NiAl2O4复合材料的制备及其催化甲烷水蒸气重整反应性能研究

The intrinsic characteristics of minerals can be utilized to solve the science and technology problems in the preparation and application of traditional synthetic materials, which is the frontier of multidisciplinary research. The potentials of activity and structural stability of traditional supported Ni-based catalysts in wet methane reforming have suffered from typical disadvantages, such as the sintering of Ni particles and inefficiencies in water transportation and dissociation. This project proposes novel and highly efficient catalysts, namely, sepiolite nanofiber-supported Ni-NiAl2O4 composite materials. On one hand, benefitting from the unique channel architecture, sepiolite nanofibers could facilitate improved efficiency of surface water adsorption as well as mass transport in the temperature range of reforming reaction. On the other hand, Ni active clusters with high stability can be achieved via a controlled reduction within the nano-confinement effect of supported NiAl2O4 particles. This work focuses on the control method on the size, crystal type and bonding interface of the components in the Ni-NiAl2O4 composite materials, aiming to realize cost-effective preparation of high performance catalysts through a simple and scalable microwave hydrothermal method. Moreover, in-situ characterization on the atomic structure and interface evolution process of sepiolite-supported Ni-NiAl2O4 catalyst during the reforming reaction will be performed by using environmental transmission electron microscope. Based on these delicate results, the specific catalytic mechanism can be revealed, and the structure-activity relationship can also be established at the atomic level. This project will lay a solid theoretical and experimental foundation for the development of functional mineral supported, environmental-friendly catalysts with low cost, high activity and high stability.

利用矿物的天然特性解决传统合成材料制备与应用中存在的科学与技术问题是多学科交叉的前沿研究方向。传统负载型Ni基催化剂在催化甲烷水蒸气重整中存在Ni颗粒烧结和水分子传质、活化的通道单一等欠缺，影响催化剂活性和结构稳定性。本项目提出利用海泡石在重整反应温度区间的表面水分子吸附及孔道内传质特性，同时借助负载NiAl2O4颗粒的纳米尺度限域作用可控还原出高稳定性的Ni活性团簇，制备新型的海泡石纳米纤维负载Ni-NiAl2O4复合材料，以期提高重整反应催化效率及稳定性。重点攻克复合材料各组分的尺寸、晶型及结合界面的控制方法，基于微波水热法低成本制备出高性能催化材料；运用环境透射电子显微镜在反应中原位表征海泡石负载Ni-NiAl2O4体系的界面结构及演变过程，探明此催化剂体系的独特反应机理并建立原子尺度的精确构效关系；本研究为基于矿物功能载体开发低成本、高活性和高稳定性的环保催化剂奠定理论与实验基础。

利用矿物的天然特性解决传统合成材料制备与应用中存在的科学与技术问题是多学科交叉的前沿研究方向。传统负载型镍基、钴基催化剂在催化甲烷重整等反应中存在镍/钴颗粒烧结和分子传质、活化的通道单一等欠缺，影响催化剂活性和结构稳定性，本项目主要研究新型、高效的矿物负载Ni-NiAl2O4（Co-CoAl2O4）/天然矿物复合催化材料。以海泡石作为功能载体，首先制备了尖晶石型CoAl2O4/海泡石复合材料，随后以复合材料中的CoAl2O4为中间层和Co源制备了Co-CoAl2O4/海泡石复合催化材料，中间层CoAl2O4在高温还原过程中可以显著抑制Co颗粒的烧结。在此基础上，该策略成功拓展到Ni-NiAl2O4/海泡石、Co-CoAl2O4/电气石、Ni-NiAl2O4/电气石复合材料的研究。在此过程中系统研究了复合材料的制备、微结构调控方法对复合材料微结构的影响规律和机制，确定了最佳制备工艺；同时探究了复合材料的生长机制、催化性能、以及结构与性能间构效关系。此外，研究发现天然矿物的引入显著提高了复合材料在甲烷-二氧化碳重整反应过程中的低温活性。该项目为高分散镍/钴基催化剂的制备提供了新的思路，同时也为基于矿物功能载体开发低成本、高活性和高稳定性的环保催化剂奠定理论与实验基础。在本项目的研究过程中，在国际刊物发表 SCI论文20余篇，其中在国际刊物发表 SCI二区及以上论文 15篇、发表国内高水平刊物（2021CiteScore为14.3）1篇；申请、授权发明专利13项；培养研究生10余名，其中已毕业研究生10名。