甲烷干气重整反应低积碳型镍基催化剂的制备与应用研究

Methane dry reforming reaction is an very important heterogeneous reaction, by which methane could be high efficiency utilized and carbon dioxide could be reduced. However, the difficulties in methane and carbon dioxide activation and the required high temperature reaction condition always resulted in the sintering of active metals and the high amounts of carbon deposition in noble and tranistion metals catalysts, which deduced a short lifespan of these catalysts. Nickel catalysts are the best catalysts, but also easy to be sintered and coked. It is a great interesting to develop low carbon nickel-based catalysts for methane dry reforming reaction. Starting from the main obstacts (sintering and carbon deposition) for this reaction, new type of core-shell Ni catalysts that different from the traditional supported catalysts will be prepared in this project. In this core-shell Ni catalyst, the sintering of nickel would be avoid due to the confinement of the shell, by which hinders the moving and contacting of nickel nanoparticles at high temperature. The carbon deposition could also be low by the assistant of oxygen storage capacity of oxides in the shell and the metal-support interaction, which would rapid gasify the cabon-precursors in the course of reaction. It is hoped that the developed core-shell nickel catalysts would show high activity and long lifespan for methane dry reforming reaction.

甲烷干气重整反应既能够实现甲烷高效利用和二氧化碳减排，是多相催化中一个非常重要的化学反应。然而由于该反应分子活化的困难性以及高温反应环境，所开发贵金属和非贵金属催化剂均遇到活性组分高温烧结和催化剂积碳量较大的问题，致使催化剂寿命不高。镍催化剂是该反应的最佳催化剂，但是其易烧结，积碳也最严重。开发低积碳型的镍基催化剂对于提高催化剂的寿命具有重要意义。从该反应遇到的难点问题出发，本课题将制备与传统担载型催化剂不一样结构的核壳型镍催化剂，利用核壳的限域作用控制镍粒子的高温移动导致的烧结，同时利用核壳层为功能性储氧型氧化物的特点，结合金属-载体相互作用快速气化积碳前驱体Cα以降低积碳的生成，以期得到具有高活性和长寿命的稳定型镍催化剂。

甲烷干气重整反应一直都是能源催化领域最具挑战性的研究方向之一。目前大部分Ni催化剂都会发生积碳和高温烧结现象，催化剂寿命不高。核壳型催化剂将纳米Ni颗粒限制在氧化物壳层中，限制其高温移动和聚集，能够保持超细Ni纳米颗粒尺寸不烧结。在本项目执行期间，我们针对甲烷干气重整反应Ni基催化剂易烧结和积碳量大的关键科学问题进行了系统研究。从核壳结构限域Ni纳米颗粒抑制烧结角度，开发了Ni尺寸低于5 nm的超细核壳结构Ni@SiO2催化剂，并对其制备条件对反应性能影响进行了深入研究。目前，该项目的研究工作已取得了一系列创新性研究成果，主要包括：① 基于络合物的微乳液方法成功制备了核壳结构Ni@SiO2催化剂；② Ni@SiO2催化剂高温甲烷干气重整反应表现出低烧结和低积碳特性；③ Ni纳米颗粒尺寸和金属-载体相互作用耦合调控高效催化甲烷干气重整反应。