Methanation of Carbon Dioxide over Zeolite‐Encapsulated Nickel Nanoparticles

Efficient methanation of CO2 relies on the development of more selective and stable heterogeneous catalysts. Herein, we present a simple and effective method to encapsulate Ni nanoparticles in zeolite silicalite‐1. In this method, the zeolite is modified by selective desilication, which creates intraparticle voids and mesopores that facilitate the formation of small and well‐dispersed nanoparticles upon impregnation and reduction. Transmission electron microscopy and X‐ray photoelectron spectroscopy analyses confirm that a significant part of the Ni nanoparticles are situated inside the zeolite rather than on the outer surface. The encapsulation results in increased metal dispersion and, consequently, high catalytic activity for CO2 methanation. With a gas hourly space velocity of 60 000 mL gcatalyst−1 h−1 and H2/CO2=4, the zeolite‐encapsulated Ni nanoparticles result in 60 % conversion at 450 °C, which corresponds to a site‐time yield of approximately 304 molCH4 molNi−1 h−1. The encapsulated Ni nanoparticles show no change in activity or selectivity after 50 h of operation, although postcatalysis characterization reveals some particle migration. An inside job: We present a simple and effective method to encapsulate Ni nanoparticles in zeolite silicalite‐1. With a high dispersion of metal within the zeolite, this catalyst is highly active for the CO2 methanation reaction. At a gas hourly space velocity of 60 000 mL gcatalyst−1 h−1 and H2/CO2=4, the catalyst shows 60 % conversion at 450 °C, albeit with some particle migration.