Controllable Preparation of Nano-Ni to Eliminate Step Edges of Carbon Deposition on Ni-Based Catalysts for Methane Dry Reforming
Dry reforming of methane (DRM) presents a sustainable approach to convert greenhouse gases CO2 and CH4 into syngas. However, the industrialization of DRM is hindered by the short catalyst lifespan due to carbon deposition. Carbon deposition on Ni-catalysts is attributed to Ni step edges, which serve as carbon nucleation centers. We propose an innovative strategy to prevent carbon nucleation by modulating Ni size to eliminate Ni step edges. Ni was loaded on MCM-41, SBA-15, and DFNS (dendritic fibrous nanosilica) to prepare three distinct Ni catalysts. By altering the precursor concentration using the proposed microemulsion antisolvent coprecipitation method, we successfully adjusted the Ni size on DFNS. Ni particles with a diameter of ∼5 nm were obtained on DFNS, exhibiting excellent Ni dispersion and a physical spacing effect due to the specific preparation method and porous structure. Carbon deposition rates on Ni/MCM-41 and Ni/SBA-15 were 30.23 mgc·gcat·–1·h–1 and 16.33 mgc·gcat·–1·h–1, respectively. Remarkably, the carbon deposition rate on Ni/DFNS was only 0.15 mgc·gcat·–1·h–1. The gasification rate of deposited C to CO on the 5 nm Ni particles loaded on Ni/DFNS was five times that of the polyhedral Ni particles of Ni/MCM-41. This was attributed to the elimination of Ni step edges, which weakened C adsorption strength and enhanced the reaction of deposited C with O* to form CO. Our proposed catalyst preparation strategy is based on designing the catalyst microstructure to eliminate carbon nucleation sites. This research provides guidance for designing or preparing Ni-based catalysts for DRM with reduced carbon deposition.
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