Highly Dispersed Nickel-Containing Mesoporous Silica with Superior Stability in Carbon Dioxide Reforming of Methane: The Effect of Anchoring.

Wenjia Cai,Xueying Chen,Yuanhang Ren,Bin Yue,Heyong He,Lin Ye,Li Zhang

doi:10.3390/ma7032340

Abstract

A series of nickel-containing mesoporous silica samples (Ni-SiO2) with different nickel content (3.1%–13.2%) were synthesized by the evaporation-induced self-assembly method. Their catalytic activity was tested in carbon dioxide reforming of methane. The characterization results revealed that the catalysts, e.g., 6.7%Ni-SiO2, with highly dispersed small nickel particles, exhibited excellent catalytic activity and long-term stability. The metallic nickel particle size was significantly affected by the metal anchoring effect between metallic nickel particles and unreduced nickel ions in the silica matrix. A strong anchoring effect was suggested to account for the remaining of small Ni particle size and the improved catalytic performance.

Highlights

Carbon dioxide reforming of methane (DRM) has received considerable attention, as it is a promising way to utilize natural gas and to reduce greenhouse gases [1,2,3,4]
(100) peak in the region of 1.0°–1.2° is observed, and a wormlike mesoporous structure can be deduced (Figure 2c–e). 13.2%Ni-SiO2 does not show any peaks in the small angle region; this indicates that high nickel content leads to the disordered mesoporous structure (Figure 2f)
TEM results of the reduced and used 6.7%Ni-SiO2 shown in Figure 6 indicate that the particle size of metal nickel dispersed on silica matrix remains stable during the reaction, resulting from the existence of the anchoring effect

Summary

Introduction

Carbon dioxide reforming of methane (DRM) has received considerable attention, as it is a promising way to utilize natural gas and to reduce greenhouse gases [1,2,3,4]. Nickel-based catalysts are more deactivated, because of carbon deposition and active metal species sintering [11,12,13]. It was reported that the anchoring effect, a concept that was described by Yermakov [22], can facilitate the formation of the active Ni nano-clusters with high dispersion under the reaction condition [1,23,24]. Mo-Pd catalysts possessed better catalytic activity in ethane hydrogenolysis in comparison with the single metallic system, due to the higher dispersion and stability of metallic Pt and Pd anchored to the partially reduced Mo [22]. For the nickel-based bimetallic catalysts, Ni-Zr-MCM-41, the strong anchoring effect and the partial activation of CO2 by Zr4+ accounted for the high activity and long-term stability of the catalysts [23]. Ni ions within a silica matrix limits the growth of Ni particles and increases its dispersion, improving the stability and activity of the catalysts

Physicochemical Properties of the Catalysts

Catalytic Performance

The Anchoring Effect

Catalyst Preparation

Characterization

Catalytic Experiments

Conclusions