Abstract
Reforming methane to produce syngas is a subject that generates considerable interest. The process requires catalysts that possess high-performance active sites to activate stable C–H bonds. Herein, we report a facile synthetic strategy to prepare Ni-based catalysts by complexation–impregnation (Ni-G/SiO2-C) and precipitation–impregnation (Ni-G/SiO2-P) methods using glycine as a complexing agent. The particle size of Ni in both types of catalysts is decreased by adding glycine in the preparation process. Nevertheless, the preparation methods and amount of glycine play a significant role in the particle size and distribution of Ni over the Ni-based catalysts. The smaller particle size and narrower distribution of Ni were obtained in the Ni-G/SiO2-P catalyst. The catalysts were comparatively tested for carbon-dioxide reforming of methane (CDR). Ni-G/SiO2-P showed better CDR performance than Ni-G/SiO2-C and Ni/SiO2 and increased stability because of the smaller particle size and narrower distribution of Ni. Moreover, a high-performance Ni-based catalyst was prepared by optimizing the amount of glycine added. An unobservable deactivation was obtained over Ni-G-2/SiO2-P and Ni-G-3/SiO2-P for CDR during TOS = 20 h. Thus, a new promising method is described for the preparation of Ni-based catalysts for CDR.
Highlights
With the rapid development of technology and social economy in recent years, the greenhouse effect caused by the burning of fossil fuels has become progressively serious [1,2]
The smaller NiO particle size in Ni-G/SiO2-P and Ni-G/SiO2-C contributes to the larger surface area, which is consistent with the results of X-ray powder diffraction (XRD) (Figure 1)
For Ni-G/SiO2-P catalysts, with an increasing molar ratio of glycine to nickel, the SBET slightly increased, which shows that the amount of glycine used for complexation plays an unimportant role in the SBET of Ni-G/SiO2-P
Summary
With the rapid development of technology and social economy in recent years, the greenhouse effect caused by the burning of fossil fuels has become progressively serious [1,2]. The key to improving the catalytic performance of the Ni-based catalysts for the CDR is to decrease the Ni particle size and prevent the sintering of Ni at higher temperatures [10,14,15]. Zhao et al successfully prepared Ni/ZrO2 catalysts with smaller Ni particle sizes by using L-arginine as a complexing agent, which showed excellent anti-sintering and anti-coking performance, resulting in higher catalytic activity and stability for CDR [34]. Glycine is the smallest amino acid, which is inexpensive and readily available, making it a promising chelating agent for synthesizing highly dispersed metal-supported catalysts [36,38,42]. The catalyst prepared by glycine and nickel hydroxide exhibited the smallest Ni particle size and narrower size distribution, resulting in higher activity and stability in the CDR reaction. A new preparation method of Ni-based catalysts for CDR is presented, which has more industrial application prospects
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