The Effect of Different Promoters (La2O3, CeO2, and ZrO2) on the Catalytic Activity of the Modified Vermiculite-Based Bimetallic NiCu/EXVTM-SiO2 Catalyst in Methane Dry Reforming.

Zhaojun Meng,Zijun Wang

doi:10.1021/acsomega.1c03959

Abstract

An X-NiCu/EXVTM-SiO2 (X = La, Ce, and Zr) catalyst was successfully prepared by using modified vermiculite as a support by the impregnation method. This experiment investigated the effects of La2O3, CeO2, and ZrO2 promoters on the activity of the NiCu/EXVTM-SiO2 catalyst. The study found that the addition of three different metal oxides did not improve the activity of the NiCu/EXVTM-SiO2 catalyst. On the contrary, some Ni active sites were covered by the promoter, which reduced the number of active sites, resulting in its catalytic activity lower than NiCu/EXVTM-SiO2. In addition, the promoted catalysts that were repeatedly calcined two times can significantly reduce the textural property as well as active sites of the catalyst, resulting in the lower activity. However, in X-NiCu/EXVTM-SiO2, Ce-NiCu/EXVTM-SiO2 showed relatively high initial catalytic activity, with the initial conversion rate of CH4 reaching 60.1% and the initial conversion rate of CO2 reaching 89.1%. This is mainly because the catalyst has a stronger basic site on the surface to facilitate the adsorption of CO2 molecules, and the smaller metal particle size is also conducive to the cleavage of C–H bonds.

Highlights

In the context of increasingly depleted fossil resources, global warming caused by excessive CO2 emissions, and serious environmental pollution, the shift to a low-carbon circular economy has become a global consensus,[1−4] mankind has made great efforts to find new energy and environmental protection
Dry methane reforming (DRM) has become a research field with potential for development, because it consumes two main greenhouse gases and provides a way to convert them into valuable hydrocarbon products, which is undoubtedly an attractive environmental protection process.[7]
To overcome the limitations of the catalyst itself, more and more scientists start from the structure of the catalytic support to study non-noble metal Nibased catalysts that are resistant to high temperature, carbon deposition, and sintering

Summary

INTRODUCTION

In the context of increasingly depleted fossil resources, global warming caused by excessive CO2 emissions, and serious environmental pollution, the shift to a low-carbon circular economy has become a global consensus,[1−4] mankind has made great efforts to find new energy and environmental protection. Our research group has studied the expansion−acidification-modified vermiculitesupported NiM/EXVTM-SiO2 (M = Co, Cu, and Fe) bimetallic catalyst for methane dry reforming reaction.[22] The study found that the NiCu/EXVTM-SiO2 catalyst showed relatively high catalytic activity and stability. CeO2 is known for its high ability to store and release oxygen, which can promote CO2 activation and inhibit carbon deposition.[27] Zhang et al successfully prepared a two-phase Ni−Ce catalyst on SBA-16 and studied the effect of cerium oxide on the structural stability and DRM performance of the NiCe/SBA-16 catalyst.[28] The study found that compared with Ni/SBA-16 without adding cerium oxide, the strong interaction between Ni and CeO2 limits the growth of Ni and reduces the close contact between the Ni metal and the SiO2 surface, thereby reducing the collapse of the SBA16 skeleton caused by the reaction. The focus is on the effects of adding different metal oxides (La2O3, CeO2, and ZrO2) on the structure properties, catalytic activity, and stability of NiCu/EXVTM-SiO2 catalysts

RESULTS AND DISCUSSION

CONCLUSIONS

EXPERIMENTAL SECTION

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