This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2020 New J. Chem. Cite this: DOI: 10.1039/d0nj00818d Preparation of biomass-derived porous carbon supported Ni nanoparticles for CO 2 reforming of CH 4 Penggang Lv, a Dawei Liu,* a Bin Tian, a Xiaoxun Ma, a Maohong Fan b and Long Xu * a Dry reforming of methane (DRM) can not only convert and utilize both CH 4 and CO 2 greenhouse gases, but also produce an ideal chemical feedstock (syngas). Nevertheless, a significant challenge is the development of a low cost as well as highly active and stable catalyst for this transformation process. Herein, we report a Ni/bio-char catalyst integrating the advantages of biomass-derived carbon supports and non-noble metals using a simple impregnation method. The bio-char supports are derived from waste walnut shells, which possess a well-developed porous structure, abundant functional groups, and an appreciable amount of alkaline earth metals, such as Ca and Mg. Compared to the Ni/CC catalyst (Ni supported on coal-derived coke), the as-prepared 10Ni/bio-char catalyst exhibits superior activity and significantly enhanced stability, achieving 90.7% CH 4 conversion and 97.6% CO 2 conversion at 800 1C. Furthermore, a simple reaction mechanism for DRM over the Ni/bio-char catalyst was proposed based on experimental results and literature studies. 1. Introduction With the emphasis on issues, such as the greenhouse effect and the shortage of resources, how to reduce the amount of CO 2 in the atmosphere and effectively utilize CO 2 to produce inter- mediates for high-valued chemicals have attracted the wide- spread attention of all countries. 1,2 To address this challenge, the reforming of CH 4 with CO 2 via the DRM reaction has become a viable route. 3,4 Since the DRM reaction (1) can not only consume two kinds of greenhouse gases, CH 4 and CO 2 , but also produce syngas with a low H 2 /CO ratio as an ideal feed- stock for the production of hydrocarbons via Fischer–Tropsch synthesis and oxygenated chemicals. 5 In addition, DRM is the most promising alternative to conventional steam reforming. 6–8 CH 4 þ CO 2 ¼ 2CO þ 2H 2 DH  298 ¼þ247:3 kJ mol 1 (1) Considering that the DRM is an extremely endothermic reaction (1), the development of catalysts with high activity, low cost and excellent stability is the research focus. 9 Recent years have witnessed that many metal-based catalysts, includ- ing noble and non-noble metals, have been explored for this important transformation. 10–15 The high cost and scarcity of noble metals restrict their application in industrial production, while the non-noble metals, such as Ni and Co, have been found to be competitive with noble metals in view of their inherent availability and affordable costs. Unfortunately, non- noble metals, especially for Ni nanoparticles, often result in the deposition of carbon through the CH 4 cracking reaction (2), which takes place on the active sites and results in the deactiva- tion of catalysts. 16 It has been found that carbon deposition involves the deposition of different types of carbon, such as amorphous carbon and graphite carbon. 17 The former has high activity and can be eliminated by CO 2 , which is also an intermediate of the DRM reaction and can improve the conver- sion of CO 2 . 18,19 The latter shows difficultly in reacting with CO 2 and inhibits the DRM reaction. 20 Over the past few decades, many contributions have been made to improve the activity and stability of catalysts, verifying that the extra addi- tion of promoters is an effective strategy. For example, Zhang et al. 21 studied the effect of alkaline earth metal Ca on the Co/AC catalyst for the DRM reaction, and found that Ca could improve the dispersion of Co nanoparticles, enhancing the anti-sintering ability of Co and improving the adsorption of CO 2 on catalysts, which is conducive to the elimination of carbon deposition on the catalyst surface by CO 2 . Kim et al. 22 a School of Chemical Engineering, Northwest University, International Science & Technology Cooperation Base of MOST for Clean Utilization of Hydrocarbon Resources, Chemical Engineering Research Center of the Ministry of Education for Advanced Use Technology of Shanbei Energy, Shaanxi Research Center of Engineering Technology for Clean Coal Conversion, Collaborative Innovation Center for Development of Energy and Chemical Industry in Northern Shaanxi, Xi’an, 710069, P. R. China. E-mail: dwliu@nwu.edu.cn, longxuxulong@163.com b Department of Chemical & Petroleum Engineering, University of Wyoming, Laramie, WY 82071, USA Received 15th February 2020, Accepted 30th June 2020 DOI: 10.1039/d0nj00818d rsc.li/njc NJC PAPER Published on 30 June 2020. Downloaded by University of Wyoming Libraries on 7/16/2020 8:58:05 PM. View Article Online View Journal