Ni/SiO2 catalyst prepared via Ni-aliphatic amine complexation for dry reforming of methane: Effect of carbon chain number and amine concentration

•The first study of effect of aliphatic amines on supported Ni catalysts.•Smaller Ni was formed by using the aliphatic amine with a larger Nc or a higher Ca.•Stronger MSI is formed with a higher Ca due to more hydrogen bonds.•78% and 70% conversion of CO2 and CH4 was obtained in NiSi-OAm for DRM.

Aliphatic amines of different carbon numbers (i.e., carbon number in one linear hydrocarbon chain, Nc) and concentrations (Ca) were used in the preparation of silicon dioxide (SiO2) supported nickel catalysts by incipient wetness impregnation (IWI) method. The results showed that both the size and the metal-support interaction (MSI) were affected by the carbon chain number and the amine concentration. On one hand, the use of the aliphatic amine with a larger carbon chain number achieved a smaller size and higher dispersion due to the stronger steric hindrance; this smaller size and higher dispersion further enhanced the MSI because of the larger contact area of Ni with the silica support. On the other hand, a higher amine concentration decreases the size and improve the dispersion because of the faster nucleation rate; also when higher concentration of amine was used, more hydrogen bonds were formed between the -NH2 and the silanol group and more electron transfer was found between Ni and the -NH2, leading to a stronger MSI. With a small size, high dispersion and strong MSI, NiSi-OAm showed the most stable catalytic performances (CO2 conversion of 78% and CH4 conversion of 70% within 20 h) with low carbon deposition (1.8 mgC/gcat h) for dry reforming of methane (DRM) reaction.

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