Which intermediate is more efficient for Ni-phyllosilicate: Ni(OH)2 or H4SiO4?

Ni(OH) 2 and H 4 SiO 4 are the two key intermediates for the synthesis of Ni-phyllosilicate, and the purpose of this work is to reveal which one is more efficient. The silica (D) was extracted from distillers' grains, which was used as the sacrificial template for Ni-phyllosilicate. The formation of Ni(OH) 2 and H 4 SiO 4 was enhanced by NaOH and NH 4 F, respectively, and Ni/D-S (assisted by sodium hydroxide) and Ni/D-A (assisted by ammonium fluoride) were obtained. Although the amount of NaOH and NH 4 F and hydrothermal synthesis procedures were identical, there was a significant difference of their Ni contents. The Ni content of Ni/D-S and Ni/D-A was 17.7 wt% and 2.5 wt%, respectively. As a result, Ni/D-S was more active for CO 2 methanation, whose CH 4 yield reached 61.6% at 450 °C, 0.1 MPa, 60 L g−1·h−1, while the maximum CH 4 yield of Ni/D-A was only 16.4% at 500 °C. However, the formation of Ni-phyllosilicate could also be improved after addition of more NH 4 F, and the increased amount of H 4 SiO 4 led to the high Ni content (33.4 wt%) of Ni/D-A-M (M refers to the addition of more ammonium fluoride) and enhanced catalytic performance for CO 2 methanation. It was concluded that Ni(OH) 2 and H 4 SiO 4 were both important for the synthesis of Ni-phyllosilicate, while Ni(OH) 2 was the more efficient one. [Display omitted] • NaOH was used to accelerate the formation of Ni(OH) 2. • NH 4 F was used to accelerate the formation of H 4 SiO 4. • Ni(OH) 2 or H 4 SiO 4 were both important for the synthesis of Ni-phyllosilicate. • Ni(OH) 2 was the more efficient intermediate compared with H 4 SiO 4. [ABSTRACT FROM AUTHOR]