Metal–support interface engineering of Ni catalysts for improved H 2 storage performance: Grafting alkyltriethoxysilane onto commercial alumina

Tuning metal–support interface in supported Ni catalysts is a promising approach for overcoming the agglomeration of Ni particles and the low reducibility of Ni species. This study describes a facile two-step method to produce active Ni catalysts for the hydrogenation of benzyltoluene. In the first step, alkyltriethoxysilanes (C n TES, n  = 1, 3, and 8) were grafted onto the surface of commercial Al 2 O 3. The maximum Si/Al ratio of the prepared C n TES-on-Al 2 O 3 materials was determined to be approximately 2.9 mol.%, which can vary depending on the surface properties of Al 2 O 3. The second step was H 2 reduction of the Ni precursor loaded on the C n TES-on-Al 2 O 3 materials to remove alkyl substituents from the grafted C n TES and form Ni particles on the surface of silica grafted onto alumina (SGA). The hydrogenation performance of the obtained Ni/SGA_C n TES catalysts was improved with increasing Si/Al ratio owing to higher Ni dispersion and more abundant metallic Ni. The activity of the Ni/SGA_2.9C n TES (Si/Al = 2.9 mol.%) catalysts exhibited a volcano-shaped relationship with the length of the alkyl substituent of grafted C n TES, reaching the maximum for C 3 TES. Notably, Ni/SGA_2.9C 3 TES showed excellent ability for the adsorption of H 2 and substrate, as well as high stability, resulting from the reduced agglomeration of Ni particles and the modulated metal–support interface. Therefore, the demonstrated synthesis approach can render Ni catalysts servable to promote the commercialization of liquid organic hydrogen carrier system.