Transition-metal catalysts are essential to realize a liquid organic hydrogen carrier (LOHC) system based on reversible hydrogenation and dehydrogenation. To attain comparable hydrogenation activity to noble metal catalysts mainly used so far, catalyst constituents need to be blended together toward improved adsorption and kinetics. For nickel catalysis in the hydrogenation of aromatic LOHC (monobenzyltoluene), mesoporous SiO₂–Al₂O₃ (MSA) supports are herein prepared by solvent-deficient precipitation using aluminum isopropoxide and alkyltriethoxysilane (C_nTES, in which n = 3, 8, and 18). Although Ni particle sizes are similar in all of the prepared catalysts, the hydrogenation activity of Ni/MSA_C_nTES is in a volcano-shaped relationship with the length of the alkyl substituent of C_nTES, where Ni/MSA_C₈TES shows 2-fold superior activity to the Ni catalyst supported on mesoporous alumina. The observed volcano trend is attributed to the adsorption of aromatic substrates affected by Lewis acidity and, more significantly, the adsorption of hydrogen on the Ni species located in the vicinity of the mixed SiO₂–Al₂O₃ domains having Brønsted acidic protons for promoted H₂ spillover. Moreover, the mesopores of MSA_C_nTES contribute to the facile transport of the reactant and the product. Therefore, these catalyst characteristics would be well balanced in single Ni catalyst bodies for boosted LOHC hydrogenation performance.