5Ga 3/SiO 2/Al 2O 3/Al-fiber catalyst for CO 2 hydrogenation to methanol at ambient pressure]]>

摘要

A series of Ni5Ga3/m-SiO2/Al2O3/Al-fiber (m?=?0, 0.5, 1.0, 3.0 and 5.0?wt%) catalysts have been developed for CO2hydrogenation to methanol at ambient pressure. Microfibrous-structured SiO2/Al2O3/Al-fiber supports are obtained though endogenous growth of free-standing boehmite (AlOOH) nanosheets onto a three-dimensional (3D) network of 60 μm-Al-fiber thin felt with the aid of steam-only hydrothermal oxidation reaction between Al metal and H2O (2?Al + 4H2O → 2?AlOOH + 3H2), followed by calcination and SiO2-modification using silica sol. The bimetallic Ni5Ga3nanoparticles are then placed onto the pore surface of as-obtained SiO2/Al2O3/Al-fiber support by co-impregnation method using Ni and Ga nitrates as precursors followed by reduction in H2at 630?°C. The promising Ni5Ga3/1-SiO2/Al2O3/Al-fiber catalyst is capable of converting 2.3% CO2into CH3OH with a high selectivity of 86.7% as well as 10.3%/3.0% selectivities to CO/CH4at 210?°C, for a feed of CO2/H2/N2(2/6/1, molar ratio). Such microfibrous-structured catalyst design combines the promising catalytic performance of Ni5Ga3with the enhanced heat transfer and high permeability of the Al2O3/Al-fiber support. The effect of SiO2loading on the formation of Ni5Ga3alloy nanoparticles is also discussed.