Effect of Pore Structures on 1,4-Butynediol Hydrogenation over Mesoporous Ni/Al2O3-SiO2 Catalysts

This work describes the 1,4-butynediol (BYD) hydrogenation to 1,4-butanediol (BDO) performance over supported Ni/Al2O3-SiO2 catalysts with different mesoporous structures (cross pore C-Ni/Al-SiO2, parallel pore P-Ni/AlSiO2, and nonmesoporous structured N-Ni/Al-SiO2). To illustrate the pore structure effects on the catalyst texture, metal-support interaction, and surface acidity, the obtained catalysts were characterized using BET, inductively coupled plasma (ICP), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), H-2 temperature-programed reduction (H-2-TPR), and H-2/NH3-temperature-programmed desorption (H-2/NH3-TPD). Based on this, we proposed the structure-activity relationship between the pore structures and the hydrogenation performance. It was found that C-Ni/Al-SiO2 had short-range staggered and cross mesopores throughout the support, which can provide a larger surface area and pore volume for the fixation of highly dispersed active sites, thus enhancing the H-2 activation ability. On the other hand, the cross channels have rich hole loops and surface defects for exposing assistant acid sites that are beneficial for the 1,4-butynediol (BYD) adsorption/activation, thus promising a superior hydrogenation ability. However, the narrow and long parallel pore structure of P-Ni/Al-SiO2 may limit the rapid diffusion of long-carbon-chain BYD in the pores, thus partially decreasing the accessibility of active sites and the catalytic activity. As for N-Ni/Al-SiO2, which has no mesoporous structure, its nickel particles are prone to aggregate seriously on the support surface, which weakens the interaction with the support and is not conducive to catalytic hydrogenation.