关键词: 复相氧化钛, 晶相组成, 甘油氢解, 1,3-丙二醇, 氢溢流

Driven by advances in the biodiesel industry, converting glycerol, the major byproduct, into valuable chemicals such as 1,3-propanediol (1,3-PDO) via selective hydrogenolysis has emerged as an important research topic. However, there is a dearth in the study of the effect of the bi-phase support on the catalytic performance of the Pt-WO_x-based catalyst in glycerol hydrogenolysis. In this contribution, we synthesized bi-phase TiO₂ (bp-TiO₂) materials with varying rutile to anatase phase ratios using a coordination-mediated self-assembly method by adjusting the amount of HCl added. These materials were then used as supports for Pt-WO_x catalysts to investigate the effect of crystal phase composition of the support on glycerol hydrogenolysis to 1,3-PDO. The Pt-WO_x/bp-TiO₂ catalysts were systematically characterized by techniques including X-ray diffraction (XRD), Raman spectrometry, N₂ physisorption, CO pulsed adsorption, transmission electron microscopy (TEM), pyridine adsorption-Fourier transform infrared spectrometry (Py-IR), temperature-programmed desorption of NH₃ (NH₃-TPD), and H₂ chemisorption, focusing on the phase composition, distribution and dispersion of the Pt and WO_x species, acidic property, and ability of hydrogen spillover. The XRD results revealed that with the increase in the HCl dosage, the content of the rutile phase in the support increased first, and then decreased, reaching a maximum of 29%. The TEM and X-ray photoelectron spectroscopy (XPS) results disclosed that the Pt particles and WO_x species were inclined to distribute on the rutile phase. The H₂ chemisorption results demonstrated that the introduction of the rutile phase greatly enhanced the hydrogen spillover ability of the catalysts. In glycerol hydrogenolysis, it is identified that the glycerol conversion generally improved with the increase in the content of the rutile phase in the support, while the selectivity to 1,3-PDO remained virtually constant at around 60%. Over the Pt-WO_x/bp-TiO₂(4) catalyst with the highest rutile content of 29%, the yield of 1,3-PDO reached the highest value of 30.3%. This catalyst also displayed good stability. It is plausible that the preferential distribution of the Pt and WO_x species on the rutile surface is conducive to the formation of more Pt-WO_x interfaces, which greatly enhances hydrogen spillover and thus boosts the yield of 1,3-PDO. This work elucidates the important role of the phase composition of bi-phase TiO₂ support on the catalytic performance of the Pt-WO_x-based catalyst in glycerol selective hydrogenolysis, which opens up new avenue for the design of high-performance glycerol hydrogenolysis catalysts by means of engineering the phase composition of the support.

Key words: bi-phase TiO₂, crystal phase composition, glycerol hydrogenolysis, 1,3-propanediol, hydrogen spillover