Influence of Impregnation Processes on Ruthenium–Molybdenum Carbon Catalysts for Selective Hydrodeoxygenation of Biomass‐Derived Sorbitol into Renewable Alkanes

Abstract

Sorbitol, as a C6 sugar related compound derived from cellulose, is regarded as a promising biomass‐derived substrate and has characteristically higher oxygen content than in fossil‐based resources. In this work, ruthenium–molybdenum carbon catalysts prepared by different impregnation processes were employed and extensively studied in a trickle‐bed reactor for sorbitol hydrodeoxygenation (HDO). Interestingly, these catalysts afforded remarkably different HDO performance. Ruthenium–molybdenum catalysts prepared by ultrasonic treatment and calcination obtained high HDO performance in sorbitol conversion with 79.8 % carbon yield of C5/C6 alkanes (pentane and hexane), almost twice that of ruthenium–molybdenum catalysts prepared without using a calcination processes. Therefore, a series of characterization studies (N2‐adsorption, XRD, HRTEM, XPS, H2‐TPR, CO‐TPD, NH3‐TPD, Py‐IR spectra, etc.) were performed over relevant catalysts to study the catalytic mechanism. The results suggest that prior calcination offers a better chance for the proximity between Ru and Mo precursors to produce the bimetallic catalytic structure Ru–MoOx, which produces high HDO performance.

Influence of acid pretreatment on the hydrodeoxygenation performance of carbon supported RuMo bimetallic catalysts on sorbitol conversion

“…Ru/C showed a main peak below 400 °C, and Mo/C gave a big peak above 500 °C. While, RuMo/C presented abig peak located at a slightly higher temperature than that of Ru/C catalyst, and the peak assignable to Mo species was nearly disappeared, which suggested that the reduction of Mo species could be promoted by the presence of Ru via H 2 spillover [17,20,21,23,40]. The evaluated value of Mo species based on the H 2 consumption was determined about + 4, which was also supported by XPS result.…”

“…S2. Unfortunately, no obvious difference was observed among the catalysts due to the amorphous property of AC and fine particles size [23,31,37]. Moreover, Raman spectra of samples were also supported in Fig.…”

“…Ru-based catalysts were well known to be active in the aqueous-phase catalytic transformation of biomass feedstocks, and our previous work have reported the selective HDO of sorbitol into C5/C6 alkane over carbon supported ruthenium-molybdenum catalysts, which presented excellent stability for 7 days without obvious decline (Fig. S7) [21][22][23][24][25]31]. Here, the effect of carbon pretreatments were studied in detailed.…”

“…Thus, those results indicated that the acid pretreatment of carbon supports can affected the HDO performance of relevant RuMo catalysts. Generally, it was supposed that the selective of C-O/C-C bond cleavage was attributed to the bimetallic Ru-MoO x structure on catalyst which suppressed the C-C cracking reaction and enhanced the HDO performance [23].…”

“…Our group aimed to directly convert biomass into renewable alkanes on trickle-bed reactor over carbon supported Ru-Mo bimetallic catalyst due to the relative cheap and hydrothermal stability of materials. To date, several attempts have been made to optimize the hydrodeoxygenation performance over carbon supported catalysts, such as adjusting the Ru/Mo composition and screening additives [21][22][23][24][25]. The purpose of this study was to investigate the influence of acid pretreatment on physicochemical properties and hydrodeoxygenation performance of carbon supported Ru-Mo bimetallic catalysts.…”