Activated Carbon, Carbon Nanofiber and Carbon Nanotube Supported Molybdenum Carbide Catalysts for the Hydrodeoxygenation of Guaiacol

Abstract

Abstract:Molybdenum carbide was supported on three types of carbon support-activated carbon; multi-walled carbon nanotubes; and carbon nanofibers-using ammonium molybdate and molybdic acid as Mo precursors. The use of activated carbon as support afforded an X-ray amorphous Mo phase, whereas crystalline molybdenum carbide phases were obtained on carbon nanofibers and, in some cases, on carbon nanotubes. When the resulting catalysts were tested in the hydrodeoxygenation (HDO) of guaiacol in dodecane, catechol and phenol were obtained as the main products, although in some instances significant amounts of cyclohexane were produced. The observation of catechol in all reaction mixtures suggests that guaiacol was converted into phenol via sequential demethylation and HDO, although the simultaneous occurrence of a direct demethoxylation pathway cannot be discounted. Catalysts based on carbon nanofibers generally afforded the highest yields of phenol; notably, the only crystalline phase detected in these samples was Mo2C or Mo2C-ζ, suggesting that crystalline Mo2C is particularly selective to phenol. At 350 °C, carbon nanofiber supported Mo2C afforded near quantitative guaiacol conversion, the selectivity to phenol approaching 50%. When guaiacol HDO was performed in the presence of acetic acid and furfural, guaiacol conversion decreased, although the selectivity to both catechol and phenol was increased. OPEN ACCESSCatalysts 2015, 5 425

Hydrodeoxygenation of Lignin-Derived Phenols: From Fundamental Studies towards Industrial Applications

“…Catalyst stability, activity as a function of time-onstream [31,33,36,39,42,43,47,48,58,59,61], reuse [30,54,[56][57][58]63], regeneration [34,36], origin of the catalyst deactivation [30], chemical composition of coke [31], thermogravimetrical analysis of the spent catalysts [62], modelling of deactivation [33] are also very important from the industrial point of view. Since the real bio-oils contain in addition to lignin derived compounds also water [59], acetic acid or furfural [56] as well several catalyst poisons, such as chlorine, potassium and sulphur containing compounds [47], it is very important not only to investigate HDO of model compounds but also the real feed [30] using different approaches, such as a single component feed, co-feed studies, real bio-oil [30], simulated bio-oil [40], adsorption studies [48,79] as well as continuous operation [33,36,39,42,43,48].…”

“…Reuse of the catalysts in HDO of phenolic compounds has been intensively investigated [49,54,56,57,62]. Mo 2 C/CNF catalyst was reused in guaiacol HDO at 350 • C under 55 bar after rinsing it with diethyl ether [54].…”

High Efficient Hydrogenation of Lignin-Derived Monophenols to Cyclohexanols over Pd/γ-Al2O3 under Mild Conditions

“…Additionally, high temperatures require more energy consumption and thus an increase in cost. Recently, much attention has been focused on the liquid phase hydrogenation of phenols [8,[17][18][19][20][21][22][23][24][25]. For example, Huang et al [26] prepared a high-performance PdRu bimetallic catalyst on mesoporous silica nanoparticles for the hydrogenation of phenol in CH 2 Cl 2 solvent.…”

Metal Carbides for Biomass Valorization

“…The precursors overcame a temperature-programmed carburization (TPC) under a stream of CH 4 /H 2 at 650 • C [30]. Jimenez et al prepared Mo 2 C carbides supported on activated carbon (AC), carbon nanofibers and carbon nanotubes, by impregnation with ammonium molybdate or molybdic acid and carbothermal hydrogen reduction at 1000 • C [39]. The catalysts obtained showed different crystalline phases depending upon both the Mo precursor used and the support (Figure 2).…”