Carbon nanofiber supported Mo2C catalysts for hydrodeoxygenation of guaiacol: The importance of the carburization process

Abstract

Molybdenum carbide catalysts supported on carbon nanofibers (β-Mo 2 C/CNF) were synthetized employing different carburization parameters: five temperatures (550-750 ºC) and four heating rates (1-10 ºC/min) were tested. The carburization process of the Mo precursor in the catalysts was studied by thermogravimetric analysis, X-ray diffraction, X-ray photoelectron spectroscopy, N 2 physisorption, inductively coupled plasma optical emission spectrometry and transmission electron microscopy. The formation of the carbide phase was confirmed by the presence of the oxycarbide and carbide phases which were observed on the surface of all catalysts. Higher carburization temperatures resulted in an increase of the carbide phase content and crystal size at the expenses of the oxycarbide phase disappearance. High carburization temperatures and low heating rates were needed in order to obtain well-defined β-Mo 2 C crystals over the

Nanostructured Carbon Material Effect on the Synthesis of Carbon-Supported Molybdenum Carbide Catalysts for Guaiacol Hydrodeoxygenation

“…These purified and oxidised carbon nanofibers are referred to as CNF in the manuscript. More details of this synthesis can be found in previous works [18,19].…”

“…Mo was incorporated on the NCM by incipient wetness impregnation using an (NH 4 ) 6 Mo 7 O 24 •4H 2 O aqueous solution (AHM) [18] in order to obtain a Mo content of 10 wt.% after drying (10.6 wt.% of Mo after the transformation of AHM into Mo 2 C in CHR process). These materials were labelled as AHM/NCM (where NCM refers to CNF, CNT, RGO or AC).…”

“…These materials were labelled as AHM/NCM (where NCM refers to CNF, CNT, RGO or AC). Although the temperature program used in the CHR was established in previous works for CNF-supported catalysts [18,19], the CHR temperature was initially optimised for the different carbon supports by using a thermobalance coupled with a mass spectrometer (TG-MS) (NETZSCH TG 209 F1 Libra ® thermobalance coupled to a MICROMERITICS AutoChem TM II 2920 mass spectrometer), where the reduction process was simulated followed by the structural analysis of the resulting catalysts (labelled as Mo 2 C/NCM) by X-ray diffraction (XRD). The impregnated NCM was introduced in the thermobalance and carboreduced for 2 h at temperatures ranging from 650 • C to 800 • C, using H 2 /Ar (10/90 vol./vol.)…”

“…Besides, the use of milder temperature conditions may mitigate the low specific surface area obtained due to the partial destruction of the support [16]. Nevertheless, several parameters are involved in the resulting crystallographic and morphological characteristics of the Mo 2 C phase, such as carburization temperature, heating rate, carburization time, Mo precursor, Mo content and the nature of the carbon support [11,12,14,[17][18][19].…”

Brief overview of electrospun polyacrylonitrile carbon nanofibers: Preparation process with applications and recent trends

“…Some interesting recent reports about the use of CNFs as catalysts include the synthesis of molybdenum carbide (MO 2 C) supported CNFs for the hydrodeoxygenation of guaiacol, where Mo 2 C/CNFs were synthetized at different carburization temperatures and heating rates, and their behavior in the liquid‐phase hydrodeoxygenation of guaiacol was tested. It has been found that high carburization temperatures and low heating rates gives well‐defined β‐Mo 2 C crystals that gives excellent catalytic activity.…”