Effect of Cu addition as a promoter on Re/SiO2 catalysts in the hydrodeoxygenation of 2-methoxyphenol as a model bio oil compound

Abstract

The promoting effect of Cu on Re/SiO 2 catalysts was studied for guaiacol hydrodeoxygenation. Cu(x)Re/SiO 2 catalysts containing from 0 to 1.91 wt% Cu and 13 wt % of Re were prepared by successive wet impregnation and characterized using Xray diffraction (XRD), nitrogen sorption, CO chemisorption, X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS) and surface acidity techniques. Batch reactions were carried out at 300°C and 5 MPa of H 2 . The Cu(x)Re/SiO 2 catalysts displayed higher activities than the Re/SiO 2 catalyst with a maximum activity at 1.58 wt% Cu. At loadings above 1.5 wt%, aggregate formation and a loss of metallic Re active sites lead to a decreased activity. The increase of the activity was attributed not only to Cu increasing the Re reducibility, but also to Cu somehow increasing the metallic Re active sites favoring guaiacol conversion. All catalysts displayed the same product distribution, confirming that the Cu in the Cu(x)Re/SiO 2 not change the nature of the active site in the metallic Re nanoparticles. biofuels from bio-oil [4,5], specifically hydrodeoxygenation (HDO), because 99% of compounds in bio oil contain oxygen. These compounds include acids, alcohols, aldehydes, esters, ketones, sugars, phenols, guaiacols, furan, phenolic lignin derivatives and terpenes [4]. Guaiacol (2-methoxyphenol) has been widely used as a model compound for HDO [6][7][8][9][10][11] because this molecule has two different organic functions (Ar-OH and Ar-OCH 3 groups), and it is considered representative of the organic phase of bio-oil.Different active phases, such as sulfides [9,12,13], nitrides [14-17] and metallic catalysts [18][19][20] have been studied for HDO. Metallic catalysts favor hydrogenation

Ni/HZSM-5 catalyst preparation by deposition-precipitation. Part 1. Effect of nickel loading and preparation conditions on catalyst properties

“…However, as seen from the chemisorption results, the dispersion is much lower than the other catalysts indicating that the particle size is larger. This deviation from the linear trend towards higher metal/support atomic ratio despite lower dispersions and larger particle sizes has been observed in various studies from the Escalona group using different supported metal catalysts with high metal loadings [31][32][33][34]. This discrepancy has been observed when there is high metal loading and high support surface coverage, because at this point the metal particles start to form larger aggregates covering up the smaller particles on the support.…”

Hydrogen Spillover‐Enhanced Heterogeneously Catalyzed Hydrodeoxygenation for Biomass Upgrading

“…[81] The results showed that Cu(x)Re/SiO 2 catalysts showed higher activity than Re/SiO 2 catalysts with the maximum activity for 1.58 wt% Cu, as shown in Figure 12b. [82] In this case, the promotion effect of Cu is due to the fact that the hydrogen spillover formed on the metallic Cu that promotes the reduction of ReO x species and improves the reduction of Re active site, which enhances the catalytic activity of Re metal. [83] In conclusion, the hydrogen spillover resulting from the addition of Cu promoter increases the number of active sites, without changing the type of active sites on the Re catalyst.…”

“…Indeed, non‐noble metals also served as promoters to enhance the catalytic activity and selectivity of HDO reactions. The promotive effect of Re/SiO 2 catalysts with different Cu loading on guaiacol hydrogenation was investigated [81] . The results showed that Cu( x )Re/SiO 2 catalysts showed higher activity than Re/SiO 2 catalysts with the maximum activity for 1.58 wt% Cu, as shown in Figure 12b [82] .…”

“…The promotive effect of Re/SiO 2 catalysts with different Cu loading on guaiacol hydrogenation was investigated [81] . The results showed that Cu( x )Re/SiO 2 catalysts showed higher activity than Re/SiO 2 catalysts with the maximum activity for 1.58 wt% Cu, as shown in Figure 12b [82] . In this case, the promotion effect of Cu is due to the fact that the hydrogen spillover formed on the metallic Cu that promotes the reduction of ReO x species and improves the reduction of Re active site, which enhances the catalytic activity of Re metal [83] .…”

Cu/KIT-5 catalysts for hydrogenation of fatty acids: a comprehensive study of the chemical species and their performance

“…Cu catalytic sites are active and highly selective to desired products in hydrogenation processes [8]. It was also used in combination with noble metals such as Re or Au to increase the catalytic performance [9,10]. It is a more environmental-friendly and inexpensive active phase compared to others.…”