Anisole Hydrodeoxygenation over Nickel-Based Catalysts: Influences of Solvent and Support Properties

Abstract

The realization of biofuels and chemicals requires the development of highly active and selective catalysts, which are resistant to deactivation. A conventional ZSM-5 (SiO 2 /Al 2 O 3 = 30) was modified with 0.2 M NaOH to generate a mesoporous zeolite support. The parent zeolite, mic-ZSM-5, the modified zeolite, hie-ZSM-5, and a mesoporous silica support, SiO 2 , were impregnated with 5% nickel and characterized using Xray powder diffraction (XRD), Brunauer−Emmett−Teller (BET) analysis of nitrogen sorption, scanning electron microscopy with energy dispersive X-ray (SEM-EDX), transmission electron microscopy (TEM), hydrogen temperature-programmed reduction (H 2 -TPR), ammonium hydrogen temperatureprogrammed desorption (NH 3 -TPD), and thermogravimetric analysis (TGA). The influences of the support properties and solvent during the hydrodeoxygenation of anisole were investigated by measuring concentration profiles and rates in a high-pressure batch reactor. NaOH treatment significantly improved the pore structure, acidity of the support, and metal dispersion as well as the interaction of nonframework Ni species with zeolite and, hence, the catalytic activity and selectivity. The highest anisole conversion of 100% was obtained in 120 min over the hie-Ni/ZSM-5 catalyst with cyclohexane selectivity of 88.1%. In addition, the Ni/SiO 2 catalyst was 84.5% selective to toluene at 48.9% anisole conversion in 120 min; as such, it was proposed that the transformation of anisole proceeds via either a direct deoxygenation−hydrogenation or isomerization−direct deoxygenation pathway. However, no substantial differences in anisole conversion or product selectivity were observed when decalin and n-decane were compared as solvents. A catalyst reusability test showed hie-Ni/ZSM-5 as the most stable of the three catalysts in terms of anisole transformation, even though the catalyst recorded the biggest weight loss of 9.2% suggesting high resistance to carbon deactivation. Therefore, with this very good catalytic activity, good selectivity to liquid product, and stability, the mesoporous Ni/ZSM-5 catalyst is a potential candidate for economically beneficial future industrial applications.

Influence of Natural Mordenite Activation Mode on Its Efficiency as Support of Nickel Catalysts for Biodiesel Upgrading to Renewable Diesel

“…NH 3 -TPD experiments were performed to investigate the acidity of the supports and the nickel catalysts [ 5 , 32 ]. Figure 5 b illustrates the corresponding curves.…”

Catalytic conversion of biomass

“…The most dominant fraction is phenolics, obtained from the rapid pyrolysis of lignin at 25-40 wt.% (containing 7-11 wt.% monomer). Typically, lignin-derived monomeric phenols include mainly phenol [24,25], guaiacol, anisole [26,27], p-cresol, m-cresol and vanillin, which are widely used as model compounds for lignin to reduce the complexity of reactivity and mechanism studies [8]. The presence of oxygenated compounds leads to deteriorating properties such as severe corrosiveness (high acidity), low calorific value, thermal and chemical instability, and incompatibility with conventional fuels, making lignin-derived bio-oils unsuitable for direct use as liquid fuels in the petrochemical industry.…”

Construction of HZSM-5 with a Mesoporous Structure and Suitable Acidity: Application in Catalytic Syngas Conversion to Light Aromatics over Na–FeMn/HZSM-5 Zeolite

“…Various methods have been proposed for the preparation of the HZSM-5 zeolite with a mesoporous structure, including the addition of structure-directing agents (such as poly­(ethylene glycol), toluene, etc.) and base treatment. − To this end, many researchers have carried out relevant studies . Ding et al developed a bifunctional catalyst with a hollow HZSM-5 shell zeolite encapsulating FeMn nanoparticles, which significantly increases the selectivity of light aromatics and suppresses coke deposition by enhancing the mass diffusion of reactants and products .…”