Anisole and Guaiacol Hydrodeoxygenation over Monolithic Pt–Sn Catalysts

Abstract

Direct vapor-phase upgrading of biomass pyrolysis products requires a catalytic reactor able to treat high reactant flow rates without generating a large pressure drop, because conventional pyrolysis reactors operate near atmospheric pressure. Monolithic catalysts exhibit important advantages that make them good candidates for this purpose. In this paper, low-surface-area Inconel monoliths were coated with in-situ-grown carbon nanofibers (CNFs), which were subsequently impregnated with catalytic species (Pt, Sn, and bimetallic PtÀSn). These monoliths were tested for the deoxygenation of guaiacol and anisole (products of lignin pyrolysis), two of the most deactivating compounds present in pyrolysis oil. The main products obtained from these feeds on the monolithic catalysts were phenol and benzene. Coating with CNFs provides increased surface area and anchoring sites for the active species (Pt and Sn), thus increasing the yield of desired products. The bimetallic PtÀSn catalysts showed higher activity and stability than monometallic Pt and Sn catalysts. These tests indicate that monoliths of PtÀSn/CNF/Inconel are potentially effective catalysts for the vapor-phase upgrading of lignin fractions present in bio-oil.

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

“…In the work of Prasomsri et al [36] the corresponding reactivity was the following: diphenyl > anisole > guaiacol > phenol > o-cresol [36]. Thus, dehydroxylation of the phenyl ring is difficult [37,39,48,61]. Reactivity of anisole higher than guaiacol reported in [39] similarly to the work of Prasomsri et al [36], can be explained by a higher bond dissociation energy required for the aromatic hydroxyl compared to methoxyl (Table 3).…”

“…MoO3/ZrO2, 60 bar, benzene [39], 9. Pt-Sn/CNF/Inconel, 1 bar, benzene [48], 10. Ni-catalyst, 1.7 bar, benzene [50], for guaiacol: 11.…”

“…Notation: Inside the area surrounded by the curve, the main products are cycloalkanes. Y gua, toluene = 63% Y ani, benzene = 38% [48] For methoxylated benzenes, such as anisole, and trimethoxybenzene (Table 1, entries 3 and 4), it is easier to achieve HDO compared to guaiacol. For example, selectivity to anisole HDO products was 100% at relatively mild temperature of 150 • C under atmospheric pressure over Mo 2 C catalyst (Table 3, entry 3) [44].…”

An Overview on Catalytic Hydrodeoxygenation of Pyrolysis Oil and Its Model Compounds

“…Moreover, it has been reported that double-oxygen compounds were much more prone to coke formation than single-oxygen compounds [115]. The HDO of anisole and guaiacol conducted by González-Borja and Resasco also suggested that more severe catalyst deactivation was observed with guaiacol relative to anisole [88]. In addition to reactant structures, catalyst properties such as acidity play an important role in coke formation.…”

Synthesis of novel catalysts for hydrodeoxygenation of bio-oil: guaiacol as a model component

“…Production of fuels from biomass is a considerable alternate and the thermochemical treatment is a valid approach for efficient biomass conversion. Pyrolysis of biomass gives bio-oil, a process that is relatively well developed (Mortensen et al [3], González-Borja and Resasco [4], Sun et al [5]). Chemical instability, small miscibility with hydrocarbons, corrosiveness, more amount of water and oxygen contents and low heating values are however the major drawbacks of bio-oil, which impede its direct application as the fuel (Saidi et al [6], Nimmanwudipong et al [7]).…”