Abstract
Mono-, and bimetallic Ni-, Ru-, and Pt-modified nanosized Beta zeolite catalysts were prepared by the post synthesis method and characterized by powder X-ray diffraction (XRD), nitrogen physisorption, HRTEM microscopy, temperature-programmed reduction (TPR-TGA), ATR FT-IR spectroscopy, and by solid-state MAS-NMR spectroscopy. The presence of nanosized nickel-oxide, ruthenium-oxide, and platinum species was detected on the catalysts. The presence of Brønsted and Lewis acid sites, and incorporation of nickel ions into zeolite lattice was proven by FT-IR of adsorbed pyridine. The structural changes in the catalyst matrix were investigated by solid state NMR spectroscopy. The catalysts were used in a gas-phase hydrodemethoxylation and dealkylation of 2-methoxy-4-propylphenol as a lignin derivative molecule for phenol synthesis.
Highlights
Lignocellulose is mainly composed of polymers of carbohydrates and aromatics
Significant progress has been made in the production of value-added compounds from platform molecules obtained by acidic hydrolysis of cellulose and hemicellulose
Acidity of the catalysts can be investigated by FT-IR spectroscopy by adsorption of a base, such as pyridine (Py)
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. The catalytic processes of selective demethoxylation and dealkylation leads to transformation of substituted phenols to phenol. Efficient dealkylation/demethoxylation of alkylphenols derived from lignocellulose was reported on bimetallic catalysts with metal active sites and Lewis and/or Brønsted sites (Pt/γ-Al2 O3 , Pt-, Ru- zeolite ZSM-5, and ZSM-22, beta) [8,9,10,11,12,13,14,15,16]. The most efficient catalyst could selectively catalyze demethoxylation and de-alkylation processes and the mixture of substituted phenols will be converted into phenol. The application of nanosized bifunctional catalysts can improve the conversion of alkyl phenols and the selectivity to phenol production. Selection of metal species is of great importance for the demethoxylation and dealkylation processes. The obtained catalysts were studied in the hydrodemethoxylation and dealkylation of 2-methoxy-4-propylphenol
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