Bimetallic effects in the hydrodeoxygenation of meta-cresol on γ-Al2O3 supported Pt-Ni and Pt-Co catalysts

• Published in: Green chemistry : an international journal and green chemistry resource : GC 2012-01, Vol.14 (5), p.1388-1397
• Main Authors: Do, Phuong T. M, Foster, Andrew J, Chen, Jingguang, Lobo, Raul F
• Format: Article
• Language: English
• Subjects: Alicyclic compounds; Alicyclic compounds, terpenoids, prostaglandins, steroids; Catalysis; Catalysts: preparations and properties; Chemistry; Exact sciences and technology; General and physical chemistry; Noncondensed benzenic compounds; Organic chemistry; Preparations and properties; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry
• ISSN: 1463-9262; 1463-9270
• DOI: 10.1039/c2gc16544a

The hydrodeoxygenation (HDO) of meta -cresol, a typical phenolic compound in bio-oils, is investigated in the vapor-phase on γ-Al 2 O 3 -supported Pt catalysts at near atmospheric hydrogen pressure. The HDO reaction yields two major hydrocarbons: toluene and methylcyclohexane. The deoxygenation of meta -cresol proceeds through two consecutive steps: hydrogenation of the aromatic ring on the Pt metal followed by dehydration reactions of the produced alcohol intermediates on the alumina support. Phenolic ring saturation is proposed to be slower than its sequential dehydration steps on Pt/γ-Al 2 O 3 . This is in a good agreement with the higher selectivity of toluene compared to that of the hydrogenated cyclic hydrocarbon, methylcyclohexane, because toluene formation requires fewer ring hydrogenation steps than its counterpart. The additions of Co and Ni into Pt not only improve the overall HDO conversion, but also modify the product distribution. The enhancement in the overall HDO activity is related to the better hydrogenation activity of bimetallic Pt-Co and Pt-Ni catalysts and the generation of additional sites for alcohol dehydration. Consequently, more saturated cyclic hydrocarbon product, methylcyclohexane, is observed on bimetallic catalysts with respect to the monometallic Pt catalyst. Hydrodeoxygenation of meta -cresol on Pt/γ-Al 2 O 3 at atmospheric hydrogen pressure yielded mostly toluene. The bimetallic Pt-Ni/γ-Al 2 O 3 and Pt-Co/γ-Al 2 O 3 not only enhanced the overall activity, but also altered the product selectivity.