Kinetics of the reactions of anisole, a model compound representative of lignin-derived bio-oils, with H 2 , catalyzed by Pt/Al 2 O 3 , were investigated with a fixed-bed tubular microflow reactor at 573−673 K, 8−14 bar, and space velocities in the range of 3−240 (g of anisole)/(g of catalyst × h). Selectivity−conversion data were used as a basis to propose an approximate reaction network and estimate parameters in approximate rate equations. The reactions include the following: anisole conversion to phenol by hydrogenolysis, to 2-methylphenol by transalkylation, to 2,4-dimethylphenol, 2,4,6-trimethylphenol, and 2,3,5,6-tetramethylphenol by transalkylation and alkylation, to benzene by hydrodeoxygenation (HDO), and to hexamethylbenzene by HDO and alkylation. The primary reactions are satisfactorily represented with the approximation that each is first-order in the organic reactant. The apparent activation energy for the hydrogenolysis reaction that leads to phenol formation is approximately 25.3 kJ/mol, and the alkylation is the reaction class characterized by the highest apparent activation energy.
Kinetics of the hydroprocessing of anisole, a compound representative of lignin-derived bio-oils, catalyzed by a commercial sulfided CoMo/Al2O3 were determined at 8-20 bar pressure and 573-673 K with a once-through flow reactor. The catalyst was sulfided in an atmosphere of H2 + H2S prior to the measurement of its performance. Selectivity-conversion data were used as a basis for determining an approximate, partially quantified reaction network showing that hydrodeoxygenation, hydrogenolysis, and alkylation reactions take place simultaneously. The data indicate that these reactions can be stopped at the point where HDO is virtually completed and hydrogenation reactions (and thus H2 consumption) are minimized. Phenol was the major product of the reactions, with direct deoxygenation of anisole to give benzene being kinetically almost insignificant under our conditions. We infer that the scission of the Cmethyl-O bond is
Catalytic hydroprocessing of 4‐methylanisole as a representative of lignin‐derived bio‐oils was catalyzed by a commercial sulphided CoMo/γ‐Al2O3 catalyst in a fixed‐bed flow reactor at various space velocities, temperatures, pressures, and feed compositions. An approximate reaction network is presented that accounts for the major products, and approximate kinetics are also presented. The kinetically significant reactions are 4‐methylanisole conversion to (a) 4‐methylphenol via hydrogenolysis, (b) toluene and benzene via hydrodeoxygenation, (c) cyclohexanone and methylcyclohexanone via hydrogenation, and (d) methylphenol derivatives via alkylation and transalkylation. The formation of toluene and benzene along with water and methanol from 4‐methylanisole is inferred to result from direct scission of the Caromatic–O bond. Cleavage of the Cmethyl–O bond is faster than cleavage of the Caromatic–O bond. The main pathway to toluene formation is the hydrogenolysis of the Caromatic–O bond of the intermediate 4‐methylphenol.
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