Characterization and Evaluation of Carbon-Supported Noble Metals for the Hydrodeoxygenation of Acetic Acid

Abstract

The gas-phase catalytic hydrodeoxygenation (HDO) of acetic acid (AA) over carbon-supported noble metals (5% M on Cp97, where M = Pt, Pd, Ru, or Rh) were studied. The temperature-dependent conversion and selectivity were studied at 1 atm from 200 to 400 °C. For Pt, Pd, and Rh, the main pathway from 200 to 300 °C was decarbonylation, and from 350 to 400 °C the main pathways were decarbonylation/decarboxylation and ketonization. For Ru, however, from 200 to 250 °C the main pathway was decarboxylation, and from 300 to 400 °C the main pathway was decarbonylation. The activity trend based on turnover frequency at 200 °C was found to be Ru > Rh ≈ Pt > Pd. The activities of all of the catalysts at 200 °C were found to decrease after reaction at 400 °C and a return to 200 °C. This is attributed to sintering and coking. The reaction orders in AA and H 2 measured at 200 °C for all of the catalysts are generally well below ∼0.5, suggesting relatively strong adsorption of both reactants on all of the metal surfaces. The temperature dependence of the reaction rates was examined over the range 200−240 °C, and apparent activation energies of around 21 kcal/mol were found for all of the catalysts since decarbonylation/ decarboxylation is the main pathway with similar product distribution.

Highly Efficient and Atom Economic Route for the Production of Methyl Acrylate and Acetic Acid from a Biorefinery Side Stream

“…In all these reactions, one of the side products found was methyl acetate, which presumably is the result of an acid-catalyzed transesterification between acetic acid and either methyl acrylate or M3AP. Also, acetic acid is known to undergo decarboxylation in the presence of palladium catalysts at these temperatures . The latter explains the lower selectivity toward AcOH compared to MA.…”

“…Also, acetic acid is known to undergo decarboxylation in the presence of palladium catalysts at these temperatures. 35 The latter explains the lower selectivity toward AcOH compared to MA. A further increase in temperature results in a large drop of the selectivity of the reaction (54% to MA and 39% to AcOH, Table 1, entry 4).…”

Carbon-Supported Raney Nickel Catalyst for Acetone Hydrogenation with High Selectivity

“…Carbon materials have a variety of advantages (such as stable chemical-mechanical properties, ease with regards to reclamation [20][21][22][23][24]), and have wide applications in the metal catalysts as supports [25][26][27][28][29][30]. Moreover, the pore structures and surface properties of carbon materials can be adjusted by changing the carbon precursor, adjusting the carbonization temperature, and doping heteroatoms [31,32].…”