Kinetic Modeling of Acetic Acid Hydrogenation to Ethanol over K-Modified PtSn Catalyst Supported on Alumina

Abstract

Experiments for acetic acid hydrogenation and catalyst characterizations were conducted to study the kinetics of hydrogenation and esterification over PtSn impregnated on Al 2 O 3 catalyst (PtSn/Al 2 O 3 ), K doped on PtSn/Al 2 O 3 catalyst (K/PtSn/ Al 2 O 3 ), and PtSn impregnated on K/Al 2 O 3 catalyst (PtSn/K/ Al 2 O 3 ). Kinetic parameters such as activation energy, dissociation enthalpy, and adsorption heat of elementary reaction for hydrogenation and esterification were determined on the basis of Langmuir−Hinshelwood model. After the addition of 0.5 wt % K to PtSn/Al 2 O 3 , activation energy of hydrogenation decreased from 20.8 to 11.5 kJ/mol and activation energy of esterification increased from 22.3 to 31.7 kJ/mol. The results of dissociation energy and adsorption heat reflect that K/PtSn/Al 2 O 3 can improve spillover of hydrogen and desorption of ethanol. PtSn/K/Al 2 O 3 had the opposite effect. Potassium also enhanced dissociation of C−OH bond to form more acetyl species. Good agreement was obtained upon comparison of the experimental and calculated data.

Kinetics of Hydrogenation of Acetic Acid over Supported Platinum Catalyst

“…45,46 In this study, the production of acetaldehyde was not apparent from the hydrogenation reaction which suggests that acetyl species reacted extremely fast as free radicals with adsorbed hydrogen species to form ethanol. 18 This was further confirmed under GC- reported for different mechanisms involving hydrogenation reactions. 29,31 A model assuming a non-dissociative adsorption of hydrogen was evaluated and was found not to be good as expected (Table S2, Table S3 and Figure S7).…”

Platinum and N-doped carbon nanostructures as catalysts in hydrodechlorination reactions

“…catalysts and a relevant contribution of adsorption to the overall HDC process rate [21,37,38] during hydrodechlorination reactions. In other hydrogenation reactions catalyzed with Pt NPs, the apparent activation energy decreased to values of 1218 kJ•mol -1 as a consequence of the optimization of the catalyst activity, which may be related to a change in the control regime, even though no mass transfer limitations were observed [39,40]. Some additional experiments were carried out using the catalyst prepared by incipient wetness impregnation in order to study the crossed effect of support doping and the method used for the synthesis of Pt NPs (Figure 10).…”

Catalytic Hydrogenation of Octanoic Acid in the Gaseous Phase on Ni Catalysts: The Effect of Support Species and Structure

“…Based on the activation barriers in potential energy profiles, hydrogen dissociation and spillover on Ni 4 /ZrO 2 is preferential as compared to the other surfaces. As reported in previous works, 41,42 the amount of spillover hydrogen can be connected with the interface between Ni clusters so hydrogenation would be easier owing to the improvement of hydrogen spillover. In addition, carboxylic acids adsorbing on the ZrO 2 surface can be activated and hydrogenated to aldehydes by the oxygen defects on the ZrO 2 surface.…”