Modeling of Hydrogenation of Nitrate in Water on Pd–Sn/Al₂O₃ Catalyst: Estimation of Microkinetic Parameters and Transport Phenomena Properties

Abstract

Excess nitrate in water is a known environmental problem, the remediation of which can be accomplished by catalytic reduction of nitrate to N 2 and NH 4 + . This work presents a model for the microkinetic modeling of a system that uses a Pd−Sn/γ-Al 2 O 3 catalyst taking into account the inherent transport phenomena. The pH control, which was carried out by flowing CO 2 , was also modeled, leading to a considerably large (and stiff) system of ordinary differential equations, which was dependent on a set of empirical parameters to be fitted. This regression was conducted using a maximum statistical likelihood criterion, employing tailor-made optimization techniques. The results indicated mass-transfer effects should be considered to obtain a complete description of the reaction system, especially regarding the pH profile.

Effect of water composition on catalytic reduction of nitrate

“…These consist of a promoter metal, being Cu [22,24,25], Sn [22,[26][27][28][29][30] and In [25,27,31,32] the most widely used, and a noble metal, most commonly Pd [31,[33][34][35][36]. Different supports have been used, being -Al2O3 [27,32,[37][38][39], TiO2 [32,[40][41][42] and activated carbon (AC) [21,31,43,44] the most frequent. Al2O3 is considered a passive support because it does not have reducible capacity, and therefore it does not participate directly in the reduction process [11].…”

Reductive dechlorination of trichloroacetic acid (TCAA) by electrochemical process over Pd-In/Al2O3 catalyst

“…The chemical environment of Pd could be modified by a second metal addition [21,22], and the second metal, such as Au, Cu, Bi, Sn etc. [18][19][20]23], acts as a promoter for the Pd-based catalysts. For instance, the polymer-protected Au/Pd bimetal alloy, with an Au core structure, exhibited a higher catalytic activity for selective hydrogenation of 1,3-cyclooctadiene than that of monometallic Au or Pd catalyst [20].…”

Glycerol acetylation considering competing dimerization

“…For deeper understanding of the underlying mathematics of the maximum likelihood method and its applications in kinetic models, the reader is referred to seminal previous applications of this method. [22][23][24] 4 RESULTS AND DISCUSSION Figure 1 shows liquid phase formation of MAG, DAG, TAG, and DGTA for Amberlyst-15, and Figure 2 for Amberlyst-70, using fits for reference model A and model B, containing the parallel dimerization reaction. Table 1 shows the values of the apparent kinetic constants.…”