The effect of support porosity on the selectivity of Pd–In/support catalysts in nitrate reduction

Abstract

The influence of support porosity on the selectivity of home-made 5%Pd-2%In/support (support = SiO 2 , Al 2 O 3 , TiO 2 ) catalysts in nitrate reduction was studied. The main final products of the reaction were N 2 and NH 4? . Together with the decrease in pore diameter, an increase in ammonia concentration in the reaction mixture was observed. It is probably caused by slow diffusion of OH -ions from narrow pores to the solution.

Highly effective photocatalytic system comprising semiconductor photocatalyst and supported bimetallic non-photocatalyst for selective reduction of nitrate to nitrogen in water

“…The materials used as a catalyst support strongly affect the catalytic performance for the conventional non-photocatalytic reduction of NO 3 -with H 2 in water over supported bimetallic-Pd catalysts [9,16,24]. ).…”

Impact of particle size and metal–support interaction on denitration behavior of well-defined Pt–Cu nanoparticles

“…Another difference between the two investigated materials is that the concentration of NO 2 − reached a maximum and then decreased with time according to the kinetic model of successive first-order reactions described by eqn ( 6) and (8).…”

“…Pd-In/Al 2 O 3 , 6 Pt-In/Al 2 O 3 , 7 Pt-In/SiO 2 or TiO 2 , 8 Pt-Sn/HZSM-5, 9 Pt-Cu/Al 2 O 3 , 10 Rh-Cu/Al 2 O 3 , 11 Pd-Sn/ZrO 2 or TiO 2 , 12 etc. The disadvantages of the impregnation route for catalyst preparation are given as follows: (i) the catalytic active phases are formed with the participation of the support (strong metal-support interaction), (ii) the size and composition of the active phase formed by the interaction (alloying) of the two metals is difficult to control, and (iii) the characterization of the catalyst is demanding because the concentration of the active components compared to the supporting materials is very low (typically a few wt%).…”

“…to the final products because the NO 2 − depletion rate depends on the interplay of both the k 1 and k 2 values according to eqn (8).…”

Colloidal nanoparticles as catalysts and catalyst precursors for nitrite hydrogenation

“…Indeed, Strukul et al reported that using large Pd/Al2O3 catalyst particles ( > 0.5 mm) enhanced ammonium formation [118]. However, this effect also explained by some other researchers with sluggish diffusion of protons in the absence of a buffer, which would induce high pH values inside the catalyst particles, increasing the selectivity to ammonium in that way [119]. Commonly, no quantum effect has been considered in this model [120,121].…”