Reactivation of severely aged commercial three-way catalysts by washing with weak EDTA and oxalic acid solutions

Characterization of phosphorus poisoning on diesel exhaust gas catalyst components containing oxide and Pt

“…This indicates that the decrease in the BET surface area and the increase in the average pore size detected after the hydrothermal ageing should be ascribed to the increase of the existing pores. The decrease in the total volume of the pores with a diameter larger than 5 nm calculated for the phosphorus poisoned sample can be associated with the physical deactivation (pore blocking) by phosphates [9]. Finally, it should be mentioned that the pore size distribution curves and the ageing-induced changes in them vary for the samples with different composition.…”

Metal Redispersion Strategies for Recycling of Supported Metal Catalysts: A Perspective

“…177 A structured monolith Pd-Rh three way catalyst was also treated with chlorine reagents (1,2-dichloropropane and dichloroacetic acid) using 0.1 M solutions flowing at 0.6 L min -1 at 50 °C for 2 h 178 , a procedure which has been reported before for the regeneration of other monolith samples via removal of poisons. 179 , 180 The dichloroacetic acid was found to be more effective than dichloropropane at recovering Pd active sites, which has been attributed to the apparent re-dispersion and restructuring of said Pd due to the chlorination and subsequent reduction.…”

Regeneration of Aged Commercial Three-Way Catalytic Converters

“…Thus, regeneration of deactivated TWCs is the result of the removal of contaminants, inhibitors and fouling agents accumulated in the aged TWC. Previous studies ascribed the improvement of OSC and catalytic performance of regenerated TWCs to the opening of closed pores, and thus exposure of active catalytic sites to reactant gases after partial removal of Ca, Zn, Mg, Al and Ce phosphates [14,16,17].…”

“…acetic, citric and oxalic acids) and chelating agents (e.g. EDTA, NTA), which dissolve the contaminant compounds and sequester the contaminant metal ions [9][10][11][12][13][14][15][16][17]. Thus, regeneration of deactivated TWCs is the result of the removal of contaminants, inhibitors and fouling agents accumulated in the aged TWC.…”

“…Expanding the durability of deactivated automobile TWCs by applying efficient as well as environmentally friendly techniques for the regeneration of their catalytic performance has attracted some scientific attention in the past few years, although TWC technology has been emerged in the mid-1970s. Scientific efforts spent so far in terms of regeneration and reutilization of severely aged TWCs might be classified in the following two main categories: (a) methods that apply thermo-chemical treatments using oxygen, hydrogen, and/ or chlorine-containing gas mixtures [3][4][5], or other chlorine-containing reagents [6][7][8], and (b) methods that involve washing of the catalyst by the use of liquid solvents, such as organic acids [9][10][11][12][13][14][15] or other chelating agents [16,17].…”