Background

Since Platinum Group Metals (PGM) are used as the catalyst in the fuel cells and e.g. auto catalytic converters, recovery of the expensive noble metals from discarded fuel cell MEAs and catalytic converters, is of great interest. Ideally, the platinum should be recovered on a form which requires minimal processing prior to redeposition as electrocatalyst nanoparticles on fresh support material, keeping in mind that the majority of methods for preparing nanoparticles of platinum on various carbon supports involve hexachloroplatinic acid (H₂PtCl₆) or potassium tetrachloroplatinate (K₂PtCl₄) salts dissolved in water or various alcohols as the source of platinum.

The conventional way of recovering platinum from fuel cell electrodes is to dissolve platinum in aqua regia after combustion of the carbon support. However, this process involves emission of NO_x gas in order to get rid of the nitric acid derived components of the solution, and so a more environmentally friendly process is desired.

Technology Overview

Potential Cycling

Several studies have shown that

dissolution of platinum is one of the degradation pathways during the lifetime of a PEM fuel cell MEA,
that it can be accelerated by subjecting the electrode material to potential cycling and
the dissolution rate is strongly dependent on the presence of chloride ions, potential range, sweep rate, etc.

This invention presents the idea of putting the degradative process of platinum dissolution to good use by its deliberate application as a means to recover platinum electrochemically. By potential cycling of PEM fuel cell electrode material in hydrochloric acid electrolyte, platinum could be recovered as chloro complexes without the need for NO_x degassing. The chloro complexes could easily be converted to the appropriate platinum salts and redeposited as electrocatalyst nanoparticles.

Benefits

Shorten value chain, transportation and lead time - simplified process can be applied individually according to customer demand with significantly reduced waiting time
Low initial investment, flexible batch process - reactors of different size and non continuous operation can be engineered according to capacity needed
Eco-friendly, reduced CO₂ emission - mild reaction conditions, environmentally friendly reagents, low energy consumption and low requirement for infrastructure
Combination of recycling with production - direct manufacture of new catalyst, possibility of a closed loop economy and new business model
Accelerate green transition - significantly reduce capital cost of recycling process equipment, secure sustainability of the renewable energy solutions

Applications

Recovery and recycling of precious metal catalysts from fuel cells and catalytic converters

Opportunity

SDU are looking for:

Collaboration for technical and engineering oriented development.
Partnership for the business model development
Investment for large-scale commercialization

Recovery of Precious Metals

Patents

IP Status

Seeking