Double recovery and regeneration of Pt/C catalysts: Both platinum from the spent proton exchange membrane fuel cell stacks and carbon from the pomelo peel

Liu

2023

Metals

The increasing carbon emissions from various fossil fuels have led to the search for efficient and clean energy sources to replace them. Proton exchange membrane fuel cells (PEMFCs) are a promising alternative, but the use of platinum as a catalyst material poses challenges due to its limited resources and low abundance. This study proposes an efficient method for platinum recovery while retaining spent membranes. The membrane and catalyst were separated using isopropanol, and the spent membrane was dissolved in a 50% ethanol solution to prepare the precursor for subsequent membrane regeneration. Hydrochloric acid (HCl) was used as the leaching agent, and the experimental parameters such as HCl concentration, H2O2 concentration, contact time, and operating temperature were optimized to achieve the highest platinum leaching rate. Finally, through isothermal leaching experiments, the leaching mechanism was investigated using the shrinking core model, indicating the involvement of both surface chemical and inner diffusion mechanisms in the platinum leaching process, primarily controlled by the inner diffusion mechanism. Under optimal conditions, the platinum leaching rate was about 90%, and the activation energy of the reaction was calculated to be 6.89 kJ/mol using the Arrhenius equation.

Section: Sonicationsupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Leaching Efficiency and Kinetics of Platinum from Spent Proton Exchange Membrane Fuel Cells by H2O2/HCl

Liu

2023

Metals

“…The second process involves heating the palladium up to 500 °C, still in the presence of chlorine gas, without exceeding 600 °C which is the decomposition temperature of PdCl 2 . This process is similar to the regeneration of other platinum group metals [ 49 ]. The resulting palladium chloride is a stable compound.…”

Section: Introductionmentioning

confidence: 99%

Recovery of Homogeneous Platinoid Catalysts from Pharmaceutical Media: Review on the Existing Treatments and the Perspectives of Membrane Processes

Magne,

Carretier,

Ubiera Ruiz

et al. 2023

Membranes

Catalyst recovery is a major challenge for reaching the objectives of green chemistry for industry. Indeed, catalysts enable quick and selective syntheses with high reaction yields. This is especially the case for homogeneous platinoid catalysts which are almost indispensable for cross-coupling reactions often used by the pharmaceutical industry. However, they are based on scarce, expensive, and toxic resources. In addition, they are quite sensitive and degrade over time at the end of the reaction. Once degraded, their regeneration is complex and hazardous to implement. Working on their recovery could lead to highly effective catalytic chemistries while limiting the environmental and economic impacts of their one-time uses. This review aims to describe and compare conventional processes for metal removal while discussing their advantages and drawbacks considering the objective of homogeneous catalyst recovery. Most of them lead to difficulty recycling active catalysts due to their ability to only treat metal ions or to chelate catalysts without the possibility to reverse the mechanism. However, membrane processes seem to offer some perspectives with limiting degradations. While membranes are not systematically the best option for recycling homogeneous catalysts, current development might help improve the separation between pharmaceutical active ingredients and catalysts and enable their recycling.

ACS Appl. Energy Mater.

“…Furthermore, catalyst recovery is also crucial for the development of the fuel cell industry. Zeng et al 18 proposed a dual recovery process, achieving a high platinum recovery rate, thereby providing an important technological foundation for cost reduction and industrial development.…”

Section: Introductionmentioning

confidence: 99%

Impact of Nonuniform Platinum Loading Distribution Design in the Catalyst Layer on the High-Temperature Proton Exchange Membrane Fuel Cell Performance

Xu,

Deng,

Zhang

et al. 2024

High-temperature proton exchange membrane fuel cells (HT-PEMFCs) are efficient and environmentally friendly energy conversion devices, and the performance and cost of the cells are influenced by the platinum loading in the catalytic layer. In this study, finite element analysis was used to determine the effective reaction thickness of the anode and cathode catalytic layers and to propose a novel platinum loading distribution to reduce costs while ensuring the cell performance. The research results indicate that platinum loading has a significant impact on the cell performance, particularly at the cathode. Furthermore, adopting higher platinum loading in the effective reaction thickness region and lower loading in the noneffective reaction thickness region can effectively reduce the platinum usage while maintaining the fuel cell performance. Specifically, when the platinum loading is 0.30 mg/ cm 2 in the effective reaction thickness region and 0.025 mg/cm 2 in the noneffective reaction thickness region, the cell performance remains unchanged, and the total platinum usage decreases by 46%. This provides valuable insights into the design of catalytic layers in HT-PEMFCs.