Method of lowering permeability of proton exchange film methy alcohol contg fluorine sulfonic acid

Abstract

The method includes steps: first, positive ionized Nano Pd granules is synthesized from Pd salt deoxidized in aqueous solution of cation polymer in ammonium class and reducing agent; then, fluorosulfuric acid type proton exchange membrane is dipped in water decentralization liquid of positive ionized Nano Pd granules; thus, Pd granules are static self-assembled to exit and entrance of sulfonic acid radical group in methanol infiltration channels formed on surface of proton exchange membrane so as to reduce penetrability of methanol to membrane. Advantages are: less loading noble metal Pd, and no inference on proton conducting power basically.

Description

technical field [0001] The invention belongs to a method for reducing the methanol permeability of a fluorine-containing sulfonic acid type proton exchange membrane. Background technique [0002] In today's global energy crisis and deteriorating environment, improving resource utilization and reducing environmental pollution has become an important subject of scientific research. As a clean energy technology, fuel cell technology has become one of the hot spots of international high-tech competition. Direct Methanol Fuel Cell (DMFC) is favored by the industry because of its abundant methanol source, easy portability and storage, and zero or low emission. In DMFC, fluorine-containing sulfonic acid type proton exchange membranes with good chemical stability and high proton conductivity are widely used at present, but the hydrophobic characteristics of the fluorine-containing main chain of the membrane polymer and the ability to conduct proton groups The hydrophilic nature of...

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Problems solved by technology

For example, Pu C. sandwiched a dense methanol-impermeable proton conductor between two layers of Nafion  A composite electrolyte membrane is formed between the membranes, but due to the increase in the thickness of the combined membrane between different layers, the proton-conducting performance of the electrolyte membrane drops sharply [J.electrochem.Soc., 1995, 142, 119]

Using Pd with proton conductivity as a modification material to chemically modify fluorine-containing sulfonic acid proton exchange membranes is a promising treatment method, Choi Won et al [J.power sources, 2001, 96, 411-414], Z.Q. Ma et al [J.Membrane Sci., 2003, 215, 327~336] and S.R.Yoon et al [J.powersources, 2002, 106, 215~423] used sputtering method in Nafion  A layer of metal palladium or palladium alloy is deposited on the surface of the membrane to reduce the methanol permeability, and the methanol permeability is successfully reduced to half of that of the pure membrane. However, there are palladium and Nafion in this method.  Membrane binding is not strong and the amount of palladium is too large; Young-Min Kim et al. [Electrochem.Commn., 2003, 5, 571-574] adopt the method of nanometer metal Pd particle deposition to synthesize alcohol-resisting proton exchange membrane, in their In the study, Nafion soaked in Pd solution  NaBH 4 Reduction to embed nano-metal Pd particles in the water channel inside the membrane, the results show that after treatment, Nafion  The ability to permeate methanol is only 1 / 8 of that before treatment, but the conductivity of the membrane has a 25% drop

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