Ammonium Metatungstate Preparing Mesoporous Tungsten Carbide Supported Metal Porphyrin Oxygen Reduction Catalyst

ammonium metatungstate powder imagemetal porphyrin structure imageMetal porphyrin complexes are the generic terms of compounds of porphyrin and metal ions, when two of maternal porphyrin pyrrole protons (N - H) is replaced by metal ions, it will form the metallic porphyrin complexes immediately. Metal porphyrin complexes is widely existing in nature, and also the organism, such as in the cytochrome, hemoglobin, chlorophyll, etc; In addition, some metal porphyrin is olefin epoxidation or hydrocarbon oxidation catalyst, and the aldehyde carbonyl catalyst, or functional materials with optical, electrical, magnetic and other properties. 
Study found that the metal porphyrin because of its high conjugate structure and chemical stability, which has a good electrical catalytic reduction on the molecular oxygen, thereby it is likely to replace noble metal catalysts for low-temperature fuel cell catalyst for oxygen reduction, therefore, carbon supported metal porphyrin of oxygen reduction catalyst has become an international research focus in the fuel cell industry. 
The method of ammonium metatungstate (AMT) as tungsten source to prepare REDOX catalyst is as following: 
1. Take a suitable amount of ammonium metatungstate powder to dissolve in water, and form the aqueous solution with 2.5 ~ 50 wt % of ammonium metatungstate; 
2. Add porphyrin monomer and metal precursors (acetate or a nitrate containing with cobalt, nickel or iron, such as cobalt acetate) into the AMT aqueous solution, and evenly mixing; 
3. Lead the mixed aqueous solution obtained in step 2 into the spray dryer under stirring condition for spray drying, and then we will get the hollow sphere metal porphyrin monomer, metal and chloroplatinic acid precursor particles; 
4. roast the hollow sphere metal porphyrin monomer, metal and chloroplatinic acid precursor particles under the reduction and carbonization atmosphere of methane and hydrogen mixture gas; after the reaction, cool the product to room temperature under the protection of inert gas, then we will get the mesoporous tungsten carbide supported metal porphyrin oxygen reduction catalyst after ground and sieved.