This method is unique in the market and implies a simple procedure to control the volume and size of the mesoporosity developed in POM-based salts. This is possible thanks to the pH increase in solution during the synthesis of mesoporous solids.
Description of the technology
The Carbon Materials and Environment research group at the University of Alicante has developed a novel procedure for synthesizing mesoporous solids from any polioxometalates (POM)-based salt in a controlled manner, both in volume and size. It is a simple and efficient method that produces a large volume of homogeneous mesoporosity within the nanoparticles, resulting in compounds used as catalysts and / or catalyst supports more economical and environmentally less harmful than those currently used by the chemical industry. The research group is looking for companies interested in acquiring this technology for commercial uses.
In recent decades, there is strong interest in developing low price (as an alternative to noble metals) and environmentally friendly . Satisfactory results have been achieved with polioxometalates based catalysts (hereinafter, POM). POMs are a large family of anionic clusters of nanoscale metal oxides that are combined with external cations to achieve electroneutrality. They can have different f shapes and sizes (Keggin, Dawson and Anderson-type structures). Many of POM properties are highly interesting for the catalysis reaction. The most important aspect is its acid properties, as they are extremely strong acids, close to the superacid range (its redox properties) proving to be efficient oxidants with the fast reversible redox reactions. When the cations are protons, then the compound is called heteropolyacid (hereinafter, HPA). The replacement of this proton by a cation, leads to the formation of the corresponding salt, greatly increasing the insolubility of the compound (Note that the type of cation that is combined with the POM, determines the solubility, thermal stability, acidity and the porosity of the salt). Given the limitations described, there is a need for a simple method that allows a controlled development of mesoporosity in POM-based salts. 1. We prepare a dispersion of a POM-based salt (ammonium tetralquilamonium salt, protonated aromatic amine, protonated aliphatic amine, protonated quinoline, pyridine or a metal belonging to groups 1, 2, 13, the group of the lanthanides, the actinides or the period of the periodic table 3) in an acid liquid medium in which the salt is not soluble. 2. Control the pH of the above solution by adding a solution containing a basic salt. 3. Stir the resulting solution at that pH for a specified time at a controlled temperature. 4. The dispersed solid obtained (ie, POM mesoporous salt) is vacuum filtered, then it is washed with an acid solution and dried in the oven. This procedure allows the controlled synthesis of mesoporous solids of any POM-based salt
Main advantages of its use
- It controls the size of the mesoporosity developed.
- It allows to obtain a certain distribution of sizes of the mesoporosity.
- It controls the volume of mesoporosity developed.
- This is a very simple method to synthesize mesoporous solids of any POM-based salt in a controlled way
- This treatment affects neither the volume of the micropores, nor the micropores size distribution in the original POM salt.
- You get homogeneous regions within the core of the nanoparticle.
- • It generates a high volume of mesoporosity (up 300% from the level of initial porosity of the original POMsalt).
- Catalysts support: Use as support of catalysts (metals, metal oxides, coordination compounds, etc.).
- Catalysts: 1/ Homogeneous (they have a high solubility in polar solvents, particularly aqueous solutions). 2/ Heterogeneous (To be used on porous solids with large surface area, or be insoluble in the reaction medium). For example, POM-based catalysts of palladium doped cesium salts used in thel production of acetic acid from ethylene and oxygen.
- The synthesis of new POM-based mesoporous solids is highly interesting for the chemical industry and the chemical, It provides a modifiable surface where it is easy to control the functionality and the addition of catalysts (based on nanoparticles of: noble metals, alloys noble metal alloys and metal oxides). They are inexpensive and environmentally friendly products.These are the main application for the said mesoporous solids: