Ionothermal Synthesis And Characterization Of Bimetallic Phosphate Compounds

In recent years,porous phosphate compounds have been widely used in the fields of petroleum and natural gas chemical industry,fine chemical industry,environmental protection,electronic components,optics and electrochemistry due to their unique pore structure and rich surface properties.So far,people have mainly focused on monometallic phosphate compounds and main group metal phosphate compounds doped with transition metal elements.There are relatively few reports on the research of double transition metal phosphate compounds.Considering that transition metal elements can not only form catalytically active centers,but also the synergistic effect between different metal elements will make them exhibit unique properties different from monometallic phosphate compounds,it is necessary to study the preparation and characterization of double transition metal phosphate compounds.Herein,the commonly used ionothermal synthesis method of porous material synthesis is adopted,and 2-imidazolidinone and urea are selected as hydrogen bond donors,which are compounded with choline chloride to form an ionic eutectic mixture as the solvent and template for the reaction.Changed the synthesis conditions,synthesized five kinds of double transition metal phosphate compounds,explored the influencing factors in the synthesis process and used X-ray diffraction（XRD）,scanning electron microscope（SEM）,thermogravimetry（TG）,energy spectrum（EDS）The analysis and test methods such as CHN element analysis and nitrogen physical adsorption characterize and analyze the physical and chemical properties of the samples,and the following main research results are obtained:（1）In an ionic eutectic mixture system consisting of choline chloride and2-imidazolidinone,two iron-manganese bimetallic phosphate compounds BMPA-1 and BMPA-2 were synthesized by changing the initial iron and manganese ratio of the reactants.In the ionic eutectic mixture system composed of choline chloride and urea,one iron manganese bimetallic phosphate compound BMPA-3 and two zinc zirconium bimetallic phosphate compounds BMPA-4 and BMPA-5 were synthesized.The study found that the thermal stability of the sample BMPA-1 is less than 300℃,and the average pore size of the samples BMPA-1,BMPA-2,BMPA-3 and BMPA-4 all belong to the range of mesopores,of which BMPA-2 has the largest specific surface area It is202.576m²/g.（2）The template effect of the eutectic mixture in the process of ionic thermal synthesis was studied.The results show that in the choline chloride/urea system,NH₄⁺,the product of thermal decomposition of urea,has a stronger template effect than the quaternary ammonium salt choline chloride.（3）The effect of the crystallization time of BMPA-1 synthesized in the choline chloride/2-imidazolidinone system on the reaction product was studied.The results showed that there is a close relationship between the crystallization time and the type and size of the reaction product.The optimal crystallization time of sample BMPA-1 is4d.（4）The effect of the initial composition of the reactant on the reaction product was studied.The results show that when the initial composition of the reactant is changed within a certain range,the type and morphology of the reaction product will change accordingly.There is no strict correspondence between the components of the reaction product and the initial composition of the reactants.When synthesizing the zinc phosphate/zirconium compound in the choline chloride/urea system,the reaction product is not sensitive enough to the change of the initial zinc and zirconium ratios of the reactants,the target product can be synthesized in a wide range of compositions.