Preparation Of Solid Heterogeneous Catalyst And Its Catalytic Synthesis Of 3,4-Dimethylfurazan

Furazan ring is a kind of nitrogen heterocyclic energetic group,which has the characteristics of high nitrogen content,high formation enthalpy,active oxygen and thermal stability in the ring.The research on new high energy density materials with structural units is already the focus of attention in many countries.3,4-dimethyl furazan is one of the important monofurazan compounds and is an important precursor compound for the synthesis of furazan-type energetic materials.The heterogeneous catalyst has good industrial application feasibility,for the efficient catalytic conversion,convenient separation and reuse ability.3,4-dimethylfurazan,the important intermediate to synthesize energetic materials,was synthesized by intramolecular dehydration of dimethylglyoxime on three kind of solid base catalysts(KOH/CaO,KOH/MgO and K2CO3/CaO)prepared by impregnation.The catalyst was characterized by X-ray diffraction,and the effects of the quantity of catalyst used,temperature,and reaction time on dehydration cyclization reaction was discussed.The results showed that yield of 3,4-dimethylfurazan were about 92%,65%and 63%,after 60 min at 160℃,respectively with three catalysts and with 10%load capacity.The catalytic conditions of KOH/CaO were optimized by orthogonal experiment.The results indicated that the highest yield of 3,4-dimethylfurazan could reach 92%under the optimal conditions of the base catalyst amount 8%,reaction temperature 160℃,and reaction time 50min.So the present solid base catalyst could provide deeper insights for heterogeneous catalysis of 3,4-dimethylfurazan.We hydrothermally prepared two different window-size metal-organic framework materials,MIL-100(Fe)and MIL-101(Cr),and successfully loaded phosphotungstic acid(PTA)into two metal-organic framework materials.The supported metal-organic frameworks PTA@MIL-100(Fe)and PTA@MIL-101(Cr)were prepared,and a novel supported metal-organic framework NH2-PTA@MIL101(Cr)which has both Br(?)nsted base and Lewis acid sites modified by amino group was further synthesized.By XRD,BET,FT-IR,TEM and ICP comparison test analysis,various physicochemical properties before and after their loading phosphotungstic acid and different loadings were characterized,and used to catalyze the catalytic dehydration synthesis of 3,4-dimethylfurazan from dimethyldioxime.The experimental results show that in the catalyst synthesis process,the catalytic effect of PTA@MIL-100(Fe)is better than that of PTA@MIL-101(Cr)at the same charge ratio,and the PTA loading reaches At 14.35%,PTA@MIL-100(Fe)has better catalytic activity for the dehydration of dimethyldioxime to dimethylfurazan,with a yield of 89.15%,and the catalyst remains relatively stable and high catalytic activity after repeated use 5 times.At the same charge ratio,the yield of 3,4-dimethylfurazan dehydration after amino-modified NH2-PTA@MIL101(Cr)is 75%,which indicates that it is relative to PTA@MIL-101(Cr)catalyst.The addition of amino group can effectively reduce the catalytic effect caused by the loss of PTA during the catalytic process,and provide some experimental support for the catalytic furanide compounds of metal organic framework materials in the future.