Methane/Ammonia Plasma Coupling Reaction For The Synthesis Of Nitrile Compounds

Methane is the main component of nature gas, and its utilization has drawn enormous attentions. Ammonia is a cheap and abundant chemical raw materials. Therefore, the direct synthesis of high value fine chemicals from methane and ammonia has a big application prospect and a profound scientific significance. In this paper, dielectric barrier discharge (DBD) has been used to study the CH4/NH3 plasma coupling reaction, and some results have been achieved as follows:Under the condition of pure DBD plasma, the N, N-dimethyl cyanamide and amino acetonitrile can be directly synthesize by a CH4/NH3 coupling reaction. The influences of the DBD reactor on the CH4/NH3 plasma coupling reaction have been investigated, and it has been found that the single dielectric barrier discharge (SDBD) reactor favors the synthesis of N, N-dimethyl cyanamide and amino acetonitrile. In the SDBD reactor, the effects of the feed gas ratio, gas residence time and the specific energy density on the synthesis of N, N-dimethyl cyanamide and amino acetonitrile were investigated. The optimized conditions are as follows: 1/1 feed gas ratio,,3.5 s residence time, and 30 W/cm3 specific energy density. Furthermore, the CH4/NH3 DBD plasma has been diagnosized by optical emission spectroscopy (OES), and the OES results indicate that the C=N radical species could be the key intermediate for the synthesis of N, N-dimethyl cyanamide and amino acetonitrile.Through the conbination of DBD palsma and supported metal catalysts, hydrogen cyanide (HCN) can be directly synthesized through a CH4/NH3 plasma-catalysis coupling reaction. Under the condition of plasma-catalysis, the influences of the catalyst support (Na-ZSM5, ZSM-5, TS-1 TiO2, fumed SiO2, r'-Al2O3 and BaTiO3) as well as the catalyst active metals (Fe, Co, Ni, Cu, Mn and Mo) on the synthesis of HCN have been investigated. The results indicate that the optimal catalyst was Cu/fumed SiO2, and its optimal loading was about 23 wt.%. At 350?, the CH4 conversion of the CH4/NH3 plasma-catalysis coupling reaction reached 29.74% with 90% HCN selectivity. The characterization results of the catalysts, before and after the reaction, indicate that the metal phase could be the active phase for the synthesis of HCN.HCN, obtained by CH4/NH3 plasma catalysis coupling reaction, is easily to form solid HCN polymer. The polymerization process of HCN has been explored. It has been found out that the polymerization of HCN was an exothermic process. The polymerization environment had little effect on the formed polymer. During the polymerization process, the color of hydrogen cyanide polymer changed from light yellow white to black. The element analysis results shows that the composition of the HCN polymer was C3N4H5. Besides, the HCN polymer was a solid alkaline and it had good thermal stability. Therefore, this HCN polymer could be used as base catalyst and carbon nitride material in the future.