Study On Novel Process Of Catalytic Synthesis Of CaC₂ And Its Specific Catalyst

The production of acetylene from calcium carbide is an important organic synthesis route. However, reaction temperature of the commercial production of calcium carbide through electrothermal method is approximately 2200℃, that is, the process is a high energy cost and serious polluting route. This paper focuses on the concept of catalytic process for the production of calcium carbide and tends to develop an effective catalyst which might reduce energy consumption and improve conversion efficiency.Based on thermodynamics analysis of the synthesis reaction, calcium carbide is successfully synthesized from coke and lime at 1700℃for 1.5h under Ar atmosphere. The content of acetylene in gas emissions from reaction of calcium carbide and water is as high as 97 percent. Effects of different carbon sources and the activity of carbon sources and calcium source on synthesis of calcium carbide are also investigated. It is found that activated carbon as carbon source has a best performance in the process and the treated calcium source also has a positive performance, however, the treated carbon sources have a passive function. Investigations on effects of binder and fluxing agents on synthesis of calcium carbide are carried out and the results indicate that the formation of liquid phase is beneficial to the synthetic process.Based on the above mentioned, potassium carbonate, ferric oxide, calcium phosphate, calcium silicate are chosen as catalyst candidates and effects of their addition on synthesis are observed by using X-ray diffraction. The gas output original data are detected on a standard device. The results suggest that calcium phosphate has a better effective function than all the other candidates, and the gas output of its product is increased by 32 percent. Therefore, calcium phosphate is chosen as specific catalyst. It is noticed that salts from Qinghai Lake have a disadvantageous influence on calcium carbide synthesis. The reaction conditions of catalytic synthesis of calcium carbide, including particle size and mole ratio of raw materials, amount of catalyst, reaction time, are optimised by orthogonal experiments, and the optimum conditions are formulated. Output of sample synthesized under optimum conditions is 257.7L/kg, and by and large meets the demands of the national standard(GB10665-2004). Thermogravimetry(TG), Gas Chromatogram(GC), Energy Disperse Spectroscopy(EDS) are employed in the investigation of catalytic mechanism of calcium phosphate. It is believed that calcium carbide facilitates the transportation of coke, improves the interaction between raw materials, and above all, serves as a medium of ion transfer.