The Mechanism And Kinetics Research For Electrochemical Coal Gasification

Electrochemical coal gasification is a process of coal gasification realized through methods of electrochemical at low temperature. Compared with traditional coal gasification, electrochemical coal gasification has many advantages with low energy consumption, environmental friendly and so on. This study has great significance in achieving high efficiency and clean utilization of coal, especially for the development of coal chemical industry.On the basis of previous researches, this paper studied the mechanism and the kinetics of electrochemical coal gasification preliminarily, by using of electrochemical methods such as chronoamperometry, polarization etc., as well as physical characterization techniques of gas chromatography(GC), Fourier Transform Infrared Spectroscopy(FTIS) and gas chromatography-mass spectrometry(GC-MS) and so on, The contents and main results of this study are as follows:(1)Gas chromatographic analyses results showed that the gas produced in the cathodic cell were pure H2, while CO2 and CO had not been detected in the process of acid-washed coal electrochemical gasification. However, a very small amount of CO2 was detected in the process of ash-free coal electrochemical gasification, while the CO was not detected. During the experiment, trace H2 generation was also detected in the anodic cell.(2)Infrared spectra analyses indicated that the C-O functional groups of phenol, alcohol, ether and OH group contents on the surface of coal were greatly increased after the electrolysis, which proved that oxygen containing functional groups generated in the process of coal electrochemical gasification.(3)In the GC-MS test, it was found that the new oxygen containing derivatives were produced in the electrolytic extract, which were mostly esters, silicone, carboxylic acids and so on. It can be concluded that in the process of coal slurry electrolysis, the organic matter in the raw coal has been oxidized, and new oxygen contained organic intermediate products have been generated.(4)The mechanism of coal chemical gasification is as follow:Below the oxygen evolution potential, the functional groups on the surface of the coal particles were oxidized to form oxygen containing functional groups and a small amount of CO2; above the oxygen evolution potential, coal particles oxidization by O2 is the main reaction, while the oxidation of coal particles on the anode surface is a side reaction.The correlation parameters of Tafel curve were obtained through the study of polarization curves, it showed that the addition of Fe2+ reduced the overpotential of the coal chemical polarization, which promoted the coal chemical gasification reaction; and the addition of Fe3+ increased the overpotential of coal chemical polarization, which hindered the reaction between coal and electrode surface.