Study On Microwave Pyrolysis Of Low Rank Coal At Methane Atmosphere

With the rapid development of the national economy, China is importing more and more crude oil. Nowadays, the foreign dependency rate of china’s oil has increased. Low-rank coal pyrolysis is used to produce coal tar, which can be processed into oil products. It has important significance for easing current fossil oil shortage. Compared with traditional catalytic hydrogenation of pyrolysis, microwave heating has been applied to study fields of coal pyrolysis and catalytic conversion of methane,but less in the field of methane-coal microwave pyrolysis. In this thesis, temperature rising characteristics of raw coal and its pyrolytic char in microwave field was fistly studied, the influence of pyrolysis temperature and coal char ratio on the characteristics of product distributions during microwave heating and conventional heating were investigate. The paper also research the influence of preparation temperature, reaction temperature, time, and space velocity on the catalytic conversion of methane decomposition, and was to illustrate the mechanism of methane decomposition catalyzed by coal char under microwave heating. And more, tow kind of Chinese coal, Inner Mongolialignite(IM) and Shenmu subbituminous coal(SM) mixed with its own char was pyrolyzed at methane atmosphere using microwave heating, the product distributions was studied. The main conclusions are as follows:(1) Raw coals, both IM and SM are weak microwave absorbers, however, the char is a very effective microwave absorption at 650 ℃. At the same condition, the productivity of char and water under microwave pyrolytic would decrease. However, the productivity of gas would increase, especially for CO and H2.(2) At the condition of microwave irradiation, coal char is an effective methane cracking catalyst. It would improve methane conversion ration with increasing of char preparation temperature, reaction temperature, and decrease space velocity.(3) Using char as microwave absorbing agent and methane cracking catalyst, at the atmosphere of CH4, The tar of Nei meng lignite and Shen mu long-flame coal under microwave pyrolysis have highest tar yield at 550℃ and 650℃ respectively, which were 1.22~1.99 times compared with N2 atmosphere.(4) From GC-MS analysis of coal tar we know that the main ingredient of coal tar are phenol(including the substituted phenols) and aliphatic hydrocarbon. The way of heating greatly influences the contents of polycyclic aromatic hydrocarbon and benzene(including the subsitituted phenyl) in the coal tar. Methane atmosphere has little impact on contents of coal tar heated by microwave.