微波加热技术具有高效、清洁、环保、安全等特点,为煤炭热解转化提供了一种新的发展方向。以乌兰察布褐煤为对象,测试了褐煤和不同微波吸收剂的介电性能,考察了不同微波吸收剂对褐煤微波加热的促进作用,研究了褐煤的微波热解特性,并初步探讨了微波热解机理。结果表明,褐煤吸波能力较差;在微波频率2 450 MHz和常温条件下,活性炭的介电性能最好,SiC、CuO次之,Fe2O3、褐煤最差;在微波吸收剂促进作用下,褐煤微波加热升温速率提高23倍,且活性炭性能最优,是褐煤微波热解较优的吸收促进剂;在活性炭促进作用下,微波热解效率显著提高,微波辐射12 min时,H2,CH4和CO产量分别为0.144,0.062和0.045 L/g。热解过程中,由于升温速率的大幅度提高,褐煤中部分官能团出现延迟裂解的现象,羧基、羰基、羟基开始大量裂解的温度分别为250,450,1 000℃左右,均高于常规热解。

Microwave (MW) heating technology has the characteristics of high efficiency,cleanness,green and safety, which provides a new development direction for coal pyrolysis. The characteristics of MW pyrolysis of Ulanqab lignite were studied,and the effects of different MW absorbers on the MW pyrolysis of lignite were investigated,and the mech- anism of MW pyrolysis of lignite was also discussed in this paper. The results indicate that under the condition of mi- crowave frequency 2 450 MHz and normal temperature,the dielectric properties of activated carbon are best,SiC and CuO are followed,and Fe2 O3 and Ulanqab lignite are the worst. Ulanqab lignite shows relatively low MW absorption, and under the action of microwave absorber,the MW heating rate of lignite is increased by nearly 2 to 3 times. Further- more,activated carbon has the best dielectric properties that could be used as a better absorber for lignite MW pyroly- sis. Under the action of activated carbon,the MW pyrolysis efficiency is improved remarkably. When the microwave ra- diation time is 12 min,the yields of H2 ,CH4 and CO are 0． 144,0． 062 and 0． 045 L / g,respectively. In pyrolysis process,the delayed pyrolysis of some functional groups on the surface of lignite results from a large increase in heating rate. The cracking temperature of most of carboxyl,carbonyl and hydroxyl groups begin at about 250,450,1 000 ℃ , which is higher than that of conventional pyrolysis.