干湿混合Ca(OH)_2对煤炭腐植酸热解的影响

Effects of Ca(OH)_2 on the Thermal Decomposition of Coal Humic Acid under Conditions of Dry and Wet Mixing

采用DTG、XRD及SEM技术,研究了干法混合与湿法混合下Ca(OH)2对煤炭腐植酸热解的影响.结果表明:热分解温度低于400°C时,无论干法和湿法,Ca(OH)2对腐植酸脱吸附水和丢失官能团影响很小;440~610°C时,湿法对应的腐植酸混合物热解失重速率高于干法;738°C时,湿法中的腐植酸芳核结构热解失重速率达到最大值0.215 8 mg/min;Ca(OH)2在腐植酸热解中起到消除002衍射峰,吸收CO2及催化作用;Ca(OH)2与腐植酸的混合物经H2O浸泡后,Ca2+可均匀负载在腐植酸分子表面发生络合反应,提高了催化热解效果.

The effects of Ca（OH）_2 on the thermal decomposition of coal humic acid under conditions of dry mixing and wet mixing were studied by means of DTG（derivative thermogravimetry）,XRD（X-ray diffraction）and SEM（scanning electron microscopy）.The results show that Ca（OH）_2 additive has slight effect on the evaporation of the adsorbed water and the decomposition of the function groups from humic acid below 400 °C,whether under condition of dry mixing（i.e.,without the soaking role of H_2O）or of wet mixing（i.e.,with the soaking role of H_2O）.The mixture of humic acid and Ca（OH）_2 under condition of wet mixing,440 °C～610 °C,presents higher weight-loss rate than the mixture under condition of dry mixing.When heated up to 738 °C,the maximum weight-loss rate of the aromatic nucleus from the humic acid mixture with the role of H_2O arrives at 0.215 8 mg/min.It is found that Ca（OH）_2 plays the role of the removal of 002 diffraction peak,the CO_2 absorption and the catalysis in thermal decomposition of humic acid.What＇s more,for the soaking role of H_2O,Ca^（2＋） ion is easily and uniformly loaded onto the molecule of humic acid,which is prone to complex reaction.As a result,the catalyse and the thermal decomposition of humic acid are enhanced.