抗生素菌渣热解N官能团变化特征及其与NOx前驱物关系研究

Evolution of nitrogen functionalities and their relation to NO_x precursors during pyrolysis of antibiotic mycelia wastes

以青霉素菌渣(PMW)和土霉素菌渣(TMW)为对象,在水平管式反应器中进行快速热解,采用X射线光电子能谱(XPS)表征和化学吸收-分光光度定量分析方法,研究了抗生素菌渣热解N官能团变化特征及其与NO_x前驱物的关系。结果表明,菌渣燃料N官能团分为无机N(N-IN)和蛋白质及其水解产物N(N-A)两种。决定菌渣NO_x前驱物以NH_3-N为主,N官能团主要为N-A,PMW占81.1%、TMW占59.0%。在低温区间,N-IN在150-250℃分解和N-A在250-450℃转化,为NH3-N主要来源;PM W和TM W产率分别为20.9%和25.6%,而HCN-N产率小于2%,基本与燃料N官能团特征无关;该阶段伴随吡啶N(N-6)和吡咯N(N-5)的生成及转化,峰值在350-400℃。在高温区间,半焦N反应,主要是N-6和N-5的转化,为NH_3-N和部分HCN-N的来源;该阶段伴随少量更稳定质子化吡啶N(N-Q)和氮氧化物N(N-X)生成。由于N-IN和不稳定N-A低温下会快速分解,250-300℃下菌渣半焦N去除高达40%、能量损失可控制在25%,因此,采用合适低温热解处理菌渣,在保证能量前提下可有效去除燃料中的N。

On the basis of rapid pyrolysis of two antibiotic mycelial wastes（ AMWs）,viz.,penicillin mycelia waste（ PMW） and terramycinmycelial waste（ TMW）,in a horizontal tubular quartz reactor,evolution of nitrogen functionalities and their relation to NOx precursors were investigated with the help of XPS and chemical absorption-spectrophotometry methods. The results indicate that inorganic-N（ N-IN） and amide-N/amine-N/amino-N（ N-A） are two kinds of nitrogen functionalities in the raw AMWs samples, determining the predominance of NH3-N among NOx precursors. N-A is found to be the main one with the proportion of 81.1%and 59. 0% for PMW and TMW,respectively. At low temperatures,the decomposition of N-IN and the conversion of N-A mainly occur at 150-250 ℃ and 250-450 ℃,respectively,which are two routes for most NH3-N with yields of 20.9%（ PMW） and 25.6%（ TMW）. While HCN-N is produced with a small amount less than 2%,having no relationship with the characteristics of nitrogen functionalities in fuels. Besides,pyridinic-N（ N-6） and pyrrolic-N（ N-5） are also formed and then converted with peak values at 350-400 ℃. At high temperatures,the conversion of N-6 and N-5 is prevailing,leading to the basically equal increments on NH3-N and HCN-N. Simultaneously,a minor amount of more stable quaternary nitrogen（ N-Q） and N-oxide（ N-X） is produced. Typically,due to the rapid decomposition of N-IN and labile N-A at low-temperature pyrolysis,nitrogen removal can reach up to 40% while energy loss can be controlled within 25% when pyrolyzing at 250-300 ℃. As a result,low-temperature pyrolysis could be an effective method for nitrogen removal whereas preserving the energy in AMWs.