抗生素菌渣热解N官能团变化特征及其与NO_x前驱物关系研究

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。

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

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 NO_x 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 NO_x 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.