铁矿石作为氧载体在熔融盐中催化甲烷燃烧

Methane Combustion in Molten Salt Using Hematite as Oxygen Carrier

熔融盐循环热载体无烟燃烧技术(noneflame combustion technology using thermal cyclic carrier of molten salt,NFCT)不会向大气中排放有害气体,是一种清洁燃烧技术。利用XRD、SEM和TG等分析手段对催化剂的性能进行了表征。在质量比为1∶1的Na2CO3和K2CO3熔融盐中研究了Fe2O3中的晶格氧对甲烷的催化燃烧性能。铁矿石在熔融盐中分别与甲烷和空气发生反应,用XRD分析生成物表明,作为铁矿石主要成分的Fe2O3可以在熔融盐中失去和恢复晶格氧,这些晶格氧可以用来催化氧化甲烷。TG分析结果表明,铁矿石被甲烷还原分为两个阶段,第一个阶段从550℃开始,680℃结束,Fe2O3被还原成Fe3O4,第二个阶段从850℃开始至1 050℃结束,第一个阶段生成的Fe3O4在这一阶段大部分被还原成了FeO。被甲烷还原的铁矿石在TG试验中与空气反应时,只出现一个明显的增重段,从350℃开始直到反应温度的上限1 100℃,增重速率较快的区间是400～850℃。从燃烧产物的气相色谱分析结果可以看出,甲烷在熔融盐中绝大部分被氧化成了CO2和H2O。因此,铁矿石可以作为氧载体在熔融盐中催化甲烷燃烧。

Noneflame combustion technology using thermal cyclic carrier of molten salt （NFCT） is a clean combustion technology that does not discharge any hurmful gas into the air. The capability of oxygen carder was characterized by means of X-ray diffraction （XRD）, scanning electron microscope （SEM） and thermogravimetric analysis （TG）. The capability of hematite that catalytic combustion of methane was studied in a molten salt. Molten salt composed with Na2CO3 and K2CO3, which weight ratio is 1： 1. Hematite reacted with methane and air. Resultants was analysed by XRD, indicated that Fe2O3, as main components of hematite, could lose and regain its lattice oxygen in molten salt. Those lattice oxygen could catalytic oxide methane. The TG experimental results show that the reduction of hematite by methane can be divided into two steps： In the first step, Fe2O3 is reduced to Fe3O4 at temperature from 550 ℃ to 680 ℃. In the second step, most of Fe3O4 produced in the first step is reduced to FeO from 850 ℃ to 1 050 ℃. Hematite reduced by methane reacted with air in TG experiment appeared only one weight increase from 350 to 1 100 ℃. Weight increase was faster at temperature 400 - 850 ℃. It can be conclude from gas chromatography that all most of methane oxide to carbon dioxide in the molten salt. Hematite could use as oxygen carrier for catalytic combustion of methane in molten salt.