煤液化残渣中硫的氧化规律

Study on oxidation of sulfur in coal liquefaction residue

利用四氢呋喃溶解煤液化残渣,将煤液化残渣分离为油相和四氢呋喃不溶物固体,之后测定其中各形态硫的含量,发现煤液化残渣中98%(质量分数)的硫存在于四氢呋喃不溶物固体中,且主要以磁黄铁矿的形式存在。故此以四氢呋喃不溶物为原料进行空气氧化,研究其中硫的氧化转化规律。结果表明,干空气氧化四氢呋喃不溶物,四氢呋喃不溶物总含硫量减少,氧化过程中生成硫酸盐和单质硫,其中单质硫在氧化过程中进入气相而脱离四氢呋喃不溶物固体;湿空气氧化四氢呋喃不溶物,四氢呋喃不溶物总含硫量基本不变,反应过程中仅有硫酸盐生成。实验条件下,氧化过程由磁黄铁矿颗粒上覆盖的硫酸盐产物层中的氧扩散控制,扩散活化能为26.25 k J/mol。

The residue of coal liquefaction was separated into oil phase and oil insoluble solid through extraction with tetrahydrofuran. The sulfur analysis showed that pyrrhotite were the main source of sulfur in the residue of coal liquefaction and 98% of the sulfur exists in the oil insoluble solid. Therefore the oxidation process was conducted using the oil insoluble solid as feed. The pyrrhotite was converted into sulfate during the oxidation process. When the oil insoluble solid was oxidized with dry air, sulfate and sulphur were formed, and the total sulfur content in the oil insoluble solid decreased because the sulfur left the oil insoluble solid as a gaseous sulfur in the effluent; when oxidized with humid air, the total amount of sulfur in oil insoluble solid kept constant, indicating no sulfur-containing product left the oil insoluble solid and the oxidation product was sulfate only. It is found that the oxidation reaction is controlled by diffusion of oxygen in the sulfate product layer covered on the pyrrhotite particles. Diffusion activation energy is found to be 26.25 kJ/mol.