微波辅助脱除煤中有机硫的机理研究

为阐明微波场联合过氧乙酸(PAA)脱除煤中有机硫的机理,选取山西临汾(LF)、宁夏宁东(ND)、山西灵石(LS)和河南洛阳(LY)脱矿物质煤及三种含硫模型化合物苄硫醇(Benzyl mercaptan, BM)、苯并(b)噻吩(Benzo (b) thiophene, BT)和二苯基亚砜(Diphenyl sulfoxide, DS)作为研究对象。微波功率为100 W,并联合PAA,辐照1-5 min,通过X射线光电子能谱仪(X-ray photoelectron spectroscopy, XPS)分析固相中硫形态的变化;通过离子色谱仪(Ion chromatography, IC)分析脱硫后液相中SO_4~(2-)的浓度;通过气相色谱-质谱联用仪(Gas chromatography/mass spectrometry, GC/MS)分析萃取物中硫形态的变化。结果表明,有机硫化物硫的含量高,脱硫率大,LY和LS最大脱硫率分别高达55.06%和45.78%,ND和LF最大脱硫率分别为31.24%和28.21%,煤中的硫醇比噻吩和亚砜更易脱除,且脱硫过程中硫形态逐渐向高价态转化,含硫键在微波场中断裂,最终可被PAA氧化为SO_4~(2-)。

Removal mechanism of organic sulfur in coal assisted by microwave irradiation

In order to clarify the effect of microwave field combined with peracetic acid (PAA) on the removal of organic sulfur in coal, four demineralized coals including Shanxi Linfeng (LF), Ningxia Ningdong (ND), Shanxi Lingshi (LS) and Henan Luoyang (LY) coal were selected,and three sulfur-containing model compounds including benzyl mercaptan (BM), benzo(b) thiophene (BT) and diphenyl sulfoxide (DS) were used as well. Each test, the microwave with the power of 100 W irradiated coal for 1-5 min combined with PAA. The change of sulfur form in the solid phase was analyzed by X-ray photoelectron spectroscopy (XPS). The concentration of SO₄^2- in the liquid phase after desulfurization was analyzed by ion chromatography (IC), and the change of sulfur form in the extract was analyzed by gas chromatography/mass spectrometry (GC/MS). The results show that the higher the organic sulfur content, the greater the desulfurization rate. The maximum desulfurization rates of LY and LS are as high as 55.06% and 45.78%, respectively, and the maximum desulfurization rates of ND and LF are 31.24% and 28.21%, respectively. It is found that the organic sulfur as mercaptan in coal is easier to remove than that as thiophene and sulfoxide, and the sulfur form gradually transforms to a high valence state during desulfurization. The sulfur-containing bond is broken in the microwave field and the sulfur can be oxidized to SO₄^2- by PAA finally.