煤含硫模型化合物的介电响应特性及其对微波脱硫的影响

为揭示煤炭微波脱硫中的微波作用机制,利用传输反射法分析了煤中含硫与不含硫模型化合物的介电特性以及含硫模型化合物对净煤样介电性质的影响,并在微波联合氧化助剂条件下研究了其介电特性对脱硫率的影响。结果表明:含硫模型化合物的介电常数实部ε'、虚部ε″和损耗角正切tanδ均大于结构相似的不含硫模型化合物,其中二苯二硫醚、二苯并噻吩砜、二苯砜具有自己的特征峰位,因此可以通过调节微波频率实现煤中含硫组分的选择性加热;当净煤样负载含硫模型化合物后,混合样品的ε'发生了较显著的变化,而ε″和tanδ与净煤样相差不大,但在混合样品的ε″和tanδ变化曲线中明显出现相应模型化合物的特征峰,因此可以通过调节微波频率实现高有机硫煤的选择性脱硫。脱硫实验结果表明在微波联合氧化助剂的条件下,ε″和tanδ高的硫醚类的脱硫率明显大于噻吩类,且二硫醚更易于被氧化脱除。

Dielectric response characteristics of coal’s sulfur-containing model compounds and theirs effects on the microwave desulfurization

In order to reveal the mechanism of microwave action in the process of coal microwave desulfurization,the dielectric property of coal’s sulfur-containing and sulfur-free model compounds,the change of dielectric properties for pure coals mixed with different proportions of sulfur-containing compounds were measured by the transmission reflection method.Then the effect of dielectric properties of sulfur-containing compounds on their desulfurization rates by microwaving was expounded.The results showed that the real part of dielectric constant ε′,imaginary part ε″ and loss tangent tan δ of sulfur-containing compounds are higher than those of sulfur-free compounds with similar structures. Among of them,the ε″ and tan δ of the diphenyl disulfide,dibenzothiophene sulfone and diphenyl sulfone have their own characteristic peaks.Therefore,the selective heating of sulfur contents in coal could be realized by adjusting the microwave frequency.When the pure coal was loaded with sulfur-containing compounds,the ε′ of them usually changed drastically.However,subtle changes in the ε″ and tan δ were observed.The ε″ and tan δ of mixture appeared the obvious characteristic peaks of corresponding sulfur-containing model compounds.So the selective desulfurization of high organic sulfur coal could be realized by adjusting the microwave frequency.The desulfurization results suggested that under the condition of microwave combined with oxidizing agent,the desulfurization rate of the sulfur ether are significantly higher than that of thiophene,and the ε″ and tan δ of former are also higher than those of latter.Disulfide is more easily removed by oxidation.