【作者】 葛涛；

【导师】 张明旭；

【作者基本信息】 安徽理工大学 ， 环境工程， 2015， 博士

【摘要】 优质的焦煤和肥煤属于稀缺煤种,硫的存在严重制约了炼焦煤的加工和利用。煤中30%以上的硫赋存是难以脱除的有机硫,而噻吩硫是烟煤中有机硫的主要组分,且结构最稳定,噻吩硫的脱除是煤脱硫的难点。微波具有穿透性和选择性加热的特点,且无温度梯度,在脱硫的同时,可以避免煤的特性变异,微波脱硫技术具有良好的应用前景。选择山西高硫炼焦煤,认知煤中有机含硫组分的禀赋特征和微观化学结构,遴选与煤中含硫结构相匹配的系列噻吩类模型化合物,研究煤与模型化合物的介频、介温谱图,掌握煤及含硫组分对微波的吸收转化特征。运用多种现代分析测试手段,结合量子化学理论,研究微波作用下噻吩类模型化合物中含硫分子属性、构象及能量变化,探索微波加快反应速率、改变反应路径机理中是否存在非热效应,解析噻吩类含硫结构对微波的响应规律。为揭示微波脱硫机理、优化脱硫工艺提供理论支持,对推动微波脱硫技术进步,降低硫在炼焦煤利用过程中的危害具有重要意义。研究表明,山西高硫炼焦煤中硫以有机硫为主,占总硫的70%左右。煤中有机硫包括硫醇、硫醚、噻吩、砜和亚砜等赋存形态,噻吩在部分炼焦煤中含量超过60%。综合利用各种分析方法,掌握煤中主要元素的结构特征,构建碳原子数为184的炼焦煤含硫大分子结构模型,选择符合硫赋存特征的系列噻吩类模型化合物,利用传输反射法,开展煤及模型化合物在微波频率为0～18GHz区间的介电参数研究。结果显示,煤和模型化合物具有较好的微波吸收特性,最大介电损耗一般出现在16-17GHz,模型化合物结构对吸波能力影响的规律性不强。基于民用微波频率的限制,利用介频谱和介温谱,重点考察煤及噻吩硫模型化合物在915MHz和2450MHz两个频点的介电性质,获知煤中噻吩类含硫结构在915MHz具有更强的吸波能力。通过介电参数测试和量子力学计算,建立了模型化合物介电性质与分子结构之间的关系,验证了在低频区用ε·描述介质极性的等价性。对炼焦煤的反射系数和噻吩硫模型化合物的微波穿透深度进行了探索,煤反射系数随频率的变化规律佐证了煤的介电损耗特征,模型化合物穿透深度与其吸波能力和微波波长具有良好的负相关性。微波作用后,炼焦煤中噻吩硫相对含量升高。微波加热致使原子相对运动加剧,相互作用减弱,分子结构趋于亚稳态,化学键解离能降低。通过微波加热和水浴加热的比较分析,获知噻吩硫模型化合物在微波加热过程中,除了热效应,还存在非热效应。运用密度泛函理论对微观结构模拟计算的结果表明,微波光子能量对噻吩硫分子极性及含硫化学键强弱影响不大,但可以改变模型化合物的分子空间构型。微波场作为矢量场,能量大小和施加方向对化学结构均具有影响。更多还原

【Abstract】 High-class coking coal and rich coal fall into the rare type. The existence of sulfur is placing a serious restriction on the processing and utilization of the coking coal. Over 30% of the sulfur occurrence in the coal is the organic sulfur difficult to deprive. As the main component of the organic sulfur in the bituminite, the thiophene organic sulfur is characterized as the most stable in structure, with the deprivation of thiophene sulfur as the difficulty in coal desulfuration. With the features of penetrability, selective heating and no temperature gradient, microwave has a possession of the advantages of avoiding the characteristic dissociation in desulfuration, rendering its utilization a good prospect.With the selection of high-sulfur coking coal in Shanxi Province and the recognition of endowment characteristics of the organic sulfur-bearing components and microscopic chemical structure in the coal, the author has chosen a series of thiophene model compounds matching the sulfur-bearing structure in the coal in an effort to conduct a research into the dielectric frequency and dielectric temperature spectrum on the part of the coal and model compounds, with the command of the features of absorption and conversion of microwave with respect to the coal and sulfur-bearing components. With the employment of multiple modern methods of analysis and testing and in combination with the theory of quantum chemistry, a research has been conducted into the changes in the attribute, conformation and energy of the sulfur-bearing molecules of thiophene model compounds under microwave with a view to carrying out an exploration into whether or not there exists non-thermal effect in the mechanisms of the accelerated response rate and the changed route in microwave and an analysis of the response regularity of thiophene sulfur-bearing structure to the microwave. This will serve as a theoretical support to the disclosure of the mechanism of microwave desulfuration and the optimization of desulfuration technology, bearing great significance to the progress of microwave desulfuration technology and the reduction of the harm of the sulfur in its application in the coking coal.The research has established that the organic sulfur in the sulfur-rich coking coal in Shanxi Province accounts for 70% of the total sulfur. The organic sulfur in the coal includes such occurrence forms as thioalcohol, thioether, thiophene, sulphone, sulfoxide, etc., with the content of thiophene making up over 60% in some parts of coking coal.With a comprehensive application of various methods of analysis, an a grasp of the structure characteristics of the main elements in the coal, a model of sulfur-bearing macromolecule structure containing 184 carbon atoms in the coking coal is put in place. Afterwards, with the selection of a series of thiophene model compounds that have a possession of sulfur-bearing features and the application of the method of transmission and reflection, a research into the dielectric parameters of the coal and its model compounds with the microwave frequency of 0-18GHz is under way. The outcome has established that the coal and its model compounds possess a relatively good absorption of the microwave, with the maximum dielectric loss in the frequency of 16-17GHz and the structure of model compounds having no obvious effect on the absorption of the microwave.With the limitation of the microwave frequency for the civil use in mind, and the employment of dielectric frequency and dielectric temperature spectrum, we have an in-depth exploration into the dielectric property of the coal and thiophene model compounds between the frequency points of 915MHz and 2450MHz, with an acquisition that thiophene sulfur-bearing structure has a possession of a better capacity to absorb microwave. With the test of dielectric parameters and the computation of quantum mechanics, a relationship between the dielectric property and the molecule structure in model compounds has been established to verify the utilization of ε’to describe the equivalence of mediator polarity in low-frequency zone.An exploration has been conducted into the reflection coefficient of the coking coal and the microwave penetration depth of thiophene sulfur-bearing model compounds, with the regularity of the former changing in line with the frequency confirming the feature of dielectric loss in the coal and the latter having good negative correlation with the microwave absorption capacity and wavelength.After an effect of the microwave, the relative content of thiophene sulfur in coking coal increased,with the microwave heating quickening the relative activities of the atoms and alleviating their interaction to render the molecule structure a metastable state and the chemical key a reduced capacity in dissociation. A comparative analysis of microwave heating and water bath heating helps the author to get to know the existence of non-thermal effect in addition to the thermal effect in the process of the microwave heating of model compounds.The analog computation of microscopic structure by means of density functional theory has demonstrated that microwave photon energy has no significant effect on the polarity of the thiophene organic sulfur-bearing molecule and the pros and cons of chemical keys, but possesses a capacity to change the steric configuration of model compounds. As a vector field, the energy magnitude and enforcement orientation of the microwave have an impact on the chemical structure.更多还原