【作者】 解恒参；

【导师】 宗志敏；

【作者基本信息】 中国矿业大学 ， 化学工艺， 2011， 博士

【摘要】 重质碳资源的高效洁净利用是解决我国能源问题的重要途径,解析和了解其结构是实现其成功解聚和有效利用的重要前提。光催化氧化法对煤和大港减压渣油的解聚能从分子角度,选择性的、非破坏性的分析煤和重油的结构特征,从而为此类重质碳资源的高效洁净利用和成功转化提供重要依据。神府煤、葛亭煤、锡林浩特煤、霍林浩特煤等因成煤时间的差异而具有不同的分子结构,它们也是中国现存煤种的典型代表。采用固相混合开放体系、非均相水合悬浮开放体系和非均相混合密闭体系分别对煤炭进行了光催化氧化,并用丙酮或甲醇萃取分离和GC/MS等方法分析后得知:不同体系的光氧化反应均能使得煤炭得到氧化解聚,只是不同体系的氧化效果不甚相同,不同煤种的氧化程度也不尽相同。与原煤相比,氧化煤中稠环芳烃和支链烷烃中的甲基、亚甲基能够被光催化氧化产生的羟基自由基优先氧化;形成的羟基化合物会进一步氧化而不同程度的解聚,氧化的最终产物为二氧化碳和水,乙酸是反应过程中重要的水溶性中间产物;氧化煤中的酯类、酮类、环氧化合物等含氧化合物的比例明显增加;芳环化合物的比例大量减少;长链烷烃的碳链能在光催化氧化下不同程度的降碳解聚。光催化氧化也能显著改变煤炭的萃取率。大港减压残渣作为一种重质油,其丰富的有机物含量足以让人们对其开发充满期待,但是它的成功解析和有效转化与煤炭类似,一直是一个期待解决的瓶颈问题。为了充分说明光催化氧化对大港减渣的氧化效果,大港减渣的环己烷溶液在非均相体系中进行了13 h的光催化氧化。GC/MS和FTIR分析显示,光催化氧化能使大港减压残渣成功转化。转化后的环己烷溶液中发现了大量的含氧化合物(相对含量92.94%),其中包括36.05%的羧酸类化合物、14.56%的酯类化合物(特别是草酸酯类化合物)和19.12%的环氧化合物;原样中70%的正构烷烃含量氧化后降低至不足30%,直链烷烃的碳链也被不同程度的解聚。为了解光催化氧化煤炭和大港减压渣油的解聚机理,通过对苯、甲苯、二甲苯、苯酚、萘系列化合物以及石蜡等模型化合物进行光催化氧化发现:羟基氧化是光催化氧化的主要途径;光催化氧化下形成的电子-空穴对对催化剂表面的水或有机物的氧化,会导致羟基自由基的形成;羟基取代大分子中的活性氢(主要是α-H)会形成仲醇、伯醇或酚,醇分子内或分子间脱水生成不饱和化合物或环氧化合物;醇类化合物也会进一步氧化形成醛、酸、酯;羧基化合物的脱羧会得到降碳解聚产物;部分环状烃在羟基的氧化下会发生开环反应。提高光催化氧化对煤和大港减压渣油的解聚效果是实现此技术实际应用的根本。本文利用煤特殊的组成,制备了掺煤的二氧化钛光催化剂。XRD和BET等技术的表征和解聚煤和大港减压渣油的应用表明:自制的掺杂光催化具有较强的光催化活性,可用作解聚内容物较为复杂的大分子有机体。优选和表征也发现掺神府煤12wt%的二氧化钛活性最高。它是一种疏松双孔径结构的锐钛型纳米颗粒,具有很强的吸附性能,作为催化剂对大港重油和煤炭的光催化氧化达到了很好的解聚效果。扩大实验样品的用量时(即小试实验)也能获得同样的氧化效果。更多还原

【Abstract】 Efficient and clean utilization of heavy carbon resources （ HCRs ） is the ultimate goal to solve energy source problems in China, but the understanding of theirs structure is still a principal question must be first considered. Photocatalytic oxidation （ PCO ） depolymerization of coals and Dagang Vacuumn Reside （DVR） can understand the structure properties of HCRs from molecular level, selective, non-destructive, and provide a basis of utilizing HCRs efficient and clean because many organic compounds in HCRs can be converted successfully into oxygen-containing compounds selectively.As important HCRs, Shenfu bituminous coal （SFBC）, Geting coal （GTC）, Xilinhaote coal （XLC） and Huolinguole coal （HLC） have different photocatalytic oxidation properties. To understand their structure in detail, three systems were used to degrade coals, including solid phase mixture open system （SPMOS）, heterogeneous hydration suspension open system （HHSOS）, heterogeneous hydration suspension closed system （HHSCS）. Separated organic matters （OMs） with acetone or methanol and analyzed with GC/MS and FTIR were finished to understand the experimental effect. The results indicate that coals can be oxidized successfully in these systems, although the different coals exist different oxidation effect. Methyl groups and methylenes in fused ring aromatic hydrocarbons or branched-chain alkyanes can be oxidized preferentially by hydroxyl free radicals substituting and produce a large number of hydroxyl compounds. Then these hydroxyl compounds were oxidized continuously in illuminating with UV light to generate to carbon dioxide and water. The species and number of oxygen-containing compounds （including acids, esters, ketones, epoxides etc.） in the oxidation coals was increasing comparing with in the raw coals. At the same time the relative content of the aromatic compounds reduced in the process and carbon chain in long chain alkyl compounds were also degraded in the photooxidation process. The extract yield of coal is improved obviously in the oxidation process, too.DVR, as heavy oil in China, contains a large number of OMs and possesses the potential application prospect, however understanding its structure is a vital problem to realize its effective conversion and utilization as similar to coals. In order to realize DVR oxidation and deploymerization, the cyclohexane solution of DVR was illuminated with low pressure mercury lamp at the room temperature for 13 hours, and the effect was detected with GC/MS. The results show that DVR has been oxidized effectively, a large number of acids （36.05%）, oxalic esters （14.56%）, epoxides compounds （19.12%） are converted from alkanes or branched-chain alkanes. So the treatment can improve the effective utilization of DVR. To explain the mechanism of PCO deploymerization coals and DVR, analytic reagents including benzene, toluene, xylene, phenol, naphthalene series compounds and liquid paraffin, as model compounds, were oxidized respectively in the same condition with coals and DVR oxidation. The experimental results indicate that the oxidation of hydroxyl radicals is an important method in PCO. The formation of free radicals in the surface of photocatalyst continuously through illuminating with UV light and the production of electrons-holes pairs （e^-/h⁺） via electron transition between conduction band and valence band are principal source of PCO. The formation of large number of free radicals cause the oxidative dehydrogention of OMs in coals and DVR. Active hydrogens substituted by the free radicals atoms in macromolecular compounds in coals or DVR, hydroxyl compounds including alcohols and phenols can be produced. Then the hydroxyl compounds reacted with each other or the other organic compounds to generate aldehydes, ketones and esters, or lead to the degradation of coals and DVR through removing water. In addition to the part of cyclic-hydrocarbons compounds had ring-opening reaction during the photo-catalytic oxidation process.To improve the PCO’ effect, different homemade photocatalysts of doping coal were prepared by Sol-Gel method and characterized by XRD, TEM and BET techniques, and then optimized selection and applied on the coals and DVR deploymerization respectively. The result shows that the SFC （12wt%）-TiO₂ photocatalyst is especially suitable for complex organic compounds deploymerization because of being with the structure of loose and dual aperture. Just the structure causes the photocatalyst with the strong adsorptive property and high activities, when the SFC-TiO₂ as photocatalyst are used in the reaction, even if expand the amount of coals and DVR the similar result can also be obtained and the oxidation effect is more remarkable as using the homemade pure TiO₂.更多还原