长焰煤热解过程中稠环芳烃可控催化转化机制的基础研究

In view of the complexity, irregularity, and serious lags in prospective applications in fused-ring aromatic hydrocarbons (FAHs) formed during catalytic pyrolysis of Long Flame Coals (LFCs), this proposal aims to focus on mechanism investigation of controlled conversion of FAHs during catalytic pyrolysis of LFCs. In continuation of the progress and achievements under the supports of the “Young Scientists Fund” and through manupulating the parameters such as pore size, acidity, metal loading and dispersion, during the fabrication of the transition-metal (M = Co, Mo, W) incorporated (Y and β) bifunctional zeolite catalysts as well as the controlled adsorption/desorption of the FAHs during catalytic reactions, the activity, stability, lifespan and anti-coking ability of the catalyst could be greatly enhanced. We hope to be able to convert FAHs to more valuable and simpler aromatics, for examples those with 2-3 aromatic rings such as naphthalene, anthracene, and phenanthrene so that the yield of toxic FAHs, such as benzo[α]pyrene may be largely reduced. Meanwhile, the separation and refining cost of tar could be sharply reduced. It is anticipated that the outcomes of this resarch should render the understaning of new grounds in terms of both theory as well as methodology for more environment-friendly and highly efficient utilization of coals.

针对长焰煤热解过程中产生的稠环芳烃的复杂性、无序性以及开发利用严重滞后的现象，我们拟在青年项目的基础上，开展长焰煤热解过程中稠环芳烃可控催化转化机制的基础研究。目的在于研制能够在热解过程中使稠环芳烃可控转化的过渡金属（M=Co，Mo，W）担载型分子筛（Zeolite=Y，β）双功能催化剂。通过改变催化剂的孔径大小、表面酸性和过渡金属的分布，调控稠环芳烃的吸附和脱附，提高催化剂活性、寿命和稳定性，抑制结焦，实现在长焰煤催化热解过程中，把稠环芳烃直接可控地转化为双环或三环等简单稠环芳烃。探索热解过程中稠环芳烃的形成机理，提高产物中萘、蒽、菲等高附加值稠环芳烃的含量，降低焦油分离精制成本，从源头控制苯并[a]芘等高毒性稠环芳烃的排放，为煤的高效利用和减少污染提供理论依据和新途径。

在实施青年面上联合基金项目的过程中，申请人紧扣研究目标，研究工作按计划完成，开展了“稠环芳烃可控催化转化的过渡金属担载型分子筛催化剂（MO/Zeolite）的设计、制备与表征；长焰煤热解过程中稠环芳烃的形成机制及其验证；长焰煤热解富产焦油催化剂催化剂的优化，产物分析，数据整理和分析等”工作，目前已整理论文7篇，3篇SCI已投，已发表4篇，其中SCI收录1篇，核心收录3篇，培养研究生8名，参加国际会议3次，参加国内学术会议5次，申请发明专利6件，授权1件，达到了预期研究目标。.1.1设计制备了MO/Zeolite催化剂并对其物理化学结构进行表征.设计制备了一系列过渡金属（Co、Mo、Ni和W）担载型分子筛（ZSM-22和Y等）催化剂，具备载量、结构、酸性、孔道可控的特点。采用多种技术手段（如SEM-EDX，TEM，XRD，NH3-TPD，N2 吸附-脱附性能，孔径分布等）对所制备的催化剂结构特性进行了表征。.1.2研究了长焰煤热解过程MO/Zeolite上中稠环芳烃的形成机制 .利用在线联用技术和离线分析手段考察了MO/Zeolite催化剂上长焰煤热解过程中稠环芳烃转化规律和产物生成规律。其中，所研制MO/ZSM-22催化剂可使热解焦油产物分布初步可控。热解焦油中链烃，芳烃和酚的选择性提高，醇类物质明显降低，其中链烃选择性接近50 %。.1.3研制了长焰煤热解富产焦油催化剂.研制了长焰煤催化热解的高效催化剂GYDS，并在榆林煤和呼伦贝尔煤热解过程中测试和优化，该催化剂均可大幅提高焦油收率至21 wt %。所得焦油芳烃含量可达31 %和43%，尤其是双环芳烃。.1.4初步揭示了稠环芳烃及其模型化合物可控催化转化的规律.煤热解过程产生大量稠环芳烃，主要为萘、蒽、菲，为深入研究稠环芳烃在热解过程中的催化转化机制，以萘，蒽为模型化合物，研究了萘，蒽的选择加氢反应。研制了用于高效催化转化萘和蒽的过渡金属NiA55催化剂（如表5所示）， 在较温和条件下，转化率和选择性均大于99 %。深入研究了金属中心和酸性中心之间的界面长度和强度的平衡。