赤泥转化生物质制备低粘度柴油的原位定向催化热解研究

Bio-oil is one of the most promising substitute fuels, but the high viscosity is the bottleneck and main obstacle to limit its direct application. In situ fast catalytic pyrolyse, is regarded as the most effective way to improve the quality of bio-oil, especially reducing the viscosity. On the other hand, red mud, as the residue from aluminium industry, has been piled up like mountains, and the incidental high alkali liquid seriously jeopardizes environment, so its disposal has been an big environmental problem. In response to the dual crisis of energy and environment, this project proposed the fundermental research of directional fast catalytic pyrolysis over red mud of converting non-edible pennycress seeds into bio-oil with low viscosity on fluidized bed.The preliminary study was carried out and showed a very exciting viscosity-decreasing results, but the mechanism are not clear till now. The project will couple different catalytic collaborative environment, emphasize on explaining the molecular structure characteristics corresponding to bio-oil viscosity, and explore the structure-activity change of red mud ontology before and after viscosity-reduing run. In the meantime, the response mechanism of the sensitive structure to oil viscosity in catalytic collaborative environment with red mud (including catalytic envionment over red mud, pyrolysis collaborative environment) will be revealed. Then, the prediction model of directional catalytic pyrolysis on multi-factor conditions converting biomass into bio-oil with low viscosity with red mud will be proposed, in order to provide scientific basis to the direct application of energy fuel from biomass.

生物油是最具前景的石油替代能源，但其高粘度特性是限制其直接应用的瓶颈和主要障碍，原位快速催化热解生物质，被认为是提高生物油品质包括降粘最有效的方式；另一方面制铝工业废渣赤泥堆积如山，高碱附液严重危害环境，其处理处置已成为世界难题。为应对能源与环境双重危机，本项目提出以赤泥为催化剂，选用非粮作物遏蓝菜籽为生物质载体，采用流化床原位催化热解方式，进行赤泥转化遏蓝菜籽制备低粘度生物油的定向催化热解基础研究。预研究发现降粘效果极好，但其作用机制未知。本项目将在不同催化协同环境下进行耦合研究，重在解译生物油粘度特性的分子结构特征，探索降粘作用前后赤泥本体的构效转变，揭示赤泥催化协同环境（包括赤泥催化环境，热解协同环境）作用下油品粘度特性敏感结构的应答机制，提出赤泥转化生物质为低粘度生物油的定向催化热解多因素环境条件预测模型，从而为生物质转化能源的直接应用提供基础科学依据。

生物油是最有前景的石油替代能源，但高粘度特性限制了其直接应用；另一方面，多种工业固废堆积如山危害环境，处理困难。为应对能源与环境双重危机，根据评审专家意见，本项目以扩展的生物质种籽和生活垃圾组分为原料，赤泥等五种工业固废为催化剂，在固定床和流化床上进行原位催化热解实验，对热解油进行物理和化学特性分析，探究不同催化剂及催化协同（温度、催化剂比例、再生等）作用下热解油的降粘机理。结果表明：除赤泥对遏蓝菜籽和独行菜籽热解油降粘效果明显，四类工业固废对生活垃圾中纸屑和果皮热解油降粘效果也很明显，铜渣对纸屑油降粘效果显著，比例为20%最优，再生催化剂降粘效果弱于原始催化剂。不同源类物料热解油粘度影响的敏感因素不同，对生物质源类，化学成分占主导作用，对生活垃圾组分源类，含水量和化学官能团共同影响。热解油粘度对成分中不溶于水的含氧化合物（如邻苯二甲酸二丁酯等酯类、烯醛、特定呋喃类等）、稠环芳烃、苯环侧链数呈正相关性；对油酸腈等含氮化合物、短链烃（C10以下）呈负相关性；对含水量呈负相关性。固废中Fe2O3、Al2Si6O13、Zn2SiO4和CuO等可分别促进物料中蛋白质化合物分解生成油酸腈，使邻苯二甲酸二丁酯等酯类分解，使可溶于水的物质如戊酮的生成，应为实验油品催化降粘的原因。以优选的纸屑-铜渣催化热解实验为基础，基于DOE理论，依托Minitab软件，采用Box-Behnken实验设计方法，热解温度、催化剂比例及装料量作为模型自变量，热解产物产率、热解油粘度等为响应变量，构建了多因素预测模型，模型曲面方程分析表明热解油粘度值随着三变量增加而降低。热解产物分布实验值与模型预测值相对标准偏差在2%左右，验证模型适用性，能够实现对热解结果的预测进而对实验工艺进行优化。本项目研究结果为高品质生物油的原位制备提供基础科学依据。