MOF材料催化的藻类生物油超临界加氢改质的研究

As for the high oxygen content and poor quality of bio-oils hydrothermally converted from algae in sub/supercritical water, additional cataytic hydrogenation upgrading process is required. However, the long carbochain molecules in bio-oil leads to serious problems for traditional catalytic method, such as diffusion barrier, high hydrogen pressure, catalyst coking and deactivation, et al. In this project, a new cataytic hydrogenation upgrading method is developed for algal bio-oils. As for the method, the MOF material with micropore and mesoporous, supported with highly dispersed active components, is used as catalyst, and the supercritical n-hexane as reaction media. And, the problems would be resolved by the special pore structure and the hydrogen storage of catalyst and the perfect solubility and diffusibility of supercritical media. .The detailed contents are following: (1) The MOF materials with micropore and mesoporous is synthetised and supported with highly dispersed active components to satisfy the requirement of high-efficient hydrogenation catalyst. (2) The hydrodeoxygenation of supported MOF catalyst for long-chain fatty acid in supercritical n-hexane is studied and the strategies for improving reaction efficience is investigated. Meanwhile, the intrinsic kinetics of hydrodeoxygenation would be setup. (3) The reaction mechanism of MOF material catalyzed hydrodeoxygenation under supercritical conditions is investigated, especially for the adsorption, dissociation and activation of hydrogen and reactant molecule. (4) The influence of nitrigen content on the model compound hydrodeoxygenation is studied. And then, the upgrading of real algal bio-oil is investigated, as well as the global reaction network...This research program will introduce a new alternative for algal bio-oils upgrading and expand the application of supercritical catalysis and MOF catalyst, which would lay the foundations for further improvement of hydrothermal liquefaction of algae to bio-oils.

藻类生物油具有含氧量高、品质不佳等不足，需要对其进行催化加氢改质。由于藻油分子尺寸大，原有方法分子扩散困难、氢压高、催化剂易失活，本课题引入兼具微孔和介孔、且有储氢特性的MOF催化剂，以超临界正己烷为反应介质，以期通过MOF催化剂的结构孔道、储氢特性和超临界介质的优异溶解、扩散特性来克服目前方法的不足，建立一种藻类生物油催化加氢改质的新方法。主要研究包括：（1）设计制备MOF负载、活性组分均匀分布的高效催化剂；（2）研究在超临界介质中进行藻类生物油催化加氢改质的机理和规律；（3）揭示模化物分子和氢分子在催化剂上吸附、解离和活化的机制；（4）研究十六烷酸等模化物的转化历程，考察生物油中其它组分对催化反应的影响；（5）采用真实藻类生物油考察验证，建立全过程的反应网络。本课题的研究将为藻类生物油的改质提供新方法，同时拓宽超临界催化反应和MOF材料催化应用的基础研究。

-藻类生物质水热液化所得的生物油需要脱氧改质提升才能使用。本课题引入具有合适孔尺寸和储氢性能的MOF类或金属/分子筛双功能催化剂，以超临界流体等为反应介质，将生物油催化提质得到高品质烷烃燃料。课题取得的主要相关研究成果如下：.（1）通过溶剂热方法将磷钨酸（PTA）直接封装在MOF结构内，得到PTA@PdCu@FeIII-MOF-5催化剂。在超临界正己烷介质、氢气氛围下，研究了在该催化剂上棕榈酸的脱氧反应。结果表明，棕榈酸可以在240°C上完全转化，十六烷的选择性最高。由于通过将PTA封装在PdCu@FeIII-MOF-5的空心纳米结构内部而提高了MOF催化剂的酸度，因此十六烷的选择性高于PdCu@FeIII-MOF-5。棕榈酸的催化加氢脱氧的优异性能与蛋黄-壳MOF纳米结构与SCF介质之间的协同作用有关。.（2）开发了一种具有金属-有机骨架结构特性的FDCA-Hf杂化物为载体的加氢脱氧高效催化剂。活性位Ru和HPW（磷钨酸）的协同作用促进了棕榈酸模化物向烷烃的转化。以超临界正己烷为介质，以HPW-Ru/FDCA-Hf为催化剂，240°C和2 MPa H2条件下，棕榈酸的烷烃转化率为100％，还产生了少量益于改善燃料特性的加氢裂化产物，研究了催化剂还原时间、反应温度、反应时间和初始氢压对棕榈酸改质反应的影响，提出了棕榈酸可能的催化提质反应机理。.（3）完成生物油模化物苯酚水相催化加氢工作，构建水热稳定性良好的MOF负载Pd纳米催化剂，活性测试发现催化剂储氢性能越好，催化加氢活性越高。进行苯酚催化加氢研究，Pd/MOF140-AA催化剂作用下，260°C、2 MPa的氢压，苯酚能够完全转化，产物为环己醇、环己烷以及环己酮，其产率分别为40.1%、29.3%和14.3%。.（4）设计制备了Mo/ZSM-22双官能催化剂，对生物油模化物棕榈酸进行了提质，能够一锅法完成脱氧和异构化。在棕榈酸的提质过程中，催化剂强酸位点被证明有利于HDC、异构化和裂解。Mo6+更倾向于支持HDC反应，而Mo4+倾向于促进HDO反应，即Mo4+/Mo6+比值显著影响HDO/HDC的选择性。HDO的改善使棕榈酸完全转化，可显著降低强酸位点对异构化的不利影响，从而得到更多的支链烷烃。. 本课题将为藻类水热液化制生物油的进一步发展奠定科学基础。