纳米Al2O3-ZrO2-Fe2O3的调控合成及其协同催化超临界水原位脱除重油中镍钒的增效机制

Serious problems would happen to the processes of heavy oil exploitation and refining if nickel and vanadium were not removed. Considering the unique physicochemical properties and potential hydrogen donor ability of supercritical water (SCW) formed during the thermal recovery process of heavy oil, the ternary nanocomposite catalyst Al2O3-ZrO2-Fe2O3 synthesized with supercritical hydrothermal method will be applied to the synergistic catalysis of SCW to remove nickel and vanadium from heavy oil.The structure and surface properties (active site, specific surface area, pore size, etc.) of the catalysts can be regulated by changing the reaction parameters of the SCW (such as flow rate of SCW, reaction temperature, reaction pressure, and cosolvent concentration, etc.), and the reaction conditions will be optimized by the response surface method. The removal performance can be investigated by analyzing the content of nickel and vanadium in the end products. The reaction (intermediate) products would be systematically analyzed and detected by means of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and other advanced characterization methods. Based on this, the removal path and mechanism of nickel and vanadium in heavy oil can be speculated by combining with the density functional theory. Moreover, the structure-activity relationship of the catalyst will be discussed with the help of detection of the active hydrogen/oxygen in reaction system and the configuration calculation of catalysts by the density functional theory. The implementation of this project not only provides reference for the efficient conversion of heavy oil into clean light oil, but also provides theoretical guidance for the in-situ removal of nickel and vanadium from heavy oil by SCW, which has certain theoretical and practical significance.

针对重油开采炼化工艺过程镍、钒带来的严重危害，基于具有独特物理化学特性及潜在供氢能力的超临界水（SCW）在重油原位改质方面的优势，本项目拟采用超临界水热法合成三元纳米复合催化剂Al2O3-ZrO2-Fe2O3，并将其应用于协同催化SCW原位脱除重油中镍、钒。通过改变SCW体系的参数（流速、反应温度、反应压力、共溶剂浓度等），调控催化剂的结构及表面性质（活性位、比表面积、孔结构），并利用响应曲面法优化反应条件；通过对产物中镍、钒含量分析探讨其脱除性能，借助傅立叶变换离子回旋共振质谱等先进仪器对反应（中间）产物进行系统分析检测，同时结合动力学分析及密度泛函理论对产物的全优化计算，探讨重油中镍、钒的SCW脱除机理；通过分析检测反应体系活性氢/氧，结合DFT对催化剂构型的计算，探讨催化剂的构效关系。本项目的实施不仅为重油高效转化为清洁轻质油提供借鉴，也可为SCW原位脱除重油中镍、钒提供理论指导。

随着原油日趋重质化和劣质化，原油中金属镍、钒含量的逐渐增加，已严重影响到原油的开采、运输以及炼化等工艺过程。针对金属镍、钒给重油开采、运输以及炼化工艺过程所带来的严重危害，基于超临界水在传质、传热、过程强化方面的优势以及潜在供氢能力，本项目旨在借助超临界水独特的物理化学性质，通过模拟实验，探索超临界水原位脱除重油金属镍、钒的可行性及机制。本项目采用超临界水热法合成三元纳米复合催化剂Al2O3-ZrO2-Fe2O3，并将其应用于催化超临界水原位脱除重油中镍、钒；首先通过改变超临界水体系的反应参数（如超临界水的流速、反应温度、反应压力、共溶剂浓度等），调控催化剂的结构及表面性质（活性位、比表面积、粒径、孔径等），并利用响应曲面法优化反应条件，以此开发出催化性能优异且结构稳定性好的纳米复合催化剂的合成方法。其次，通过对产物中镍、钒含量分析发现，催化超临界水过程强化可以高效脱除重油的金属镍、钒； X射线吸收精细结构（XAFS）谱等表征分析表明，镍、钒脱除后主要赋存焦炭中；通过傅立叶变换离子回旋共振质谱（FT-ICR MS）对反应（中间）产物的检测，同时结合动力学分析及密度泛函理论（DFT）全优化计算，发现重油中镍、钒的脱除主要遵循自由基机理，而催化剂的添加会促使高活性氢的产生，进而造成金属卟啉环逐步加氢开环，从而实现Ni、V的脱除；最后，通过内标法和电子顺磁共振波谱仪（ESR）分析检测反应体系活性氢/氧，同时结合DFT对催化剂构型的计算发现，原油中镍、钒的脱除与催化剂中的活性组分Fe2O3密切相关，该活性组分一方面促进水分解产氢，另一方面则通过氧化裂化重油大分子维持催化剂活性。