限域离子胶催化剂的制备及其在超低温水煤气变换反应中的应用

Confined ionogel catalysts with cage pore structure will be prepared and applied in ultra-low-temperature (<200 oC) water-gas shift (WGS) reaction to overcome the drawbacks of low activity of commerical WGS catalysts at ultra-low-temperature and deactivation of supported ionic liquid phase catalysts in heterogenous reactions. The activated components are firstly dissolved in an ionic liquid, and mixed with an inorganic support precursor, then the ionogel catalysts which the activated components are confined in support are prepared by sol-gel methods. The catalysts particle size and pore structure are controlled by the content of support precursor and ionic liquids. The solubility of gas phase reactant in the ionic liquids will be modified by the anions and cations structure of the ionic liquids. The effect of activated components, support, catalyst pore structure, structure of ionic liquid and reaction conditions (temperature, pressure, ratio of steam to CO) on the WGS activity will be systemically studied so that highly active ionogel catalysts can be designed for application in pure syngas. Based on the above studies, ionogel catalysts with H2S adsorption ability will be further designed through functional ionic liquids and the WGS activity in sour syngas will be studied. The mechanism of the WGS reaction will be investigated by in-situ spectroscopies and kinetic studies. This study will supply some academic foundation and application prospects for ultra-low-temperature WGS catalysts with high activity and sulfur tolerant stability.

为克服商业水煤气变换反应（WGS）催化剂在超低温（<200 oC）活性较低及固载化离子液体在连续相反应中易失活的缺点，本项目拟设计具有笼型孔道结构的介孔氧化物限域离子胶催化剂，并将其应用于超低温WGS反应。活性组分先溶解在离子液体中，再加入无机载体前躯体，采用溶胶-凝胶法将活性组分限域在载体中制备离子胶催化剂。通过控制载体前躯体和离子液体用量调控催化剂颗粒大小、孔道结构；通过调节离子液体结构，调控气相分子在离子液体中的溶解能力。系统考察活性组分、孔道结构、载体、离子液体结构和反应条件（温度、压强、水汽比）等对催化剂在纯合成气中WGS活性的影响，开发出高活性离子胶催化剂。进一步设计具有吸附H2S能力的离子胶催化剂，考察其在含硫合成气中WGS活性。通过原位光谱和动力学分析等手段，研究离子胶催化剂WGS反应机理。本项目对开发在具有较高WGS活性和耐硫稳定性的催化剂提供一定理论基础和应用前景。

为克服商业水煤气变换反应（WGS）催化剂在超低温（<200 ºC）活性较低及固载化离子液体在连续相反应中易失活的缺点，本项目拟设计具有一定孔道结构的介孔氧化物限域离子胶催化剂，并将其应用于超低温WGS反应。1..制备了一系列钌基离子胶催化剂，随着离子液体的含量增大，催化剂的CO转化率也逐渐增大。这一方面是由于随着离子液体含量的增大，催化剂的孔体积和孔径都增大，使反应物分子和产物分子能够更容易的接近催化剂的活性中心钌，减小了扩散阻力；另一方面，高含量的离子液体也有增加了CO在其中的溶解能力，平衡了低温时，CO和水蒸气在Ru活性中心的吸附。表征结果反应的活性中心主要为零价的羰基钌化物。2.以[BMIM]BF4为保护剂，制备了不同大小的Ru纳米颗粒，酸性水解的催化剂具有很好的限域作用，使催化剂具有很高的活性和稳定系。碱性条件下水解缩聚过程明显大于水解过程，导致部分离子液体保护的Ru纳米颗粒没有被包裹在SiO2内部，催化剂反应后被氧化。3.使用不同还原剂（NaBH4,乙二醇、H2）制备了活性炭担载的钌基催化剂，添加K2CO3， 发现可以显著促进其催化活性，且有效抑制副反应甲烷化的生成，这主要是由于一方面K+与贵金属Ru间的电子转移使部分Ru成氧化态，从而形成新的活性中心，另一方面，亲水性的K2CO3增加了活性中心水的浓度，平衡了CO和水在Ru上的吸附。