采用挤出成型法制备蜂窝状氮化硼催化剂,考察了水粉比、溶胶种类、溶胶含量及羟丙基甲基纤维素含量等因素对成型效果的影响。筛选出合适的水粉比为0.85∶1,粘结剂为硅溶胶(所含SiO₂质量占氮化硼粉体的10%)和5%羟丙基甲基纤维素。对制备的蜂窝状氮化硼进行表征表明,片状氮化硼在剪切应力的作用下沿挤出方向定向排列,片体表面分布有球形的SiO₂颗粒,二者之间形成B—O—Si键。分析了蜂窝状氮化硼成型过程中发生变形和开裂的原因并提出优化方向。初步应用于丙烷氧化脱氢反应结果表明,蜂窝状氮化硼催化剂在高空速条件下表现出比粉末氮化硼更优异的性能。

A honeycomb boron nitride catalyst is prepared via extrusion molding method.The impacts of water-powder ratio,sol type,sol content and hydroxypropyl methylcellulose content on molding effect are investigated.It is found that the suitable ratio of water to powder is 0.85∶1,and silica sol (mass ratio of SiO₂ to boron nitride powder is 10%) and 5% hydroxypropyl methylcellulose are used as the binder.The characterization shows that boron nitride plates are directionally arranged along the extrusion direction under the action of shear stress,and spherical SiO₂ particles are distributed on the surface of the plates with B-O-Si bonds formed between them.The causes of deformation and cracking in the molding process of honeycomb boron nitride are analyzed,and the feasible optimization direction is put forward.It is shown through application in the oxidative dehydrogenation of propane that honeycomb boron nitride catalyst presents better performance than powder boron nitride at a high space velocity.

岳雨蒙(1997-),女,硕士生,研究方向为氮化硼成型工艺及其催化应用,357949379@qq.com