Mesoporous boron nitride in contact with water - chemical stability and adsorption properties

In this research project we synthesized two different porous boron nitrides - a mesoporous one (BN-meso) and a reference micro-mesoporous one (BN-ref). Our goal was to identify the influence of different pore sizes towards the chemical stability of these materials. We focussed mainly on water, as it is present in a significant amount of industrial adsorption applications. The samples were exposed to humid air, water vapor and liquid water for multiple weeks. Prior to and after this exposure we characterized the materials with XRD, XPS, SEM, mercury intrusion, ATR-IR, TG and nitrogen sorption. Additionally, we calculated pore size distributions using QSDFT for the adsorption branch of nitrogen sorption at 77 K on carbon with slit and cylindrical pores. Based on the water vapor adsorption isotherms and pore size distributions we conclude that mesoporous BN ist stable against water in the vapor phase. Micro-mesoporous BN is stable neither towards vapor nor liquid water.

在本项研究项目中，我们合成了两种不同的多孔氮化硼材料——一种介孔型（BN-meso）和一种参考型微介孔型（BN-ref）。我们的目标是探究不同孔径对这些材料化学稳定性的影响。我们主要关注水，因为水在工业吸附应用中占据着显著的比例。样品被暴露于潮湿空气、水蒸气和液态水中数周之久。在暴露前后，我们利用XRD、XPS、SEM、汞渗透法、ATR-IR、TG和氮气吸附等方法对这些材料进行了表征。此外，我们利用QSDFT计算了77 K下碳吸附氮气分支的孔径分布。基于水蒸气吸附等温线和孔径分布，我们得出结论：介孔氮化硼对气相中的水具有稳定性。微介孔氮化硼对气相水蒸气和液态水均不具有稳定性。