การกำจัดก๊าซไนโตรเจนมอนอกไซด์ด้วยตัวเร่งปฏิกิริยา Ce-Cu/Core-shell Al-MCM-41: ผลของการเคลือบไซเลน (NOx REMOVAL BY CE-CU/CORE-SHELL AL-MCM-41 CATALYST: EFFECT OF SILANE COATING)

Abstract

Air pollution and global warming have affected to human living and created many fatal diseases.
This work, thus, aims to decrease nitrogen monoxide, which is one of greenhouse gases and can cause acid rain, by converting it to N₂ and H₂O through a reduction pathway. In order to prolong the activity of the catalyst used, silane (i.e., chlorodimethylsilane, CDMS) was used to modify the surface of the catalyst—Ce and Cu loaded on a core-shell mesoporous silica-aluminosilicate composite (1.5%-Ce-SEI-Cu/Al-MCM-41).
The physico-chemical properties of the synthesized catalysts were characterized by using an X-ray diffraction (XRD), scanning electron microscope (SEM), transmitting electron microscope (TEM), and H₂ temperature-programmed reduction (H₂-TPR). It was found that when higher concentration of silane was used to modify the catalysts, the lower NO conversion was obtained from the NO reduction conducted under dry condition using catalysts modified with different silane concentration. The pristine 1.5%-Ce-SEI-Cu/Al-MCM-41 catalyst gave the average NO conversion of 53%, while the 1.5%-Ce-SEI-Cu/Al-MCM-41 coated with 0.1, 0.25, 0.5, and 0.75 mmol of silane gave average NO conversions of 52, 48, 45, and 44%, respectively. However, under wet condition using the 1.5%-Ce-SEI-Cu/Al-MCM-41 modified with 0.5 mmol silane yielded the highest NO conversion of 53%, which is much higher than that of pristine 1.5%-Ce-SEI-Cu/Al-MCM-41 catalyst. It can be concluded that the hydrophobicity of silane helps the catalyst to prolong its activity under wet condition by retarding the deactivation of catalyst caused by water.