Development of a Strategy To Reuse Spent Cr Adsorbents as Efficient Catalysts: From the Perspective of Practical Application

Recycling waste Cr adsorbents as efficient catalysts reflects a new avenue of green chemistry and has important implications for environmental protection. In particular, the investigation of the effect of additional impurity ions is considered to be applicable for real Cr adsorbents. In the present work, reused Cr adsorbent syntheses from streams containing competing ions were developed for CH3SH abatment and propane dehydrogenation. Good dispersion of Cr species was obtained through this special procedure of preparation, and its difference from the traditional impregnation method was also examined. Furthermore, these reused Cr adsorbents with exposure to additional impurity ions provided different physicochemical properties, and different catalytic activities were shown accordingly. The results indicated that the impurity cations had little effect on the catalytic activity of the reused Cr adsorbents, while the impurity anions caused the destruction of the siliceous framework of the MCM-41 support and led to the formation of some inactive Cr(VI) species, thus exhibiting decreased reactivity. Consequently, avoiding the addition of some anions was considered to be the premise for reusing the waste Cr adsorbents.