Hydrotreating processes for catalytic abatement of water pollutants

Abstract

Opportunities and problems in application of catalytic hydrotreating processes, which are presented a viable approach in the abatement of water pollutants, are discussed. Analysis of the hydrodechlorination (HDC) and hydrodenitrification (HDN) using Pd-based catalysts supported on various materials like granulated activated carbon (GAC), fibrous activated carbon cloths (ACCs) or glass fiber cloths (GFCs) studied recently in our laboratory suggests the following perspectives:(1)Exhaustive regeneration of Pd/GAC saturated with p-chlorophenol can be achieved in a two-step approach, incorporating gas-phase HDC by hydrogen followed by oxidation by air.(2)Pd/ACC catalysts are good candidates for the liquid-phase HDC showing activity higher than that of Pd/GAC or Pd/GFC; the high adsorption capacity of Pd/ACC lead suggesting its use in a technology with periodic adsorption and HDC, in similarity to adsorption with regeneration of GAC.(3)Pd/GFC and Pd–Cu/GFC are promising catalyst for removal of nitrites and nitrates, showing activity and selectivity that compares favorably with those of powdered catalysts.