A Highly Active Pd on Ni–B Bimetallic Catalyst for Liquid-Phase Hydrodechlorination of 4-Chlorophenol Under Mild Conditions

Catalytic Hydrodechlorination of Chlorophenols in a Continuous Flow Pd/CNT-Ni Foam Micro Reactor Using Formic Acid as a Hydrogen Source

Catalytic hydrodechlorination (HDC) has been considered as a promising method for the treatment of wastewater containing chlorinated organic pollutants. A continuous flow Pd/carbon nanotube (CNT)-Ni foam micro reactor system was first developed for the rapid and highly efficient HDC with formic acid (FA) as a hydrogen source. This micro reactor system, exhibiting a higher catalytic activity of HDC than the conventional packed bed reactor, reduced the residence time and formic acid consumption significantly. The desired outcomes (dichlorination >99.9%, 4-chlorophenol outlet concentration <0.1 mg/L) can be obtained under a very low FA/substrate molar ratio (5:1) and short reaction cycle (3 min). Field emission scanning electron microcopy (FESEM) and deactivation experiment results indicated that the accumulation of phenol (the main product during the HDC of chlorophenols) on the Pd catalyst surface can be the main factor for the long-term deactivation of the Pd/CNT-Ni foam micro reactor. The catalytic activity deactivation of the micro reactor could be almost completely regenerated by the efficient removal of the absorbed phenol from the Pd catalyst surface.

A simple and effective approach for catalytic reductive dechlorination of aromatic compounds

An efficient process for the preparation of 2(3),9(10),16(17),23(24)-octa(n-hexyl)cobalt(II)phthalocyanine, ((n-hexyl)8CoPc) (2) was described. The novel cobalt(II)phthalocyanine was characterized by spectroscopic methods. It was employed as a catalyst for the room temperature reductive dechlorination of chlorinated aromatic compounds (CACs). The results were showed that the CACs were completely dechlorinated within 110–120 min.

Palladium encapsulated within magnetic hollow mesoporous TiO2 spheres (Pd/Fe3O4@hTiO2) as a highly efficient and recyclable catalysts for hydrodechlorination of chlorophenols

Herein, we introduced a method to encapsulate Pd(0) within TiO₂ hollow mesoporous nanostructures.

Enhanced mitigation of para-chlorophenol using stratified activated carbon adsorption columns

The adsorptive removal of toxic para-chlorophenol using activated carbon adsorption columns is a proven effective engineering process. This paper examined the possibility to stratify an adsorbent bed into layers, in order to enhance the adsorption process performance in terms of increased column service time and adsorbent bed saturation. Four different types of fixed-bed adsorption columns are used and compared under the same operating conditions, but with the variation of column geometry and activated carbon particle size stratification. The Type 3 column - a cylindrical column with particle stratification packing, is found to be the most efficient choice, as the extent of column service time and adsorbent bed saturation are the largest. This could eventually decrease the frequency of adsorbent replacement/regeneration and hence reduce the operating cost of the fixed-bed adsorption process. The Homogeneous Surface Diffusion Model (HSDM) was applied successfully to describe the dynamic adsorption of para-chlorophenol onto Filtrasorb 400 (F400) activated carbon in different types of columns. The Redlich-Peterson isotherm model equation, an experimentally derived external mass transfer correlation and a constant surface diffusivity are used in the HSDM. The optimised surface diffusivity of para-chlorophenol is found to be 1.20E-8 cm(2)/s, which is in good agreement with other phenolics/F400 carbon diffusing systems in literature.