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

Abstract

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.

Pt/γ‐Al2O3 Catalyst for Liquid‐Phase Hydrogen‐Transfer Hydrodechlorination of 4‐Chlorophenol in Alkaline Isopropanol

“…Supporting information contains a literature survey on the hydrogen-transfer hydrodechlorination of 4-chlorophenol in liquid phase with additional references, [53][54][55][56][57][58][59][60][61][62][63][64][65][66][67][68][69][70][71][72] XRD patterns of γ-Al 2 O 3 support and its prepared catalysts, XPS spectra of the synthesized catalysts, HAADF-STEM images of fresh and spent Pt/γ-Al…”

“…Supporting information contains a literature survey on the hydrogen‐transfer hydrodechlorination of 4‐chlorophenol in liquid phase with additional references, [53–72] XRD patterns of γ‐Al 2 O 3 support and its prepared catalysts, XPS spectra of the synthesized catalysts, HAADF‐STEM images of fresh and spent Pt/γ‐Al 2 O 3 catalyst, SEM images and EDX‐spectra of Pt/γ‐Al 2 O 3 , Rh/γ‐Al 2 O 3 , Ru/γ‐Al 2 O 3 and Pt/γ‐Al 2 O 3 catalysts, GC chromatograms of starting materials, products and representative examples of some experiments.…”

Catalytic hydrogenative dechlorination reaction for efficient synthesis of a key intermediate of SDHI fungicides under continuous-flow conditions

“…To complete the synthesis of DFMMP from the given 3-chlorodifluoromethyl pyrazole (CDFMMP 5 ), efficient hydrodechlorination is required; however, previous research indicated its difficulty when utilizing the usual hydrogenation technologies due to the high resistance of the C(sp 3 )–Cl bond to reduction conditions. 8 As a useful method from the latest literature, Braun et al reported catalytic hydrogenation using Pd/C as a catalyst. This protocol provided the target DFMMP in 97% yield at 110 °C in the presence of K 2 CO 3 as a base, but a high hydrogen pressure of 11 bar (1.1 MPa) is required and this may be affected by the production of over-hydrogenation products in a small amount.…”

Catalytic Methods in Flow Chemistry

“…Zirconium-functionalized silica monoliths constituted the core of the reactor and performed well in promoting the reduction of cyclohexanone and other ketones and aldehydes using 2-butanol as the hydrogen donor. Important kinetic parameters and data on the reaction rates were the main output of this study.In the context of the treatment of wastewater containing chlorinated organic pollutants, a continuous flow process for hydrodechlorination of chlorophenols was reported [6]. The process relies on the use of a Pd/carbon nanotube (CNT)-Ni foam microreactor system and formic acid as the hydrogen source.…”

“…In the context of the treatment of wastewater containing chlorinated organic pollutants, a continuous flow process for hydrodechlorination of chlorophenols was reported [6]. The process relies on the use of a Pd/carbon nanotube (CNT)-Ni foam microreactor system and formic acid as the hydrogen source.…”