Hydrodechlorination of p-Chlorophenol on Pd-Coated Fe3O4@polypyrrole Catalyst with Ammonia Borane as Hydrogen Donor

Efficient hydrogenation of p-chlorophenol and Cr(VI) driven by hydrogen rich balls over Pd/C catalysts

Catalytic hydrogenation can selectively destabilize and detoxify specific contaminants in water. Herein, to explore safer and more efficient hydrogen sources, hydrogen rich balls (HRBs) were researched and applied for hydrogenating p-chlorophenol and Cr(VI) over Pd/C catalyst. The results showed that HRBs can realize the sustained release of H₂ by replacing the hydrogen in water, and generate the refined (micro/nano-sized) H₂ bubble, which effectively improves the adsorption and activation effectively of H₂ molecules on Pd/C catalyst, and the hydrogen atoms utilization efficiency during p-chlorophenol hydrodechlorination is as high as 3.5 %. Continuous flow experiments showed that rapid removal of p-chlorophenol with different concentrations could be achieved by adjusting the flow rate. Moreover, the high-toxic Cr(VI) was successfully reduced to the low-toxic Cr(III) in an appropriate pH range. This research is of far-reaching significance for realizing the detoxification of environmental pollutants and promoting the development of hydrogen economy.

Promoted catalytic hydrodechlorination for deep degradation of chlorophenols over Rh-La/SiO2 catalyst

Deep degradation of chlorophenols (CPs) into safe and ecofriendly cyclohexanol during catalytic hydrodechlorination (HDC), shows important practical significance and attractive prospect in the treatment of wastewater containing chlorophenols. An efficient Rh-La/SiO₂ catalyst was developed, by employing La as promoter. The presence of La in catalyst promoted catalytic performance of HDC significantly. Characterization results revealed that the interaction occurred between Rh and La in Rh-La/SiO₂ catalyst. This interaction accompanied with the high dispersion and finely particle size of active Rh, and generation of abundant Rh sites neighboring La atom. Kinetic study illustrated that Rh-La(1:1)/SiO₂ catalyst possessed the fastest kinetic constants, and minimized the apparent activation energies of 4-CP, phenol and cyclohexanone greatly. Complete degradation of 4-CP with a very high yield of cyclohexanol (> 98%) can be achieved at room temperature, making Rh-La(1:1)/SiO₂ catalyst to be a promising candidate for deep degradation of CPs during HDC and other Rh catalyzed hydrogenation reactions.

Oxygenated functional group-driven spontaneous fabrication of Pd nanoparticles decorated porous carbon nanosheets for electrocatalytic hydrodechlorination of 4-chlorophenol

Researchers have been committed to reducing the hazardous pollutants by developing efficient catalysts while ignoring the pollution caused by the use of toxic surface capping agents, reductants and/or organic solvents in the catalyst preparation process. To alleviate such problems, we here report a novel one-step oxygenated functional group-driven electroless deposition strategy to synthesize clean and uniformly distributed Pd nanoparticles (NPs) using porous carbon nanosheets (PCN) as both substrates and reducing agents. It is observed that the oxygenated functional groups enriched PCN possesses a low work function and allows the spontaneous reduction of PdCl₄^2- ions to Pd NPs deposited on the PCN support (Pd/PCN). The particle size of Pd NPs can be flexibly modulated by simply controlling the immersing time and thereby their maximum catalytic performances can be achieved. Specifically, the optimal Pd/PCN-08 with a Pd loading of 3.0 wt% shows an excellent activity with a turnover frequency of 0.38 min^-1 for electrocatalytic hydrodechlorination (ECH) of 4-chlorophenol (4-CP), superior to the previously reported materials. The stability of Pd/PCN-08 for 4-CP ECH is impressive in repetitive cycles. This work proposes a facile and efficient strategy to synthesize high-performance catalysts for detoxifying the hazardous organic pollutants.

Zeolitic imidazolate framework-8 templated synthesis of a heterogeneous Pd catalyst for remediation of chlorophenols pollution

Herein, a heterogeneous Pd catalyst was prepared by embedding Pd nanoparticles in a highly porous nitrogen-doped mesoporous carbon (NMCs) synthesized by the ZIF-8 template. The as-prepared Pd/NMC catalyst was efficient and recyclable in mild catalytic hydrodechlorination of 4-chlorophenol, 2,4-dichlorophenol and 2,4,6-trichlorophenol, showing superior performances to those of the activated carbon-supported Pd commercial catalysts.

A Polypyrrole-Modified Pd-Ag Bimetallic Electrode for the Electrocatalytic Reduction of 4-Chlorophenol

A polypyrrole-modified bimetallic electrode composed of Pd-Ag on a Ti substrate (Pd-Ag/PPY/Ti) was successfully prepared via a chemical deposition method, and was applied to the electrocatalytic hydrodechlorination of 4-chlorophenol (4-CP) in aqueous solution. The electrode was characterized by cyclic voltammetry (CV), scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Various influences on the dechlorination efficiency of 4-chlorophenol, including applied current, initial pH value, and temperature, were studied. The dechlorination efficiency of 4-CP reached 94% within 120 min under the optimum conditions, i.e., a dechlorination current of 6 mA, an initial pH of 2.30, and a temperature of 303 K. The apparent activation energy of the dechlorination of 4-CP by the Pd-Ag/PPY/Ti electrode was calculated to be 49.6 kJ/mol. The equivalent conversion rate constant kPd was 0.63 L.gPd−1·min−1, which was higher than the findings presented in comparable literature. Thus, a highly effective bimetallic electrode with promising application prospects and low Pd loading was fabricated.