Oxidation Of Chlorobenzene Research Articles

Simultaneous removal of chlorobenzene and Cr(VI) from groundwater using microbial fuel cell with low-cost Si modified ferrihydrite electrodes

Aromatic chlorinated compounds and Cr(VI) in groundwater pose significant challenges due to their resistance. This study explores microbial fuel cells using low-cost Si-modified ferrihydrite (SiFh) electrodes for simultaneous chlorobenzene and Cr(VI) removal. The voltage output of MFC assembled with SiFh modified electrode was approximately 1.63 times higher than the bare electrode, achieving 1.23 times higher in chlorobenzene degradation efficiency. CF-SiFh loaded MFC had the highest power generation and best EET efficiency, which was positive to greatest and fastest chlorobenzene removal. Microbial community analysis identified the dominance of Cupriavidus and Pandoraea in chlorobenzene oxidation, while Lentimicrobiaceae and Rhodobacteraceae were key genera that may facilitate direct and indirect electron transfer within the biofilms. Cr species analysis in solution and solids confirmed it was reduced to Cr(OH)3 or CrxFe1-x(OH)3 coprecipitates at cathode. MFCs with SiFh-modified electrodes thus offer a promising technology for simultaneous chlorinated compound and Cr(VI) removal, promising in contaminated groundwater remediation.

Theoretical insight into the active sites for chlorobenzene oxidation: From phosphate to M3 clusters

Theoretical insight into the active sites for chlorobenzene oxidation: From phosphate to M3 clusters

Sulfur-resistant mechanism of MnOx@CeO2@MgO core-shell catalyst in simultaneous removal of NOx and chlorobenzene

Herein, Mn-Ce based catalysts with different structures were rationally designed to explore their sulfur-resistant mechanism for simultaneous removal of NOx and chlorobenzene (CB) from waste incineration at low temperature. In the presence of SO2, MnOx@CeO2@MgO exhibits the highest sulfur resistance among prepared catalysts. Both NOx and CB conversion over MnOx@CeO2@MgO can reach up to 80% at 300 °C. However, the significant deactivation is observed for MnCeMgOx within all temperature ranges. For the selectivity of products, MnOx@CeO2@MgO displays the excellent N2 selectivity (93%) and good CO2 selectivity (80%) at 300 °C. Compared with NO reduction, SO2 has a greater impact on CB destruction due to the consumption of reactive oxygen species during SO2 oxidation. The reduction of active oxygen is proposed to be the reason for the significant inhibition of CB oxidation. The addition of MgO shell increases the proportion of lattice oxygen, which is beneficial to improving the sulfur resistance of MnOx@CeO2@MgO catalyst. In addition, SO2 can react with MgO preferentially to protect the active sites and improve the sulfur resistance. This work indicates that MnOx@CeO2@MgO core-shell catalyst with good sulfur tolerance and stability is expected to be applied in the potential application.

Manipulation of Mn/Ce ratio for deep chlorobenzene oxidation: Catalytic mechanisms and byproducts analysis

In this research, a sequence of spatial porous MnCeOx catalysts with varying Mn/Ce from 3:1 to 1:7 were synthesized using the sol–gel method for chlorobenzene (CB) oxidation. Mn1Ce1 exhibited the best performance due to its high lattice oxygen content and the strong interaction between Ce and Mn. The increase in Mn content in CeO2 catalysts resulted in enhanced redox properties and acidity, which was beneficial for the adsorption and activation of CB, thus enhancing the selectivity and the desorption of HCl on the catalyst surface. Carbon deposition and the formation of metal chloride were the main reasons for catalyst deactivation. At low temperature regions (150 ∼ 300 °C), insufficient oxidation capability and the chlorine deposition on the catalyst surface resulted in the formation of various chlorinated compounds. As the temperature increases (300 ∼ 450 °C), the release of HCl and more reactive oxygen species is available on the catalytic interface, generating various oxygen-containing degradation intermediates. This work proposed a fine-designed, low-cost mixed metal oxide catalysts for low temperature CB oxidation, and provided novel in-depth understandings of degradation intermediate formation thermodynamics. Our findings would be helpful for deep purification of chlorinated VOCs polluted industrial tail gas.

Promoting C-Cl Bond Activation via a Preoccupied Anchoring Strategy on Vanadia-Based Catalysts for Multi-Pollutant Control of NOx and Chlorinated Aromatics.

Regulating vanadia-based oxides has been widely utilized for fabricating effective difunctional catalysts for the simultaneous elimination of NOx and chlorobenzene (CB). However, the notorious accumulation of polychlorinated species and excessively strong NH3 adsorption on the catalysts lead to the deterioration of multipollutant control (MPC) activity. Herein, protonated sulfate (-HSO4) supported on vanadium-titanium catalysts via a preoccupied anchoring strategy are designed to prevent polychlorinated species and alleviate NH3 adsorption for the multipollutant control. The obtained catalysts with -HSO4 modification achieve an excellent NOx and CB conversion with turnover frequency values of ∼ 3.63 and 17.7 times higher than those of the pristine, respectively. The protonated sulfate promotes the formation of polymeric vanadyl with a higher chemical state and d-band center of V. The modulated catalysts not only substantially alleviate the competitive adsorption of multipollutant via the "V 3d-O 2p-S 3p" network, but also distinctly strengthen the Brønsted acid sites. Besides, the introduced proton donor of the -HSO4 connecting polymeric structure could markedly reduce the reaction barrier of breaking the C-Cl bond. This work paves an advanced way for low-loading vanadium SCR catalysts to achieve highly efficient NOx and CB oxidation at a low temperature.

Enhanced catalytic performance and antichlorine poisoning over Cu-doped cobalt oxide nanosheets for chlorobenzene oxidation

The degradation of Chlorinated volatile organic compounds (CVOCs) by catalytic oxidation forms toxic products, and catalysts may be poisoned by chlorine at low temperatures. To address this, a Cu-assisted strategy is proposed for enhancing the catalytic degradation of chlorobenzene (CB) over cobalt oxide nanosheets. The Cu-doped Co3O4 catalysts exhibited lower T90 values (temperatures with 90 % conversion) and improved stability compared to the unmodified catalyst. These results were attributed to strong metal-metal interactions between Cu species and cobalt oxide nanosheets, which showed a high specific surface area, reduced binding energy of lattice oxygen, higher surface oxygen concentration, and more surface Co3+ species. These properties promoted low-temperature catalytic activity. In addition, the disappearance of Cu2+ satellite peak after the catalyst is used, indicating that the Cu2+ also contributes to the catalytic activity. Furthermore, the in situ FTIR spectra provided details about the reaction mechanism of CB degradation over Cu-doped cobalt oxide nanosheets. The oxygen vacancy generation and the surface absorption of chlorine-containing intermediates were calculated using density functional theory calculations. This study provides new insight into novel pathways for catalyst design aimed at CB degradation.

Chlorobenzene oxidation by electrochemical catalysis with La modified Ti/IrO2-Ta2O5

As a typical VOCs emitted from petrochemical industry, chlorobenzene was selected to study its removal by wet oxidation with electrochemical catalysis. Ti based IrO2-Ta2O5 electrode was used in the advanced oxidation of chlorobenzene, and Sn, Sb, Pt and La were used to modify Ti/IrO2-Ta2O5. Ti/IrO2-Ta2O5-La showed the highest removal rate of chlorobenzene and it reached 99.2 % for the chlorobenzene oxidation, which was 20 % higher than those of the other 3 additions. Oxygen evolution overpotential of Ti/IrO2-Ta2O5-La increased to 1.17 V when compared with Ti/IrO2-Ta2O5 of 1.08 V. EPR tests for free radicals and GC-MS tests for intermediates showed that the main active substance was ·OH, and the element Cl in chlorobenzene dissociated from the benzene ring under the action with ·OH to form ·Cl and ClO· radicals. Degradation pathway of chlorobenzene was figured out as chlorobenzene→ phenols→ organic acids→ CO2+H2O.

Refining catalytic oxidation of volatile organic compounds over Gd-Sr-Co perovskite-based oxides fabricated via viscous mixture induction: Unveiling the crucial factors influencing catalytic activity

A series of Gd-Sr-Co perovskite-based oxides have been successfully synthesized by thermally driving viscous mixture, wherein only very trace amounts of water need and the metal salts powders do not need to be thoroughly mixed. By the characterization of XRD, XPS, EPR, and Raman, the levels of oxygen vacancies, lattice oxygen, and adsorbed oxygen in the catalyst are controlled by varying the amount of Sr doping. Unlike traditional conclusions, we found that the catalytic activities of the catalysts did not enhance with the increase in the contents of adsorbed oxygen and oxygen vacancies. H2-TPR and O2-TPD confirmed that the migration of lattice oxygen in catalysts determined their activities. Comparative activity of individual catalysts was evaluated by catalytic oxidation of toluene. The best active catalyst also showed superior catalytic activity for the oxidation of acetone, ethyl acetate, and chlorobenzene. The effects of humidity and weight hourly space velocity on the stability of the catalyst were also evaluated. Catalyst’s surface structural changes in toluene oxidation were also analyzed by in-situ DRIFTS. This study provides a simple approach to tailor perovskite-based oxide structures, crucial for effective catalytic oxidation of VOCs.

Plasma driven exsolution of Ca as the adjacent dechlorinated site in La0.8Ca0.2MnO3 perovskite: A highly mineralization chlorobenzene oxidation catalyst

The degradation of chlorine-containing volatile organic compounds (CVOCs) catalytic combustion technology is subject to the catalyst chlorine poisoning, which is resulted from the chlorination of active phases, even though the structural stable perovskite. The reaction between Ca species and dissociated chlorine species is demonstrated as an efficient way to inhibited chlorine poisoning of the active phase. Herein, a Ca substituted partial La prepared La0.8Ca0.2MnO3 (named as L8C2MO) perovskite was treated by 5% H2/Ar plasma driven route (the treated sample was denoted as L8C2MO-P), which was applied for the chlorobenzene oxidation removal. The integrated characterization results of XRD, XPS, HRTEM, etc. confirmed that Ca (mainly exhibited as CaCO3) was successfully exsolved from La0.8Ca0.2MnO3 and simultaneously leaved oxygen vacancies on the surficial layers. The continuous catalytic oxidation experiments illustrated that the conversion efficiency of L8C2MO was unexpectedly decreased compared with that of LaMnO3 (LMO in short) sample, while that of L8C2MO-P was nearly maintained the oxidation capacity, with approximately 12 °C of 90% chlorobenzene conversion temperature (T90) higher than that of LMO. Importantly, the CO2 and inorganic chlorine species yields were significantly enhanced for L8C2MO and L8C2MO-P. The characteristic of used samples showed a possible chlorinated Ca species formation while the status of Mn phases was hardly changed, suggesting the exsolved Ca could inhibit the poison of Mn sites by binding with dissociative chlorine species. Additionally, oxygen vacancies that generated along with Ca exsolution process was definitely contributed to the deep oxidation of chlorobenzene. The possible reaction route was also studied by in situ DRIFTS and GCMS. The work provides a potential route as in situ growth of adjacent sites to protect active phases from chlorine poison in CVOCs catalytic oxidation process.

Catalytic Oxidation of Chlorobenzene over Amorphous Manganese-Chromium Catalysts Supported by UiO-66-Derived ZrOx.

The development of efficient catalysts with longevity to remove chlorobenzene is challenging due to Cl poisoning. Herein, a series of Mn-Cr/ZrOx catalysts supported by Zr-based metal-organic framework (UiO-66)-derived ZrOx was prepared and investigated for chlorobenzene (CB) catalytic oxidation. MnCr/ZrOx-M prepared via a wet impregnation method presented an amorphous structure, indicating the homogeneous dispersion of Cr and Mn, which improved acid and redox properties. 40Mn7Cr3/ZrOx-M exhibited the best catalytic activity for chlorobenzene oxidation with T90 of 293 °C, which is mainly due to the strong interaction between manganese and chromium promoted by the large specific surface area of the ZrOx support. Furthermore, 40Mn7Cr3/ZrOx-M presented excellent stability for chlorobenzene oxidation.

Hierarchical molecular sieve-based Ce-Ru oxide for enhanced catalytic oxidation of chlorobenzene: Insight into the synergistic effect of Ce and Ru, the role of molecular sieve

In this work, a series of hierarchical molecular sieve were synthesized via adjusting the ratio of Si/Al. Then, Ce and Ru were supported on the molecular sieve and the loading amount of Ru were optimized. Catalytic evaluation showed that 5Ce0.5Ru/HZ-3 with the value Si/Al ratio of 80 performed the best catalytic activity of chlorobenzene oxidation with T50 and T90 values of 238 ℃ and 278 ℃, respectively and no chlorobenzene conversion can be seen on the 5Ce/HZ-3 and HZ-3, indicating that Ru was the active sites on 5Ce0.5Ru/HZ-3 and Ce played a promoter role in chlorobenzene oxidation. Catalytic stability showed that 5Ce0.5Ru/HZ-3 can maintain the complete conversion of chlorobenzene oxidation at 300°C for 190 h and the CO2 and HCl selectivity kept around 80% and 27%, respectively, while 5Ce0.5Ru performed worse catalytic stability and no HCl was detected. Subsequently, characterization results implied that HZ-3 with the Si/Al ratio of 80 had the biggest mesoporous volume of 0.5193 cm3·g−1 on the basis of micropore volume around 0.1236 cm3·g−1, which was beneficial to the diffusion of reactant molecule; Raman spectra implied that there is a strong interaction between Ce and Ru. H2-TPR and O2-TPD showed that 5Ce0.5Ru/HZ-3 possessed the biggest consumption of hydrogen (0.486 mmol·g−1), surface adsorbed oxygen (0.683 mmol·g−1) and surface lattice oxygen (0.626 mmol·g−1), which was conducive to the adsorption and dissociation of reactant molecule; XPS showed 5Ce0.5Ru/HZ-3 had the biggest molar percentage of Ru4+ species (79.50%) and Ce3+ species (44.14%), which can induce the generation of much more oxygen vacancies. Overall, the introduction of Ce can result in the improvement of physical-chemical properties of 5Ce0.5Ru/HZ-3. Finally, the possible reaction route was given based on the in-situ DRIFTS and TD/GC-MS result.

Chlorobenzene Oxidation over Phosphotungstic-Acid-Coated Cerium Oxide: Synergistic Effect of Phosphotungstic and Cerium Oxide and Inhibition Mechanism of Sulfur Dioxide

Ce–based catalysts exhibit a poor stability and activity in chlorinated volatile organic compound (Cl–VOC) oxidation due to their rapid Cl poisoning. Herein, phosphotungstic acid (HPW) was coated on CeO2 to improve its activity and stability for chlorobenzene (CB) oxidation. The HPW coating not only promoted CB adsorption onto CeO2, but also provided Brønsted acid sites to CeO2 for Cl species removal as HCl, thus avoiding Cl poisoning. Hence, a synergistic effect of CeO2 and HPW on HPW/CeO2 was observed, resulting in superior CB oxidation activity and stability. Additionally, to improve the sulfur resistance of the catalyst, the inhibition mechanism of SO2 on CB oxidation by HPW/CeO2 was explored. HPW/CeO2 was prone to sulfation due to the formation of Ce2(SO4)3 from the reaction of SO2 and CeO2. Thus, the oxidation ability of HPW/CeO2; the amount of adsorption sites for CB adsorption; and the amounts of Ce4+ bonded with O2−, lattice oxygen species, and adsorbed oxygen species were decreased by SO2. Meanwhile, SO2 competed with CB for the adsorption sites on HPW/CeO2. Therefore, CB oxidation by HPW/CeO2 was remarkably restrained by SO2. The present work promotes further work on Cl–VOC removal by Ce-based catalysts for anti-SO2 poisoning modification in the future.

Efficient Catalytic Elimination of Chlorobenzene Based on the Water Vapor-Promoting Effect within Mn-Based Catalysts: Activity Enhancement and Polychlorinated Byproduct Inhibition.

Achieving no or low polychlorinated byproduct selectivity is essential for the chlorinated volatile organic compounds (CVOCs) degradation, and the positive roles of water vapor may contribute to this goal. Herein, the oxidation behaviors of chlorobenzene over typical Mn-based catalysts (MnO2 and acid-modified MnO2) under dry and humid conditions were fully explored. The results showed that the presence of water vapor significantly facilitates the deep mineralization of chlorobenzene and restrains the formation of Cl2 and dichlorobenzene. This remarkable water vapor-promoting effect was conferred by the MnO2 substrate, which could suitably synergize with the postconstructed acidic sites, leading to good activity, stability, and desirable product distribution of acid-modified MnO2 catalysts under humid conditions. A series of experiments including isotope-traced (D2O and H218O) CB-TPO provided complete insights into the direct involvement of water molecules in chlorobenzene oxidation reaction and attributed the root cause of the water vapor-promoting effect to the proton-rich environment and highly reactive water-source oxygen species rather than to the commonly assumed cleaning effect or hydrogen proton transfer processes (generation of active OOH). This work demonstrates the application potential of Mn-based catalysts in CVOCs elimination under practical application conditions (containing water vapor) and provides the guidance for the development of superior industrial catalysts.

Catalytic Oxidation of Chlorobenzene over HSiW/CeO2 as a Co-Benefit of NOx Reduction: Remarkable Inhibition of Chlorobenzene Oxidation by NH3.

There is an urgent need to develop novel and high-performance catalysts for chlorinated volatile organic compound oxidation as a co-benefit of NOx. In this work, HSiW/CeO2 was used for chlorobenzene (CB) oxidation as a co-benefit of NOx reduction and the inhibition mechanism of NH3 was explored. CB oxidation over HSiW/CeO2 primarily followed the Mars-van-Krevelen mechanism and the Eley-Rideal mechanism, and the CB oxidation rate was influenced by the concentrations of surface adsorbed CB, Ce4+ ions, lattice oxygen species, gaseous CB, and surface adsorbed oxygen species. NH3 not only strongly inhibited CB adsorption onto HSiW/CeO2, but also noticeably decreased the amount of lattice oxygen species; hence, NH3 had a detrimental effect on the Mars-van-Krevelen mechanism. Meanwhile, NH3 caused a decrease in the amount of oxygen species adsorbed on HSiW/CeO2, which hindered the Eley-Rideal mechanism of CB oxidation. Hence, NH3 significantly hindered CB oxidation over HSiW/CeO2. This suggests that the removal of NOx and CB over this catalyst operated more like a two-stage process rather than a synergistic one. Therefore, to achieve simultaneous NOx and CB removal, it would be more meaningful to focus on improving the performances of HSiW/CeO2 for NOx reduction and CB oxidation separately.

Efficient MnCeOx catalyst derived from MnCe-MOF for chlorobenzene oxidation: Effects of metal ratio, pyrolysis atmosphere and pyrolysis temperature

In this study, a series of binary metal oxide composite materials, MnCeOx, derived from metal-organic framework (MOFs), were successfully synthesized and employed in the catalytic oxidation of chlorobenzene. The metal ratio, pyrolysis atmosphere, pyrolysis temperature, and stepwise pyrolysis have significant effects on the structure and catalytic activity of the materials. The catalytic activity evaluations demonstrated that MnCeOx with a Mn/Ce ratio of 4:1, obtained by pyrolysis at 400 °C first in an argon atmosphere and then in air, exhibited the best catalytic activity (T90 = 196 °C). This notable activity is attributed to its larger specific surface area, mesoporous structure, smaller nanoparticle size, better low-temperature reducibility, and improved oxygen activation ability. The presence of inorganic chlorine on its surface was identified as the primary factor leading to the decline in catalytic activity. By increasing the reaction temperature, the deactivation could be suppressed for more than 90 h.

Deep Oxidation of Chlorinated VOCs by Efficient Catalytic Peroxide Activation over Nanoconfined Co@NCNT Catalysts.

The catalytic removal of chlorinated VOCs (CVOCs) in gas-solid reactions usually suffers from chlorine-containing byproduct formation and catalyst deactivation. AOP wet scrubber has recently attracted ever-increasing interest in VOC treatment due to its advantages of high efficiency and no gaseous byproduct emission. Herein, the low-valence Co nanoparticles (NPs) confined in a N-doped carbon nanotube (Co@NCNT) were studied to activate peroxymonosulfate (PMS) for efficient CVOC removal in a wet scrubber. Co@NCNT exhibited unprecedented catalytic activity, recyclability, and low Co ion leakage (0.19 mg L-1) for chlorobenzene degradation in a very wide pH range (3-11). The chlorobenzene removal efficiency was kept stable above 90% over Co@NCNT, much higher than that of nonconfined Co@NCNS (45%). The low-valence Co NPs achieved a continuous electron redox cycling (Co0/Co2+ → Co3+ → Co0/Co2+) and greatly promoted the O-O bond dissociation of PMS with the least energy (0.83 eV) inside the channel of Co@NCNT to form abundant HO• and SO4•-. Thus, the deep oxidation of chlorobenzene was achieved without any biphenyl byproducts from the coupling reaction. This study provided a new avenue for designing novel nanoconfined catalysts with outstanding activity, paving the way for the deep oxidation of CVOC waste gas via AOP wet scrubber.

Significant inhibition of secondary pollution in the catalytic oxidation of chloroaromatics over a bifunctional Ru1/CeO2 single-atom catalyst

Single atomic Ru supported CeO2 seems to be a more promising and selective catalyst for chlorobenzene oxidation than RuO2 NPs, which enables the inhibition of HCl conversion to Cl2 and stepwise formation of polychlorinated by-products.

Enhanced Catalytic Performance and Poison Resistance of Cu–Mn–Ce Ternary Mixed Oxide for Chlorobenzene Oxidation

Enhanced Catalytic Performance and Poison Resistance of Cu–Mn–Ce Ternary Mixed Oxide for Chlorobenzene Oxidation

Boosting SO2‑tolerant oxidation of Hg0 and chlorobenzene over MnCo2O4@TiO2 catalyst via constructing shielding effects

Currently, it was still challenging to improve the SO2-tolerant catalytic oxidation of Hg0 and chlorobenzene in flue gas. Herein, we developed a MnCo2O4@TiO2 core–shell material that employed a self-shielding mechanism to prevent sulfate deposition. The optimal MnCo2O4@TiO2-2 catalyst achieved 100 % Hg0 removal efficiency at 250 °C under 150–600 ppm SO2, and also showed enhanced SO2 resistance during chlorobenzene conversion at 275 °C. The strong interaction between MnCo2O4 and TiO2 facilitated the electronic transfer from MnCo2O4 to TiO2, thereby producing more Co3+ and maintaining the high reactivity. Further, the mesoporous TiO2 layer facilitated the generation of moderate acid sites, improved the distribution of surface oxygen species, and weakened SO2 adsorption on catalyst. Under the protection of mesoporous TiO2 layer, the generation of Mn/Co sulfates could be inhibited effectively. In particular, the suitable TiO2 shell balanced the chemical adsorption and oxidation processes of Hg0 on the catalyst. This enhancement led to improved single Hg0 removal efficiency and SO2-tolerant Hg0 removal performance. During chlorobenzene degradation in presence of SO2, the oxidation path of chlorobenzene on MnCo2O4@TiO2 occurred via chlorobenzene → phenolates → maleates → formates/acetates → CO2 and H2O. Although sulfate formation would cover the active surface and inhibit the reaction path, the TiO2 shell could attenuate this negative effect. This study provided a new approach for the development of SO2-tolerant transition metal oxide with superior performance, holding significant academic and practical value.

Highly efficient MnOx catalysts derived from Mn-MOFs for chlorobenzene oxidation: The influence of MOFs precursors, oxidant and doping of Ce metal

In this research, we introduce a simple, effective, and eco-friendly approach for preparing MnOx materials with a hierarchical porous structure and apply it to the catalytic oxidation of chlorobenzene. In this method, different Mn-based MOFs are used as templates, and MnOx materials with various morphologies and structures are prepared through an alkaline hydrolysis-oxidation method. Different Mn-MOF precursors, oxidants and doping of different metals have a considerable influence on the structural morphology of the obtained MnOx materials. Through adjusting the structural morphology, it is conducive to transfer, diffusion and enrichment of chlorobenzene during the reaction process, and improving the reaction activity. MnO2-74 catalyst derived from Mn-MOF-74 in the presence of H2O2 showed the best catalytic activity (T90 = 174 °C). The exceptional catalytic efficiency is attributed to its large specific surface area, mesoporous structure, better low-temperature reducibility, sufficient acidic sites, and enhanced oxygen activation ability. The primary cause of the decrease in catalytic activity is the existence of surface carbon and inorganic chlorine on the catalyst. This green, efficient, and economical preparation method introduces a novel strategy for the traditional derivatization of MOFs to prepare metal oxide materials for the catalytic oxidation of chlorinated volatile organic compounds (CVOCs).