Benzene Oxidation Process Research Articles

Assessing the environmental risk of fire and explosion events associated with chemical process routes

The development of inherently environmentally friendly chemical process plants is one approach to reduce or avoid potential harmful environmental consequences that could occur due to chemical plant accidents. This can be achieved by selecting the chemical process route involving the least environmental risk, during preliminary design stage. To assist the route selection process a risk-based index called Inherent Environmental Risk Index for Fires and Explosions (F&E-IERI) is proposed. The F&E-IERI assesses and ranks chemical process routes considering environmental impacts caused by accidental fires and explosions that could occur in a chemical plant. This index considers the environmental impact magnitude, fire or explosion event occurrence frequency, and the environmental element vulnerability. A higher index associated with the route indicates a higher environmental risk. The proposed index has been applied in four possible routes to produce acetone. The p-diisopropyl benzene oxidation process route to produce acetone showed the lowest F&E-IERI value indicating the route having the lowest environmental risk.

Development of a Kinetic Model for the Direct Oxidation of Benzene to Phenol by Oxygen in Dielectric Barrier Discharge

A simplified model of the process of benzene oxidation by oxygen in a dielectric barrier discharge has been developed. A kinetic scheme of oxidation is proposed that reflects the real chemistry of the process. The simulation results confirm the earlier assumptions about the main stages of the benzene oxidation process with oxygen.

Lattice Compressive Strain of Co3O4 Induced by Synthetic Solvents Promotes Efficient Oxidation of Benzene at Low Temperature.

A series of Co3O4 with different surface defective structures were prepared by the solvothermal method and tested for the activity of benzene oxidation. The characterizations revealed that the synthetic solvent had a dramatic effect on the composition of Co3O4 precursors as well as the physicochemical properties of Co3O4. Although all Co3O4 exhibited a cubic spinel structure, Co3O4 prepared with triethylene glycol (Co-TEG) had the highest compressive strain due to the nature of high viscosity of triethylene glycol. These in turn affected the surface chemical structure and the low-temperature redox properties. Co-TEG exhibited the best benzene oxidation activity and showed excellent stability and good water resistance. In situ diffuse reflectance infrared Fourier transform spectroscopy was used to study the oxidation process of benzene. It was found that Co-TEG with more defective structures had abundant surface adsorbed oxygen and active lattice oxygen, which promoted the conversion of benzene and the corresponding intermediates at low temperature.

Investigation on the effect of water addition on benzene oxidation over palladium-oxide nanoparticle via ReaxFF molecular dynamics

Additives in the benzene oxidation process will have a greater impact. The oxidation processes of benzene (C6H6) with water addition are studied by reactive force field molecular dynamics (ReaxFF MD). The possible reaction pathways of C6H6 and the effect of water addition at 2000 K are discussed. The influence of water addition is investigated, the results show that the types of product are basically the same no matter with or without the water addition. But the addition of water will cause the increase of hydroxyl groups, occupying the active sites that should belong to the oxygen group, thus inhibits the oxidation of C6H6. And the hydroxyl group mainly affects the benzene oxidation process by affecting the oxidation of the carbon components in benzene, but has little effect on the dehydrogenation of benzene. This may be helpful to understand the water inhibition during the oxidation process that found in the experiments.

Electric field assisted benzene oxidation over Pt-Ce-Zr nano-catalysts at low temperature

A novel catalytic system for benzene oxidation at low temperature is constructed by combining electric field with Pt-Ce-Zr nano-catalyst. The 1 wt% Pt/Ce0.75Zr0.25O2 catalyst assisted by electric field shows the best catalytic performance with 90% benzene conversion at 96.5 °C and excellent water resistance. The effect of electric field on catalysts and catalytic process is comprehensively investigated. The results of XRD, TEM, XPS and H2-TPR reveal that the electric field show negligible influence on the crystal structure and surface morphology of the catalyst, but it can lead to more oxygen vacancies. Therefore, more adsorbed oxygen with higher activity will be produced on the catalyst surface. The redox performance is improved due to the fact that valence distribution of Pt is changed in forms of more active sites composed of high valence oxides (PtO) generated in electric field. In situ DRIFTS is used to investigate the oxidation process of benzene and the results prove that electric field could accelerate the production and consumption of intermediate products, and produce new intermediate products such as carboxylic acid species, indicating that the introduction of electric field may open up a new rapid reaction path and promote the activation of benzene at low temperature.

Insights into the active sites of chlorine-resistant Pt-based bimetallic catalysts for benzene oxidation

Since the Pt-based catalysts often suffer severe deactivation by chlorine, development of a catalyst with good activity and chlorine-resistant ability is of importance in effectively controlling emissions of (chlorinated) volatile organic compounds ((C)VOCs). In this work, we prepared the Al2O3-supported bimetallic catalysts with narrow metal particle size distributions and their application in benzene oxidation. It is found that PtW/Al2O3 showed the highest catalytic activity and the lowest activation energy. The characterization results were well correlated with the catalytic activities, and a Pt–MOx (M = W, Mo) bimetallic synergistic effect was proposed. In situ FTIR studies reveal that the transformation from phenol to benzoquinone was the key step in benzene oxidation process. The influence of 1,2-dichloroethane (DCE) on catalytic activity for benzene oxidation of the as-obtained samples was also examined. It is demonstrated that there was a competitive adsorption between benzene and DCE molecules, and the DCE exerted an inhibitive effect on benzene oxidation. We conclude that excellent catalytic performance of the bimetallic sample was associated with its good abilities to adsorb and activate benzene on small ensembles of the MOx in proximity contact with Pt as well as the strong interaction between the highly dispersed metallic Pt species and the MOx clusters (which led to enhancement in anti-deactivation of the Pt species under the oxygen-rich and Cl-containing reaction conditions). We are sure that the present work can provide an idea for understanding the nature of bimetallic active sites and rationally designing the efficient bimetallic catalysts for the oxidative removal of VOCs.

Photocatalytic oxidation process for treatment of gas phase benzene using Ti3+ self-doped TiO2 microsphere with sea urchin-like structure

Photocatalytic oxidation processes (PCO processes) are a promising technology for controlling the pollution of working environments, namely, the low concentrations of volatile organic compounds (VOCs) generated in industrial processes, and improving the efficiency of this process is an important issue. In this study, the photocatalytic oxidation of gas-phase benzene was carried out with TiO2 microspheres with a sea-urchin-like structure, and the effect of Ti3+ self-doping on the catalytic performance of TiO2 was investigated in detail. The structures and properties were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, UV–visible diffuse reflectance spectroscopy, electron spin resonance, scanning electron microscopy, and high-resolution transmission electron microscopy. Ti3+ ions were formed in TiO2 microspheres by heating under vacuum, which improved the catalytic performance of TiO2 for the complete oxidation of benzene to CO2 and CO. The photoelectrochemical measurements showed that the incorporation of Ti3+ into TiO2 microspheres reduced electron-hole recombination and increased the light absorption capacity, which contributed to improving the photocatalytic activity. In situ FTIR spectroscopic studies revealed that in the benzene oxidation process, Ti3+ self-doped TiO2 microspheres suppressed the formation of strongly bound byproduct compounds on the TiO2 surface, which affected the rate of benzene oxidation. Thus, the Ti3+ self-doped TiO2 microspheres are effective catalysts for efficient use of UV light and suppression of catalyst deactivation during benzene oxidation.

Insight into the combined catalytic removal properties of Pd modification V/TiO2 catalysts for the nitrogen oxides and benzene by: An experiment and DFT study

The effect of Pd on the combined catalytic removal properties of Vy/TiO2 for benzene and NOx has been investigated. It was found that the benzene conversion, NOx conversion and CO2 selectivity of Vy/TiO2 catalysts improved significantly after the modified by Pd at a space velocity (SV) of 12,000 mL·g−1·h−1, especially the Pd0.12V4/TiO2 catalyst. Accor ding to the characterization and calculation results, additional reaction active sites on anatase-TiO2 surfaces were provided after the addition of 1.2%Pd and facile redox cycle (2V4+ + Pd2+ ↔ 2V5+ +Pd0) can be explained for the excellent benzene and NOx catalytic performance of Pd0.12V4/TiO2 catalyst. The possible catalytic removal transformation mechanism of benzene and NOx by Pd0.12V4/TiO2 catalyst was proposed, respectively. Additionally, in the combined catalytic removal process of NOx and benzene, NO2 and NO may become the O-materials for benzene oxidation process over Pd0.12V4/TiO2 catalyst, and NOx is reduced to N2.

The oxidation mechanism investigation of benzene catalyzed by palladium nanoparticle: A ReaxFF molecular dynamics

The precious metal palladium has exhibited well catalytic effect on soot oxidation. In order to study the catalytic mechanism of palladium on soot oxidation, the oxidation process of benzene (C6H6), an important soot precursor, on the surface of palladium (Pd) particles is studied by reactive force field molecular dynamics (ReaxFF MD). The possible reaction pathways of C6H6 oxidation and state conversion of metal Pd during the oxidation process are discussed. The results show that C6H6 is mainly oxidized through dehydrogenation, until the hydrogen number is less than 3, then the oxygenation reaction gradually dominates. The intermediate species, most of which is C6HO. For the important step of C6H6 oxidation, the ring-open is more likely to occur at the oxygen-containing site (accounted for 88%), and C2 species are mainly final products under current simulation conditions. The oxygen migration is then investigated, and the results show that the dissociated oxygen will entrance the Pd-lattice with the gaseous oxygen consumed, and finally return to the outer-surface. It is interesting to note that the oxygen in hydrocarbon oxidation products mainly (over 57%) comes from the Pd-inner lattice even during the period of the dissociated oxygen atoms keeping balance. This may be helpful to understand the coexistence of Pd and PdO during the oxidation process that found in the experiments.

Electrochemical oxidation of gaseous benzene on a Sb-SnO2/foam Ti nano-coating electrode in all-solid cell

An all-solid cell with a solid polymer electrolyte was applied to electrochemical oxidation of low-concentration indoor gaseous aromatic pollution. Antimony-doped tin dioxide nanocoatings deposited on a titanium foam substrate (Ti/Sb-SnO2) with different Sb/Sn ratios (4.8–14.0 mol%) and loading weight of Sb-SnO2 (4.4–7.7 mg cm-2) were used as dimensionally stable anodes. Sn and Sb were homogeneously dispersed on the substrate, and a crack-free nanocoating was built when the loading of nanocoating was increased to 6.3 mg cm-2. The activity tests for oxidation of benzene showed that 40 ppm gaseous benzene was converted to CO2 with high selectivity (85%) at the low cell voltage of 2.0 V in this all-solid cell. The conversion of benzene was greatly increased from 30% to 100% upon increasing the Sb/Sn ratio of the nanocoating from 4.7 mol% to 14.0 mol%. With the increase of nanocoating loading (Sb/Sn = 14.0 mol%) from 6.3 to 7.7 mg cm-2, the conversion of 100 ppm benzene was increased from 70% to 100%. Cyclic voltammetry revealed that high Sb content in the oxide nanocoating increased the overpotential and current intensity of the oxygen evolution reaction. The large outer charge qo∗ related to the electroactive surface of the SS-7.7/Ti3 electrode was up to 305.3 mC cm−2, which were responsible for its excellent electrochemical performance in the benzene oxidation process. Our studies provide a potential method for removal of indoor VOCs at ambient temperature.

Electrochemical oxidation of volatile organic compounds in all-solid cell at ambient temperature

The catalytic elimination of indoor low-concentration gaseous benzene, toluene and o-xylene (BTX) under ambient conditions remains a challenge. Here, we firstly report a facile gas-solid interface electrochemical oxidation method for the mineralization of BTX at ambient temperature. A membrane electrode assembly (MEA) was used in the all-solid cell. An antimony-doped SnO2 catalyst was coated onto the surface of a porous Ti foam to act as the anode, and reduced graphene oxide/carbon fiber paper-supported Pt (Pt/rGO/CFP) was employed as the cathode. The activity test results showed that 100% BTX conversion to CO2 (85–99%) and CO (15–1%) was achieved within 4–5 h at the optimal cell voltage of 2.0 V at relative humidity 60%. Proton-transfer-reaction time-of-flight mass spectrometry and Fourier transform infrared spectroscopy results showed that no organic byproducts could be detected in the anodic reservoir. OH generated from water vapor discharge was measured directly by laser-induced fluorescence techniques. The electrochemical behavior of the working electrode in benzene solutions with different concentrations revealed that the benzene oxidation process was mainly mediated by OH at the onset potential of OER (2.0 V vs Ag/AgCl, saturated KCl). Our findings provide evidence that the gas-solid interface electrochemical oxidation method can be a potential method for ambient VOC destruction in indoor air environments.

Study of Humidity Effect on Benzene Decomposition by the Dielectric Barrier Discharge Nonthermal Plasma Reactor**supported by National Natural Science Foundation of China (Nos. 11205007 and 11205029)

The humidity effects on the benzene decomposition process were investigated by the dielectric barrier discharge (DBD) plasma reactor. The results showed that the water vapor played an important role in the benzene oxidation process. It was found that there was an optimum humidity value for the benzene removal efficiency, and at around 60% relative humidity (RH), the optimum benzene removal efficiency was achieved. At a SIE of 378 J/L, the removal efficiency was 66% at 0% RH, while the removal efficiency reached 75.3% at 60% RH and dropped to 69% at 80% RH. Furthermore, the addition of water inhibited the formation of ozone and NO2 remarkably. Both of the concentrations of ozone and NO2 decreased with increasing of the RH at the same specific input energy. At a SIE of 256 J/L, the concentrations of ozone and NO2 were 5.4 mg/L and 1791 ppm under dry conditions, whereas they were only 3.4 mg/L and 1119 ppm at 63.5% RH, respectively. Finally, the outlet gas after benzene degradation was qualitatively analyzed by FT-IR and GC-MS to determine possible intermediate byproducts. The results suggested that the byproducts in decomposition of benzene primarily consisted of phenol and substitutions of phenol. Based on these byproducts a benzene degradation mechanism was proposed.

Photodegradation of gaseous C6H6 using CdO+CdTiO3 and TiO2 thin films obtained by sol–gel technique

Abstract In this work, TiO2 and CdO + CdTiO3 multicomponent oxide thin films growth was performed with different Ti/Cd ratios (0, 0.20, 0.49, 0.60, 0.65, 0.70 and 1) by the sol–gel route in order to degrade benzene in gas phase with an initial concentration level of 110 ± 10 ppm, under different conditions of relative humidity (RH): 25%, 50% and 80% in a batch type reactor, at room temperature. The results showed a degradation near to 100% at t = 75 min, using the CdO + CdTiO3 multicomponent oxide semiconductor with a Ti/Cd ratio of 0.65. On the other hand, the TiO2 thin films reached only a degradation of 70% in t = 240 min. A decrease of the oxidation process of benzene was observed in all films studied, as the relative humidity increased.

Electrochemical oxidation of benzene on boron-doped diamond electrodes

This work presents an electrochemical investigation of the benzene oxidation process in aqueous solution on boron-doped diamond (BDD) electrodes. Additionally, in order to determine the main products generated during the oxidation process, electrolysis and high performance liquid chromatography experiments were carried out. The complete degradation of this compound was performed aiming to a further application in waste water treatment. The cyclic voltammetry studies indicate that benzene is irreversibly oxidized in acid medium (H 2SO 4 0.5 M) on the BDD electrode surface at 2.0 V versus Ag/AgCl in a diffusion controlled process. During the cycling, other products are generated, and a pair of peaks was observed that can be associated with the oxi-reduction of anyone of the following species: hydroquinone, benzoquinone, resorcinol or catechol. The electrolysis experiments were carried out at 2.4 and 2.5 V on the BDD electrode surface in a solution containing 1 × 10 −2 M of benzene (below the saturation concentration in aqueous solution), for 3 and 5 h, respectively. The main products measured were: hydroquinone, resorcinol, p-benzoquinone, catechol and phenol. The complete electrochemical benzene degradation was performed in the electrolysis experiments using a rotating BDD disc electrode (2.5 V for 5 h) and the main products detected were all measured at concentrations lower than 10 −5 M in this condition. The boron-doped diamond electrode had proved to be a valuable tool for the electrochemical degradation of the benzene, a very stable chemical compound.

SD continues to make news in maleic anhydride. ICI again selects SD's benzene oxidation process.

SD continues to make news in maleic anhydride. ICI again selects SD's benzene oxidation process.