Reaction Mechanism Of Desulfurization Research Articles

Constructing Ni/ZnMOx composite metal oxide adsorbents with excellent desulfurization capacity and thermal stability for reactive adsorption desulfurization

For a long time, Ni/ZnO reactive adsorption desulfurization adsorbent have suffered from low desulfurization performance and poor regeneration efficiency. In this paper, a series of Ni/ZnMOx composite metal oxide adsorbents are prepared by introducing the third metal M (Mn, Co, Mo) into ZnO to enhance their sulfur capacity and thermal stability. By employing DFT calculation, the feasibility of forming composite metal oxides in terms of thermodynamics is confirmed. The formation mechanism of composite metal oxides ZnMOx are finely investigated by XRD and TG-MS. Thanks to the unique structure of ZnMOx, the particle size and thermal stability of ZnO-based adsorbents are improved prominently. Experimental results demonstrate that the addition of the third metal can promote the desulfurization performance. It’s important to note that the desulfurization rate of NZCo and NZMo remains above 98% after high temperature calcination. Through characterizing the adsorbents before and after reaction, the desulfurization reaction mechanism for the Ni/ZnO adsorbent doped with metal M (Mn, Co, Mo) has been proposed. In this mechanism, Ni mainly acts as the desulfurization active centre, while ZnO and the generated composite metal oxides play the role of sulfur adsorbents. This study will provide a new idea for the rational design of conventional Ni/ZnO adsorbent to improve its desulfurization performance and thermal stability.

Effect of rare earth oxides on desulfurization reaction at CaO ceramic surface during smelting of Ni-based superalloy

The surface desulfurization reaction mechanism during smelting of Ni-based superalloys with CaO, REO and CaO-REO ceramic system was investigated. By means of SEM-EDS, EPMA, XRD and XPS, surface layer mixed with CaS and 12CaO·7Al2O3 are found after the reaction between CaO and melt. CaS was the product after desulfurization and 12CaO·7Al2O3 was the intermediate transfer medium connected CaO and alloy melt at 1500 °C. Pure REO have no effect on desulfurization, only react with active element Al in superalloy to form binary oxides of RE and Al. The addition of REO in CaO will change the transfer medium of the interface and cause stratification. The desulfurization product CaS is in the outermost layer and the transfer medium CaxREyAlzOm is in the middle layer.

Highly dispersed tungsten-based quantum dots confined in porous channel induced by ionic liquid with remarkable desulfurization behavior

Developing highly dispersed species has been regarded as an effective approach to achieve high catalytic performance. In this work, tungsten-containing precursor were control confined in porous channel of SBA-15. Profiting from the ionic liquid, quantum dots (such as WO3 QDs) in SBA-15 with highly dispersion can be obtained after thermal treatment. This prepared tungsten-based QDs confined SBA-15 materials can deliver excellent catalytic performance for oxidation desulfurization, in which 100 % DBT can be removed in 1 h. The oxidation desulfurization reaction mechanism is also explored and main active specie is determined to be ·OH. This strategy provides an accessible pathway for preparation of other catalysts with highly dispersed species.

Desulfurization Ability of Blast Furnace Slag Containing High Al2O3 at 1773 K

With the consumption of high-quality iron ore resources, the grade of iron ore raw used in the iron making process has gradually decreased. The high aluminum raw materials has led to an increase in the Al2O3 content in the blast furnace slag, which has affected the normal operation of the blast furnace. The activity of the components involved in the desulfurization reaction is an important factor affecting the desulfurization process. In this paper, the effects of B(w(CaO)/w(SiO2)) and w(MgO)/w(Al2O3) on the desulfurization ability of a CaO-SiO2-MgO-Al2O3 quaternary blast furnace slag system were studied by using a double-layer graphite crucible to simulate the process of molten iron dropping through the slag at 1773 K. The desulfurization reaction mechanism of high alumina blast furnace slag is explained from the aspects of slag structure and component activity, which provides a theoretical basis for the reasonable selection of a slag making system under the condition of a high alumina content. The effects of different B and w(MgO)/w(Al2O3) on the slag structure 2343 analyzed by Fourier transform infrared spectroscopy (FT-IR). The results show that when w(MgO)/w(Al2O3) = 0.50 and w(Al2O3) = 20%, the desulfurization ability and MgO activity of slag increased with the increase of B; when w(Al2O3) = 20% and B = 1.30, the desulfurization ability and MgO activity of the slag increased with the increase of w(MgO)/w(Al2O3). The FT-IR analysis showed that with the increase of B or w(MgO)/w(Al2O3), the dissociated free oxygen ions (O2−) in the slag increased, and the dissociated free oxygen ions (O2−) interacted with the bridging oxygen (O0) of silicate, which made the complex Si-O structure in the slag gradually depolymerize and increase the desulfurization ability.

Anthracene-Based Highly Selective and Sensitive Fluorescent "Turn-on" Chemodosimeter for Hg2.

Three π-extended anthracene-bearing thioacetals (1–3) have been synthesized, and their fluorescence “turn-on” responses to Hg2+ ions are studied. The chemodosimetric fluorescence-sensing behavior and their resulting hydrolysis via a desulfurization reaction mechanism leads to the formation of highly fluorescent respective aldehyde substitutions. Furthermore, this mechanism was supported by increase in the quantum yields of their resulting aldehydes and is correlated to their molecular substitution. The chemosensors 1–3 have exhibited to be promising receptors toward Hg2+ ions in the presence of other competitive metal ions. Moreover, the detection limits of 1–3 have been found to be in the nanomolar range (94, 59, and 235, respectively). Fluorescence microscopic imaging studies show that 1–2 have been found to be effective for fluorescence imaging in live cells. Moreover, compounds 1–3 act as potential candidates for the detection of Hg2+ in environmental and biological systems as well as real samples.

Reactive adsorption desulfurization of NiO and Ni0 over NiO/ZnO-Al2O3-SiO2 adsorbents: role of hydrogen pretreatment.

Reactive adsorption desulfurization (RADS) of Fluidized Catalytically Cracked (FCC) gasoline on reduced and unreduced NiO/ZnO–Al2O3–SiO2 adsorbents was studied. Various characterizations such as powder X-ray diffraction (XRD), H2-temperature-programmed reduction (H2-TPR), the H2/O2 pulse titration (HOPT), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) are used to evaluate the effects of hydrogen pretreatment of the adsorbents. XRD and HOPT results indicate that NiO is hard to be reduced to Ni0 under the conditions of RADS. H2-TPR shows that NiO might be reduced to Ni0 at the temperature of 598 °C, much higher than the temperature of RADS. The Ni 2p3/2 spectrum of Ni0 is not observed for the reduced adsorbent, but the main peak of Ni 2p3/2 of NiS is found for the spent adsorbent. The unreduced NiO/ZnO–Al2O3–SiO2 adsorbent performs a better desulfurization than the reduced adsorbent at the beginning of desulfurization process. NiO and Ni0 are assumed as the main active components and present a good desulfurization ability in RADS. Finally, a change in the RADS mechanism is presented and discussed.

In situ hydrothermal preparation and photocatalytic desulfurization performance of metallophthalocyanine sensitized SnO2

Photocatalytic oxidation technology has been demonstrated to be an effectively method to remove thiophene from fuel. Herein, metallophthalocyanine/SnO2 (MTcPc/SnO2) composites were synthesized by a facile “in situ hydrothermal” technique, utilizing Sn(OH)4 and MTcPc as the precursors. The crystal structure, morphology and chemical environment of the catalysts were respectively confirmed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Photocatalytic activities of MTcPc/SnO2 composites were evaluated by the oxidation of thiophene in fuel under visible light with O2 as the oxidant. Compared with pure SnO2, MTcPc/SnO2 presented a significantly enhanced photocatalytic activity for the degradation of thiophene in fuel under visible irradiation. The desulfurization reaction mechanism by molecular oxygen was proposed to be the formation of the SnO2/ZnTcPc–O2 complex.

A new 4-Amino-7-Nitro-2,1,3-Benzoxadiazole (ANBD)-Based Fluorescent Probe for the Detection of Hg2.

Based on the photoinduced electron transfer (PET) principle, 4-amino-7-nitro-2,1,3-benzoxadiazole (ANBD) has been used as a fluorophore to develop a new fluorescent probe, 4-(2-N,N-dimethylthioacetamide)amino-7-nitro-2,1,3-benzoxadiazole (2), for the detection of Hg2+. Upon the addition of Hg2+, a 46-fold fluorescence enhancement occurs. Moreover the probe 2 exhibits a high selectivity and sensitivity to Hg2+, even in the presence of other common metal ions. Under optimal reaction conditions, a good linearity can be obtained in the range of 0.5-2.5μM, and the detection limit is 0.05μM. In addition, the desulfurization reaction mechanism is proposed based on electrospray ionization mass spectrum. The present study is not only a supplement to the detection method of Hg2+, but also a merit to the development of ANBD-based fluorescent probes.

Wet removal of sulfur dioxide and nitrogen oxides from simulated flue gas by ca(ClO)2 solution

To study the simultaneous removal of Sulfur Dioxide (SO2) and Nitrogen Oxides (NOx) from simulated flue gas by wet method, a bubbling device containing calcium hypochlorite (Ca(ClO)2) solution was used in the experiments. In the first place, thermodynamic analysis was conducted to determine the depth of reaction process, and the reaction mechanism of desulfurization and denitration was proposed. After that, experimental results exhibited that SO2 could be removed by Ca(ClO)2 solution completely while the removal efficiency of NOx was 41.2%. Moreover, on the basis of high SO2 removal efficiency, the effects of various factors on the removal efficiency of NOx, such as: the height of liquid layer, Ca(ClO)2 concentration, reaction temperature, initial pH value, O2 percent, SO2 concentration, and additives were investigated, respectively. Finally, simultaneous removal of SO2 and NOx under the optimized conditions were investigated, SO2 removal efficiency of 100% and NOx removal efficiency of 85.9% were achieved. The analysis of reaction products indicated that the main anions in the liquid phase were and . © 2015 American Institute of Chemical Engineers Environ Prog, 34: 1586–1595, 2015

Desulfurization and denitrogenation from flue gas using Fenton reagent

The experiments of simultaneous desulfurization and denitrogenation from flue gas were carried out at a bubbling reactor with Fenton reagent. The effects of reaction temperature, concentration of each component in Fenton reagent, initial pH value, gas flow, and initial concentrations of SO2 and NO in flue gas on the simultaneous removal of SO2 and NO were investigated systematically. The simultaneous removal efficiencies of 100% for SO2 and more than 90% for NO were obtained under the established optimal experimental conditions, i.e., 328K, 0.02m3/h (0.1MPa, 328K) of flue gas flow, 11.0% (w/w) of H2O2 concentration, 2.8mmol/L of Fe(II) concentration, and 3.0 of the solution pH. According to the characterizations of the products, the comparison of the standard electrode potentials and the relative references, the reaction mechanism of desulfurization and denitrogenation was revealed. Additionally, a variety of thermodynamic parameters were figured out based on the basic thermodynamic principle to verify the feasibility of the oxidation reactions of SO2 and NO with Fenton reagent.

Transformation of RN=CHPh to R(R′3Si)NCH2Ph in the Catalytic Desulfurization of Secondary Thioamide with R′3SiH Promoted by an Iron Complex

ABSTRACTThe reaction of imine (RN=CHPh) with hydrosilane (R′3SiH) in the presence of CpFe(CO)2Me (1) revealed the formation of a hydrosilylation product (R(R′3Si)NCH2Ph). The findings helped us to understand the reaction mechanism of desulfurization of secondary thioamide catalyzed by 1 to give the corresponding imine and amine as a major and minor product, respectively.

A new rhodamine-based fluorescent chemosensor for mercury in aqueous media

Abstract A new fluorescent “on–off” chemosensor for Hg2+ initiated by a derivative of rhodamine B was designed and synthesized. Compound 1 exhibited high sensitivity and selectivity for Hg2+ over other commonly coexistent metal ions in aqueous media. Upon the addition of Hg2+, the spirocyclic ring of probe is opened and a significant enhancement of visible color and fluorescence in the range of 500–600 nm is observed. The colorimetric and fluorescent response to Hg2+ can be conveniently detected by the naked eye, which provides a facile method for visual detection of Hg2+. From the molecular structure and spectral results of 1, an irreversible, hydrolysis, desulfurization reaction mechanism is proposed.

Adsorption and desulfurization reaction mechanism of thiophene and its hydrogenated derivatives over NbC(001) and NbN(001): an ab initio DFT study

Herein, we present periodic DFT-based calculations on the thiophene and its H-derivatives adsorption and reaction pathways over niobium carbide and nitride cubic face-centered (001) surfaces.