Incipient Impregnation Method Research Articles

Removal of Greenhouse Gas (N2O) by Catalytic Decomposition on Natural Clinoptilolite Zeolites Impregnated with Cobalt

In this work, natural zeolite, clinoptilolite were treated with acid (0.6 N HCl; code “Z-AM”) and alkaline solutions (1.5 N NaOH; code “Z-BM”). Thereafter, non-modified (as parent zeolite; code “Z-NM”) and modified zeolites were impregnated with cobalt using wet incipient impregnation method (Codes: “Z-AM-Co-0.5,1,1.5”, “Z-BM-Co-0.5,1,1.5”, “Z-NM-Co-0.5,1,1.5”). The prepared zeolites were characterized by XRD, ICP-OES, BET, NH3-TPD and H2-TPR. Also, these materials were studied for the catalytic decomposition of nitrous oxide (a greenhouse gas) to nitrogen and oxygen. The obtained results showed that the applied modifications had no significant influence (destruction) on the main structure of the zeolites including clinoptilolite, quartz and cristobalite. In addition results showed that acid modification increases the nitrous oxide decomposition because of surface area increment and the higher amount of CO/Al as well as the strong acid sites of this zeolite compared to other zeolites. Also, experiments showed that the main active species in nitrous oxide decomposition are mono-atomic (Co2+ cations) and other species exhibit much lower activity. In conclusion, natural clinoptilolite zeolites treated with acid and impregnated with Cobalt (Z-AM-CO-1.5) could be a very effective and cost-benefit catalyst for reducing N2O as a greenhouse gas, due to its very low price, high chemical stability and high availability.

Synthesis of lanthanide series (La, Ce, Pr, Eu & Gd) promoted Ni/γ-Al2O3 catalysts for methanation of CO2 at low temperature under atmospheric pressure

A series of Ni/γ-Al2O3 and 5%X-12%Ni/γ-Al2O3 (X=La, Ce, Pr, Eu & Gd) catalysts was synthesized by using aqueous incipient impregnation method for methanation of carbon dioxide. 5%Pr-12%Ni/γ-Al2O3 showed the highest CO2 conversion of 98.2% with 100% CH4 selectivity at 300°C for investigated reaction conditions. The catalyst activity was also tested for 48h which showed the stability of synthesized catalyst for CO2 conversion and CH4 selectivity. The TEM, BET and XRD analysis demonstrated the high metal dispersion, no remarkable effect on textural properties of 5%Pr-12%Ni/γ-Al2O3 as compared to 12%Ni/γ-Al2O3 and phases of alumina, nickel and lanthanide series promoters for γ-Al2O3 support, 12%Ni/γ-Al2O3 and 5%X-12%Ni/γ-Al2O3 catalysts.

Plasma-treated Ce/TiO2–SiO2 catalyst for the NH3-SCR of NOx

ABSTRACTCe/TiO2–SiO2 catalysts with different Ti/Si molar ratios are prepared by the incipient impregnation method and their NH3-SCR activities are evaluated at 100–500°C on a fixed reactor. The Ce/TiO2–SiO2 (3/1) catalyst, modified by non-thermal plasma (NTP) treatment and then activated by thermal treatment at 500°C for 4 h, exhibits best performance. Comprehensive deNOx performance of the catalyst is evidently improved and its efficiency reaches up to 99.21% at 350°C. NO conversion efficiency of the treated catalyst doped with K remains about 90.23% at 300°C and the catalyst also shows improved activity at lower temperatures. Various characterization methods show that the activity enhancement is correlated only with NTP treatment, as it increases the number of Ce3+ species, which generates more chemisorbed oxygen, leads to improved dispersion of Brønsted and Lewis acidic sites and finally has an inherent etching effect.

Direct Convertion Of Methane To Liquid Hydrocarbons Using HZSM-5 Zeolite Catalyst Loaded With Metal

Methane is the main component of natural gas and this research provides the platrorm on the potential of utilizing natural gas, found abundant in Indonesia, to form gasoline. The objectives of the research are to modify HZSM-5 zeolite with a series of transition metals (Cr, Mn, Co, Ni, Cu, and Pt) and Ga , and to evaluate the performances of these catalyst for the single step conversion of methane to gasoline. The oxidation of methane were carried out in a micro-packed bed reactor at atmoepheric pressure, temperature 800 0C, F/W = 10440 ml/g.hr and 9%vol O2. Metals were loaded into the HZSM-5 zeolite by the wetness incipient impregnation method. The characterization results indicated that the ionic metals (Mn+) occupy the H+ position of HZSM-5 and metal loaded HZSM-5. Ni- HZSM-5, Cu- HZSM-5 and Ga- HZSM-5 gave a high methane conversion and high gasoline selectivity. Among the catalyst samles tested, Cr- HZSM-5 showed the highest Research Octane Number (RON=86). These catalyst have the potential to convert natural gas to C5+ liquid hydrocarbons provided the oxidation, dehydration and oligomerization function of the metals are in balance.Keywords : direct conversion, methane, liquid hydrocarbons, metal, HZSM-5

Effect of different precursor species on the metal dispersion of a Ni/\u03b3-Al2O3 adsorbent for sulfur adsorption

Nickel adsorbents supported on the γ-Al2O3 with different nickel precursor species were prepared by the incipient impregnation method to investigate the influence of different precursor species on the metal dispersion and the sulfur capacity of the adsorbents. The adsorbents were characterized by N2 adsorption–desorption, H2 temperature-programmed reduction (TPR), transmission electron microscopy (TEM), O2–H2 chemisorption, and FT-IR of adsorbed pyridine. The sulfur adsorption performance was investigated at ambient temperature and pressure. The results showed that adsorbent’s metal dispersion and sulfur capacity were influenced significantly by the metal precursor species. The adsorbents prepared by nickel nitrate exhibited higher sulfur capacity and metal dispersion compared to the adsorbents prepared by nickel formate and nickel acetate. The higher performance of adsorbent prepared by nickel nitrate can be mainly attributed to the relatively more uniform metal dispersion and the smaller particle size of the nickel particles. This study demonstrates that the precursor species is an important factor for affecting the adsorption performance and provides a novel design idea of high metal dispersed catalysts.Graphical abstract

Facet–Activity Relationship of TiO2 in Fe2O3/TiO2 Nanocatalysts for Selective Catalytic Reduction of NO with NH3: In Situ DRIFTs and DFT Studies

Anatase TiO2 nanosheets (TiO2-NS) and nanospindles (TiO2-NSP) have been successfully prepared with F– and glacial acetic acid as structure-directing agents, respectively. The Fe2O3/TiO2-NS and Fe2O3/TiO2-NSP nanocatalysts were prepared by a wet incipient impregnation method with a monolayer amount of Fe2O3. All the catalysts were employed for the selective catalytic reduction of NO with NH3 (NH3-SCR) in order to understand the morphology-dependent effects. It is interesting that the Fe2O3/TiO2-NS nanocatalyst exhibited better removal efficiency of NOx in the temperature range of 100–450 °C, which was attributed to more oxygen defects and active oxygen, acid sites, as well as adsorbed nitrate species based on Raman spectra, XPS, NH3-TPD, NO+O2-TPD, and in situ DRIFTS. The density functional theory (DFT) method was used to clarify the NO and NH3 adsorption abilities over the catalyst models of Fe2O3/TiO2{001} and Fe2O3/TiO2{101}. The results showed that the NH3 adsorption energy over the TiO2{001} (−2.00 eV...

Preparation of Cu-Fe nanocomposites loaded diatomite and their excellent performance in simultaneous adsorption/oxidation of hydrogen sulfide and phosphine at low temperature

Abstract In the study, a variety of supported metal oxide adsorbents were evaluated for simultaneous adsorption/oxidation of hydrogen sulfide (H2S) and phosphine (PH3) from crude acetylene gas at low temperature (80 °C), and the materials were synthesized using incipient impregnation method. Test results showed that the Cu Fe nanocomposites/modified diatomite adsorbent (Cu Fe/MKL) was determined to be the most promising adsorbent for simultaneous removal of H2S and PH3. The removal efficiency of H2S and PH3 may have a strong connection to the variety and amounts of functional groups and active components available as well as calcination temperatures. When the copper and iron loading amounts were 10 wt% and 6 wt% at 450 °C, the Cu Fe/MKL adsorbent achieved the best removal efficiency and had the largest breakthrough adsorption capacity. It kept an impressive efficiency (100%) for 150 min and 60 min for H2S and PH3, respectively, at a relatively low reaction temperature of 80 °C and a GHSV of 10,000 h−1. The adsorbents were also characterized by different methods, such as FT-IR, BET, TGA, XRD, SEM, XPS and in-situ IR. FT-IR results showed that the adsorbents modification by hydrochloric acid can provide more O H, C O and C C groups, which may generate more unsaturated sites to promote the removal performance for H2S and PH3. BET results indicated that the addition of Cu Fe composites did not change the structure of diatomite and it was optimized for simultaneous adsorption/oxidation of H2S and PH3 when the pore size distribution was approximately 7–10 nm. Moreover, XRD and TGA results revealed that metal oxides were detected after calcination, and the main active components available should be Cu Fe nanocomposites. Furthermore, SEM images showed that iron species may play an important role to promote the dispersion of active components. In addition, in-situ IR and XPS analysis indicated that the exhaustion of sample may be determined by the loss of active components and the accumulations of products. It was considered that the excellent performance of adsorbents may be determined by the synergism of function groups, active components and dispersion capacity of them. However, because the components of diatomite were complex, the mechanism was difficult to investigate in this study.

Synthesis of Ni-based catalysts supported on nitrogen-incorporated SBA-16 and their catalytic performance in the reforming of methane with carbon dioxide

SBA-16 molecular sieve was synthesized by soft template method and modified with ammonia under high temperature to obtain the nitrogen-incorporated SBA-16 (SBA-16-N); with SBA-16 and SBA-16-N as the supports, nickel based catalysts (Ni/SBA-16 and Ni/SBA-16-N) were prepared by the incipient impregnation method. The related supports and Ni-based catalysts were characterized by transmission electron microscope, X-ray photoelectron spectroscopy, nitrogen physisorption, carbon dioxide temperature programmed desorption, X-ray diffraction and thermogravimetric analysis; the catalytic performance of Ni/SBA-16 and Ni/SBA-16-N in the reforming of methane with carbon dioxide was comparatively investigated under 500–800°C. The results indicate that after the nitriding modification, the Ni/SBA-16-N catalyst exhibits much higher activity in methane reforming with CO2 and higher selectivity to syngas than the Ni/SBA-16 catalyst without nitridation treatment. During the nitriding modification at high temperature, O atoms in the SBA-16 skeleton are partially replaced by N atoms, which can strengthen the support basicity and the interaction between the support and the nickel nanoparticles. All these may promote the dispersion of nickel nanoparticles on SBA-16-N and the adsorption of CO2 on Ni/SBA-16-N, leading to the improvement of the activity and stability of the Ni/SBA-16-N catalysts in methane reforming with carbon dioxide.

Effect of mesoporosity of bimetallic Ni-Ru-Al2O3 catalysts for hydrogen production during supercritical water gasification of glucose

A well-known problem with metal supported alumina catalysts during gasification processes for H2 formation is catalyst deactivation by coke formation and pore plugging. Poorly controlled catalyst structure with low surface area and microporous structure also accounts for low catalyst activity. This work investigated bimetallic Ni-Ru/Al2O3 catalysts that are both effective and durable for glucose gasification in supercritical water with minimal coke formation. Both non-ionic (Pluronic P-123) and cationic (CTAB) templates were examined for mesoporous alumina synthesis with Ni and Ru loadings and compared with a conventional incipient impregnation method. Gas formation during SCWG catalysis was monitored for hydrogen formation while the catalysts were examined both before and after reaction by a variety of physico-chemical techniques including BET surface area, BJH pore size analysis, XRD, TG-DTA, TPR, TPO, Raman spectroscopy & TEM microscopy. The results showed that templating helped disperse both Ni and Ru particles homogeneously inside the pores of mesoporous Al2O3 catalysts; whereas the impregnated catalyst gave poorer dispersion. Comparing with the impregnation method, a six-fold increase of BET surface area was observed using the one-pot synthesis method. Hydrogen production during glucose gasification increased by 25mol% for both templated catalysts, with the CTAB catalyst showing slightly higher activity. This method provided insignificant coke deposition indicating that the new Ru-Ni/Al2O3 templated catalyst is promising for the development of hydrogen production for an emerging biorefinery.

Effect of Preparation Mode on the Properties of Mn-Na-W/SiO2 Catalysts for Oxidative Coupling of Methane: Conventional Methods vs. POSS Nanotechnology

<p>Reflectance spectroscopic methods the electronic, redox and structural properties of Mn-Na-W/SiO<sub>2</sub> catalysts prepared by the incipient wetness impregnation method and mixture slurry method were studied in detail. Since POSS nanotechnology (POSS = polyhedral oligomeric silsesquioxanes) has attracted attention as tooling for synthesis of catalysts with novel properties and functionalities, we expanded this method for the preparation of Mn-Na-W/SiO<sub>2</sub> catalyst. The physicochemical and catalytic properties of Mn-Na-W/SiO<sub>2</sub> catalysts prepared by conventional methods and POSS nanotechnology were examined comparatively. In all studied Mn-Na-W/SiO<sub>2</sub> catalysts both individual oxides (MnO<sub>x</sub>, WO<sub>3</sub>) and bimetal oxide phases (Na<sub>2</sub>WO<sub>4</sub>, MnWO<sub>4</sub>) are found in addition to oxide particles of high dispersion. The UV-Vis Diffuse Reflectance indicates that Na<sup>+</sup> cations facilitates stabilization of octahedrally coordinated Mn<sup>3+</sup><sub>Oh</sub> cations in the isolated state, while Mn<sup>3+</sup><sub>Oh</sub> promote the disordering of W<sup>6+</sup> cations in the supported system. The Mn-Na-W/SiO<sub>2</sub> prepared using metal-POSS precursors marks out presence of unglobular SiO<sub>2</sub> particles, higher dispersion of MnO<sub>x</sub> and MnWO<sub>4</sub> particles and more easily reducible metal-oxide species. The catalysts prepared by incipient impregnation method and mixture slurry method have practically similar catalytic performance while the catalyst prepared by POSS nanotechnology method shows lower activity and selectivity. At 800‒850 °C the increase of C<sub>2</sub> hydrocarbons yield from 4 to 15% and the rise of molar ratio С<sub>2</sub>Н<sub>4</sub>/C<sub>2</sub>H<sub>6</sub> from 0.2 to 1 are observed when impregnation or mixture slurry method are used for catalyst preparation instead of POSS nanotechnology method.</p>

Novel Fluidizable K-Doped HAc-Li4SiO4 Sorbent for CO2 Capture Preparation and Characterization

A novel fluidizable K-doped HAc-Li4SiO4 sorbent using an incipient impregnation method was prepared in this work. The produced sorbent displayed an excellent CO2 sorption capacity and stability under expected reaction conditions. Glacial acetic acid treatment was first used to modify the Li4SiO4 sorbent microstructure. Following this step, an incipient impregnation method was applied to dope potassium onto the sorbent in order to further enhance the sorbent sorption capacity. This novel K-doped HAc-Li4SiO4 sorbent was characterized using X-ray diffraction, N2 adsorption–desorption, CO2 temperature-programmed carbonation (CO2-TPC), and CO2 temperature-programmed decarbonation (CO2-TPDC) analyses. The experimental results showed that the CO2 sorption capacity of the K-doped HAc-Li4SiO4 sorbent is approximately 100 cm3 STP CO2/g sorbent. This was five times that of the Li4SiO4 sorbent. Furthermore, the cyclic test of the K-doped HAc-Li4SiO4 sorbent demonstrated it to be high and stable for CO2 capture.

Liquid phase hydrogenation of adiponitrile over acid-activated sepiolite supported K–La–Ni trimetallic catalysts

Acid-activated sepiolite (ASEP) supported K–La–Ni trimetallic catalysts were prepared and tested in the liquid phase hydrogenation of adiponitrile (ADN). The sepiolite was treated with dilute hydrochloric acid solution to obtain ASEP, ASEP supported K–La–Ni trimetallic catalysts were prepared by the incipient impregnation method and characterized by nitrogen adsorption–desorption, temperature programmed reduction, hydrogen chemisorption, powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy and energy dispersive X-ray. It was revealed that potassium could inhibit the formation of the 1-azacycloheptane by-product by neutralizing some acid sites on the catalyst, and the potassium and lanthanum could efficiently reduce nickel particles size and improve its dispersion. Sepiolite treated with hydrochloric acid increases the number of silanol groups (Si–OH) on the sepiolite surface, which is helpful to nickel particles adsorption and dispersion. ASEP supported K–La–Ni trimetallic catalysts (K–La–Ni/ASEP) present better catalytic performance under mild reaction conditions of 373 K and 2.0 MPa, the ADN conversion reaches to 90.03 %, the selectivity to 6-aminocapronitrile and hexamethylenediamine is up to 90.22 %.

Structural and microstructural analysis of different CaO–NiO composites and their application as CO2 or CO–O2 captors

In this work, CaO–NiO mixed oxide powders were prepared by mechanical mixing and incipient impregnation methods. The samples were characterized structurally and microstructurally, where it was determined that microstructural properties changed depending on the NiO addition method. The CO2 and CO–O2 capture evaluations were performed in a thermogravimetric analyzer. These results showed that the presence of nickel significantly modified the CO2 and CO capture processes. In both cases, the CO2 or CO capture temperature was shifted to lower values in the CaO–NiO composites in comparison to the CaO sample. Nevertheless, the carbon oxide captures seemed to decrease as a function of the nickel addition. It was associated to the nickel superficial deposition over the CaO particles. On the other hand, the CO–O2 oxidation was importantly enhanced and maintained, for long times, with the presence of nickel independently of the calcium oxide carbonation process.

Synthesis of a highly dispersed Ni/Al2O3 catalyst with enhanced catalytic performance for CO2 reforming of methane by an electrospinning method

An alumina (Al2O3) nanofibre supported nickel (Ni) catalyst has been successfully synthesized using electrospinning technique and systematically characterized by inductively coupled plasma (ICP), scanning electron microscopy (SEM), N2 sorption, X-ray diffraction (XRD), high resolution-transmission electron microscopy (HR-TEM), temperature-programmed oxidation (O2-TPO) and X-ray photoelectron spectroscopy (XPS) measurements. In the electrospinning synthesized Ni/Al2O3 catalyst, metallic Ni nanoparticles were highly dispersed over Al2O3 nanofibres with an average particle size of 3.4 nm. Compared with the Ni/Al2O3 catalyst conventionally prepared by the incipient impregnation method using commercial Al2O3 powder as the support, the electrospun Ni/Al2O3 catalyst exhibited improved metal dispersion, leading to higher activity and superior coke resistance in carbon dioxide (CO2) reforming of methane. The present work demonstrates that electrospinning is a simple and efficient technique for the fabrication of supported catalysts with improved metal dispersion and enhanced catalytic performance.

Glycerol effect on the inhibition of spontaneous combustion of subbituminous coal

Factors favoring the phenomenon of spontaneous combustion in coal mainly depend on the intrinsic properties such as coal particle size, moisture content, among others; the medium in which it is located and how it is stored. Consistent with this, the objective of this work is to evaluate the effect of glycerol on the inhibition of self-combustion as water re-adsorption reducer through the addition of glycerol in different amounts (4, 8, 18 and 28% wt). The coal sample was extracted from the Córdoba department, Colombia. Incipient impregnation method was used to perform the addition of glycerol to the desired quantities. Characterizing the coal samples was performed by: TGA-DTG, nitrogen adsorption at -196 °C, C-H-N-O, FTIR, and SEM. The TGA of the coals evaluated in an air atmosphere, show changes in combustion properties of each sample. Di ignition index is reduced as the coal is impregnated with glycerol, obtaining its lowest value for 8wt% of glycerol. The effect of glycerol in inhibiting the spontaneous combustion of coal is exposed in the adsorption equilibrium; the sample with 8wt% glycerol shows the highest reduction of water adsorption in coal validating the proposed technology as inhibitor agent spontaneous combustion phenomenon found in Colombian coal.

VOx–K2O/γ-Al2O3 catalyst for nonoxidative dehydrogenation of isobutane

V–K/γ-Al2O3 catalysts were prepared using an incipient impregnation method and characterized by N2 adsorption, MAS-NMR, TPR, FT-IR, XPS and Py-FT-IR techniques. The catalytic activity of V–K/γ-Al2O3 in non-oxidative dehydrogenation of isobutane was investigated in a continuous flow packed bed micro reactor. The results indicate that V–K/γ-Al2O3 catalysts display a bifunctional effect. Characterization study suggests that the distribution of various VOx species were influenced by vanadium loadings to a great extent. The catalytic activity of vanadium-based catalysts was consequently promoted to different degrees by diverse VOx species and the highest dehydrogenation activity was obtained for the sample with the highest dispersion of the oligomeric VOx species. The reduced state of vanadium oxide i.e. V3+ and V4+ sites were proved to be the catalytic active sites for dehydrogenation reaction. Moreover, the activity and selectivity of catalysts were strongly related with the acidity of the catalysts. The ratio of Lewis acid sites to Brønsted acid sites (NLS/NBS) was negatively correlated to the isobutene selectivity. Among the tested catalysts, V–K/γ-Al2O3 with an optimum vanadium loading of 10% showed the highest isobutene yield of 42.5%, with ideal stability of presenting yield up to 37.8% after 10h continuous dehydrogenation reaction.

Surface chemistry and catalytic properties of VOX/Ti-MCM-41 catalysts for dibenzothiophene oxidation in a biphasic system

A series of vanadium oxide supported on Ti-MCM-41 catalysts was synthesized via the incipient impregnation method by varying the vanadia loading from 5wt% to 10, 15, 20 and 25wt%. These catalysts were characterized by a variety of advanced techniques for investigating their crystalline structure, textural properties, and surface chemistry information including surface acidity, reducibility, vanadium oxidation states, and morphological features. The catalytic activities of the catalysts were evaluated in a biphasic reaction system for oxidative desulfurization (ODS) of a model diesel containing 300ppm of dibenzothiophene (DBT) where acetonitrile was used as extraction solvent and H2O2 as oxidant. ODS activity was found to be proportional to the V5+/(V4++V5+) values of the catalysts, indicating that the surface vanadium pentoxide (V2O5) was the active phase. Reaction temperature would influence significantly the ODS efficiency; high temperature, i.e., 80°C, would lead to low ODS reaction due to the partial decomposition of oxidant. All the catalysts contained both Lewis and Brønsted acid sites but the former was predominant. The catalysts with low vanadia loading (5 or 10 wt%V2O5) had many Lewis acid sites and could strongly adsorb DBT molecule via the electron donation/acceptance action which resulted in an inhibition for the reaction of DBT with the surface peroxometallic species. The catalyst with high vanadia loading (25wt%V2O5/Ti-MCM-41) showed the highest catalytic activity and could remove 99.9% of DBT at 60°C within 60min.

Direct Synthesis of Methanol by Partial Oxidation of Methane with Oxygen over Cobalt Modified Mesoporous H-ZSM-5 Catalyst

Partial oxidation of methane over mesoporous catalyst cobalt modified H-ZSM-5 has been carried out. Mesoporous Na-ZSM-5 (Si/Al = 35.4) was successfully synthesized using double template method which has high surface area (450 m2/g) and average pore diameter distribution of 1.9 nm. The as-synthesized Na-ZSM-5 was converted to H-ZSM-5 through multi-exchange treatment with ammonium ion solution, causing decreased crystallinity and surface area, but increased porous diameter, due to dealumination during treatment process. Moreover, H-ZSM-5 was loaded with cobalt (Co = 2.5% w) by the incipient impregnation method and calcined at 550 °C. Partial oxidation of methane was performed in the batch reactor with 0.75 bar methane and 2 bar of nitrogen (with impurities of 0.5% oxygen) as the input at various reaction time (30, 60 and 120 min). The reaction results show that cobalt species in catalyst has an important role, because H-ZSM-5 cannot produce methanol in partial oxidation of methane. The presence of molecular oxygen increased the percentage of methanol yield. The reaction is time-dependent with the highest methanol yield (79%) was acquired using Co/H-ZSM-5 catalyst for 60 min.

Effects of pore sizes and oxygen-containing functional groups on desulfurization activity of Fe/NAC prepared by ultrasonic-assisted impregnation

A series of Fe-loaded activated carbons treated by HNO3 (Fe/NAC) were prepared by incipient impregnation method with or without ultrasonic assistance and characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy with energy disperse spectroscope (SEM-EDS), transmission electron microscopy (TEM) and N2 adsorption/desorption. The desulfurization activities were evaluated at a fixed bed reactor under a mixed gas simulated from flue gas. The results showed that desulfurization activity from excellent to poor is as follows: Fe/NAC-60>Fe/NAC-80>Fe/NAC-30>Fe/NAC-15>Fe/NAC-0>Fe/NAC-100>NAC. Fe/NAC-60 exhibits the best desulfurization activity and has breakthrough sulfur capacity of 319mg/g and breakthrough time of 540min. The introduction of ultrasonic oscillation does not change the form of Fe oxides on activated carbon but can change the dispersion and relative contents of Fe3O4. The types of oxygen-containing functional groups have no obvious change for all samples but the texture properties show some differences when they are oscillated for different times. The fresh Fe/NAC-60 has a surface area of 1045m2/g and total pore volume of 0.961cm3/g with micropore volume of 0.437cm3/g and is larger than Fe/NAC-0 (823m2/g, 0.733 and 0.342cm3/g). After desulfurization, surface area and pore volume of all samples decrease significantly, and those of the exhausted Fe/NAC-60 decrease to 233m2/g and 0.481cm3/g, indicating that some byproducts deposit on surface to cover pores. Pore size distribution influences SO2 adsorption, and fresh Fe/NAC-60 has more pore widths centralized at about 0.7nm and 1.0⿿2.0nm and corresponds to an excellent desulfurization activity, showing that micropore is conducive to the removal of SO2.

Synergic promotion effects of Ni and Mn on the synthesis of higher alcohols from syngas over alkali Co–MoS2 catalyst

A series of Ni and Mn-promoted K–Co–MoS2 catalysts supported on multi-walled carbon nanotubes (MWCNTs) were prepared via incipient impregnation method. All catalysts were characterized in oxide and sulfide state using different techniques. The influence of promoters on the catalytic performance in higher alcohols synthesis from syngas was investigated in a fixed-bed micro-reactor. Phase analysis as well as physico-chemical characteristics studies were applied for the interpretation of the results. The temperature programmed reduction results showed that simultaneous addition of Ni and Mn led to easier reduction of active metals. Diffraction peaks representing the characteristics of K–Mo–S phase were demonstrated in the X-ray diffraction pattern of sulfide forms of catalysts. The maximum total alcohol space time yield of 0.323 g/(g of catalyst)/h and total alcohols selectivity of 52.40 % were observed in the catalyst with 3 wt% Mn, 3 wt% Ni, 4 wt% Co, 8 wt% K, and 15 wt% Mo on MWCNTs in reaction conditions.