Activated Carbon Support Research Articles

Effective Catalytic Performance of Plasma-Enhanced W2N/AC as Catalysts for Acetylene Hydrochlorination

It is a significant environment goal to find searching green and low-price non-precious metal catalysts to replace HgCl2 in the catalytic hydrochlorination of acetylene to yield polyvinylchloride (PVC). Transition metal nitrides exhibit excellent chemical stability and high performance in many reactions, and may be the desirable candidates for this reaction. Herein, tungsten nitride, W2N, is applied as the active ingredient in the synthesis of vinyl chloride monomer (VCM), for the first time. Two catalysts were prepared. The first was prepared by depositing tungsten onto an activated carbon support, whereas the second was prepared from using the first catalyst via plasma treatment. This treatment increased the interaction between the support material and the active ingredient, and generated nanoparticles that exhibit greater level of aggregation. However, the plasma treatment also turned to enhance the catalytic performance. Additionally, it increased the number of W–N bond in the catalyst and reduced the deposition of coke on the catalyst surface.

Fischer-Tropsch synthesis to light olefins over iron-based catalysts supported on KMnO4 modified activated carbon by a facile method

Fischer-Tropsch synthesis to light olefins (FTO) using biomass-derived syngas is an economical and renewable way to produce olefins. By using KMnO4 as precursor, a number of low cost iron based catalysts was produced and their FTO performances were tested. Firstly, a series of KMnO4 solutions with different concentrations were used to pretreat activated carbon (AC). Support was coated uniformly by K-doped birnessite MnO2 and substantial amount of surface oxygen-containing groups and defects were obtained simultaneously. Then, iron catalysts loaded on KMnO4 modified AC support was prepared by incipient wetness impregnation method. Characterization of the catalyst showed that α-Fe2O3 nanoparticles were uniformly loaded on the surface of KMnO4 treated AC. The valent of manganese (IV) was then transformed into Mn (II) and Mn (III) with AC served as a reducing agent. The redox reaction during preparation leads to a lower Mn chemical valence, which makes it easier to further reduction. More defects on support after calcination procedure were also observed due to the enrichment of oxygen-containing groups, which was helpful in anchoring α-Fe2O3 particles and decreasing its average particle size. High-content manganese played not only as a structural promoter to anchor Fe2O3 nanoparticles, but also a H2 adsorption competitor that decreased H2/CO ratio over active sites to reduce the possibility of further hydrogenation of olefins. The KMnO4 modified iron catalysts exhibited high CO conversion and olefins selectivity (∼40%) due to the improved distribution of iron and the auxiliary functions of Mn. Residual potassium is also in favor of the formation of iron carbides to increase CO conversion.

NiMo-sulfide supported on activated carbon to produce renewable diesel

Due to their weak polarity and large surface area, activated carbon supports have the potential to enhance the dispersion of metal-sulfides. It is expected that the absence of a strong metal-support interaction can result in the formation of a very active and stable Ni-Mo-S phase. In this study, catalysts with different amounts of nickel and molybdenum supported on a commercial activated carbon were prepared by a co-impregnation method and characterized by BET, XRF, and SEM techniques. The catalytic activity for hydroprocessing of Jatropha oil was evaluated in a batch reactor, and the composition of the liquid and gaseous products were determined. Results showed that gaseous products are mainly composed of high amounts of propane and small amounts of other light hydrocarbons (C1 to C5). Liquid hydrocarbon products consisted of a mixture containing mainly n-paraffins of C15-C18 and some oxygenated compounds. The catalysts with a mass fraction<br />of 3 % Ni, 15 % Mo (Ni3Mo15/AC) presented the highest selectivity toward C17-C18 hydrocarbons, with a product distribution similar to a commercial<br />alumina-supported Ni-Mo-S catalyst.

Activated carbon supported palladium-iron oxide catalysts fabricated by atomic layer deposition for hydrodechlorination of 1,4-dichlorobenzene

Fe2O3 and Pd are successively deposited on an activated carbon support by atomic layer deposition (ALD), producing a large surface area catalyst containing varied loadings of Pd and Fe2O3. Various structural characterization techniques reveal that the Fe2O3 species forms a uniformly distributed amorphous layer on which Pd nanoparticles are anchored. In the hydrodechlorination of 1,4-dichlorobenzene ALD Pd/Fe2O3/AC catalysts outperform a series of control samples including impregnated Pd-Fe2O3-AC and mixtures of ALD Pd/AC and Fe2O3/AC. The improved catalytic performance is mostly attributed to the anti-poisoning effect of Fe2O3 located in close vicinity to Pd.

Gold Nanoparticles Supported over Low-Cost Supports for Hydrogen Generation from a Hydrogen Feedstock Material

Gold nanoparticles were supported over activated carbon (AC) and glasswool (GW), and were tested for their catalytic activity. The catalytic activity of supported and unsupported gold nanoparticles in the hydrogen evolution reaction of sodium borohydride solution was compared against the catalytic activity of uncoated AC and GW supports. Data suggests that the gold nanoparticle supports over AC are more efficient at generating hydrogen than GW supports and non-coated substrates.

Synergized mechanistic and solar photocatalysis features of N-TiO<sub>2</sub> functionalised activated carbon

A TiO2 photocatalysts was successfully functionalised by employing nitrogen (N) as a dopant on activated carbon (AC) support as synergist. Two different types of activated carbon adopting namely Garcinia mangostana and palm shell as precursor were chosen as an activated carbon support. Thus the synthesized samples were examined for its physical and chemistry properties through advanced microscopic and spectroscopic techniques. The results revealed the contribution of adsorbent support through the rich surface area while doping of nitrogen contributed for effectively utilizing the incident photons by narrowing the band gap energy. The synergetic adsorption-photocatalytic activity was investigated by adopting batik dye, Remazol Brilliant Blue Dye (RBB) as model pollutant. Thus the N-TiO2 functionalised activated carbon demonstrated excellent adsorption-photocatalytic activity with 80% removal efficiency in 6 h. The synergism of adsorption-photocatalysis portrayed the alternative for treating recalcitrant RBB a predominant dye found in batik textile industry wastewater.

The effect of activated carbon support surface modification on characteristics of carbon nanospheres prepared by deposition precipitation of Fe-catalyst

In this study the effect of activated carbon support modification to synthesis of CNSs was observed. Modification of activated carbon was done by using nitric acid. The effect of modification was analyzed from its FTIR spectra. The Fe catalysts were deposited on to the support by using urea deposition precipitation method at various initial catalysts concentration. CNSs was synthesized by utilizing cooking palm oil as renewable carbon source, and pyrolized at 700°C for 1 hour under nitrogen atmosphere. The products obtained then analyzed using SEM-EDS, TEM, XRD, and Raman spectroscopy. The modification of activated carbon support had increased the oxygen functional group. This increase resulted on increase of metal catalysts deposited on activated carbon surface. Peak of C (100) was observed, while ID/IG of samples were obtained around 0.9, which is commonly obtained for CNSs. High catalysts loading on modified activated carbon support caused decomposition of CNSs and formation carbon onion.

Multicomponent NiSnCeO2/C catalysts for the low-temperature glycerol steam reforming

In this work, the low-temperature hydrogen production via glycerol steam reforming over activated carbon-supported Ni and Ni-Sn catalysts promoted by ceria was studied. A combination of N2 adsorption, powder X-ray diffraction, temperature-programmed reduction with H2, X-ray photoelectron spectroscopy and TEM analysis were used to characterise the Ni-Sn-CeO2 interactions and the CeO2 dispersion over the activated carbon support. The catalytic activity results show that the presence of ceria enhances the water-gas shift reaction, thus promoting the selectivity towards hydrogen. The inclusion of Sn stresses the influence of ceria in the displayed performance. Moreover, the formation of a Ni-Sn alloy seems to be an efficient way to mitigate Ni sintering and therefore to improve the overall catalyst’s stability.

Ni–Co bimetallic nanoparticles anchored reduced graphene oxide as an efficient counter electrode for the application of dye sensitized solar cells

The bimetallic Ni–Co nanoparticles anchored reduced graphene oxide (rGO) nanocomposite was prepared by one-pot chemical reduction technique and utilized as an efficient counter electrode in dye sensitized solar cells (DSSC). The spherical shaped Ni–Co nanoparticles with the average diameter of 8 nm were uniformly anchored over the surface of rGO sheets and its face centered crystalline structure was explored by the diffraction patterns. The structural interaction exerted between the active carbon support and bimetallic nanoparticles was evaluated by using Fourier Transform Infrared analysis. rGO/Ni–Co composite exhibited the maximum electroreduction toward I3 −/I− as evidenced from the cyclic voltammetric studies, owing to the synergetic effects of rGO sheets and Ni–Co bimetallic nanoparticles. Furthermore, rGO/Ni–Co counter electrode equipped DSSC exhibited the maximum solar to electrical energy conversion efficiency (η) of 3.10 % under 1 sun illumination with the fill factor (FF) of 0.48. The time and cost efficient preparation technique associated with the better electrochemical properties and high power conversion efficiency observed for the rGO/Ni–Co counter electrode demonstrated its potential utilization in DSSCs.

Ethylene/ethane separation by CuCl/AC adsorbent prepared using CuCl2 as a precursor

Activated carbon (AC) supported CuCl (CuCl/AC) for ethylene/ethane separation has been prepared with CuCl2 as precursor by a solid-state dispersion method. The samples are characterized by inductively coupled plasma optical emission spectrometry, X-ray diffraction, N2 adsorption/desorption and X-ray photoelectron spectroscopy, and investigated for ethylene (C2H4) and ethane (C2H6) adsorptions. The characterization results reveal that CuCl2 supported on AC can be highly dispersed on the surfaces of AC support and completely converted to CuCl after activation at 543 K in N2. The resultant adsorbent displays high ethylene adsorption capacity, high C2H4/C2H6 adsorption selectivity and excellent reversibility. The adsorption isotherms of ethylene and ethane on CuCl/AC at temperatures up to 333 K can be well fitted by the Sips models, and the corresponding isosteric heats of adsorption are calculated from the Clausius–Clapeyron equation. The value of isosteric heat of adsorption suggests that the interaction of ethylene with CuCl/AC is between physisorption and chemisorption.

Influence of surface oxygenated groups on the formation of active Cu species and the catalytic activity of Cu/AC catalyst for the synthesis of dimethyl carbonate

Activated carbon (AC) supported Cu catalysts are employed to study the influence of surface oxygenated groups on the formation of active Cu species and the catalytic activity of Cu/AC catalyst for oxidative carbonylation of methanol to dimethyl carbonate (DMC). The AC supports are thermal treated under different temperatures in order to adjust the levels of surface oxygenated groups. The AC supports are characterized by BET, TPD-MS and XRD, and the Cu/AC catalysts are characterized by BET, XRD, TEM, XPS, AAS, CH3OH-TPD and N2O chemisorption. The results show that as the treatment temperature is below 800°C, the BET surface area of the corresponding AC supports are nearly unchanged and close to that of the original AC (1529.6m2/g). But as the thermal treatment temperature is elevated from 1000 to 1600°C, the BET surface area of AC supports gradually decreases from 1407.6 to 972.2m2/g. After loading of Cu, the BET surface area of copper catalysts is in the range of 834.4 to 1545.3m2/g, which is slightly less than that of the respective supports. When AC is thermal treated at 400 and 600°C, the unstable carboxylic acid and anhydrides groups are selectively removed, which has weakened the mobility and agglomeration of Cu species during the calcination process, and thus improve the Cu species dispersion over AC support. But as the treatment temperature is elevated from 600°C to 1200°C, the Cu species dispersion begins to decline suggesting further removal of stable surface oxygenated groups is unfavorable for Cu species dispersion. Moreover, higher thermal treatment temperature (above 1200°C) promotes the graphitization degree of AC and leds to the decrease of Cu loading on AC support. Meanwhile, the removal of surface oxygenated groups by thermal treatment is conducive to the formation of more π-sites, and thus promote the reduction of Cu2+ to Cu+ and Cu0 as active centers. The specific surface area of (Cu++Cu0) is improved by thermal treatment of AC, however, the space time yield of DMC on unit specific surface area of (Cu++Cu0) is in the range of 23.1–49.1mgh−1m−2, which is much less than that (77.6mgh−1m−2) of the original catalyst. The possible reason is that the removal of surface oxygenated groups results in AC support transforms from hydrophilicity to hydrophobicity, which is detrimental for the adsorption of CH3OH resulting in the decreased local concentration of CH3OH on active Cu species.

Photodegradation of Molasses Wastewater Using TiO2–ZnO Nanohybrid Photocatalyst Supported on Activated Carbon

Molasses wastewater (MWW) is characterized by high organic loading and a recalcitrant dark brown color. A study was carried out to determine the photocatalytic efficiency of TiO2–ZnO nanohybrid supported onto activated carbon (AC) for the remediation of MWW. Immobilization of ZnO onto TiO2 formed TiO2–ZnO, which was then supported onto AC forming TiO2–ZnO–AC composite. X-ray diffraction (XRD), scanning electron (SEM), energy-dispersive X-ray (EDX) and Fourier transform infrared (FTIR) spectroscopies, and transmission electron (TEM) microscopy revealed the successful hybridization of TiO2 and ZnO, and the subsequent support of the hybrid onto AC. Photoluminescence (PL) spectroscopy further revealed a restrained electron-hole pair recombination resulting from both the successful formation of a heterojunction, and the introduction of electron accepting AC support. Photodegradation process was monitored by color and total organic carbon (TOC) reductions. It was observed that TiO2–ZnO (ratio 3:1) supported onto AC (30% loading) had a higher adsorptive capacity and catalytic activity than bare TiO2–ZnO resulting in a 14% increment in overall color reduction. UV-photodegradation was found to be very effective for color as compared to TOC reduction, with 96% and 9% reductions, respectively, after 1 hour of irradiation. A pH of 5 was found to be optimum for photodegradation.

Preparation and Preliminary Electrochemical Characteristics of Cooking Oil Based Nano Carbons As Electrode Materials for Lithium Ion Batteries

In the past decades, the development of nano- carbon materials with well-defined characteristics such as fullerenes, nanotubes and graphene have been a very active area of research. Carbon nanospheres (CNSs) are other class of nanostructured carbon materials, and have shown good prospects for application as alternative LIB anodes. CNSs possess some remarkable characteristics such as high specific capacity and good rate capability as anode materials in LIB. Those specific characteristics are attributed to a combination of several factors, including a short diffusion paths for Li+ ions; good porosity and high surface area. In this study, carbon nanospheres (CNSs) were synthesized by thermal assisted pyrolysis process using palm oil as carbon precursors, Fe-catalyst and activated carbon support. Prior to the synthesis of carbon nanospheres, Fe-catalyst on carbon supports was prepared by deposition precipitation by varying the amount of catalyst (10%, 20% and 30% w with respect to the mass of carbon support). The effect of catalyst amount on the morphology and structural characteristics of carbon products was investigated by x-ray diffraction (XRD), Raman spectroscopy and transmission electron microscope (TEM). The study indicated that structural properties are changed when a Fe catalyst amount is increased from 10 to 30 wt%. The stable cycle performances of carbon products were demonstrated when they are utilized as anode materials in lithium ion batteries. However, it can be observed that the highest specific capacity was shown by the carbon samples produced at the highest content of Fe catalyst.

Supported Al–Ti bimetallic catalysts for 1-decene oligomerization: Activity, stability and deactivation mechanism

A variety of supported bimetallic catalysts were prepared through immobilization of AlCl3 and TiCl4 on different porous materials and used for the oligomerization of 1-decene in a fixed-bed reactor. The supported catalysts were characterized by various techniques including X-rayphotoelectron spectroscopy (XPS), 27Al MAS NMR, N2 adsorption, adsorbed pyridine infrared (Py-IR), thermogravimetry and differential scanning calorimetry (TG–DSC), energy-dispersive spectrometry (EDS), and content measurement of active species. Their catalytic activity was examined and the underlying deactivation mechanism was explored. The initial catalytic activity was observed to be a linear function of the chlorine content of the supported catalyst. A catalyst using a coal-derived activated carbon support has the highest loading and exhibits the highest yield of polyalphaolefin (PAO), while a γ-Al2O3-supported catalyst gives higher stability. In addition, thermal treatment of the γ-Al2O3-supported catalyst results in reduced initial activity but enhanced stability. Both the loss of active species and the blockage and coverage of the pore structure by oligomers account for the deactivation of the supported catalyst.

The Influence of Active Carbon Supports Toward the Electrocatalytic Behavior of Fe3O4 Nanoparticles for the Extended Energy Generation of Mediatorless Microbial Fuel Cells.

Magnetite (Fe3O4) nanoparticles anchored over the different active carbon supports were developed by a simple wet solution method. The developed nanostructures were magnetically self-assembled over the electrode surface and exploited as anode catalysts in mediatorless microbial fuel cells (MFC). The morphological characterizations revealed that 3∼8-nm-sized Fe3O4 nanoparticles were homogeneously anchored over the different carbon matrices and the obtained diffraction patterns ensured the cubic inverse spinel structure of prepared Fe3O4 nanoparticles. The morphology, size, and structure of Fe3O4 nanoparticles anchored over the different active carbon supports were maintained identical, and the influence of active carbon support toward the effectual MFC performances was evaluated under various electrochemical regimes and conditions by using Escherichia coli as a catalytic microorganism. The electrochemical characterizations revealed that carbon nanotube (CNT)-supported Fe3O4 nanoparticles exhibited lower charge transfer resistance and high coulombic efficiency in comparison with the graphene and graphite nanofiber-supported composites. Among the studied anode catalysts, Fe3O4/CNT composite exhibited the maximum MFC power density of 865mWm(-2) associated with excellent durability performances, owing to the specific interaction exerted between the microorganisms and the Fe3O4/CNT composite. Thus, the binder-free electrode modification process, mediatorless environment, rapid electron transfer kinetics, high power generation, and long durability performances achieved for the developed system paved futuristic dimensions for the high performance MFCs.

Pd/CNT Catalysts for Electrochemical Oxidation of Small Organic Molecules in Alkaline Media

The development of the alkaline anion exchange membrane (AEM) for the direct liquid fuel cell opened up opportunities for the use of new fuels (that oxidized inefficiently in PEM fuel cells) and new catalysts (that corroded easily in PEM fuel cells). In this work, we explore the effect of a CNT support for Pd catalysts for the oxidation of various alcohol and formate fuels in alkaline media. We found that the CNT support provided a significant advantage over standard, activated carbon support in several of the fuels. The increase in oxidation rate in formate, for example, was 5-fold. However, the oxidation rate of propanol was not significantly enhanced by the CNT support. We are presently exploring the scientific reason for the enhanced oxidation rates by the CNT support using XRD and XPS analysis. Masel, et al, suggested that in formic acid the CNT provides enhancement due to its electronic properties, and a shift in Pd 3d5/2­ binding energy supports this. However, we are presently investigating why the promotion in alkaline media is so much greater than in acidic media, even for the formate (compared with formic acid).

Nitrogen-Doped Carbon Encapsulated Cobalt Oxide Nanoparticles As a Synergistic Catalyst for Oxygen Reduction Reaction in Alkaline Solution

: The development of high-performance and low-cost catalytic materials for the oxygen reduction reaction (ORR) has been a major task for the large-scale application of fuels cells.[1] Currently, platinum and platinum-based alloys catalysts are generally used as effective cathode catalysts for oxygen reduction reaction (ORR). However, the high price and degradation of Pt catalytic activity severely with time restrict the practical application. Thus, alternative catalysts based on metal-free materials, or nonprecious metals have attracted much attention. Among the metal-free materials for ORR, carbon doped with nitrogen is a promising catalyst because the long-pair electron from nitrogen can active the π electrons in carbon for ORR; thus, O2 molecules are reduced on the positively charged C atoms that neighbor N atoms. Recently, the N-doped carbons, after further supporting the transition metal-based materials such as Co3O4, exhibit comparable ORR activity to commercial Pt/C.[2] The enhancement of the activity is the evidence of synergetic effect between the active nanoparticles and carbon support. In this work, we have focused on the research work on the preparation of nitrogen-doped carbon encapsulated cobalt-based nanoparticles (Co3O4@N-doped carbon) as a synergistic catalyst for ORR in an alkaline solution. We employed an impregnation and calcination method to prepare Co3O4 nanocrystals supported on the surface of carbon (Vulcan XC-72R). Subsequently, the obtained Co3O4/C was mixed with melamine which is used as nitrogen and carbon source. The mixture was heated at 700 ℃ for 1 h in argon atmosphere. During this procedure, most Co3O4 particles are reduced to cobalt by carbon matrix, and residual cobalt oxide (Co3O4) is on the surface of these cobalt particles. The morphological and electronic structure of the resulting Co3O4@N-doped carbon hybrid catalysts were characterized by transmission electron microscopy (TEM), X–ray diffraction (XRD). The results show that the prepared nanocrystals are uniformly dispersed on surface of the support. The average diameter of nanocrystals is about 10 nm. The obtained hybrid catalyst exhibits improved electro–catalytic activity for ORR in 1 M NaOH solution, which is close to that of a commercial Pt/C (E-TEK) under the same condition. The enhanced activity toward ORR on this hybrid catalyst can be explained by strong electronic interaction between particles and nitrogen-doped carbon. Moreover, in this material, three common nitrogen bonding configurations are identified within the carbon lattice, including quaternary N (or graphitic N), pyridinic N, and pyrrolic N respectively. The active nitrogen content among these hybrid materials is estimated to be 4.13 at.%, which can effectively increase the electrochemically active surface areas of the catalysts. Reference: [1]Y. Liang, Y. Li, H. Wang, J. Zhou, J. Wang, T. Regier and H. Dai, Nat. Mater. , 2011,10:780-786 [2]Wu J, Xue Y, Yan X, Yan W, Cheng Q, Xie Y, Nano Research, 2012,5:521-530

Gas phase electrocatalytic conversion of CO2 to syn-fuels on Cu based catalysts-electrodes

A novel electrocatalytic system based on a low temperature proton exchange membrane (Sterion) was developed for the gas phase electrocatalytic conversion of CO2. This configuration allows the introduction of renewable energy in the chemical production chain via fuels production from direct CO2 electro-reduction at atmospheric pressure and low temperatures (below 90°C). For that purpose, three different Membrane Electrode Assemblies (MEAs) based on three different Cu based cathodic-catalysts were prepared and characterized: Cu-G/Sterion/IrO2, Cu-AC/Sterion/IrO2 and Cu-CNF/Sterion/IrO2; graphite (G), activated carbon (AC) and carbon nanofibers (CNF). Thus, H2O was fed and electrolyzed on the IrO2 anode of the cell, thereby supplying H+ across the membrane to react with CO2 in the cathodic-catalyst and leading to the production of a mixture of syn-fuels (syn-gas, methanol, methane…). Remarkably, the nature of the cathodic-catalyst carbon support had a strong influence on the electrocatalytic activity and selectivity of the system. Hence, the Cu-AC-based cathodic-catalyst showed the highest CO2 electrocatalytic activity, due to the highest surface area of the AC support and the larger metal dispersion of the Cu particles leading to acetaldehyde and methanol as the main reaction products. Besides the lower conductivity of the AC support, the lowest energy consumption values for CO2 conversion and methanol and acetaldehyde production was also achieved with the MEA based on Cu-AC cathodic catalyst due to its higher electrocatalytic activity.

Recycling rice straw derived, activated carbon supported, nanoscaled Fe3O4 as a highly efficient catalyst for Fenton oxidation of real coal gasification wastewater

Recycled rice straw was converted into an activated carbon support for nanoscaled Fe3O4.

Continuous catalytic upgrading of ethanol to n-butanol over Cu-CeO2/AC catalysts.

Cu-CeO2/AC catalysts exhibited extraordinary catalytic performance in the upgradation of ethanol to n-butanol. To the best of our knowledge, this is the first report that the highest n-butanol yields of 21.6% and nearly 20% could be achieved over heterogeneous catalysts under mild reaction conditions in batch and fixed-bed reactors, respectively. The high catalytic activity, selectivity and stability of these catalysts could be ascribed to the synergy of Cu, CeO2 and the activated carbon support.