Loading Of Active Components Research Articles

CO-hydrogenation of syngas to fuel using silica supported Fe–Cu–K catalysts: Effects of active components

Fe–Cu–K/SiO2 catalysts prepared by varying the amount of active components have been investigated to explain the effects of active components on the activity, selectivity, product carbon number distribution, and nature of coke formation during Fischer–Tropsch synthesis. The catalysts were prepared by co-precipitation technique using silica as support, followed by adding K promoters by wet impregnation technique. Active component composition, textural properties, metal dispersion and acidity of the catalysts were determined by ICP, BJH, pulse chemisorptions and NH3 -TPD methods. Further surface morphology, structural characteristics and structural changes occurred during the course of FT synthesis were studied by XRD, SEM and EDAX (quantity and X-ray mapping). Fischer–Tropsch synthesis has been investigated in a fixed bed micro-reactor with in situ reduction of catalysts, using H2 as a reducing agent. The identification of different key components present in liquid products formed was done by GC-MS method. The spent catalyst was also characterized to understand the catalyst deactivation. The results have been discussed in relation to the loading of active components on catalysts and their influence on the textural and morphological properties, structural characteristics, as well as catalytic activity, selectivity towards product distribution and properties and nature of coke formation.

Development of solid adsorbent for carbon dioxide capture from flue gas

The adsorption of carbon dioxide (CO2) from simulated flue gas using newly developed solid adsorbents has been studied in the present work. Adsorptive capture of CO2 from flue gas streams is a promising technology for greenhouse gas mitigation. The success of CO2 capture using solid sorbents is greatly dependent on the development of a low cost, regenerable sorbent with high CO2 adsorption capacity. Solid sorbent is expected to offer the benefits over the liquid amines used in the typical absorption process, with the added advantages that solids do not give corrosion problems like liquid amines. In the present study, alkali-impregnated meso-porous solid sorbents have been developed and their performances for CO2 capture from simulated flue gas were evaluated by using a fixed bed reactor. The effect of various process parameters like temperature, CO2 concentration and loading of active component has been studied. The adsorbent with 20wt% Na2CO3 loading have shown the best CO2 adsorption capacity among the studied adsorbents and the adsorption capacity lies in the range of 0.35–0.39mmol/g of adsorbent at a temperature of about 55°C and atmospheric pressure.

A novel three-dimensional macrocellular carbonaceous biofuel cell

Here we report the first membrane-free biofuel cell obtained using three-dimensional carbonaceous foam electrodes. We first developed a new synthetic pathway to produce a new carbonaceous foam electrode material bearing porosity both on the meso and macroporous scales. We proved that by increasing the porosity of our three-dimensional foams we could increase the current density of our modified electrodes. Then, by choosing the right combination of enzyme and mediator, and the right loading of active components, we achieved high current densities for an anodic system. Finally, we combined the improved cathode and anode to build a new membrane-free hybrid enzymatic biofuel cell consisting of a mediated anode and a mediator-free cathode.

Preparation of ZnO/SiO2 gel composites and their performance of H2S removal at room temperature

ZnO/SiO2 gel composites with different active component loading were prepared by sol–gel method combined with ambient drying process, followed by thermal treatment. The gel composites were characterized by scanning electron microscopy (SEM), nitrogen adsorption, X-ray diffraction (XRD), FTIR and X-ray photoelectron spectroscopy (XPS), and their performances for H2S removal were evaluated by dynamic testing at room temperature. The as prepared materials exhibited high surface area with multimodal pore size distributions in micropore and mesopore region. The porous properties were significantly influenced both by the ZnO loading ratio and the treated temperature. The gel composites showed a high performance for H2S removal, with the highest H2S adsorption capacity of 96.4mg/g for the sample treated at 400°C with 30wt% ZnO. Both physisorption and the active phase reactivation governed the H2S removal process. It needs to optimize the composites’ porous structure and active component loading amount.

Research on Decomposition of Hydrogen Sulfide Using Nonthermal Plasma with Metal Oxide Catalysis

The paper made a research on synergetic effect of hydrogen sulfide decomposition using dielectric barrier discharge (DBD) plasma combined with metal oxide catalysis. Effects of metal oxide types and active component loading on simultaneous removal of H2S and O3 were investigated. The synergistic mechanism that O3 assisted non-thermal plasma (NTP) for H2S decomposition were also analyzed. It was showed that in the presence of metal oxide catalyst, H2S removal efficiency was obviously higher than that with NTP alone. In terms of H2S removal efficiency, metal oxide catalysts could be ranked as follows: Mn>Ag>Cu>Fe, which also accorded with the sequence of O3 decomposition ability. At the same applied voltage, the larger decomposition amount of O3, the higher removal efficiency of H2S. With XPS spectra results, it was deduced that H2S was oxidized into SO2, SO3 in the process of NTP with catalysis, ultimately formed S,H2SO3 and H2SO4.

Mixed oxides of transition metals as catalysts for total ethanol oxidation

AbstractOxides of transition metals could be suitable alternatives to catalysts based on noble metals in the oxidation processes used for the abatement of volatile organic compounds. Mixed oxides of transition metals can exhibit good efficiency and thermal stability, as well as being inexpensive. In this work, oxide catalysts containing various combinations of Cu, Co, Ni, Mn, and Al, grained or supported on oxidised aluminium foil Al2O3/Al, were studied in terms of their chemical and physical properties, including their chemical composition, porous structure, phase composition, reducibility, and activity in total ethanol oxidation. Ternary co-precipitated catalysts in the form of grains obtained from layered double hydroxide-like precursors were highly active, especially those containing manganese. Deposition of the selected precursors on an anodised aluminium foil-support afforded less active catalysts, mainly because the required metal molar ratios were not achieved, and insufficient amounts of metals were deposited. However, by controlling the preparation conditions (pH), higher loading of active components and higher catalytic activity were obtained.

Ni-based sol–gel catalysts as promising systems for crude bio-oil upgrading: Guaiacol hydrodeoxygenation study

Catalytic hydrotreatment or hydrodeoxygenation (HDO) has been researched extensively with the crude bio-oil and its model compounds over conventional sulfided Ni(Mo), Co(Mo) catalysts and supported noble metal catalysts. These types of catalysts showed themselves unsuitable for the target HDO process, which resulted in an urgent need to search for a new catalytic system meeting such requirements as low cost, stability against coke formation and leaching of active components due to adverse effect of the acidic medium (bio-oil). In the present work a series of Ni-based catalysts with different stabilizing components has been tested in the hydrodeoxygenation (HDO) of guaiacol (2-methoxyphenol), bio-oil model compound. The process has been carried out in an autoclave at 320°C and 17MPa H2. The main products were cyclohexane, 1-methylcyclohexane-1,2-diol, and cyclohexanone. The reaction scheme of guaiacol conversion explaining the formation of main products has been suggested. The catalyst activity was found to rise with an increase in the active component loading and depend on the catalyst preparation method. The most active catalysts in HDO of guaiacol were Ni-based catalysts prepared by a sol–gel method and stabilized with SiO2 and ZrO2. According to TPR, XRD, XPS, and HRTEM, the high activity of these catalysts correlates with the high nickel loading and the high specific area of active component provided by the formation of nickel oxide–silicate species. The effect of temperature on the product distribution and catalyst activity in the target process (HDO) has been investigated as well. The catalysts were shown to be very promising systems for the production of hydrocarbon fuels by the catalytic upgrading of bio-oil.

A Generalized Approach to the Synthesis of Mesoporous Mixed Metal Oxides Using the Cation-Anion Double Hydrolysis Method

A series of mesoporous mixed metal oxide were prepared by using a cation-anion double hydrolysis method, which was demonstrated to be a generalized approach for the synthesis of meso-porous mixed metal oxides. The mesoporous mixed oxide were characterized by N adsorption, X-ray diffraction, transmission electronic microscopy and energy dispersive X-ray analysis techniques. Results showed that thus obtained mixed metal oxide catalysts possess a high surface area, high loading of active component together with high dispersion, verifying that this approach is advantageous over the conventional wet impregnation method. The prepared mesoporous mixed oxides exhibit a great potential in replacing the traditional catalysts currently used in many important chemical processes.

Polymer supported N-benzyl-N-nitroso-4-toluenesulfonamide: An improved reagent for the derivatization of the acidic markers of nerve agents

We report herein the synthesis, characterization, stability study of a new solid supported derivatizing agent, N-benzyl-N-nitroso-4-poly(styrene-co-divinylbenzene)sulfonamide beads, for the preparation of phenyldiazomethane (PDM). The active component loading was found to be 2.0 ± 0.1 mmol g−1. This derivatizing agent is easy to synthesize and purify. The impurities and byproducts generated during the formation of PDM remain bound to the polymer backbone. These byproducts can be easily removed by filtration. Thus, pure PDM is obtained without the need for further purification. Due to the formation of a dilute solution of PDM, the chances of explosion and intoxication are minimized. The PDM from this derivatizing agent was used for the benzylation of a variety of acids. We have evaluated this derivatizing agent for the benzylation of alkylphosphonic acids (APAs) and alkyl alkylphosphonic acids (AAPAs). Subsequently, this reagent was applied for analysis of a real sample containing pinacolyl methylphosphonic acid by onflow LC-UV-1H NMR analysis.

Relationships in formation of silicon nitride-supported metal nanoparticles

The state of the particles of silicon nitride-supported metal (platinum, palladium, silver) depending on the support preparation conditions and the active component loading technique was examined in relation to the structural features and phase composition of the support. The common and different features in formation of the metal nanoparticles on the silicon nitride surface were identified.

Gas oil hydrocracking on NiW/USY catalyst: Effect of tungsten and nickel loading

Hydrocraking activity of NiW supported on ultra-stable Y zeolite (USY) with different loading of active component (tungsten) and promoter (nickel) was studied in this investigation. Hydrocracking of petroleum gas oil was carried out in a high-pressure shaking reactor at reaction temperature of 450 °C, contact time of 90 min and catalyst to gas oil ratio of 0.04. A series of NiW/USY catalysts with different nickel (NiO = 0–10.4 wt%) and tungsten (WO3 = 0–30 wt%) concentrations were prepared using the incipient wetness method. A promoting effect of nickel is observed in all prepared samples and found that the optimum content of nickel was 5 wt%. At this loading of nickel, the values of total conversion and yield of total distillate fuels were 63.3 and 52.3 wt%, respectively. The catalyst activity and properties were enhanced with increasing the tungsten content and the maximum values of total conversion and yield of total distillate fuels were 68.7 and 51.4 wt%, respectively. The catalysts characterizations were presented in terms of SEM, TGA-TPD acidity and TGA thermal stability.

Optimization of the active component distribution through the catalyst bed for the case of adiabatic reactor

This article is the next one in the previous series of publications concerning the optimal active component distribution. The aim of the present work is to extend the optimization problem taking into account the energy balance. The variational problem on searching for the optimal active component distribution profile along the catalyst bed was formulated for the case of an adiabatic reactor at an arbitrary form of reaction rate expression. The Euler differential equation was derived and the existence conditions for the solution of variational problem were obtained. A numerical algorithm was suggested and the optimal profiles of the active component distribution were calculated for the first-order reaction. Under isothermal conditions with linear dependence of the reaction rate on reactant concentration at a constant mass transfer coefficient, the uniform distribution is optimal. As opposed to the case of an isothermal reactor with a first-order catalytic reaction, in an adiabatic reactor considerable economy in the active component loading might be achieved due to optimization of its distribution. It was shown that the optimal active component distribution profiles were axially decreasing for the first-order exothermic reactions and increasing for endothermic reactions. The optimal active component distribution profile was calculated for the case of methane combustion on catalytic monoliths.

Improvement of the catalytic monoliths efficiency for CO oxidation using non-uniform active component distribution along the monolith length

It is shown that the efficiency of catalytic packages can be improved using two approaches. The monotone increase of the active component concentration towards the monolith outlet is shown optimal for minimization of the total active component loading at the preserved purification degree. To resolve the problem of achieving the maximal purification degree at a fixed quantity of the active component, it is preferable to concentrate the active component near the duct entrance.

Low-Temperature H2S Removal from Steam-Containing Gas Mixtures with ZnO for Fuel Cell Application. 2. Wash-Coated Monolith

This work is part of our efforts to explore more-effective ways to remove hydrogen sulfide (H2S) for fuel cell applications. Various absorbents (ZnO, SnO2, coprecipitated NiO−MoO3, supported CuO−ZnO, V2O5−ZnO, and ZnO supported on γ-alumina) were tested for H2S removal. The absorbents that were wash-coated onto the monolith were compared with particulate traps in the inlet H2S concentration range of 0.5−8 parts per million by volume (ppmv). The monolith provides much-higher dynamic capacity (the amount of H2S trapped before breakthrough) under the same conditions. The ZnO-based monolith demonstrated the best performance. An extremely low H2S outlet concentration (as low as 20 parts per billion, by volume (20 ppbv)) was observed over ZnO-based monolith samples for extended periods of time, under various conditions relevant for the desulfurization of gas products from the autothermal reforming of hydrocarbon fuels for a proton-exchange membrane fuel cell. The capacity of the H2S trap is dependent on the monolith characteristics (active component loading per cubic inch, and the number of cells per square inch) and operating conditions (including inlet H2S concentration, space velocity, and temperature). Wash−coating of ZnO that was chemically modified by an ammonium carbonate treatment onto a monolith with 400 cells per square inch gave the best H2S absorbence with higher dynamic capacity.

PREPARATION OF DIETHYL OXALATE BY CO COUPLING REACTION IN A GAS-SOLID FIXED BED REACTOR

The preparation of diethyl oxalate in gaseous phase by carbon monoxide coupling reaction on supported dimetal catalyst Pd-Fe/Al2O3 was studied. The influences of carrier, loading of active component in catalyst, amount of promoter, and temperature of calcining carrier on the reaction behavior were studied. The catalysts were tested in scale-up experiment(200 times) for 1 000 h continuously. The results indicated that the total conversion of carbon monoxide was nearly 100%; the one-way conversion of carbon monoxide was more than 60%; the selectivity to diethyl oxalate was over 95%; and the STY of diethyl oxalate was above 600g/L.h.