Effect Of Activation Temperature Research Articles

Promotional effect of Gd over Ni/Y2O3 catalyst used in dry reforming of CH4 for H2 production

Hydrogen is renewable, ecofriendly, lightweight, high combustion efficiency and zero-emission fuel. Dry reforming of methane is the growing technology for producing hydrogen. In this study, dry reforming of methane was conducted over Ni/Y2O3 catalyst calcined at different temperatures. The effect of activation temperature and time to get the optimized catalytic performance was investigated. A maximum hydrogen yield of (82.8%) was achieved at 800 °C calcination, 800 °C activation and reaction temperature at 700 °C. To suppress the extent of carbon deposition, the promoting effect of Gd was studied. It was observed that even a small amount of Gd promoter (1 wt%) could reduce the carbon formation mechanism significantly. CO2-TPD results showed that Gd-promoted catalysts have a very high basicity when compared to non-promoted Ni/Y2O3 catalyst. The formation of carbon nanotube over spent catalyst was observed in the HRTEM analysis.

Physical Activation of Oil Palm Empty Fruit Bunch via CO2 Activation Gas for CO2 Adsorption

In this study, different parameters for the preparation of activated carbon were investigated for their yield and CO2 capture capabilities. The activated carbon was prepared from Oil Palm Empty Fruit Bunch (OPEFB) via a 2-step physical activation process. The OPEFB was pyrolyzed under inert conditions at 500 °C and activated via CO2. A 2-factorial design was employed and the effects of activation temperature, activation dwell time and gas flow rate on yield and CO2 capture capabilities were compared and studied. The yield obtained ranged from between 20 – 26, whereby the temperature was determined to be the most significant factor in influencing CO2 uptake. The CO2 capture capacity was determined using Temperature Programmed Desorption (TPD) technique. The CO2 uptake of EFB activated carbon achieved was between 1.85 – 2.09 mmol/g. TPD analysis has shown that the surface of AC were of basic nature. AC was found to be able to withhold the CO2 up to 663°C before maximum desorption occurs. The surface area and pore size of OPEFB obtained from BET analysis is 2.17 m2 g-1 and 0.01 cm3 g-1. After activation, both surface area and pore size increased with a maximum observed surface area and pore size of 548.07 m2 g-1 and 0.26 cm3 g-1. Surface morphology, functional groups, pore size and surface area were analyzed using SEM, FT-IR, TPD and BET.

The effect of activation temperature on properties of activated carbon prepared from wine industry pressing waste

The effect of activation temperature on properties of activated carbon prepared from wine industry pressing waste

Evaluation of cassava (Manihot Esculentum) seed waste Activated carbon for kinetic study on methylene blue dye adsorption from aqueous solution

The effect of activation temperature on activated carbon was studied at 400o C, 500oC and 600oC respectively. The characterization properties showed that increased in temperature reduces yield, moisture content, ash content and volatile content but increased fixed carbon, pore volume and porosity. Batch experiment was conducted by varying the dosage of activated carbon (0.2g – 0.6g) and contact time (40 -120 min) on adsorption of methylene blue dye from aqueous solution. The experimental data was fitted to pseudo first and second order kinetics in order to verify the rate controlling mechanism. The pseudo second order model showed a better fit with the highest correlation coefficient of 0.998. The adsorption capacity q computed was found to be 6.561 mg/g and 16.129 mg/g showed deviation from the experimental value of 11.00 mg/g for the both kinetics. The equilibrated isotherm data was also fitted to Langmuir, Freundlich and Dabinin-Radushkevich. Freundlich model has the best fit with R2 = 0.914. The energy of adsorption was calculated using the Dabinin-Radushkevich model and found to be 5.89 kJ/ mol.

The Influence of the Activation Temperature on the Structural Properties of the Activated Carbon Xerogels and Their Electrochemical Performance

The effect of activation temperature on the structural properties and the electrochemical performance of KOH-activated carbon xerogel was investigated in range of 700 to 1000°C. At a high temperature (1000°C), the chemical activation regenerated a more crystalline network structure of activated carbon xerogels, which was observed by Raman, XRD, and TEM images. Additionally, SEM images, BET, BJH, and t-plot were used to study the structural properties of carbon xerogels. The carbon xerogel sample activated at 900°C was found with the most appropriate structure, which has the high micropore area and a more-balanced porosity between the micropores and mesopores, for using as an electrode material. The highest obtained specific capacitance value was 270 Fg−1 in 6 M KOH electrolyte at scan rate of 5 mVs−1 from the cyclic voltammetry.

The application of homemade Neosinocalamus affinis AC in electrokinetic removal technology on heavy metal removal from the MSWI fly ash.

This present paper was focused on the manufacture of activated carbon (AC) and its application in the electrokinetic remediation (EKR) technology on removal of the heavy metals (HMs) from the municipal solid waste incineration fly ash. AC was produced from Neosinocalamus affinis (NF) by chemical activation with H3PO4 in N2 atmosphere, the effects of activation temperatures, soaking time and impregnation ratios on the adsorption capacity of AC on HMs were examined through equilibrium adsorption experiments. The AC produced under the condition of 450 °C of activation temperature, 10 h of soaking time and 1.5 of impregnation ration was applied in the EKR experiment. The addition of AC in the S3-region of the electrolyzer could effectively improve the removal efficiencies of HMs. The technical parameters of voltage gradient, processing time and proportion were further optimized in the coupled experiments, the maximum removal of Cu, Zn, Cd, and Pb was 84.93%, 69.61%, 79.57%, and 78.55% respectively obtained under the optimal operating conditions of 2 V/cm of voltage gradient, 8 d of processing time and 20% of proportion.

Hydrogen production by catalytic methane decomposition over Ni, Co, and Ni-Co/Al2O3 catalyst

ABSTRACTHydrogen is a chief source of energy. Catalytic decomposition produces hydrogen and carbon. In this work, x%M/Al2O3 (where M is Ni, Co and combined Ni-Co, and x is 10%, 15%, and 30%) has been successfully employed as a catalyst. The effect of activation temperature and active metal type and loading on catalyst perfomance was investigated. The catalysts were characterized with BET, XRD, TPO, TPR, TEM, XPS, and Raman. The results displayed that the 30%Co/Al2O3 catalyst activated at 500°C provided the greatest catalytic performance toward methane conversion. 30%Co/Al2O3 catalyst activated at 500°C formed amorphous carbon.

Production of a new industrially viable green-activated carbon from Artocarpus integer fruit processing waste and evaluation of its chemical, morphological and adsorption properties

Artocarpus integer is widely cultivated in Malaysia for its edible fruit which is used as an ingredient in the production of various confectioneries. The large amount of thick solid peel waste formed from processing of this fruit is a burden to local Artocarpus integer fruit processing industries. In this work, the feasibility of converting Artocarpus integer fruit processing waste into an industrially viable and low-cost green-activated carbon was evaluated. The novel activated carbon was prepared by physical activation with steam and characterized by elemental analysis, Boehm titration method, Fourier Transform Infrared Spectroscope (FTIR), Scanning Electron Microscope (SEM) and X-ray powder Diffraction (XRD). In addition, the potential use of the prepared activated carbon as an adsorbent and the effects of activation temperature and duration on iodine adsorption were examined. Experimental results revealed the suitability of Artocarpus integer fruit processing waste to be used as a precursor for activated carbon. The raw waste material was found to be a lignocellulosic biomass which is rich in cellulose (53.6 wt%) and carbon (60.8 wt%). Steam activation temperature, 750 °C and a short activation time of 60 min were appropriate to attain a high quality activated carbon with a large iodine adsorption capacity (1411 mg/g), highly micro-porous and amorphous structure with predominantly basic surface functional groups which are all advantageous properties for adsorption applications. The newly developed activated carbon is a promising cost-effective (∼1.67 US$ per kg) alternative to commercial carbon which may be used as a cleaner and ecologically compatible adsorbent for improving water and air quality, consequently, benefiting human health and wellbeing.

Effects of activation temperature on the deoxygenation, specific surface area and supercapacitor performance of graphene

This paper systematically studies the influence of temperature during KOH activation of graphene on quantities and types of oxygen-containing groups, pore structure, specific surface area, and performance of supercapacitor. The changes of the amount and types of oxygen-containing functional groups were observed with the aid of Fourier transform infrared spectroscopy, Raman and X-ray photoelectron spectroscopy. The pore structure and specific surface area were characterized by means of X-ray powder diffraction, N2 adsorption-desorption and transmission electron microscopy. Electrochemical properties were assessed by cyclic voltammetry, electrochemical impedance and galvanostatic charge-discharge. As the temperature increased, the oxygen content of activated graphene decreased, while its specific surface area increased. The specific capacitance of the activated graphene first increased and then decreased with a maximum (326 F/g) at 400 °C. When the temperature was 800 °C, the surface area of the material peaked (3269 m2/g), and the specific capacitance was 204 F/g.

Rapeseed and Raspberry Seed Cakes as Inexpensive Raw Materials in the Production of Activated Carbon by Physical Activation: Effect of Activation Conditions on Textural and Phenol Adsorption Characteristics.

The production of activated carbons (ACs) from rapeseed cake and raspberry seed cake using slow pyrolysis followed by physical activation of the obtained solid residues is the topic of this study. The effect of activation temperature (850, 900 and 950 °C), activation time (30, 60, 90 and 120 min) and agent (steam and CO2) on the textural characteristics of the ACs is investigated by N2 adsorption. In general, higher activation temperatures and longer activation times increase the BET specific surface area and the porosity of the ACs, regardless of the activation agent or raw material. Steam is more reactive than CO2 in terms of pore development, especially in the case of raspberry seed cake. The performance of the ACs in liquid adsorption is evaluated by batch phenol adsorption tests. Experimental data are best fitted by the Freundlich isotherm model. Based on total yield, textural characteristics and phenol adsorption, steam activation at 900 °C for 90 min and CO2 activation at 900 °C for 120 min are found as the best activation conditions. Raspberry seed cake turns out to be a better raw material than rapeseed cake. Moreover, AC from raspberry seed cake produced by steam activation at 900 °C for 90 min performs as well as commercial AC (Norit GAC 1240) in phenol adsorption. The adsorption kinetics of the selected ACs are best fitted by the pseudo-second-order model.

Preparation and Characterization of a Novel Activated Carbon from Vine Shoots by ZnCl2 Activation and Investigation of Its Rifampicine Removal Capability

Preparation and characterization of a novel activated carbon obtained from vine shoots by ZnCl2 activation and its rifampicine removal capacity were investigated in this study. The effects of activation temperature and impregnation ratio (precursor/ZnCl2) on the activated carbon properties were investigated. The prepared activated carbon was characterized by BET surface area, surface functional group analysis by Boehm’s titration and FT-IR analysis, pHpzc, iodine number, SEM-EDX, and particle size distribution. The results showed that the surface area, pore size, and pore volume of the activated carbon increased with the increasing temperature and impregnation ratio and reached maxima at the impregnation ratio of 40/30 at 700 °C. Under the optimal conditions, it was determined that the BET surface area, total pore volume, iodine number, and pHpzc of the activated carbon were 1689 m2/g, 0.842 cm3/g, 1276 mg/g, and 4.8, respectively, and it has mainly acidic functional groups (total 0.2516 meq/g) on its surface. The activated carbon obtained was evaluated for rifampicine removal efficiency depending on contact time, adsorbent dosage, and initial concentration of rifampicine. Maximum adsorption capacity of rifampicine by the activated carbon (Q°) was determined according to Langmuir adsorption isotherm. The adsorption data was best fitted to the Langmuir isotherm with R 2 of 0.983 and Q° was found to be 476.2 mg/g.

Mesoporous activated carbon from industrial laundry sewage sludge: Adsorption studies of reactive dye Remazol Brilliant Blue R

Mesoporous activated carbon (AC) was prepared from sewage sludge of industrial laundry by slow pyrolysis followed of physical activation with CO2 and applied to remove reactive dye Remazol Brillant Blue R (RBBR) from aqueous solutions. The effect of activation temperature was investigated. The materials were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and N2 adsorption-desorption isotherms. The ACs prepared at activation temperatures of 750°C (AC750), 800°C (AC800) and 850°C (AC850) exhibited BET surface areas (SBET) of 159m2g−1, 156m2g−1 and 65m2g−1, respectively, and mesoporous features with average pore diameters ranging from 4.56 to 5.88nm. The SEM images indicated the formation of cavities on the surfaces of ACs with increasing temperature. The XRD patterns showed the presence of minerals in ACs and sewage sludge such as quartz, muscovite, dolomite and calcite. Inorganic and organic contents were evidenced by TGA, and surface groups by FT-IR. The values of pHPZC indicated basic characteristics for AC750, and acidic for AC800 and AC850. The AC750 was applied in the RBBR adsorption from aqueous solution. Adsorption kinetics and adsorption equilibrium showed that the pseudo-second order and Freundlich models were best fitted to experimental data. The Langmuir monolayer maximum adsorption capacity was 33.47mgg−1. The thermodynamic parameters indicated the adsorption is a spontaneous process and favored at higher temperatures (endothermic reaction). The thermal regeneration of spent AC750 showed it can be reused on adsorption processes.

Activated Carbons from Residue after Supercritical Extraction for Removal of Nitrogen Dioxide

The aim of this study was to obtain activated carbons by physical activation of the waste left after supercritical extraction of marigold and hops, provided by the Institute of New Chemical Syntheses in Pulawy (Poland). The precursors were first subjected to carbonisation at 500oC in nitrogen atmosphere. The chars were next subjected to physical activation at 700 and 800oC in carbon dioxide atmosphere. The effect of activation temperature on the physicochemical properties of the adsorbents prepared has been tested. The carbonaceous materials were characterised by low-temperature nitrogen sorption as well as determination of the number of surface oxygen groups. The sorption properties of the chars and activated carbons obtained were characterised by nitrogen dioxide adsorption. The results have shown that activated carbons are characterised by low developed surface area varying from 2 to 413 m2/g and show alkaline character of the surface. It has been proved that appropriate choice of the activation parameters and the presence of steam have a positive effect on adsorption of nitrogen dioxide by activated carbons obtained. The highest sorption capacity toward nitrogen dioxide in wet conditions was 72.1 mg/gads, while in dry conditions it was 38.7 mg/gads. The results have also shown that future research should be aimed at the optimum choice of the temperature of activation or activating agent in order to significantly improve the textural parameters of the activated carbons.

Growth of carbonaceous nanomaterials over stainless steel foams. Effect of activation temperature

Some of the problems that occur during the operation of chemical reactors based of structured catalytic substrates, as monoliths, foams, membranes, cloths, fibres and other systems, are related to the preparation of long term stable coatings. Frequently, the deposition of the catalytic layer is carried out by washcoating, requiring this step a cautious attention, especially in the case of complex geometries, like of that of foams or cloths. In the case of the deposition of layers of carbonaceous materials (CNMs), an alternative route, avoiding the washcoating, it is their direct growth by catalytic decomposition light hydrocarbons (also called CCVD), over the surface of the metallic substrate. In this case, if the metallic substrate is of stainless steel, it already contains the catalytic active phases like Fe and Ni.In order to optimize the process of CNMs growth over structured metallic substrates, we are studying the effect of the main operational variables of the ethane decomposition reaction on stainless steel foams. In this contribution we present a study of the influence of the temperature of the activation (oxidation and reduction) stage on the type and morphology of the carbonaceous materials formed. The results obtained allow us to determine the optimal operating conditions to maximize the amount and the selectivity of the process to obtain a given type of CNM.

Activated Carbon from Rubber Wood Sawdust by Carbon Dioxide Activation

Activated carbon (AC) is an organic adsorbent and mostly used to adsorb volatile organic compound pollutants. In the present work, AC was produced from rubber wood sawdust via a physical activation method using CO2 gas. Prior to activation process, the biomass was carbonized under N2 gas flow of 600mL/min for 1h at a corresponding temperature to produce char. The effect of activation temperature (700, 720, 740, and 760°C) and time (60, 90, and 120min) on the mass yield and characteristics of activated carbon was investigated. In overall, the yield of AC decreased when heated at higher activation temperature and increased at longer time. Under nitrogen adsorption analysis, surface area and pore volume of AC were determined. At higher temperature, surface area and pore volume increased, but excessive heating could break the pore structure. Next, the performance of activated carbon was tested in term of adsorption capacity for gas and liquid phase adsorption represented by benzene and trichloroethylene, respectively. Preliminary results suggested that the AC could adsorb both compounds efficiently.

Porous carbon based on polyvinylidene fluoride: Enhancement of CO2 adsorption by physical activation

Global warming has become a crucial issue and various efforts have been made to mitigate the emission of CO2, the most dominant greenhouse gas. Adsorption is considered a promising technology for CO2 capture, and carbon materials are good candidates for CO2 adsorption. In this study, highly porous carbons were prepared from polyvinylidene fluoride by single-step physical activation under CO2 flow at temperatures of 700–950 °C. The effect of activation temperature on the characteristics and CO2 adsorption properties of the prepared porous carbons was studied. Additionally, the dependence of CO2 adsorption capacity on various textural properties was investigated to identify the most important factor that determines CO2 adsorption. Both surface area and pore volume increased proportionally with activation temperature because of the newly produced pores and enlarged pore size within the carbon. Additionally, CO2 adsorption is highly dependent on the volume of pores that are below 0.70 nm in size. Among the samples tested, the porous carbon prepared at 800 °C exhibited maximum CO2 adsorption capacities of 6.05 and 3.84 mol kg−1 at 0 and 25 °C, respectively, besides showing good CO2/N2 selectivity, excellent recyclability, easy regeneration, and rapid adsorption–desorption kinetics.

The use of microwave radiation for obtaining carbonaceous adsorbents from biomass and their use in elimination of inorganic pollutants

A new technology of obtaining activated carbons by physical and direct activation of biomass with the use of microwave radiation is described. The effect of activation temperature (700 and 800 °C) and two periods of time (15 and 30 min) on the textural parameters, acid–base character of the surface and sorption properties of activated carbons was tested. The resulting carbons were characterized by low-temperature nitrogen sorption and determination of pH as well as the number of surface oxygen groups. The sorption properties of the activated carbons obtained were characterized by determination of nitrogen dioxide and hydrogen sulphide adsorption in dry and wet conditions as well as by iodine removal from aqueous solution. The final products were adsorbents of surface area ranging from 291 to 368 m2/g and pore volume from 0.20 to 0.26 cm3/g, showing basic character of the surface. The results obtained in our study have proved that suitable choice of the pyrolysis and activation procedure for hay with the use of microwave radiation permit producing adsorbents with good capacity toward toxic gases of acidic character as well as inorganic pollutants of molecules of size similar to that of iodine molecules.

Single-step synthesis of magnetic activated carbon from peanut shell

Magnetic peanut shell based activated carbon (MPSAC) was first prepared via a simple one-step method in the existence of K2CO3 and Fe3O4. The effects of activation temperature and activation time on the structures and properties of the activated samples were analyzed. Results show that the development of the porous structures can be facilitated by increasing the activation temperature or the activation time. Compared with the activation time, the activation temperature was found to play the key role in the formation of magnet Fe3C. At 750°C for 1.5h or 800°C for 1h, Fe3O4 was almost converted into Fe3C. The prepared MPSAC-750-1.5 and MPSAC-800-1 demonstrated the high surface area with a micro-, mesopores and macropores combination.

EFFECT OF ACTIVATION TEMPERATURE AND ZnCl2 CONCENTRATION FOR MERCURY ADSORPTION IN NATURAL GAS BY ACTIVATED COCONUT CARBONS

Elemental mercury from natural gas has increasingly become an environmental concern due to its high volatility and toxicity. Activated carbon adsorption is an effective mercury control method. Mercury content in natural gas should be removed to avoid equipment damage in the gas processing plant or the pipeline transmission system. This research describes the process of mercury removal from natural gas by coconut active carbon impregnated with ZnCl2. Activation temperature and ZnCl2 solution concentration are significant affect the mercury adsorption capacity. Charcoal was prepared from coconut shell and activated at 500, 700 and 900oC in constant fl ow of nitrogen. The effect of activation temperature and ZnCl2 concentration for mercury adsorption on adsorbent show that the adsorption ability of adsorbent is affected by increasing activation temperature up to an optimum temperature of 700oC. Ability of adsorption increases with increasing ZnCl2 concentration and mercury adsorption was optimum at 7% concentration of ZnCl2. The results indicated that the adsorption capacity of mercury in natural gas by activated carbon-impregnated chlor is very signifi cant. The conclusion of this paper is that optimum activation temperature 700oC and 7% ZnCl2 impregnated on adsorbent can improve the mercury adsorption in natural gas.

The use of microwave radiation for obtaining activated carbons from sawdust and their potential application in removal of NO2 and H2S

Activated carbons obtained from sawdust pellets from coniferous wood were used as adsorbents of nitrogen dioxide and hydrogen sulphide. The precursor was subjected to pyrolysis at 400°C in nitrogen atmosphere and next to physical activation at 600 and 700°C by CO2. Some part of the precursor was also subjected to direct activation at 600°C by CO2. The effect of activation temperature on the textural parameters, acid–base character of the surface and sorption properties of activated carbons was analysed. The resulting carbons were characterized by low-temperature nitrogen sorption, determination of pH and the number of surface oxygen groups by Boehm method. The adsorption of NO2 and H2S was carried out from dry or moist (70% humidity) air.The results have shown that NO2 and H2S sorption properties of activated carbons depend on the temperature of activation and the conditions of adsorption. The results obtained in our study have proved that a suitable choice of the pyrolysis and activation procedure of sawdust can give adsorbents with high capacity of nitrogen dioxide, reaching to 54.7 and 28.8mgNO2/g in dry and wet conditions, respectively and low capacity of hydrogen sulphide of 4.1 and 6.2mgH2S/g in dry and wet conditions, respectively.