Dissertations / Theses on the topic 'Activated carbon/Methanol'

Etude experimentale et simulation dynamique de systemes de pompe a chaleur a adsorption solide. Les systemes methanol-charbon actif et eau-zeolite sont etudies. Les conditions de temperature des composants (adsorbeur, condenseur et evaporateur) doivent etre homogenes pour la simulation. On considere les cycles intermittents (simple effet), a double effet et a triple effet (cycle a cascades). Determination d'un coefficient de performance pour la production du froid

Une nouvelle technique experimentale a ete mise au point pour etudier la cinetique d'adsorption due aux transferts de masse et de chaleur. Application a l'adsorption du methanol sur la zeolite x et le charbon actif

Dissertation (Ph.D.) -- Worcester Polytechnic Institute.
Keywords: Activated carbons; Hydrogen cyanide; Methyl ethyl ketone; Adsorption; Mercury; Monte-Carlo; Solvents; Molecular simulations; Zeolites; Water; Methanol; Nanopores. Includes bibliographical references (leaves 147-150).

Le biogaz doit être purifié pour devenir un combustible renouvelable. De nombreux traitements actuels ne sont pas satisfaisants car, pour des raisons de coûts les procédés de séparation privilégiés aboutissent souvent au rejet direct ou indirect du sulfure d'hydrogène (H2S) à l’atmosphère, c’est le cas de la séparation à l’eau sous pression. Les objectifs de la thèse portent d’abord sur l’étude et la modélisation des méthodes connues de séparation de l'hydrogène sulfuré du méthane. Les concentrations typiques varient de 200 à 5000 ppm, et la séparation devra réduire la teneur résiduelle en H2S à moins de 1 ppm. Parallèlement seront étudiées les méthodes de traitement de H2S. Une fois la (ou les) méthode(s) de séparation sélectionnée(s), des essais de validation seront effectués sur un système traitant de l’ordre de 85 Nm3/h de méthane où seront injectées des quantités de H2S variant entre 1 et 100 ppm.Cette thèse requiert des modélisations réalistes sous Aspen Plus® ou sous un code équivalent pour établir a priori des efficacités de séparation selon différentes conditions opératoires et en prenant en compte le paramètre température. L’énergie dépensée pour la séparation effective sera un des critères fort de la comparaison, de même que l’économie de matière.Une approche système est indispensable pour étudier la rétroaction de la méthode de valorisation du H2S sur la ou les méthodes séparatives. A priori c’est aussi l’outil Aspen Plus® ou équivalent qui permettra cette approche système.L’étude du procédé sera menée selon la double approche modélisation et expérimentation, pour l’étude expérimentale des méthodes séparatives, l’échelle du banc sera semi-industrielle et le banc permettra d’étudier les méthodes de séparation jusqu’à -90°C
Biogas must be purified for becoming a renewable fuel. At now, the most part of the purification techniques are not satisfactory because they imply hydrogen sulfides (H2S) rejection to the atmosphere. One example of these methods is the treatment with high pressure water. The first objective of the thesis is modeling the conventional methods for separating H2S from methane. Typical concentrations of H2S in methane vary from 200 to 5000 pm. Separation methods must decrease the concentration of H2S in methane to less than 1 ppm. At the same time, methods for H2S treatment will be studied.Once the most appropriated separation methods will be selected, some test will be carried out on a pilot plant capable of treating 85 Nm3/h of methane, where quantities of H2S ranging from 1 and 100 ppm will be injected. These tests will allow validating the modeling of the separation process. On the basis of the obtained results, a specific test bench will be conceived and constructed for validating the selected process.The thesis work requires simulating the separation process using the software Aspen Plus® or an equivalent one. The effectiveness of different operative conditions will be tested, varying also the parameter temperature. The energy necessary for the separation will be one of the most important criteria for the comparison, as well as the mass consumption of the different fluids involved in the process.A system approach is fundamental for evaluating the backward effect of the H2S valorization method on the separation techniques. The process simulator (Aspen Plus® or equivalent) will allow the system approach.The study will involve modeling and experimental parts. The experimental part will be carried out taking advantage of a semi-industrial size test bench, allowing studying the separation methods down to -90°C

Solid adsorption refrigeration systems are attracting much research interest because they have numerous advantages, such as using low grade thermal energy and being environment friendly. In recent decades many efforts have been put into developing various prototypes. The adsorption refrigeration tube (ART) is one such development. Through better system integration, a module consisting of a number of individually working ARTs can achieve significant refrigeration capacity, which may solve the vacuum leaking problem that besets large adsorption systems. In order to propose a feasible ART, this thesis undertakes a study of adsorptive properties of three types of activated carbon/methanol working pairs and modelling of the adsorption refrigeration cycle. In this examination of adsorptive properties, three activated carbon samples, Calgon 207C, 207EA and WS-480, were used to test and determine their pressure-temperature-concentration (P−T−x) relationship with methanol as the adsorbate. Based on the experimental data, three adsorption state equations, Langmuir equation, Freundlich equation and Dubinin-Astakov (D-A) equation, were compared in terms of their agreement with experimental data and their format impact on calculating coefficient of performance (COP) and refrigeration output (Qr), if one of the formats was used for presenting experimental data. Moreover, a sensitivity analysis was conducted to reveal the parameters’ sensitivity to calculation of COP and Qr. It was found in this study that the D-A equation is the best state equation for presenting the adsorptive properties of the tested activated carbon/methanol working pairs in terms of the best agreement of P−T−x correlation and least sensitivities to parameters’ errors. A1-D dynamic model was established and validated experimentally, in which a local non-equilibrium treatment and dynamic boundary condition were introduced to the mathematical model. Regarding thermal non-equilibrium treatment, the temperatures of the local solid phase (activated carbon and adsorbed methanol) and local fluid phase were treated separately. Due to this non-equilibrium treatment, i.e. a two temperature treatment, convective heat transfer within the transport pores of activated carbon can be considered in the mathematical model. Moreover, a mathematically defined function was introduced to present the transient pressure process at the beginning of an adsorption process. Using this function, the temperature jump phenomenon can be well predicted by the mathematical model. After the mathematical model had been established and validated, a parametric analysis was conducted using the mathematical model. The effects of the cylindrical activated carbon column’s diameter and evaporating temperature on cycle time, COP and specific cooling power (SCP) were examined. Furthermore, a case study of cycle time optimisation was conducted. Finally, based on the parametric analysis, a practical solution using integrated groups of individual ART was proposed for home or domestic application. A preliminary economics analysis was also conducted to evaluate the potential of this application.
Thesis (M.Eng.Sc.) -- University of Adelaide, School of Mechanical Engineering, 2011

碩士
國立臺灣科技大學
化學工程系
89
Can sugar was used in this research as the raw material to prepare activated carbon. The carbon was then applied as a support to prepare Ni/AC catalyst. The activity and the stability of the catalyst in the carbonylation of methanol were subsequently examined. A method described as chemical activation was employed in this research to prepare the activated carbon. A mixture of ammonium phosphate [(NH4)2HPO4] and ammonium sulfate [(NH4)2SO4] was used as the activation agent. Activation temperature and composition of the activation agent were the variables studied in carbon preparation while reaction temperature and the time on stream were the variables investigated in catalyst activity tests. Instruments such as BET, XRD, TPD, TGA, DTA, EA, SEM&EDS, and FTIR were used to characterize the catalysts and the support (activated carbon). The characterizations revealed that activated carbon of lower surface area and pore volume and higher average pore size would be obtained if the activation agent employed in the preparation contained ammonium phosphate. Activated carbon of the maximum surface area and pore volume and minimum average pore size would be obtained by activating can sugar at 700℃. Activated carbon of more acid sites and greater acid strength would be obtained if the activation agent employed in the preparation contained ammonium phosphate. The characteristic peak of graphite was the only peak appeared in the XRD spectra of Ni/AC catalysts, showing nickel, sulfur and phosphorus were well dispersed on the catalysts. The peak appeared on the carbon activated at as low as 400℃, revealing the temperature was sufficient for the formation of activated carbon. Increasing the activation temperature would result in an increase in carbon content and decreases in hydrogen, oxygen, nitrogen, and sulfur contents in the carbon. The presence of ammonium phosphate in the activation agent and the use of high activation temperature both could result in carbon of finer sizes. The presence of ammonium phosphate in the activation agent could also enhance the bond strength between the sulfur and the carbon. The optimum temperature for activation of cane sugar was between 600 and 700℃. Using the carbon prepared at the temperature could give a Ni/AC catalyst of the highest activity in converting methanol to methyl acetate. The highest selectivity of methyl acetate could be found on the Ni/AC catalyst with the carbon being activated at 600℃. The conversion of methanol and the selectivity of methyl acetate were both increased with the content of ammonium phosphate in the activation agent. The conversion of methanol increased with the reaction temperature and started to leveled off when the reaction temperature reached 250℃. Maximum selectivity of methyl acetate was found at a reaction temperature of 200℃. Stability tests showed that the catalyst prepared from the carbon activated with the agent containing ammonium phosphate deactivated at a slower rate in comparison with those without ammonium phosphate. The catalysts could also be stabilized in a shorter time after the reaction.

碩士
靜宜大學
應用化學系
90
Catalytic synthesis of propionitrile from methanol and acetonitrile was achieved by using PAN based activated carbon fiber containing sodium. The activity of the catalysts depends on the source of sodium. The catalyst shows the highest activity when the Na2CO3 was used as a raw material for the preparation of catalysts. The conversion of acetonitrile reaches 75%, and the selectivity of propionitrile is 80%. The activity site of catalyst is sodium. The activity of catalysts deactive with increasing reaction time. The reason of deactivation was by the sodium losing. The activity of the catalysts can be enhanced upon the addition of silver. The catalytic activity of catalysts correlates well with the adsorption capacities of methanol and acetonitrile on the catalysts surface measured by the TPD method. A small amount of silver addition resulted an increasing in catalyst surface area. The adsorption capacities of methanol and acetonitrile were enhanced by the addition of silver.

碩士
國立台灣工業技術學院
化學工程技術研究所
85
This article aimed at comparing the catalytic properties of activated carbon and carbon fiber supported nickel catalysts for the carbonylation of methanol. The compared items included the physical properties, the selectivity, and the deactivation of the catalysts. The effect of MeI concentration on the carbonylation was also investigated. The instruments used for the research were BET, chemisorption, EDS of SEM system, TPD, and a reaction system. The results indicated Ni/C catalyst had larger BET surface area and pores volume than Ni/FC. Ni/C had wider pores distribution than Ni/FC. The dispersion of nickel on Ni/C was lower than that on Ni/FC. There were several different sites on Ni/FC for MeOH and MeI adsorption but only one on Ni/C. Ni/FC catalyst could adsorbs more CO than Ni/C catalyst. Ni/FC catalyst''s surface was acidic and contained well dispersed phosphor and sulfur . The conversion of methanol on Ni/FC was higher than that on Ni/C. But the selectivity of AcOMe and AcOH on Ni/FC catalyst is lower than that on Ni/C. The highest activity of Ni/FC and Ni/C catalysts on methanol carbonylation was reached at 300oC.A further increase in the temperature would not increase the activity. The highest catalyst activity was obtained by a feed with 0.1 MeI/MeOH molar ratio. Ni/C and Ni/FC deactivated slightly in the initial two hours on stream, then remained stable for the next 5h in operation.

碩士
國立臺灣科技大學
化學工程系
87
Sulfur and phosphorus were used to modify activated carbon fiber(ACF). The reasulting fibers,denoted as ACFS and ACFP respectively,were then used to prepare Ni/ACFS and Ni/ACFP catalysts. These catalysts along with Ni/ACF were employed in the carbonylation of methanol. The effects of S- and P- incorporations were examined by comparing the activity,selectivity,and deactivation of the catalysts before and after modification. The instruments used for catalyst characterization included BET,XRD,TPD,and ESCA. A reaction system to test the activities of the catalysts was also used. BET measurement revealed a drop in surface area if sulfur was added to ACF while there was no such a drop if phosphorus was incorporated. Acidity of ACF could be significantly enhanced by adding sulfur or phosphorus to the ACF, whit the latter being more effective than the former. ESCA spectra showed a remarkable increase in surface oxygen when ACF was modified by phosphorus. This observation implied a significant change in surface functional groups. Incorporating phosphorus could also enhance the dispersion of nickel. The amount of chemisorption of CO on Ni/ACF,Ni/ACFS, and Ni/ACFP was much more than that of hydrogen. Several explanations could be used to interpret the observation. Spill over of CO was one of them. The interaction between CO and bulk Ni to form carbonyl nickel with consumed excess CO was another one. The coverage of nickel particles by surrounding carbon, hindering the chemisorption of H2, constituted the third reason. The dispersion of nickel,as determined from H2-chemisorption data, had the following order: 5%Ni/ACFP > 5%Ni/ACF > 5%Ni/ACFS. The order become 5%Ni/ACF > 5%Ni/ACFS > 5%Ni/ACFP if CO chemisorption data were used. The order demonstrated the incorporation of phosphorus on ACF could hinder the spill over of CO. The characteristic peaks of nickel,sulfur, and phosphorus were not detected in XRD analysis showing these elements were well dispersed. The incorporation of sulfur or phosphorus could be easily discovered by EDS analysis. Activity of carbonylation of methanol of Ni/ACF could be improved by modifying the ACF with S. The improvement was eapecially obvious at low reaction temperature(e.g. 150℃). Another change in the reaction by the modification was the significant enhancement in the selectivity of acetic acid on the S-modified catalyst. The incorporation phosphorus markedly lowered the carbonylation activity of Ni/ACF catalyst. Due to the increase in the amount of acid sites by incorporation phosphorus, the principle product on Ni/ACFP was dimethyl ether, followed by methyl acetate. There was no acetic acid being detected. 5%Ni/ACF and 5%Ni/ACFS both suffered an initial deactivation in the reaction. The catalysts deactivated about 10% in the first 3 hours on stream. Then the catalysts become rather stable.

This thesis seeks to investigate the adsorption capabilities of activated carbon and carbon nanotubes. The adsorption of methanol on both of these substances was tested for their application in a solar based refrigeration cycle. Research on carbon nanotubes and their growth has been carried out for applications in the semiconductor industry. Enough focus has not been given to the use of nanotubes for refrigeration purposes. Adsorption refrigerators have been designed with the energy source being solar energy. Various adsorbent/adsorbate pairs have been tested in literature. The present work focuses on carbon nanotubes because theoretically, nanotubes should be able to adsorb better than activated carbon due to their high surface to volume ratios and hence a higher number of adsorption sites available for methanol to adsorb. The amount of adsorption of methanol on nanotubes depends on whether the end caps of the nanotubes are open or closed and also on the hydrophilic nature of the nanotubes. Nanotubes with ends closed are supposed to adsorb less than the nanotubes with their ends opened. The ends of carbon nanotubes can be blocked because of iron and other impurities. In this project, nanotubes are annealed under high vacuum to open the end caps. The hydrophobic nature of the nanotubes is corrected by treating them with concentrated nitric acid. The hydrophobic nature of the nanotubes is corrected by treating them with concentrated nitric acid. The acid treated nanotubes are used to obtain adsorption data at different temperatures. The adsorption of methanol on activated carbon, pristine and treated carbon nanotubes is measured at different temperatures. Electron microscopy is used to validate that annealing the nanotubes at high temperature under vacuum opens the end caps of the nanotubes. Finally, a matrix of nanotubes and carbon powder is prepared with different concentrations. The mixture is tested for adsorption of methanol. It is observed that the carbon nanotubes, pristine or treated, do not perform better than activated carbon. However, performance seems to increase when mixtures of activated carbon and carbon nanotubes are used as adsorbent. Also, it is found that mixtures containing annealed nanotubes perform better than mixtures with pristine nanotubes. Kinetics of the adsorption process is calculated for the different adsorbents used, which is used to explain the increase in the amount of methanol adsorbed for the activated carbon-carbon nanotube mixture.

The thesis presents the outcomes of a study on the accumulated performance of a solar thermal powered adsorption refrigeration system. The solar-powered solid adsorption refrigeration system has numerous advantages including no moving parts during operation, using solar energy as the only heat input to run the whole system and being environmentally benign. The methanol and activated carbon selected as a working pair are due to advantages of their ice-making capacity, high efficiency and low price. The system, in its simplest form, runs according to the intermittent daily solar cycle, only making cooling at night and not during the daytime. The previous research mainly focuses on the individual daily cycle under the assumption that the system restores back to its original point every day, regardless of a real climate condition. In reality, for such a refrigeration system, its real performance depends not only on the current day’s weather condition but also on the previous day’s situation. However, the accumulated performance of the system over a period has only been little studied, which brings out three research questions that remain to be answered: How should a new configuration be modified, in order to make the system accumulate cooling capacity without removing ice daily? How many situations should be involved in the new accumulated cycles with consideration of real daily and hourly climate conditions? How should the mathematical models be established, in order to simulate the accumulated performance of the system more realistic and accurately? Therefore, the aim of the research is to develop a better understanding of an accumulated performance of an activated carbon/methanol refrigeration system if running over a period, e.g. days or weeks, by developing two validated simulation models. The thesis complies with the graduation by publication format of the University of Adelaide, which consists of one published journal article and one submitted journal article which is currently under review. The two articles are able to demonstrate the outcomes of the study and also form the main part of the thesis. Additional introduction and a literature review are provided to establish the context and significance of this work. The main outcomes of the study include: The new configuration of such a system, which can accumulate the cooling capacity without removing ice daily, has been established. In the configuration, the receiver and evaporator must be separated by adding separation valves between them. Possible cycles of such a system have been identified with consideration of realistic daily climate conditions. The mathematical model using daily weather data, with consideration of possible leftover liquid in the receiver, has been developed. The model has been validated against the published experimental data with an acceptable agreement. A desktop case-study for 50 consecutive days has been used to demonstrate the difference in the simulation of accumulated performance by two models, i.e. the model using daily climate conditions and the model under ideal assumptions. It has been concluded that the developed model using daily climate conditions is more accurate than the model under the ideal assumptions. The second mathematical model using hourly weather data has been developed based on seven possible cycles. These cycles, which are involved in the initial heating process and condensing process during the daytime, have been identified. The mathematical model using hourly climate conditions has been validated against the published experimental data with a more accurate agreement, compared to that of the model using daily climate conditions. A desktop case-study for three climatic days has been conducted to demonstrate the difference in the simulation of performance when the model using daily climate conditions and hourly climate conditions respectively. The daily performance (i.e. daily-evaporated methanol liquid) simulated from the new model could be 31.3% more than that from the first mathematical model in a special climatic day.
Thesis (MPhil) -- University of Adelaide, School of Mechanical Engineering, 2019

碩士
嘉南藥理科技大學
環境工程與科學系
100
Copper nitrate、copper sulfate、and cobalt chloride were used as the impregnating agent with agriculture waste - coconut shell for preparing activated carbon catalyst. The impregnated coconut shells were activated to form activated carbon catalyst and applied for catalytic oxidation of methane with air. The oxidation activities of catalyst were investigated by considered the porosity and dispersion of active metal on activated carbon. The influence of impregnating agent on the pore characteristics of catalyst were investigated by BET analysis. The morphology and dispersion of active metal were observed by SEM-EDS. The catalytic oxidations were carried on by considering the ratio of air/methane, operating temperature, and activated carbon properties. It was found that the activated carbons with impregnated copper nitrate own the highest surface area, 993 m2/g. The pore volume of catalyst is mainly contributed by the micro pore volume and the mean pore size of this activated carbon is about 10.2 Å. It was also found that the oxidation activity of carbon catalysts are following in copper nitrate> copper sulfate> cobalt chloride as the impregnating agent in catalyst preparation. The catalytic oxidation activity of carbon catalyst depends on the active metal dispersion and adsorption area of carbon catalyst. The higher impregnating agent did not proportional promote a higher surface area and more active sizes on the catalyst due to the high viscosity metal salt hindered the penetration into the coconut shell structure. The optimum concentration of impregnating agent owns the higher surface area and active sizes on the carbon catalyst. In the case of impregnating agent with 0.05M, the methane conversion achieved 100%, 67.7%, and 65.9% (copper nitrate, copper sulfate, cobalt chloride) at 300℃ in oxidation. It was also found that the excess oxidant did not benefit the conversion of methane in oxidation due to the decline in pollutant adsorption on the catalyst.

Natural gas is stored as compressed natural gas (CNG) in heavy steel cylinders under pressures of 200-250 atm. However, such a method of storage has certain disadvantages which include multistage compression costs, limited driving range and safety aspects. Hence, alternative methods of storage such as adsorbed natural gas (ANG) which involve adsorbing natural gas at moderate pressures and room temperatures in a suitable nanoporous material are currently being explored. In this thesis, we have isolated model carbon nanostructures and defect geometries most likely to be found in these materials and investigated their specific interactions with methane. The thesis is concerned with ab-initio density functional theory calculations on these various model carbon nanostructures in order to identify the potential candidates that enhance methane adsorption. The adsorption energies of methane on graphite and graphene sheets were similar, with a value of 12.3 kJ/mol for graphene. The Stone-Wales defect in graphene was found to increase the methane adsorption energy to 37.2 kJ/mol, and small surface undulations on the graphene sheet resulted in a smaller increase (16 kJ/mol) in the adsorption energy relative to graphene. The presence of an interstitial carbon was found to significantly reduce the adsorption energy to 5.2 kJ/mol. The enhanced adsorption energy in the case of the Stone-Wales defect was attributed to the significant charge redistribution in the vicinity of the defect. A variety of functional groups such as carboxylic acid (COOH), carbonyl (CO), phenol (OH), pyran (-O-), phenone (=O), peroxide (OOH) and amine (NH2) groups have been observed on carbon surfaces. Extensive density functional calculations of methane adsorbed on various chemically functionalized graphene nanoribbons were carried out to evaluate their methane adsorption energies. A significant finding in this study, is the increased adsorption energies (relative to graphene) that occur for the functional groups containing the OH moiety. The adsorption energies for edge functionalized graphene nanoribbons are 27.6 and 69.7 kJ/mol for COOH and OOH functionalization. Additional computations reveal a strong correlation between the induced dipole moment on methane and the strength of the adsorption energies obtained for the extended nanoribbons. Adsorption isotherms for methane were obtained using grand canonical Monte Carlo simulations for slit-like graphitic pores with and without functional groups. For both OH and COOH functionalized graphite, we observe more than a 40 % increase in the volumetric loading over bare graphite for the highest weight % of the functional group and smallest pore width considered. The maximum volumetric loading decreases with a decrease in the wt% of the functional groups and with an increase in the pore width.