Methanation of CO (Eq.1) was first reported by Sabatier and Senderens [i] and has been widely used in several industrial processes including purification of H2-rich streams by removing CO traces to avoid catalyst poisoning in polymer electrolyte fuel cells [ii]. CO methanation presents an important connection with biomass conversion [iii,iv] since it has a critical role in methane production from synthesis gas, and also is an obvious starting point in Fischer-Tropsch synthesis for long-chain hydrocarbons formation [v]. This reaction takes place along with water-gas shift reaction (WGS), which converts CO to CO2 (Eq. 2). However, WGS is not normally treated as a separated stoichiometric reaction. (1) (2)
The mechanism of methanation reaction
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In contrast, WGS reaction (Eq. 2) which occurs concomitantly with CO methanation has received considerable attention because of its potential application in automotive exhaust gas cleaning with respect to CO emissions [xxvii,xxviii]. This reaction is accepted to follow a simple Langmuir-Hinshelwood (LH) process whereby CO2 is formed through the associative reaction of chemisorbed CO with the oxygen surface atoms produced by water activation. CO*+O* oxidation step is mostly believed as the kinetically-relevant due to the significant activation barrier of this step on Pt surfaces [xxix]. In addition, CO can also be oxidized by OH* forming formate (HCOO*) or carboxyl (COOH*) surface intermediates [xxx], which then directly decompose or react with OH* or O* forming CO2. Literature reports that COOH*+OH* step has lower barrier energy than direct CO*+O*, but at low reaction temperatures the surface is mostly saturated with CO*, making COOH*+OH* path unlikely to occur [30]. A current challenge comprises unifying CO2 formation elementary steps from WGS mechanism with CO methanation steps in order to provide a consistent mechanism that explains CH4, H2O and CO2
CO2 is not very reactive at normal temperatures, but it does form carbonic acid, (H2CO3 ) in aqueous solution. This will undergo the typical reactions of a weak acid to form salts. I call it carbonic acid because in the presence of moisture, which we have all around us, it will make an acid. CO2 is also responsible for the acidic pH of rain water. So that nasty stuff called “acid rain” is caused by CO2. A solid hydrate CO28H20 separates from aqueous solutions of CO2 that are colder at elevated pressures. It is very stable at normal temperatures, but forms CO and O2 when heated above 1700oC.
The purpose of the experiment is to study the rate of reaction through varying of concentrations of a catalyst or temperatures with a constant pH, and through the data obtained the rate law, constants, and activation energies can be experimentally determined. The rate law determines how the speed of a reaction occurs thus allowing the study of the overall mechanism formation in reactions. In the general form of the rate law it is A + B C or r=k[A]x[B]y. The rate of reaction can be affected by the concentration such as A and B in the previous equation, order of reactions, and the rate constant with each species in an overall chemical reaction. As a result, the rate law must be determined experimentally. In general, in a multi-step reac...
Fossil fuels, such as coal and oil, are Carbon rich compounds, the combustion of which produces Carbon Dioxide, a pollutant and a greenhouse gas. A large amount of energy is released during this process, which is why the pollutants off products are tolerated. This process occurs constantly throughout the world, in power stations, vehicles and cooking ovens, leading to an immense volume of CO2 being released every second, 50% of which is absorbed by oceans (Oce...
The overall objective of this experiment was to perform a Wittig reaction from creating an ylide and mixing it with a carbonyl (C=O) compound, cinnamaldehyde. The completion of the reaction was confirmed ultimately from the initial TLC analysis. Since TLC separates the components of the spotted material, as long as the retention factor values were different for cinnamaldehyde, the starting reagent, and the product(s), it was evident that some of the reaction had gone to completion. However, as seen in Figure 3, there was some blurred area between the product spots. This indicated that there still existed some impurities, most likely the starting reagent, which was affecting the movement of the compounds through the solvent, petroleum
[11]: Selective catalytic reduction of nitric oxide by hydrocarbons Michael D. Amiridisa, Tiejun Zhanga, Robert J. Farrautob, Applied Catalysis B: Environmental, Volume 10, Issues 1–3, 14 September 1996, Pages 203–227
There is an overwhelming use of catalysts - a substance that changes the rate of reaction without being consumed by the reaction itself- in various industrial processes. According to certain estimates [cite-wiki10] around 90% of all “commercially produced chemical products involve catalysts at some stage in the process of their manufacture.” Chemical products worth $900 billion were generated by catalytic processes worldwide in 2005 [cite – wiki11]. The close affiliation of the catalysts and the process of catalysis to a variety of industries and the proximity of these industries with consumers raise questions regarding the application of catalysts and their effects on products.
Human activities have led to an exponential increase in the use of fossil fuel. The benefits of using fossil fuels are short lived in comparison to its long-term negative effects. In the last couple of decades, the major consumption of fossil fuel played a significant role in the rise of concentration of CO2 in the atmosphere. Roughly two trillion metric tons of CO2 have been emitted in the atmosphere and over a quarter of these got mixed with the ocean water resulting in ocean acidification (Buffie and Carr, 2010).
Carbon dioxide (CO2) is a key global warming gas that is proposed to have direct linkage to global climate changes [1, 2]. Therefore, there is a growing interest in developing technologies for efficient capture and sequestration of large quantities of CO2. An efficient and economical capture material is needed to capture and separate the CO2 produced during various industrial processes. There are four potential sources of carbon dioxide emission; industrial processes, fossil fueled power plants, de-carbonization (production of hydrogen from carbon rich feed stock), and transportation [3]. Among the carbon dioxide emission sources, fossil fueled power plants are ranked the number one potential source. Fossil fuels provide 81 percent of the world’s commercial energy supply [4]. Consumption of fossil fuels produces nearly 30 Pg (petagram) of carbon dioxide annually. About three-fourths of the increase in atmospheric carbon dioxide is attributed to burning of fossil fuels [5].
Kinetic equations are utilized in this article to describe the dependence of the reaction between carbon and oxygen atoms and their environment. The research is trying to answer how the reaction area affects porous particles, especially carbon in this research article. Carbon combusts in two different modes, high-rate and low-rate. The high-rate combustion of the homogeneous reaction consumes the oxygen particles above the surface of the particle. The heterogeneous reaction inside the particle is endothermic, meaning that heat is absorbed thus decreasing the particle temperature resulting in a higher rate of combustion. The low-rate combustion does not allow the homogeneous reaction to happen, but instead only the heterogeneous reaction inside the particle, concluding that a higher temperature increases the rate of combustion.
Predictions may be made about the suitability of possible catalysts by assuming that the mechanism of catalysis consists of two stages, either of which can be first:
...ch is used to replace natural gas. He also stated that, among the equipment used to burn the biofuel, the suspension burner have the ability to exceed 99% efficiency and whole-tree burner can reduce the cost of harvesting and handling woody fuels by about 35% (Brown, 2003). Moreover, the usage of bio-energy in long term is to provide a degree of ecological balance and climate change, avoid acid rain, reduce soil erosion and minimize water pollution (Gevorkian, 2007). Therefore, biomass is environmental friendly like solar energy. Based on the research that has been carried out regarding the synthesis of gas from biomass, the gas gasifies in the internal combustion engine. The relative energy density of synthesis gas is higher than the fossil fuel under certain conditions. In addition, the relative flame speed of synthesis gas can reduce the time for spark ignition.
Hester, R. and Harrison, R., 2002. Global environmental change. 1st ed. Cambridge, U.K.: Royal Society of Chemistry.
Biomass gasification is a process by which biofuel is produced. It has been used for over 180 years but in the last decades it has been reconsidered as an interesting technique due to the fact that oil supplies are decreasing. As mentioned before, gasification is a thermal process. Heat is added up in order to convert the organic mass to biofuel. The biomass usually undergoes drying, pyrolysis, partial oxidation and reduction. Nowadays the configurations used for gasification are three: fixed bed gasifier, fluidized bed gasifier and entrained bed gasifiers. The simplest configuration is the
Audus, H, Kaarstad, O, and Kowal, M, Decarbonisation of fossil fuels: Hydrogen as an energy carrier,[ presented at the CO2 Conf., Boston/Cambridge, MA, 1997, published in Energy Conversion Management, vol. 38, Suppl., pp. 431–436.
The reaction of carbon with CO2 is important in a variety of the applications including power generation using coal gasification and the smelting of iron and steel. Since several commercial gasifiers for IGCC operates at a high temperature and a high pressure (1200-1600 0C, 2.5 MPa). Form the existing literature, information on coal gasification characteristics at atmospheric pressure can be found [1-3]. However, only a few fundamental studies on coal gasification reactivity at high temperature and elevated pressure were reported [4-7]. The gasification of coal consists of two major reactions: pyrolysis of coal and gasification of char. Since the rate of char-gasification is much slower than that of devolatilisation, the gasification characteristics o...