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DME has been received the attention as a renewable energy due to its thermal efficiencies equivalent to diesel fuel, lower NOx emission, near-zero smoke and non-toxic. DME can be obtained by methanol dehydration over solid acid catalysts or directly from syngas over bifunctional catalysts. The catalytic dehydration of methanol to DME has been widely studied in the literature over pure or modified γ -aluminas (γ-Al2O3) and zeolites. Mesoporous silica has obtained much consideration due to its well-defined structural order, high surface area, and tunable pore diameter. In this work, sulfonic acid and aluminium modified mesoporous silica were synthesized and tested as catalysts for production of dimethyl ether from methanol. The modified silicas were studied utilizing XRD, N2 physisorption, pyridine adsorption, and scanning electronic microscopy. The effects of reaction temperature and water deactivation on the methanol selectivity and conversion to dimethyl ether were investigated. Sulfonic acid modified mesoporous silica showed higher selectivity and stability of DME than that of aluminosilicate. The grafting of mesoporous silica with sulfonic groups displayed much more enhanced hydrothermal stability than Al-MCM-41 and γ-Al2O3.

The influence of a catalyst's surface acidity on the catalytic activity and deactivation in the dehydration of methanol to DME was investigated. Different materials including propylsulfonic acid functionalized silica with different Brønsted acidities, silica-alumina, and propyl and phenylsulfonic acid functionalized silica-alumina catalysts were prepared. All the samples were characterized by XRD, TGA, XPS, N2-sorption, ICP-OES and SEM analysis. It was found that the Brønsted and Lewis acidity of the SiO2/Al2O3-PhSO3H catalyst played a critical role in the performance of methanol to DME transformation. The grafting of sulfonic acid groups on silica-alumina enhanced the surface Brønsted acidity and also the reaction activity and selectivity for the dehydration of methanol to DME. In addition, the phenylsulfonic acid functionalized silica-alumina catalyst exhibited the highest activity and stability for the dehydration reaction at relatively low temperatures at which the γ-Al2O3 catalyst, commercial reference, displayed low dehydration activity. The effect of water was also investigated because in the indirect process to produce DME using acidic γ-alumina, it had the most important effect on catalyst deactivation. As a result, water had a positive effect on methanol dehydration over the SiO2/Al2O3-PhSO3H catalyst in contrast to γ-Al2O3 which was rapidly deactivated. Thus, Brønsted and Lewis acid sites with suitable strength may be responsible for the effective conversion of methanol to DME with high stability and selectivity. This journal is

The global issue of contamination and power reserves has given dimethyl ether (DME) considerable attention. It is an encouraging and clean green material for the future resulting from its clean combustion properties. In this paper, a novel MCM-41-propyl-SO3H catalyst was successfully prepared with tethering of the active sulfonic acid groups onto the support via covalent bonds. This material was investigated as catalyst for DME synthesis via methanol dehydration in a fixed bed flow reactor at different experimental settings. TGA, NH3-TPD, SEM, XRD and BET techniques​ were utilized to characterize the synthesized material. MCM-41 sulfonated catalyst showed great thermal stability, high surface area and significant acid loading. The catalytic tests also demonstrated that the maximum methanol conversion was observed at 350 °C and catalyst contact time of 8 s. In addition, the catalyst showed a total selectivity to DME; light hydrocarbons and higher oxygenated compounds were not formed at temperatures above 300° C.

Dimethyl ether (DME) is an environmentally friendly fuel that is being widely considered as an alternative fuel to replace petroleum fuels. DME can be produced by dehydration reaction of methanol by using solid catalysts in catalytic reactions. This study shows the influence of catalyst's surface acidity on the catalytic activity in the dehydration of methanol to DME. In this work, the conversion of methanol to dimethyl ether has been investigated using a continuous flow fixed-bed reactor at temperatures between 60°C and 350°C and 1 bar. Sulfonated catalysts with-SO3H acid function were tested and compared with conventional catalysts as γ-Al2O3. SiO2, MCM-41 and fluoropolymer were used as inorganic and organic supports for sulfonic groups. The experimental results demonstrate a good catalytic activity for the functionalized MCM-41 and the fluoropolymeric material. Effects of H2O on the activity and deactivation of these catalysts were also studied.

BACKGROUND: The methanol dehydration to dimethyl ether (DME) has received considerable attention in the literature, because of its potential use as a multipurpose fuel. A wide literature of kinetic studies is available for γ-Al2O3, reference commercial catalyst but only a few authors report a kinetic analysis of attractive and alternative catalysts to γ-Al2O3 in DME production. The aim of this work was to contribute in this direction, by performing a catalytic test focused on the determination of kinetic parameters for methanol dehydration over sulfonic acid catalysts and polymeric materials. RESULTS: The catalytic and kinetic behavior of these materials for the methanol to DME dehydration reaction has been investigated using a fixed bed reactor at total pressure of 1 bar within a temperature range of 50 to 450 °C. The sulfonated fluoropolymer (Aquivion) exhibited the highest activity and stability for the dehydration reaction at relatively low temperatures at which the γ-Al2O3 did not display any dehydration activity. The tested catalysts showed good time stability when both methanol and methanol/water mixtures were used as feed reactants. Good agreement was achieved between experimental data and the proposed model. CONCLUSION: The -SO3H groups enhanced the surface acidity and the catalytic performances. The sulfonated perfluorinated polymer (Aquivion) was able to catalyze the methanol/DME conversion at temperatures as low as 90 °C. The selectivity to DME at lower temperatures was 100%. Apparent activation energy for this reaction was experimentally evaluated to 110 KJ/mol and theoretical calculated to 96 KJ/mol: there was a comparable and good agreement with the experimental data. © 2020 Society of Chemical Industry.

Sulfonic acids grafted on inorganic support such as SiO2 and MCM41 was used as catalysts for conversion of methanol to dimethyl ether. In this experimental work the catalysts were compared for their catalytic properties in a continuous flow fixed-bed reactor at temperatures between 180 and 320 °C and 1 bar. It was found that all SO3H-functionalized materials in this study were active, selective and stable for DME synthesis. According to the experimental results MCM-41-(CH2)3-SO3H exhibited the best performance, related to its higher surface area and acidity.

This paper investigates a new concept for the CO2 emission mitigation in the ceramic industry based on carbon reduction and methane formation. The concept is analysed as a retrofit to the natural gas fuelled ceramic kiln that represents the main responsible of this industry in terms of energy consumption and exhaust emissions. The carbon dioxide conversion to methane is obtained by reduction with hydrogen on a Ni catalyst and thus methane is used to fuel the standard burners that equip the kiln. The paper addresses different sources for the hydrogen used as a feedstock for the proposed concept as well as alternative catalysts are explored and compared in terms of reduction efficiency and costs. A lumped and distributed parameter simulation of the entire ceramic kiln is combined to the CFD simulation of the reactor to estimate the efficiency of the CO2 reduction and the corresponding methane production for a reference ceramic kiln. The results of the numerical simulations are then employed to discuss the potential benefits of the proposed concept in terms of carbon dioxide emission reduction for the ceramic production. An economic assessment of the system analysed is also carried out concept to determine the investment necessary to implement the technology in an existing ceramic kiln. The potential replicability for other industrial sector is also addressed.

The Bunsen reaction identifies the chemical formation of sulfuric acid and hydriodic acid when sulfur dioxide is oxidized by molecular iodine in aqueous solutions. This reaction occurs spontaneousl...

The poisoning effect of I−/I2 mixtures on ferrous oxide based catalysts was investigated. These catalysts were used in the sulfuric acid thermal decomposition that is the highest endothermic step i...

The carbon dioxide uptake by resorcinol solutions has been investigated under different operational procedures and experimental conditions. Batch experiments have been carried out in aqueous and glycerol-water solutions of KOH, KHCO3 or K2CO3, and the yield of resorcinol carbonatation has been investigated as a function of the CO2 partial pressure as well as reaction temperature and time. The β-resorcylic acid (2,4-dihydroxy benzoic acid) has been isolated in the solid state and identified on the basis of its IR spectrum. The 13C NMR analysis has been applied to identify and quantify the carbonated species in solution upon CO2 uptake and after thermal resorcinol regeneration. The maximum yield of resorcinol conversion into β-resorcylic acid was 60% with 1.0 bar of CO2 and 120 min reaction time at 110 °C. A 34% yield of resorcinol conversion was also obtained with the resorcinol/K2CO3 solution in the absence of CO2. A relationship between the CO2 absorption capacity and the possible mechanism of CO2 capture has been proposed. The CO2 absorption efficiency from a simulated flue gases (15% CO2 in air) has been measured in continuous cycles of CO2 absorption-desorption carried out in packed columns and with a glycerol-water solution of resorcinol/KOH/KHCO3. The maximum absorption efficiency was 82% at absorption-desorption temperatures of 70 °C and, respectively, 170 °C. Oxidative conditions and the presence of H2S did not affect the yield of β-resorcylic acid and the resorcinol capacity of CO2 capture. Finally, a simple method for the selective separation of H2S from CO2 has been reported. © 2015 Elsevier Ltd. All rights reserved.

An experimental study describes the reversible fixation of CO2 by non-aqueous solutions of 2-amino-2-methyl-1-propanol (AMP). The captured CO2 is stored in solution as AMP carbamate and alcohol carbonates in different relative amounts as a function of the CO2–AMP ratio. The identification and the quantification of the species in solution were obtained from 13C NMR spectroscopic analysis. The bench-scale experiments of CO2 fixation and solvent regeneration have been carried out in a continuous cycle where the CO2-loaded and regenerated solutions are continuously circulated between the desorber and absorber. The carbonated solutions are decomposed in the desorber at 80–90 °C to regenerate the free amine for its reuse, affording CO2 absorption efficiency over 90%. The replacement of water with an organic solvent and the relatively low temperature of the desorption-regeneration step, could have the potential of reducing some disadvantages of aqueous absorbents, namely the amine loss by degradation and evaporation, equipment corrosion and energy cost of the regeneration step, yet preserving the high efficiency of aqueous amines.

Methanation is an alternative route to treat CO2, which allows the enhancement of carbon in the molecule, through its conversion to methane. A very wide catalytic system is available to operate the transformation. A review of the materials and their performances is presented together with some industrial applications. These technologies are useful methods to store energy as chemical energy.

A study has been conducted to determine the effects of gas-feed composition and RF power on the deposition rate and on the surface nitrogen content of thin films produced by plasma polymerization of allylamine/3-amino-propyltriethoxysilane (AA/3-APTS) mixtures. It has been found that while the deposition rate decreases slightly by increasing the AA content in the mixture, the surface nitrogen content, determined by XPS as N : Si molar ratios, increases up to a value of 8 : 1. Moreover, the nitrogen increase is not linear with the AA concentration and a maximum in the N/Si values is found for AA/APTS ratios close to 3 : 1, at all RF powers. The discussion on the polymerization mechanism for the mixture is based on evaluating and combining the behavior of each component, when plasma-polymerized alone in similar conditions.

The poisoning effect of I-/I2 mixtures on ferrous oxide based catalysts was investigated. These catalysts were used in the sulfuric acid thermal decomposition that is the highest endothermic step in the sulfur-iodine thermochemical cycle for hydrogen production by water splitting. This decomposition reaction needs a temperature as high as 1100 K to occur with a convenient thermodynamic yield for SO2 formation, and it is affected by kinetic limitations. Therefore only the use of a suitable catalyst allows for a large decrease in the H2SO4 decomposition temperature and attaining reaction yields close to the thermodynamic limits. I2 and HI present even in traces in the sulfuric acid feeding stream could lead to the poisoning of the catalyst used for the decomposition process and must therefore be minimized. In this study, two Fe2O3 catalysts supported on quartz wool and on alumina were used in the temperature range 873-1073 K in ordinary pressure conditions. The SO2 formation rates were measured before and after the catalyst poisoning. Kinetics measurements and scanning electron microscopy (SEM) analysis show that I-/I2 contamination reduced the catalytic activity by modifying its surface properties.

The deposition rate of n-doped μc-Si:H,Cl GD films has been found to increase with the gas phase phosphine content, while the opposite behaviour has been observed for p-doped specimens. The optical gap ranges between 1.8 ÷ 2.6 eV and its variation seems related to hydrogen and chlorine contents. The effectiveness of the doping has been tested by electrical conductivity measurements.

The growing use of fossil fuels (solid, liquid and gas) as the main primary energy sources, inevitably leads to an increasing amount of carbon dioxide released into the atmosphere. On the other hand, the increasing CO2 concentration in the atmosphere is indicated as the main cause of the greenhouse effect on the planet with consequent climate change. These reasons motivated in recent years growing efforts, from both technical-scientific and political communities, to control the accumulation of the atmospheric CO2. Carbon capture technologies are a well stabilized route to reduce the concentration of the greenhouse gas (CO2) from the atmosphere. However, the introduction of these capture processes always requires additional costs regardless of the adopted technology (post-combustion capture, pre-combustion capture or oxy-combustion). Despite higher costs, the adoption of efficient technologies for capturing CO2 is essential for the preservation of the environment. Besides the capture of CO2, its final sequestration in geologically stable sites is currently proposed for storing enormous quantities of gas involved. However, the geological storage of a given amount of CO2 avoids the possible use of C for about 27% wt. Therefore it seems reasonable to question if we can take advantage of this huge amount of carbon. As a matter of fact, the CO2 could become an important source of carbon for the synthesis of organic and inorganic compounds. In particular, there is a growing interest around the possibility to treat the CO2 in a reducing environment to convert it to methanol or methane. This option is an alternative to the well documented reduction of CO2 to carbon monoxide. Our interest is focused on the conversion to methane by hydrogen reduction. When the hydrogen is obtained by renewable energy, the method is a good way to store the electricity generated from renewable sources such as chemical energy; it is easily accessible and transportable thanks to the widespread presence of methane distribution network. We investigate the hydrogenation of CO2 on various Ni based catalysts. The conversion yield, the time stability and the poison sensitivity has been studied up to the temperature of 723 K and at atmospheric pressure. © 2013 The Authors.