Low-temperature methanol

Due to methanol s corrosivity and its affinity for water, it cannot be readily distributed in today s fuel infrastructure. Methanol burns with a nearly invisible flame. Available luminosity additives won t reform in the low-temperature methanol steam reformers. Methanol is more acutely toxic than gasoline. Additives that are likely to be needed for safety and health reasons will impact the fuel processor s performance and cost. 

The elemental sulfur is removed by conventional technology. The gases are purified by the Lurgi Rectisol process which uses a low temperature methanol wash to remove H2S, COS and CO2. The acid gas stream is then passed to a Stretford unit which is preferred to the Claus unit because of the high percentage of carbon dioxide in the stream. Sulfur in the stack gas would be removed by conventional flue gas desulfurization techniques and the sulfur would then remain as sulphite sludge and not be recovered as elemental sulfur. 

Spinel oxides with a general formula AB2O4 (i.e. the so-called normal spinels) are important materials in industrial catalysis. They are thermally stable and maintain enhanced and sustained activities for a variety of industrially important reactions including decomposition of nitrous oxide [1], oxidation and dehydrogenation of hydrocarbons [2], low temperature methanol synthesis [3], oxidation of carbon monoxide and hydrocarbon [4], and oxidative dehydrogenation of butanes [5]. A major problem in the applications of this class of compound as catalyst, however, lies in their usually low specific surface area [6]. 

Skeletal Cu-Zn catalysts show great potential as alternatives to coprecipitated Cu0-Zn0-Al203 catalysts used commercially for low temperature methanol synthesis and water gas shift (WGS) reactions. They can also be used for other reactions such as steam reforming of methanol, methyl formate production by dehydrogenation of methanol, and hydrogenolysis of alkyl formates to produce alcohols. In all these reactions zinc oxide-promoted skeletal copper catalysts have been found to have high activity and selectivity. 

To summarize the qualitative findings, the methanol synthesis activity in the binary Cu/ZnO catalysts appears to be linked to sites that also irreversibly chemisorb CO and not to sites that adsorb CO reversibly. Since irreversible adsorption of CO follows linearly the concentration of amorphous copper in zinc oxide, these sites are likely to be that part of the copper solute that is present on the zinc oxide surface. No correlation of the catalyst activity and the copper metal surface area, titrated by reversible form of CO or by oxygen, could be found in the binary Cu/ZnO catalysts (43). In contrast with this result, it has been claimed that the synthesis activity is proportional to copper metal area in copper-chromia (47), copper-zinc aluminate (27), and copper-zinc oxide-alumina (46) catalysts. In these latter communications (27,46,47), the amount of amorphous copper has not been determined, and obviously there is much room for further research to confirm one or another set of results and interpretations. However, in view of the lack of activity of pure copper metal quoted earlier, it is unlikely that the synthesis activity is simply proportional to the copper metal surface area in any of the low-temperature methanol-synthesis catalysts. 

Low temperature methanol Dimethyl ethers of polyethylene glycol Di-isopropanolamine dissolved in sulfolane and water Monoethanolamine (MEA) or diglycolamine... 

Low-temperature methanol synthesis process was proposed for such high CO conversion. In the process, nickel and alkoxide catalyst was applied in liquid phase at 373 K, IMPa. 90% CO conversion was reported at the mild conditions (5, 4). Unfortunately the alkoxide is not stable with water and carbon dioxide and thorough removal of the impurity in syngas is necessary to avoid deactivation. Industrialization of the process is not realized by the defect of the catalyst. 

The reforming reactions require the input of water and heat. Overall, the reformer thermal efficiency is calculated as the latent heat of vaporization (LHV) of the product hydrogen divided by the LHV of the total input fuel. This thermal efficiency depends on the efficiencies of the individual processes, the effectiveness to which heat can be transferred from one process to another, and the amount of energy that can be recovered through means such as turbochargers. In the end, high-temperature reformer efficiencies are approximately 65% and low-temperature methanol reformers can achieve 70%-75%. 

SYNTHESIS OF HIGHER ALCOHOLS ON LOW-TEMPERATURE METHANOL CATALYSTS... 

In our recent studies, a characterization of the properties and of the catalytic behaviour in the low temperature methanol synthesis of Cu Zn Me (Me= A1 and/or Cr) catalysts have been reported as a function of the composition (26-28). The aim of this paper was to investigate the possible parameters which influence the selectivity of these catalysts towards the synthesis of H.M.A., with a particular emphasis on reaction conditions. Thus we tested catalysts chosen among the... 

With the hydrogen-rich feed typical of the recycling loop in an industrial plant for the low temperature methanol synthesis, only methanol was observed. Appreciable productivities of H.M.A. were obtained for H /CO ratios 2, with the maximum for every alcohol progressively displacec towards the lower values of the H /CO ratio when che chain length increases. / t the same time a li-... 

H.M.A. together with methanol was obtained with low temperature methanol catalysts, without and with the addition of potassium. In this latter case the productivity in H.M.A. increased up to about 0.4% of the added potassium, after which a deactivation was observed with a trend similar to that observed for the copper surface area. It is noteworthy that all the catalysts showed lowest values after reaction, attributable to the presence of high molecular weight compounds adsorbed on the surface. In all cases the deactivation must be attributed to an interaction of the potassium with the active phase. 

Synthesis of Higher Alcohols on Low-Temperature Methanol Catalysts",... 

The best catalyst for the synthesis of methanol from CO + H2 mixtures is copper/zinc oxide/alumina. Intermetallic compounds of rare earth and copper can be used as precursors for low-temperature methanol synthesis as first reported by Wallace et al. (1982) for RCu2 compounds (R = La, Ce, Pr, Ho and Th). The catalytic reaction was performed under 50 bar of CO + H2 at 300°C, and XRD analyses revealed the decomposition of the intermetallic into lanthanide oxide, 20-30 nm copper particles and copper oxide. Owen et al. (1987) compared the catalytic activity of RCux compounds, where R stands mainly for cerium in various amounts, but La, Pr, Nd, Gd, Dy and even Ti and Zr were also studied (table 4). The intermetallic compounds were inactive and activation involved oxidation of the alloys using the synthesis gas itself. It started at low pressures (a few bars) and low temperatures (from 353 K upwards). Methane was first produced, then methanol was formed and it is believed that the activation on, for example, CeCu2, involved the following reaction, as already proposed for ThCu2 (Baglin et al. 1981) ... 

Copper-zinc-alumina mixed oxide catalysts has been investigated in the low-temperature methanol synthesis. Three different copper-containing species were identified in the spent catalysts (i) metallic copper, (ii) CuO, and (iii) copper not detectable by XRD analysis, the latter being probably related to the ZnO matrix. While no correlation existed between the catalytic activity and only one of these... 

The low total carbon conversion of the gas-phase reaction resulted from the highly exothermic reaction from which heat and product cannot be removed rapidly from the catalyst bed. The heat and product removal from the catalyst bed, which would improve the reaction activity, was achieved when SC n-hexane was introduced into the reaction. The highest total carbon conversion was obtained by using the alcohols as SC catalytic fluids. SC alcohol improved the conversion by promoting the reaction not only by the SCF advantage, but also by the catalytic effect as behaved in the low temperature methanol synthesis. The methanol synthesis could significantly be improved by the combination of SCF advantage and catalytic effect when alcohol was used as an... 

Wang C, Boucher M, Yang M et al (2014) ZnO-modified zirconia as gold catalyst support for the low-temperature methanol steam reforming reaction. Appl Catal B 154-155 142-152... 

Studies of chemisorption of hydrogen, water, carbon monoxide, and carbon dioxide alone and in sequence on a Cu-Cr-Zn low temperature methanol synthesis catalyst show that the catalyst surface contains two different types of active sites. Hydrogen and water are chemisorbed in competition on one type, carbon monoxide and carbon dioxide on the other. The results for Cu-Zn-Al catalysts follow the same pattern. 

Garcia, G., Baglio, V, Stassi, A., Pastor, E., Antonucci, V Arico, A.S. Investigation of Pt-Ru nanoparticle catalysts for low temperature methanol electro-oxidation. J. Solid State Electrochem. 11 (2007), pp. 1229-1238. 

At low temperature, methanol is mainly molecularly physisorbed, therefore, methanol molecular weight should be considered in order to calculate molar adsorption from the weight gain value. However, methanol adsorbs as surface methoxylated species at 100°C as discussed earlier. 

As shown in Figure 10, with the increase of the mole fraction of [MMImJDMP, the saturated vapor pressure was significantly reduced. The saturated vapor pressure of the [MMImJDMP-methanol solution at normal temperatures is lower than that of pure methanol at 5°C. This means that the normal temperatures solution can absorbs the low-temperature methanol vapor, which makes the [MMlm]DMP-methanol solution suitable for absorption refrigeration as the working pair. 

For temperatures lower than about -40 F, glycol injection is impractical because of the high viscosity of glycol solutions at such low temperatures. Methanol s low viscosity and other favorable characteristics make it the fluid of choice for hydrate inhibition in very low... 

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