Methanol various catalysts

In addition, we should note that data of H, NMR spectroscopy, mass-spectra, and elemental analysis given in [138] did not contradict the structure of compound 98, being regioisomer of 97. The similar situation had already been shown in the synthesis of 3-aminoimidazo[l,2-a]pyrimidines [139]. Mandair et al. carried out the model MCRs of 2-aminopyrimidine with several aldehydes and isonitrile components in the methanol under the ambient temperamre with the various catalysts. As a result, 3-aminoimidazo[l,2-a]pyrimidine and position isomeric 2-aminoimidazo[l,2-a]pyrimidines were isolated from the reaction mixture in different ratio (Scheme 45). The stmctures of the isomers obtained in this case were confirmed by the X-ray diffraction analysis, as well as the structures of the side-products isolated. 

The Fischer-Tropsch reaction involves reduction of CO with H2 and combination with methanol and olefins in presence of various catalysts to produce an array of oxygenate products of high industrial values. 

The current two-step industrial route for the synthesis of methanol, from coal or methane to synthesis gas and then from synthesis gas to methanol, has certain drawbacks. The economic viability of the whole process depends on the first step, which is highly endothermic. Thus a substantial amount of the carbon source is burned to provide the heat for the reaction. It would be highly desirable, therefore, to replace this technology with a technically simpler, single-step process. This could be the direct partial oxidation of methane to methanol, allowing an excellent way to utilize the vast natural-gas resources. Although various catalysts, some with reasonable selectivity, have been found to catalyze this reaction (see Sections 9.1.1 and 9.6.1), the very low methane conversion does not make this process economically feasible at present. 

Beside methanol and formaldehyde, the oxidation of methane may be directed to another route, leading to the formation of its condensation products, for example, ethane, ethylene and benzene. This route may provide an alternative way for the chemical use of natural sources of methane. Here, various catalysts were also tested using both 02 and N20 as the oxidants [22], The general picture observed by most authors was similar to that with methane oxidation to oxygenates. The conversion of methane was always higher with 02 than with N20. However, the selectivity to the coupling products showed an opposite trend. 

Gold has emerged as an effective catalyst for the selective oxidation of methane to methanol. Various possible pathways for the oxidation are discussed.29 Suitably substituted furans are transformed into phenols by the use of gold catalyst (1). It has been suggested, on the basis of kinetic isotope effect and trapping studies, that the key intermediate is an arene oxide. The postulation is also supported by DFT calculations.30... 

Dudfield et al. [88] presented results generated in the scope of the Mercatox program funded by the European Community aimed at a combined methanol steam reformer/combustor with consecutive CO clean-up by PrOx. First, various catalysts were tested for the reaction as micro spheres in a test reactor which was similar to a macroscopic shell-and-tube heat exchanger (Figure 2.57). 

Direct one-stage oxidation of methane to methanol is performed by two methods catalytic and thermal. Modernization of the process of methane conversion to methanol using various catalysts is ineffective, because in this case methane conversion is usually below 13%. At the present time, methane conversion to methanol has been raised to 24% [122] however, this is still insufficient for an economic assessment of the process. Hence, thermal... 

Provided that a material is sufficiently crystalline to diffract X rays and is present in an amount greater than 1%, X-ray diffraction (XRD) can be used for qualitative and quantitative analyses. The principle of this technique is that crystal structures possess planes made by repetitive arrangements of atoms, which are capable of diffracting X rays. The angles of diffraction differ for the various planes within the crystal, and thus every compound or element has its own somewhat unique diffraction pattern. The differences in these patterns, therefore, allow the differentiation of various structures within the catalyst. Figure 12 shows the XRD pattern of a methanol synthesis catalyst composed of CuO, ZnO, and AI2O3. 

Exchange Current Densities and Tafel Slopes lor the Oxidation of Methanol to Carbon Dioxide on Various Catalysts... 

Although all three requirements must be satisfied by a good methanol catalyst, there is evidence that activation of carbon monoxide is more difficult than that of hydrogen. It is therefore instructive first to examine the ability of various catalysts to activate CO by nondissociative chemisorption. 

Acetic acid. Various catalysts (h e. Co, Nt, Rh) upon heating under CO pressure can isomerize methyl formate to acetic acid [49. Again iodine Is needed. An economic advantage of producing acetic acid through isomerization may he given in comparison with the methanol-acetic acid process. 

The process of catalytic partial oxidation of methanol with air in a fuel-rich mixture has been commercialized to produce formaldehyde since about 1890. Various catalysts have been used but silver catalyst is by far most widely used. Song and Hwang [1991] used a packed-bed porous membrane tubular reactor wi the catalyst packed on the shell side. They used a model consmicted essentially from Equations (10-36) and (10-44) with the permeation terms replaced by some terms similar to Equation (10-56) and k- =0. The partial oxidation of methanol can be conveniently described by... 

Catalytic hydrogenation of carbon dioxide was studied for the simultaneous synthesis of methanol and dimethyl ether (oxygenates). Various combinations of methanol synthesis catalysts and methanol dehydration catalysts have been examined for the hydrogenation. The hybrid catalyst of Cu/ZnO/CraOs and CuNaY zeolite was found to be very efficient for the production of oxygenates. 

Methanol synthesis by catalytic hydrogenation of carbon dioxide is evaluated as one of the most promissing processes for conversion of carbon dioxide into valuable chemicals[l]. While various catalysts for methanol synthesis from carbon dioxide and hydrogen have been investigated, their durability - an important factor for evaluating their practicability-have not been reported[2,3,4,5]. The authors prepared CuO-ZnO-AI 2 O 3 catalysts for methanol synthesis from carbon dioxide and examined their activities and durabilities. 

Introduction.—The oxidative dehydrogenation of alcohols to aldehydes and ketones over various catalysts, including copper and particularly silver, is a well-established industrial process. The conversion of methanol to formaldehyde over silver catalysts is the most common process, with reaction at 750—900 K under conditions of excess methanol and at high oxygen conversion selectivities are in the region 80—95%. Isopropanol and isobutanol are also oxidized commercially in a similar manner. By-products from these reactions include carbon dioxide, carbon monoxide, hydrogen, carboxylic acids, alkenes, and alkanes. 

Fluidized Bed Catalytic- Various Catalysts Pressure (1-10 atm) No Oxygen Required 0.5 ODT/D Wood Various others Methane, hydrogen, and synthesis gases for ammonia, methanol and liquid hydrocarbons Current PDU for Operational catalyst screening studies - concept applicable to various gasi fiers ... 

The catalytic CO hydrogenation activity for methanol production over Cu based catalysts are listed in Table 2. In Table 2, the activity of conventional copper based methanol synthesis catalysts, Cu/Zn0/Cr203 (Cu Zn Cr = 6 3 1) and Cu/Zn0/Al203 (Cu Zn AI = 4 5 1), as well as Cu-Yb203 prepared in the present work at various reaction... 

Methanol and higher oxygenate syntheses follow different mechanistic and kinetic patterns over the various catalysts discussed here. Each such pattern is regular, however, and can be modeled with a few kinetic parameters based on fundamental mechanistic steps involved in the C-H, C-C, and C-0 bond forming reactions. Alkali co-catalysts play an important role by promoting... 

Various catalysts can be used for converting methanol to DME and water (ref. 11). The fixed-bed MTG process uses a 7-alumina catalyst which has high selectivity for methanol conversion to DME and water and low selectivity for methanol decomposition and coke. These properties are important as any loss of methanol to byproducts directly affects gasoline yield. Commercially, it is preferred to have one DME reactor per ZSM-5 train. Thus, high coke formation in the DME catalyst would necessitate the additional expense of multiple DME reactors. 

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