Catalytic partial oxidation of methanol

Catalytic partial oxidation of methanol can be expressed by the following equation ... 

The results of catalytic partial oxidation of methanol over the spinel catalysts derived from CoAl- and CoAISn-LDH are presented in Table 2. A methanol conversion of 30 to 50 mol % was obtained over catalyst derived from CoAI-LDH. The products obtained were H2, H20, CO and C02. Other products such as formaldehyde, methyl formate or dimethyl ether was not observed under the present experimental conditions. The selectivity of H20 was very high (= 40 to 60 %), probably because of the involvement of the complete oxidation of methanol over these catalysts. It is interesting to note from the Table that the methanol conversion rate and the selectivity of CO2 increased over the catalyst derived from the Sn-containing analogue. The observation that only traces of CO is produced in the Sn-containing catalyst, is attractive for the development of catalyst for POM reaction to produce H2 for fuel cell applications. The only inconvenience is the higher selectivity of H2O by complete oxidation, probably because of the higher Co content in the sample. 

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 partial oxidation of methanol H2 production for fuel cells... 

The present work demonstrates that the mixed oxide catalyst with inhomogeneous nanocrystalline MosOu-type oxide with minor amount of M0O3- and Mo02-type material. Thermal treatment of the catalyst shows a better performance in the formation of the crystals and the catalytic activity. The structural analysis suggests that the catalytic performance of the MoVW- mixed oxide catalyst in the partial oxidation of methanol is related to the formation of the M05O14 t3 e mixed oxide. 

Activity Measurements. To test catalytic properties of various samples partial oxidation of methanol to formaldehyde was studied in a flow micro-reactor operating under normal atmospheric pressure (10). For each run about 0.2 g of catalyst sample was used and the activities were measured at 173 C in the absence of any diffusional effects. The feed gas consisted of 72, 2 and by volume of nitrogen, oxygen and methanol vapor respectively. Reaction products were analysed with a 10% Carbowax 20 M column (2m long) maintained at 60 C oven temperature. 

Monolayer coverage of vanadium oxide on tin oxide support was determined by a simple method of low temperature oxygen chemisorption and was supported by solid-state NMR and ESR techniques. These results clearly indicate the completion of a monolayer formation at about 3.2 wt.% V2O5 on tin oxide support (30 m g" surface area). The oxygen uptake capacity of the catalysts directly correlates with their catalytic activity for the partial oxidation of methanol confirming that the sites responsible for oxygen chemisorption and oxidation activity are one and the same. The monolayer catalysts are the best partial oxidation catalysts. 

Synthesis and characterization of a new Sn-incorporated CoAl-layered double hydroxide (LDH) and catalytic performance of Co-spinel microcrystallites in the partial oxidation of methanol... 

M(lI)AlSn-LDHs with M(II) being Mg, Ni or Co were synthesized by a coprecipitation method. The influence of Sn on the thermal transformations and redox properties were investigated in detail using XRD, TG/DTA, SEM, TPR, 1 l9Sn-MAS NMR and UV-visible diffuse-reflectance (DR) spectroscopy methods. Some of these samples calcined at 450 °C were tested as catalysts in the partial oxidation of methanol (POM) reaction. In this paper we discuss briefly the effect of Sn-incorporation on the structural features and reducibility of CoAI-LDH. The catalytic performance of Co-spinel microcrystallites derived from CoAl-, and CoAlSn-LDHs was also evaluated. 

Sn-incorporation on the structural and redox properties of the CoAl-LDHs. The catalytic activity of spinel catalysts obtained from these LDH precursors has been tested in the partial oxidation of methanol (POM) to H2 fuel for fuel cells. 

In conclusion, a new Sn-incorporated CoAI-LDH has been synthesized. The effect of Sn-incorporation on the thermal transformation into spinels and their reducibility are investigated. Incorporation of Sn diminishes reducibility of Co species because of the enhanced polarization of Co-0 bonds. The Sn-containing spinel exhibits better catalytic performance in the partial oxidation of methanol to produce H2 and CO2 useful for fuel cells. 

Hydroxide (LDH) and Catalytic Performance of Co-spinel Microcrystallites in the Partial Oxidation of Methanol S. Velu and K. Suzuki... 

Recently, intensive studies have been carried out on the catalytic partial oxidation of CH4 to synthesis gas [1-3]. This process has advantages over the conventional steam reforming of CH4 to make synthesis gas, as the latter process is highly endothermic and produces synthesis gas having a H2/CO ratio > 3. The partial oxidation of CH4, expected to afford synthesis gas having H2/CO ratio of about 2, makes methanol synthesis an ideal follow-up process. 

Silver catalysts have been used for the partial oxidation of methanol to formaldehyde this is a very important process in the chemical industry. The role of the silver catalyst and, in particular, the influence of its atomic structure on the catalytic process have been extensively studied with various surface science tools [44—50]. In these investigations, Raman spectroscopy was employed to identify and confirm the role of the oxygen species for the catalytic process. These studies were performed under reaction conditions close to those in industrial processes using Ag(lll) and Ag(llO) samples. Upon extended exposure to oxygen at high temperatures, both samples restructure to (111) planes with a well-defined microstructure and with mesoscopic roughness (on a scale of 1 pm). Therefore, in the course of the oxygen pretreatment, the local nature of the surface of the two samples becomes nearly identical and, hence, their Raman spectra are quite similar [44]. 

Wang and Willey (19) synthesized fine iron oxide particles (FejOs) made out of a solution of iron (Ill)acetylacetonate in methanol and water this solution (no gel was formed at room temperature) was poured into an autoclave and evacuated with respect to the conditions of supercritical methanol. The iron oxide aerogel developed a specific surface area of 10 mVg. The primary particle dimensions were found to be 8-30 nm, as shown by XRD technique. The catalytic test run was the partial oxidation of methanol in the autoclave in the presence of supercritical COj at temperatures varying from 225 up to 325°C and the pressure was 91 bars. The main reaction product formed was dimethyl-ether, small amounts of formaldehyde, and methyl formate with a selectivity below 10% for both minor products. A 20% iron oxide-molybdenum oxide aerogel tested in the same supercritical conditions showed a very good selectivity of 94% for formaldehyde, the other product being only dimethyl-ether. 

Coated foams have been integrated for co-heating the steam reforming of natural gas by the catalytic partial oxidation of natural gas in adjacent microsized slits for easy scale-up for offshore synthesis gas production and subsequent Fischer-Tropsch or methanol synthesis [46]. The catalyst was solution coated on a 40 pores cm foam and inserted in 640 pm slits. No information was given on the catalytically active species used. The conversion which was given exceeded 95%. However, this is the value yielded after combustion of the produced synthesis gas (exhaust). 

From investigations of the active phase of a bulk metallic copper catalyst under reaction conditions of the partial methanol oxidation by means of in situ XAS at the oxygen K-edge and copper L2-,L3-edges it was concluded that the partial oxidation of methanol to formaldehyde is catalysed by a copper plus oxygen phase where oxygen atoms probe defects of tiie copper lattice, which represent the catalytically active sites [3, 4, 6j. 

Also under oxidizing conditions, like the partial oxidation of methanol to hydrogen, water, and CO2, intermetallic compounds can be formed. As in the case of methanol steam reforming over Pd/ZnO, the intermetallic compound ZnPd is part of the catalytic system Pd-Zn/Al203 under these conditions (125). The observation of intermetallic compounds is not limited to oxidation reactions involving methanol. Also in the oxidation of aldoses such as lactose and glucose over... 

In Table 1 the ancxlic reactions that have been studied so far in small cogenerative solid oxide fuel cells are listed. One simple and interesting rule which has emerged from these studies is that the selection of the anodic electrocatalyst for a selective electrocatalytic oxidation can be based on the heterogeneous catalytic literature for the corresponding selective catalytic oxidation. Thus, the selectivity of Pt and Pt-Rh alloy electrocatalysts for the anodic NH3 oxidation to NO turns out to be comparable (>95%) to the selectivity of Pt and Pt-Rh alloy catalysts for the corresponding commercial catalytic oxidation. The same applies for Ag, which turns out to be equally selective as an electrocatalyst for the anodic partial oxidation of methanol to formaldehyde, ... 

Problem 9-12 (Level 2) Formaldehyde is manufactured by the partial oxidation of methanol in a flxed-bed catalytic reactor at steady state. In one process, 50 mol% of methanol in air is passed over a nonporous silver catalyst at 600 °C and atmospheric... 

Synthesis Gas Chemicals. Hydrocarbons are used to generate synthesis gas, a mixture of carbon monoxide and hydrogen, for conversion to other chemicals. The primary chemical made from synthesis gas is methanol, though acetic acid and acetic anhydride are also made by this route. Carbon monoxide (qv) is produced by partial oxidation of hydrocarbons or by the catalytic steam reforming of natural gas. About 96% of synthesis gas is made by steam reforming, followed by the water gas shift reaction to give the desired H2 /CO ratio. 

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