Mechanism of the vapour‐phase dehydrogenation of methanol on silver

Aneke, L. E.; Ridder, J. J. J. Den; Berg, P.J. Van Den

doi:10.1002/recl.19811000606

Cited by 3 publications

(4 citation statements)

References 8 publications

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“…Accordingly, this trend led to a decrease in the productivity to CH 2 O (Figure 6, Table 1). The favored decomposition of CH 2 O to CO and H 2 at longer residence time as well as the required high GHSV for the production of CH 2 O in the non‐oxidative dehydrogenation of CH 3 OH are in agreement with studies concerning other catalysts [37,49] . S (DME) and S (MF) remained constant in the investigated range of residence times.…”

Section: Resultssupporting

confidence: 88%

“…These differences may also be a reason for the considerable differences in CH 2 O yield, since CH 2 O is known to decompose at long contact times. [37] In our study, the observed decrease in CO x yield despite the simultaneous increase in CH 2 O yield together with the absence of CH 4 production at T below 415 °C suggests that CO x is formed in parallel and not in a consecutive reaction by CH 2 O decomposition. Thus, we suggest that the reaction of CH 3 OH with H 2 O originating from the dehydration reaction (3) causes the formation of CO 2 (methanol steam reforming, MSR, (Eq.…”

Section: Resultssupporting

confidence: 48%

“…The favored decomposition of CH 2 O to CO and H 2 at longer residence time as well as the required high GHSV for the production of CH 2 O in the non-oxidative dehydrogenation of CH 3 OH are in agreement with studies concerning other catalysts. [37,49] S(DME) and S(MF) remained constant in the investigated range of residence times. After 300 min TOS conversion had decreased significantly for all space velocities, but the lower productivity to CH 2 O at higher residence time was still observed.…”

Section: Chemcatchemmentioning

confidence: 79%

“…The reported conversion was higher (>95 %) despite the higher methanol concentration in the feed stream (18 %) due to the higher catalyst amount (1 g vs. 50 mg) and the longer residence time (1 s vs. <0.11 s) in comparison to the reaction conditions in this study. These differences may also be a reason for the considerable differences in CH 2 O yield, since CH 2 O is known to decompose at long contact times [37] …”

Section: Resultsmentioning

confidence: 99%

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Non‐oxidative Dehydrogenation of Methanol to Formaldehyde over Bulk β‐Ga₂O₃

Merko

Busser

2022

ChemCatChem

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The non-oxidative dehydrogenation of methanol to formaldehyde is considered a dream reaction compared with the classical oxidative route, because the valuable coupled product hydrogen is formed instead of water, and the produced anhydrous formaldehyde is highly suitable for the further synthesis of oxygenated synthetic fuels. This study reports on the high catalytic performance of pure β-Ga 2 O 3 in this reaction at temperatures between 500 °C and 650 °C. At 550 °C and a GHSV of 45500 h À 1 , an initial selectivity to formaldehyde of 77 % was obtained at a methanol conversion of 72 %. Performing the reaction at temperatures beyond this range and lower GHSV resulted in a lower formaldehyde selectivity. The catalyst suffered from deactivation caused by formation of carbon deposits, but it was possible to regenerate its initial activity at 500 °C and 550 °C completely by an oxidative treatment. Irreversible deactivation occurred at 650 °C due to partial volatilization of Ga 2 O 3 .

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Section: Resultssupporting

confidence: 88%

Section: Resultssupporting

confidence: 48%

Section: Chemcatchemmentioning

confidence: 79%

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

Non‐oxidative Dehydrogenation of Methanol to Formaldehyde over Bulk β‐Ga₂O₃

Merko

Busser

2022

ChemCatChem

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Catalytic dehydrogenation of methanol to water‐free formaldehyde

Zaza

Renken

1994

Chem Eng & Technol

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Catalytic dehydrogenation of methanol is a promising process of producing water-free formaldehyde. The present paper reviews research in this field. As effective catalysts mainly transition metal compounds as well as oxides and salts containing sodium have been reported. Several catalysts exhibit high activity and high selectivity, for formaldehyde at low conversions while further efforts have to be made to improve catalyst stability and selectivity at high conversions. Catalytic dehydrogenation of methanol to formaldehyde is compared with methanol oxidation. Current Production and Uses of FormaldehydeSince its initial discovery in 1859 by Butlerov, formaldehyde has become one of the most important chemicals in industry. In 1985 its world production amounted to about five million tons [l]. At room temperature, formaldehyde is a colourless gas with a pungent odour. It is unstable and polymerizes easily to form polyoxymethylenes both in the gas phase and in solutions. One of its properties of practical importance is the condensation reaction with compounds containing active hydrogen to produce water and compounds with -CH20H or -CH2 groups. Apart from being soluble in most organic solvents, in water it is strongly solvated or in the form of low molar mass polymers. Therefore, its vapour pressure is very low over aqueous solutions and it forms azeotropes with water [2]. This makes its separation from water difficult.Although oxidation of hydrocarbons is used to obtain formaldehyde, more than 90% of the world's formaldehyde production is at present achieved through catalytic oxidation of methanol [3]. Two processes, namely the silver catalyst process and the formox process, are commonly employed [3 -51. In the former, a methanol-rich methanolair-steam mixture (36 -45% methanol) is passed through the catalyst bed at 870 -970 K. The following reactions occur:CH30H + CH20 + H2 , AH900 = + 92 kJ/mol , (1) The conversion may either be complete or, alternatively, incomplete with recycling of methanol. The selectivity is about go%, with carbon oxides, methyl formate, methane and formic acid as by-products. The formox process differs from the silver catalyst process in the nature of the catalyst (iron-molybdenum oxides), methanol concentration (5 -10% methanol) and oxidation temperature (570 -670 K). Only reactions 2 and 3 take place under these conditions. In both processes, aqueous solutions are obtained and marketed as final products. Formaldehyde is also available commercially in its solid form, i.e., paraformaldehyde, which consists of polyoxymethylenes and is easily decomposed to formaldehyde. It is produced by distilling formaldehyde solutions under vacuum.Formaldehyde finds a wide application in industry. Although it is used to make other chemicals, most of its production is used to synthesize aminophenol and polyacetal resins through condensation reactions. Water in the aqueous solutions often interferes with these processes. When a small quantity of water is tolerable, paraformaldehyde can be used instead. Occasion...

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