Formaldehyde, synthesis

Drivers Ibr Performing Formaldehyde Synthesis in Micro Reactors... 

Beneficial Micro Reactor Properties for Formaldehyde Synthesis... 

GP 4] [R 5] Formaldehyde synthesis has been known at BASF for more than 100 years [1, 49-51,108]. Hence it was expected to be able to handle the synthesis of substituted analogue, an undisclosed methanol derivative, with the same processsing concepts, major problems not being anticipated. This expectation was still supported by first attempts with the tried and tested pan-like reactor concept (5 cm diameter), which were promising. At 50% conversion, a selectivity of 90% was achieved. However, transfer to production scale using a 3 m production reac-... 

Because formaldehyde synthesis is exothermic, the reactor requires a coolant to remove the excess enthalpy of reaction. Thermodynamically, we should run the reaction at as low a temperature as possible to increase conversion, but at low temperatures, however, the rate of reaction decreases. At high reaction ten era-tures unwanted side reactions occur. Commercially, the reaction occurs fi om 600 °C (1110 °F) to 650 C (1200 °F), which results in a methanol conversion of 77 to 87 % when using a silver catalyst [24]. Because formaldehyde and methanol can form flammable mixtures with oxygen, we should carry out the reaction with mixture compositions outside of its flammability range. The oxygen used is less than the stoichiometric amount. 

Table 3.4.4 Stream Properties - Formaldehyde-Synthesis Reactor... 

Ixibsle FM, Francis SM, Davis R, Xiang N, Haq S, Bowker M (1994) Scanning-tunneling-microscopy studies of formaldehyde synthesis on Cu(l 10). Phys Rev Lett 72 2569... 

Before the advent of oxygenate ethers like MTBE, formaldehyde production was the largest single application of methanol, with at least 16 manufacturers and consuming over 30% of the methanol produced. Formaldehyde is used in the manufacture of urea-formaldehyde resins, phenol-formaldehyde resins, melamine-formaldehyde resins, acetal resins, acetylenic chemicals, etc. The reactions involved in formaldehyde synthesis are ... 

The reactions involved in formaldehyde synthesis from methanol are ... 

Streets, D. G. and S. T. Waldhoff (2000) Present and future emissions of air pollutants in China SO2, NO, and CO. Atmospheric Environment 34, 363-374 Stribling, R. and S. L. Miller (1987) Energy yields for hydrogen cyanide and formaldehyde synthesis the HCN and amino acid concentrations in the primitive ocean. Origins of Life... 

Aniline is prepared by the reduction of nitrobenzene with Fe/HCl. For the formaldehyde synthesis, see Section 26.1.2. 

The retentate of the membrane module, which constitutes the major portion of the synthesis gas produced at the synthesis stage, is obtained at essentially the feed pressure. Thus, the syngas supplied to the formaldehyde synthesis stage does not require further compression. 

Similar IR experiments were performed to establish the reaction mechanism for methanol oxidation on unsupported and sihca-supported vanadia, which are more selective catalysts for formaldehyde synthesis than vanadia-titania. The formation of methoxy groups from methanol dissociative or condensative adsorption was determined while it was established that formaldehyde (directly adsorbed or produced by methoxy group oxidation) mainly adsorbs in the form of dioxymethylene species, stable only at relatively low temperatures. It was concluded that dioxymethylene can react with methanol at low conversion to give rise to dimethoxymethane while it preferentially desorbs as formaldehyde at higher conversions and temperatures. The weakness of the adsorption of formaldehyde was considered to be the key feature of catalysts allowing high selectivity in formaldehyde synthesis. 

Yield A alues calculated from this constant indicate that the reaction would appear to be hopelessly unfa orable as a means of formaldehyde synthesis. ... 

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