HCN production

Figure 5 shows rates of HCN and N2 synthesis from CH -NH3 mixtures for fixed NHj with CH pressures Indicated ( ). The rates of HCN production are seen to exhibit a maximum near stoichiometric ratios and fall off for excess CH. These rates can be fit accurately by the expressions... 

The mechanism Implied by these expressions Is that of a submonolayer of surface carbon which blocks n sites for NH adsorption. This suppresses NH decomposition which would occur on the clean surface (Figure 3(a)) and allows NH fragments to react with carbon to form HCN. Selectlvltles of HCN production exceed 90% at 1 Torr, and reaction probabilities (fraction of CH flux yielding HCN) approach 0.01. 

In this system there is only one exothermic set of products and the problem consists of determining the vibrational distribution of the CO product in both its ground and first excited electronic states. The results can be compared with the experimental determination of Adams, Babcock, et al.,80 as well as the approximate treatment of Bates.79 Assuming some success in this endeavor, we propose to study reaction 33 to determine the HNC/HCN product ratio with potential surfaces from a French quantum chemistry group.81... 

Vennesland, B., E.K. Pistorius, and H.S. Gewitz. 1981a. HCN production by microalgae. Pages 349-361 in B. Vennesland, E.E. Conn, C.J. Knowles, J. Westley, and F. Wissing (eds.). Cyanide in Biology. Academic Press, New York. 

HCN is produced commercially by the reaction of ammonia, methane, and air over a platinum catalyst or from the reaction of ammonia and methane. HCN is also obtained as a by-product in the manufacture of acrylonitrile and may be generated during many other manufacturing processes (Pesce 1994). In 1999, there were 34 companies operating 47 HCN production facilities in... 

Ozone decomposition in airplanes Selective catalytic reduction of NOx Arrays of corrugated plates Arrays of fibers Gauzes Ag Methanol -> formaldehyde Pt/Rh NO production from ammonia HCN production from methane Foams Catalytic membranes reactors... 

BASF has obtained European patent 1,110,913, which describes HCN production by the thermolytic reaction of gaseous formamide in the presence of a fine-particle, solid catalyst in a fluidized bed. They claim that the process is more economical and results in less equipment damage. They also received patent DE 10,144,891 for production of HCN from formamide in a flow-type reactor with electric resistance heating. 

Depending on the type of ACRN process and the operating conditions, HCN production will be equivalent to between 10% and 24% of the ACRN that is produced46. US Patent 5,840,648 describes a catalyst that permits more HCN production. 

During the 1990 s several patents were issued in relation to the addition of methanol to the feed stream of an ACRN plant to increase HCN production. The benefits of methanol addition are described in European patent 878,464, in US patent 5,288,473 and US patent 6,204,407. 

In 1999 a total of 34 companies were operating 47 HCN production facilites in the USA, Western Europe and Japan. Capacity in these three regions was about 3.6 billion pounds (1.6 million tonnes). Direct production accounts for 75% of total capacity, and the balance is co-product from ACRN production. Worldwide capacity is about 1.8 million tonnes. DuPont owns or has a financial interest in about 36% of this capacity while Degussa-Huls and Rohm and Haas... 

HCN is usually consumed at its production site, and most consumers without on-site HCN production capability are believed to be developing plans to eliminate HCN shipments. For example, BASF in the United Kingdom produces by-product HCN in an ACRN plant and ships HCN railcars to Lucite. This HCN is used to produce acetone cyanohydrin (ACH) in a methyl methacrylate plant. To eliminate these shipments, BASF and Lucite plan to 1) install an ACH plant on the BASF plant site and 2) transfer the ACH to Lucite via a 9 km pipeline136. 

As can be seen from the above equation, formation of HCN is in reality a hetero-bimolecular oxidative coupling reaction of methane with ammonia. The ammoxidation reactor construction is a simple fixed-bed multi-tube and the catalyst is usually a platinum or sometimes a Group V or VI metal oxide on a silica or alumina support. The HCN product is recovered by condensation and fractionation. With the reaction simplicity and yield, and widespread availability of starting materials, in-situ HCN generation is an ideal industry solution to HCN supply. (See Chapter 29 for more details.)... 

BASF has obtained European patent 1,110,913, which describes HCN production from gaseous formamide in a fluidized bed. Elements of the commercialized formamide process are included in a methyl methacrylate process that Mitsubishi Gas Chemical started up in 1997. The formamide is obtained by reacting hydroxyisobutyramide with methyl formate. Therefore the external requirements for HCN are reduced to the replacement of... 

ACRN.46 U.S. Patent 5,840,648 describes a catalyst that permits more HCN production. 

Neither rates were influenced by the reaction locale, that is, by whether the reaction took place in the luminous discharge zone or some short distance from it (Fig. 12). However, unlike the HCN production rate, the CN rate generally tended to attain constant value after 1 h. In consequence, the (CN)2/HCN yield ratio increased slowly as reaction progressed. For a Canadian coal (88.3% C, 5.1% H) this ratio changed with temperature of the reactor, steadily decreasing up to 460 K and thereafter rising again (Fig. 13). The inset in Fig. 13 shows the manner in which... 

Hasenberg and Schmidt (119) studied the synthesis of HCN from CH4 + NH3 mixtures at 0.01 to 10 torr over a polycrystalline Pt surface that was initially clean. Under reaction conditions the surface was covered with nearly a monolayer of carbon. Addition of 02 to the reaction mixture reduced the carbon coverage, decreasing the HCN production rate at the expense of NO production. A kinetic model was developed that fit the data well. 

HCN production in the ingested frond material. In the case of large ruminants, it has been concluded that the cyanogenic principles of bracken offer only a marginal if any contribution to the overall bracken poisoning scenario [196],... 

OH -I- CHgOH products OH -I- CHgOOH products OH -I- HC(0)0H products OH -I- HCN products... 

ORIGIN/INDUSTRY SOURCES/USES HCN production of organic chemicals insecticide for fumigating enclosed spaces gas chamber executions... 

The Ewing model is based on a three-atom approximation of the dimer. As such it is best applied to dimers in which the initial excitation is in the bond that is part of the van der Waals bond. Hence, in the previously cited example of HCN—HCCH, the model is much more likely to succeed in the case of the linear isomer in which the acetylenic C—H stretch has been excited rather than the C—H stretch on the HCN molecule and to the T-shaped isomer in which the C—H stretch in the HCN molecule has been excited. Suppose that the C—H stretch in HCN at ca. 3300 cm" is excited in the T-shaped isomer. If the 2045 mode in the HCN product is excited during the vibrational predissociation, then just 500 cm" remains in translation. Thus we obtain a A x = 5.5 and predict a lifetime of about 1 nsec, which is precisely the measured lifetime of 1.3 nsec. However, it is evident that as the complexity of the molecules increases, there will be numerous combinations of product vibrations and rotations which could be excited. Which one is dominant is difficult to determine a priori. 

Hydrogen Cyanide (HCN) Production from Methane and Nitrogen in Non-Thermal Plasma... 

The production of hydrogen cyanide from methane and nitrogen can be presented as process (9-16) assuming a = 2. Plasma-chemical HCN production is an endothermic process ... 

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