MANUFACTURE OF HYDROGEN

Outline one method for the manufacture of hydrogen from either crude oil or natural gas. State two important uses of hydrogen. Give explanations and illustrate reactions for the following statements ... 

Appreciable quantities are also obtained as a by-product in the manufacture of hydrogen from naphtha-gaseous hydrocarbons. In this process the gaseous hydrocarbon and superheated steam under a pressure of about 10 atmospheres and at a temperature of 1000 K are passed over a nickel-chromium catalyst. Carbon monoxide and hydrogen are produced ... 

This reaction is an undesirable side reaction in the manufacture of hydrogen but utilised as a means of removing traces of carbon monoxide left at the end of the second stage reaction. The gases are passed over a nickel catalyst at 450 K when traces of carbon monoxide form methane. (Methane does not poison the catalyst in the Haber process -carbon monoxide Joes.)... 

Interest has continued in on-site manufacture of hydrogen peroxide from the elements, particularly for remote sites located considerable distances from wodd-scale anthraquinone processes. However, no commercial-scale direct combination plants have been constmcted as of this writing. 

Table 7. U.S. and North American Manufacturers of Hydrogen Peroxide, ...

At present about 77% of the industrial hydrogen produced is from petrochemicals, 18% from coal, 4% by electrolysis of aqueous solutions and at most 1% from other sources. Thus, hydrogen is produced as a byproduct of the brine electrolysis process for the manufacture of chlorine and sodium hydroxide (p. 798). The ratio of H2 Cl2 NaOH is, of course, fixed by stoichiometry and this is an economic determinant since bulk transport of the byproduct hydrogen is expensive. To illustrate the scde of the problem the total world chlorine production capacity is about 38 million tonnes per year which corresponds to 105000 toimes of hydrogen (1.3 x I0 m ). Plants designed specifically for the electrolytic manufacture of hydrogen as the main product, use steel cells and aqueous potassium hydroxide as electrolyte. The cells may be operated at atmospheric pressure (Knowles cells) or at 30 atm (Lonza cells). 

Saha, N., Rinard, I. H., Miniplant design methodology a case study -manufacture of hydrogen cyanide, in Proceedings of the 4th International Conference on Microreaction Technology, IMRET 4, pp. 327-333 (5-9 March 2000), AIChE Topical Conf. Proc., Atlanta, USA. 

Table 6.13 Mole fractions at equilibrium for the manufacture of hydrogen.

Table 6.15 Product mole fractions for the manufacture of hydrogen on a dry basis.

The SMR is by far the most important and widely used process for the industrial manufacture of hydrogen, amounting to about 40% of the total world production [7]. The technology is well developed and commercially available at a wide capacity range, from <1 t/h H2 for small decentralized units to about 100 t/h H2 for large ammonia manufacturing plants [8]. 

To operate the above process for the manufacture of hydrogen it is necessary that the aluminium should be as pure as possible and should not contain copper. The commercial light alloy known as "duralumin, which contains about 94 per cent, of aluminium and 4 per cent, of copper, is entirely unsuitable for generating hydrogen in the method above described, as it is almost unattacked by even boiling water containing a small quantity of a mercury salt... 

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