Synthetic ammonia process

CO2 can be readily obtained in small amounts by the action of acids on carbonates. On an industrial scale the main source Is as a byproduct of the synthetic ammonia process in which the H2 required is generated either by the catalytic reaction (a) or by the water-gas shift reaction (b) ... 

Casale The first synthetic ammonia process, designed by L. Casale, who founded Ammonia Casale of Lugano, Switzerland, in 1921. See Claude (1). 

Haber process. This method, which is sometimes called the synthetic ammonia process, is based on the following reactions ... 

Synthesis of Urea from CO2. Although urea was the first of the organic compounds to be formed synthetically, its commercial production had to await the development of the synthetic ammonia process. Here the principal product, NH , and a by-product, COi, which constitute the raw materials for urea production, are prepared cheaply. 

The synthetic-ammonia process represents at present the largest single demand for hydrogen, followed by petroleum processing (a poor second), fat hydrogenation, and synthetic methanol. At the end of 1956 there were more than 63 synthetic-ammonia plants in this country with a capacity of about 4.8 million tons of ammonia per year. This quantity of ammonia is equivalent to a yearly demand of about 850,000 tons of hydrogen. 

The period following the war has apparently favored the direct synthetic ammonia process. The capacities in tons of nitrogen installed and building for the various processes at this time are arc, 5 plants of 44,750 tons cyanamide, 28 plants of 315,500 tons direct synthetic ammonia, 51 plants of 979,000 tons. 

There followed the appointment of a committee of scientists and engineers of the National Academy of Sciences 111 co-operation with the American Chemical Society at tlie request of the Secretary of War. In addition, two investigators were sent abroad to study and report on conditions ill Europe. In the meantime the General Chemical Company had worked up aod patented a modification uf the direct synthetic ammonia process as operated in Czermany, and made preparations for the erection of a plant. This plant of 7,5 tons of ammonia per day capacity was to be erected at Shadyside, New York. 

The 6 per cent of nitrogen produced liy the arc process consumed 37 per cent of tlm total power used in fixing nitrogen, die 24 per cent by the cyanamide prncess consumed 35 per cent, while the 70 per cent by the direct synthetic ammonia process consumed only 28 per cent of the total power. 

The possibility at this time far marked improvements in operation efficiency is not hopeful and there are indications of the arc process giving way to the direct synthetic ammonia process. 

The largest source of hydrogen for the commercial fixation of nitrogen according to the direct synthetic ammonia process is water gas. This gas results from blowing steam over a bed of glowing coke and has the following approximate composition ... 

Although electrolytic hydrogen is ideal for ammonia synthesis because of its purity it accounts for only 15 per cent of the ammonia produced by the direct synthetic ammonia process. The capital cost of a plant for the electrolysis is high, and except for a few especially favorable locations, electrical energy is more valuable for other industries. Although better results are claimed for certain cells, experience shows that the larger installations in this country have consumed... 

The flow diagram shown In the frontispiece and the model of a complete equipment assembly. Figure V, give a clearer picture of the direct synthetic ammonia process in commercial plant operation. 

There are a number of other developments. All, how -ever, are essentially modifications of the Haber method of operation of the direct synthesis ammonia process. In the United States It is understood that all the companies operating the direct synthetic ammonia process are licensed to operate under the original Haber patents which are controlled by the Chemical Foundation Incorporated. 

There will undoubtedly be some cyanamide production for some time to come, but the Increase In capacity will be according to the direct synthetic ammonia process, resulting in a continually smaller percentage of the fixation according to the cyanamide process. Such shifts in location as the reerection in Russia of the cyanamide units dismantled in Sweden to make room for synthetic ammonia capacity will tend to create the impression for a time of Increase In capacity, but the actual trend is a decrease. 

The reason for this shift to synthetic ammonia is a purely economic one. Nitrogen can be fixed in utilizable forms at a lower cost according to the direct synthetic ammonia process than by the other processes. 

The effect of synthetic ammonia in the L nited States is very marked. Before the advent of tfie direct synthetic ammonia process, liquid anhydrous ammonia was sellin r in the Eastern states at 32 cents per pound in cylinders. In addition, it was the practice for the dealer to receive a deposit for the cylinder so that his investment was tied up only in those cylinders which were idle at his plant or warehouses. At the present time this ammonia is being purchased by the Government on contract with the Mathieson Alkali Works at 10j/2 cents per pound in 100 pound cylinders, delivered to point of consumption, and no cylinder deposit is required. In bulk, It has sold for as low as 6 cents per pound. 

The preceding chapters indicate tliat from tlie present viewpoint at least the nitrogen source of the future will be the direct synthetic ammonia process for the fixation of atmospheric nitrogen. Chile nitrate, the arc process and the cyanamide process are all gradually but nevertheless efi ectively being displaced as sources of supply by the synthetic ammonia process. 

In view of this condition, then, it is of the greatest importance to those interested in the fixation of atmospheric nitrogen to consider the conversion products of ammonia, the immediate fixed nitrogen product of the direct synthetic ammonia process. Although ammonia is used as such in refrigeration and the chemical industry, its greatest use at this time is undoubtedly as the nitrogen carrier for various fertilizer salts. As was mentioned earlier, these salts may be formed by the neutralization of various acids with ammonia. 

The gypsum metliod of sulphate of ammonia productio i is rather well adapted to that form of the synthetic ammonia process which utilizes hydrogen from water gas, as the necessary carbon dioxide is a waste gas in the production of hydrogen from water gas. 

Of the 807,000 tons of nitrogen represented by the 5 6 per cent from die atmosphere, only 39,000 tons or less than 5 per cent was fixed by the arc process, 175,000 tons or less than 22 per cent was fixed according to the cyanamide process, while 593> o or over 73 per cent was fixed according to the direct synthetic ammonia process, A comparison of these figures with those for the previous year leaves no doubt of the trend of development. Of the 641,000 tons produced during the year ending June 30, 1926, the arc process ac-... 

Fixed atmospheric nitrogen and more especially the direct synthetic ammonia process is fast approaching the position once enjoyed by Chile nitrate, but it can never from present indications actuary achieve that position. Ammonia it is believed will always be produced as a by-product of the operation of the coke ovens. The production of by-product ammonia will increase, but it is believed its increase w lll be very slow. 

All statistics point clearly to the fact that the important source of fixed atmospheric nitrogen of the future, as It is of the present, will be the direct synthetic ammonia process. The maximuni annual capacity of all the plants now operating is 720,660 tons of nitrogen per year, w hile there is under actual construction additional capacity of 225,345 tons of nitrogen, or nearly 1,000,000 tons capacity operating and under construction. 

The Atmospheric Nitrogen Corporation, now operating the largest direct synthetic ammonia plant in the United States, is preparing for the erection of a large plant for this process for the production of fertilizer materials at Hope-well, Virginia. Indeed it is reported that construction has already started on the Hopewell site and that much of the equipment has been ordered and the fabrication of some completed. This plant will mark the entrance of the direct synthetic ammonia process for fertilizer production in this country and it is expected that expansion will be rapid. 

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