SU1527155A1 - Method of ammonia synthesis - Google Patents

Abstract

This invention relates to the synthesis of ammonia and can be used in the chemical industry. The method involves the synthesis of ammonia from nitrogen and hydrogen in the presence of an intermetallic compound, in which the process is conducted by contacting hydrogen with the intermetallic compound in order to reduce the energy consumption and increase the ammonia yield per unit mass of the intermetallic compound, then the reaction volume is filled with nitrogen under a pressure of 30 to 200 atm and heat the reaction mixture to 150-400 ° C. As an intermetallic compound (IC), a compound of type LANI ₅ or TIFE is used. The method allows to reduce energy consumption by eliminating the need for hydrogen compression and using the heat of ammonia reaction, as well as increasing the removal of ammonia per unit mass of the intermetallic compound from 1.8-2.5 to 30-60 g / kg IC. 1 hp ff, 1 tab.

Description

This invention relates to the synthesis of ammonia and can be used in the chemical industry.

The purpose of the invention is to reduce the energy consumption and increase the ammonia output per unit mass of the intermetallic compound.

The essence of the invention is that uncompressed hydrogen is brought into contact with an intermetallic compound (IC) of the type LaNij or type TiFe at ambient temperature - thus forming the hydride IC. The nitrogen is then compressed to a pressure in the range of 30–200 atm and blown into the reactor with the hydride. Then the reactor is heated to a temperature of 150-400 ° C, depending on the degree of precompression of nitrogen and the selected IC.

Here, the hydride decomposes with heat absorption and hydrogen evolution. Hydrogen, when released, reacts with nitrogen to form ammonia. The heat that is formed during the formation of ammonia supports the endothermic reaction of hydrogen release (the heat of ammonia synthesis reaction is 7.5-10 kcal / mol H, 7-10 kcal / mol H requires about hydrogen evolution), which allows practically make full use of the heat of ammonia formation directly in the reaction zone and thereby cover a significant part of the heat demand for hydrogen evolution.

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At the end of the reaction (after 1 to 6 minutes), the products are removed from the reactor and the cycle begins anew.

The minimum value of preliminary nitrogen compression of 30 atm is determined by the fact that at lower values a very large reactor will be required and a practically significant yield of ammonia will not be achieved. Compressing nitrogen to a JQ pressure above 200 atm is impractical because it requires the use of special vessels that withstand the pressures that develop during the reaction above 300 atm, and the yield of the product will increase insignificantly.

The experimentally determined minimum reaction temperature of 150 ° C is determined by the fact that at

lower temperatures, the reaction rate is too low. At Bbmie temperatures of the upper limit (), used ICs undergo irreversible decomposition into a mixture of metals and binary hydrides and thus lose their properties.

Example 1. In a steel reactor with a volume of 20 cm, containing 10 g of IMC-LaNij-powder, hydrogen is injected at room temperature under a pressure of 2 atm. In this case, a hydride formation reaction takes place, which ends in 0.5-1 minutes. The reactor is then filled with nitrogen at a pressure of 30 atm and heated to A for a minute. In the resulting gas mixture 33% ammonia, pressure 90 atm. The ammonia yield is 42 g per 1 kg IC.

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Examples 2-8. All operations are similar to example 1, the process parameters are given in the table.,

In all examples, external heating is required practically only to bring the temperature to a predetermined value. Further, the reaction is almost completely autothermal, i.e. ammonia heat transfer is used by the inside of the reactor.

The advantage of the proposed method is to reduce energy consumption, since there is no need for pre-compression of hydrogen, as well as the use of heat of ammonia synthesis reaction. In addition, the proposed method allows an increase in the removal of ammonia per unit mass of the intermetallic compound from 1.8-2.5 to 30-60 g / kg of IC.

Claims (2)

1. Method of synthesis of ammonia from nitrogen and hydrogen in the presence of intermetall-. This is done by contacting hydrogen with the intermetallic compound, then the reaction volume is filled with nitrogen under a pressure of 30–200 atm and heated to reduce the energy consumption, increase the yield of ammonia per unit mass of the intermetaplic compound. the reaction mixture to 150-400 ° C. 2. A method according to claim 1, characterized in that a compound of the type LaNi or TlFe is used as an intermetallic compound,