CS257579B1 - A method for reducing acidic sulfur compounds - Google Patents

Abstract

The method of reducing sulfur oxide compounds, especially alkali metal sulfates and sulfites, consists in treating aqueous solutions of sulfates and sulfites with hydrogen, or synthesis gas, in the presence of catalysts resistant to sulfur poisoning at a temperature of 250 to 450° Celsius, preferably at a temperature of 300 to 400° C. and at a pressure of 1 to 20 MPa, preferably 2 to 5 MPa. This method can be used where there is a sufficient source of excess hydrogen and at the same time a source of waste sulfates or sulfites.

Description

The invention relates to a process for the reduction of oxygen-containing sulfur compounds, in particular waste ammonium and alkali metal sulphates and sulphites.

The energy and chemical industries are generating a large amount of waste sulfur oxides, which are a major environmental problem and are an environmental burden. A number of methods have been developed, tested and operationally implemented for their capture. Sulfates and sulphites are formed which also result in a number of other chemical productions and their use is sometimes very problematic.

A very advantageous way of utilizing waste sulphates and sulphites would be their selective reduction to elemental sulfur, possibly via hydrogen sulphide. Although this reaction is possible, for example, with various chemical agents and biochemically, the processing of large quantities of raw materials has so far been technically unrealistic and economically unacceptable.

The process according to the invention solves the reduction of oxygen-containing sulfur compounds, in particular waste sulphates and sulphites of ammonium and alkali metals. It is based on the fact that aqueous solutions of sulphates and sulphites are catalytically reduced by hydrogen to give the lowest oxidation degrees of sulfur, elemental sulfur and hydrogen sulphide. The catalytic reduction is carried out at a temperature of 250 to 450 ° C, preferably at a temperature of 300 to 400 ° C and at a pressure of 1 to 20 MPa, preferably 2 to 5 MPa. It is preferred to carry out the reduction with transition metal sulphide catalysts.

The invention can be advantageously applied where there is a sufficient source of excess or very cheap hydrogen and at the same time a source of waste sulphates or sulphites. The main advantage is the possibility of utilization of sulphate sulfur with the formation of elemental sulfur, eventually via transient hydrogen sulphide. Elemental sulfur has many uses in the national economy.

The invention is illustrated by the following examples.

Example 1

A solution of 66 g of ammonium sulfate (NH 4) ₂ SO 4 in 100 mL of water was hydrogenated in a rotary pressure autoclave in the presence of 10 wt. of NOS ₂ catalyst at an initial hydrogen pressure of 8 MPa, at a temperature of 350 ° C for half an hour. During the reaction, the sulfate was reduced by 99%.

Example 2

Under the conditions of Example 1, but at 3 MPa, a 99% reduction of the sulfate was achieved.

Claims (2)

OBJECT OF THE INVENTION Process for the reduction of oxygen-containing sulfur compounds, in particular ammonium and alkali metal sulphates and sulphites, characterized in that aqueous solutions of sulphates and sulphites are treated with hydrogen or a synthesis gas in the presence of catalysts resistant to sulfur poisoning at a temperature of 250 to 450 ° C , preferably at a temperature of 300 to 400 ° C, and at a pressure of 1 to 20 MPa, preferably 2 to 5 MPa. 2. The process of claim 1, wherein the reduction is carried out in the presence of transition metal sulphide catalysts.