CS219209B1 - Catalyser for thermooxidation method of fixing the mercury - Google Patents

Abstract

Catalyst for thermooxidation method determination of mercury by amalgamation technique atomic absorption spectrophotometry. Catalyst for thermooxidation assay method mercury consists of a combustion product fuel / oxidant mixtures. Oxidizer is 10 parts by weight of permanganate potassium and 2 to 4 parts by weight calcium organic compounds and 4-6 weight parts cobalt organic compounds.

Description

The present invention relates to a catalyst for the thermo-oxidative method of determination of mercury by the amalgamation technique using atomic absorption spectrophotometry.

The catalysts used for the thermo-oxidative methods of determining mercury are usually mixed catalysts in combinations separately deposited in layers in the combustion tube. In the first layer, for example, cobalt-cobalt dioxide CO 3 is used, and in the second layer, it is the decomposition products of potassium permanganate KMnCU of 65% / MnOa and 35 percent of potassium K2O. These catalysts are adjusted to a suitable texture by using inert mechanical carriers such as alumina Al 2 O 3 or ceramic shard, optionally by mixing with sodium silicate solution as a binder.

This is followed by a laborious process of drying, calcining, crushing and separating the appropriate catalyst fraction. When using supports, the catalyst is diluted and its efficiency and service life decreases. When using binders, these binders adversely affect the durability of the quartz tube used for the thermo-oxidative determination of mercury. Without texture modification, the catalysts are difficult to use as they easily block the passage of the tube to the passing gases and exhibit a high resistance to the passage.

The preparation of the second part of the potassium permanganate decomposition product catalyst KMnOa of suitable properties is solved by a process for its production by combustion of a mixture of calcium acetate fuel and potassium permanganate oxidant, whereby the increased alkalinity of the obtained catalyst prevents the acid gases S and N from passing through the reaction tube. These gases are undesirable in the amalgamator and measuring cell area.

These deficiencies are overcome by a mercury thermo-oxidative method catalyst consisting of the combustion product of the fuel-oxidant composition of the present invention, wherein the oxidant is 10 parts by weight of potassium permanganate and 2 to 4 parts by weight of calcium organic compound and 4 to 6 parts by weight of cobalt organic compounds.

In the combustion reaction, the mixture of gaseous products H 2 O _(g) and CO 2 _(g) released during the combustion loosens the catalyst mass and the exothermic reaction temperature solidifies the loosened mass by partial sintering. This catalyst provides a low resistance to the passing gases, containing components to catalyze the oxidation of the passing gases cobalt-cobalt dioxide CO 3 and manganese dioxide MnO 2 as well as alkaline components providing chemisorption properties to acid oxides 5 and N, namely potassium K 2 O and calcium CaO.

The combustion temperature of the reaction mixture in the preparation of the catalyst also ensures perfect removal of undesirable mercury impurities in the catalyst. All the advantages of the catalyst obtained by burning calcium acetate as fuel and potassium permanganate as oxidant are retained.

For preparing the catalyst, an organic calcium compound and an organic cobalt compound are used as fuels, for example calcium acetate, calcium benzoate, calcium citrate, calcium oxalate, calcium tartrate, calcium malonate, cobalt oxalate, cobalt acetate. The oxidant is always potassium permanganate. The greater the proportion of organic calcium compound in the fuel, the more basic the nature of the resulting catalyst.

The fuel / oxidant mixture is incinerated freely in air and the 0.25-1.0 mm fraction is collected as a tube for the mercury thermo-oxidative determination.

Example 1

A mixture of 10 parts by weight of potassium permanganate, 5 parts by weight of cobalt oxalate and 2 parts by weight of calcium acetate was prepared.

Example 2

A mixture of 10 parts by weight of potassium permanganate, 5 parts by weight of cobalt acetate and 4 parts by weight of calcium citrate was prepared.

Example 3

A mixture of 10 parts by weight of potassium permanganate, 5 parts by weight of cobalt oxalate and 2 parts by weight of calcium tartrate was prepared.

The homogeneous mixture of the examples was ignited in an iron bowl with a gas burner. From the resulting combustion product, a fraction of 0.25 to 1.0 mm was prepared and this fraction was used as the only fill of the quartz combustion tube of the thermo-oxidative method of mercury determination by amalgation technique using atomic absorption spectrophotometry.

Claims (1)

Catalyst for the mercury thermo-oxidation method, consisting of a combustion product of a fuel-oxidant mixture, characterized in that the oxidant is 10 parts by weight of potassium permanganate and 2 to 4 parts by weight of calcium organic compound and 4 to 6 parts by weight of cocatalyst.