Processing of the catalyst used in reforming natural gas

. Today, in the world industry, special attention is paid to the synthesis of high-strength, low hydraulic resistance, improved geometry and increased specific surface area of catalyst granules. In this aspect an important task is to develop a technology for the production of our own highly efficient and durable catalysts based on the processing of spent industrial catalysts. To do this, it is necessary to substantiate a number scientific solutions, including in the following areas: development of technology for extracting nickel from spent industrial catalysts of the GIAP-8 series, technology for producing high-strength alumina carriers and scientific basis for obtaining a nickel-containing catalyst on a carrier of aluminum oxide.


Introduction
In the world, meeting the needs of the country's population in food products is impossible without the use of nitrogen fertilizers, such as ammonium nitrate, urea and ammonium sulfate. Their production is based on the production of hydrogen by conversion of natural gas on nickel-containing catalysts. Huge amounts of spent nickel-containing catalysts are produced every year during the production of hydrogen. Due to the lack of nickel production in the country, its high cost, in recent years, much attention has been paid to the use of spent industrial catalysts as secondary raw materials.
Currently, scientific research is being carried out in the world on the synthesis of catalysts with high strength, low hydraulic resistance and specific surface area. In this regard, special attention is paid to the creation technologies for the production of our own highly efficient and durable catalysts based on the processing of used industrial catalysts ; development of technology for extracting nickel from spent industrial catalysts; technologies for obtaining high-strength carriers for reforming catalysts and the scientific basis for obtaining a nickel-containing catalyst on a high-strength carrier.
Literary Review. Russia, Ukraine, Indonesia, Australia, Cuba, USA, Philippines, Brazil, have the largest reserves of nickel ores. Greece, etc. Japan can be attributed to the main producer of nickel, despite its territory there are no reserves of these ores.
The largest reserves of copper-nickel ores are located in the areas of Norilsk, Taimyr, the Kola Peninsula (Russia), Canada and Australia. In Canada , INKO is the leading company in the processing of copper-nickel ores.
In these deposits, copper-nickel ores are mainly represented in the form of pentlandite (Ni, Fe) S -an isomorphic mixture of Fe and Ni sulfides with a variable ratio.
To obtain pure nickel, its own waste is also used. In table. Table 1 shows the stocks and main characteristics of wastes containing the element nickel (Russia). The amounts of nickel-containing slags from ore furnaces and flotation tailings are discussed in [1].
The technical characteristics of the catalysts are presented from the production of ammonia synthesis by JSC "Korund" and "Kuibyshevazot". Taking into account the bulk weight of the catalyst and the productivity of ammonia production, it is possible to determine the order of volumes and discharges of nickel-containing waste generated per year.

Results and Discussion
Nickel is the main active component of nickel-containing catalysts used in the chemical and petrochemical industries of the GIAP-8, GIAP-16, R -67, AHM brands. The cost of nickelcontaining catalysts is largely determined by the price of non-ferrous nickel. Nickel consumption is increasing sharply in the world; at the end of the 20th century, world production of nickel increased from 500 tons/year to 1 million tons/year.
The growing deficit of nickel on the planet led to a fairly high price for nickel and, according to [2], at the end of 1997 it averaged $5957/t. This level allows organizing costeffective processing of nickel-containing industrial waste. Figures 1 and 2 show the results of X-ray diffraction, IR spectroscopy, and a micrograph of scanning electron microscopy of used GIAP-8.
On Figure 1 shows an X-ray diffraction pattern of the spent nickel-containing GIAP-8 catalyst, which has intense peaks of 2   Scanning electron microscopy data of the original, spent nickel-containing catalyst GIAP-8 with bar-graphs and determination of the quantitative characteristics present in the spent catalysts of chemical elements ( Figure 2). It indicates that the main elements are aluminum, oxygen, nickel.
Studies on the effect of temperature on the extraction process and duration on the degree of nickel extraction from the spent nickel-containing GIAP-8 catalyst were carried out using 30% nitric acid at a temperature of 30℃ and a duration of 4 hours. The results are shown in table. 3.
The table shows that with an increase in the norm of 30% nitric acid from 80% to 130% of the stoichiometry, for the components present in the spent catalysts, the content of nickel oxide in the liquid phase decreases from 16.76 ÷ 17.14% at an acid norm of 80 % up to 14.56÷14.72% at an acid rate of 100% and up to 12.64÷12.73% at an acid rate of 130%. At the same time, the degree of nickel extraction increases from 72.52÷74.56% at an acid rate of 80% to 81.05÷81.49% at a rate of 100% and up to 91.62÷91.68% at a rate of 130%.
The content of nickel oxide in the liquid phase and the degree of nickel recovery are practically independent of the composition of the samples of the spent GIAP-8 catalyst. Thus, at a rate of 30% nitric acid, the content of nickel oxide in the liquid phase is 14 The results show that the optimal conditions for nickel leaching are: nitric acid rate -100%, temperature -30÷35℃ and process duration -4 hours, at which the degree of zinc extraction is achieved -92.07%. In this regard, the density and viscosity of solutions obtained by leaching nickel from a spent catalyst with nitric acid solutions at a rate of 100% of stoichiometry were studied depending on the concentration and temperatures of solutions of 20, 40, 60 and 80℃. The data obtained are given in table. 4.
From the data obtained, it can be seen that with an increase in the acid concentration at its rate of 100% of the stoichiometry, the density and viscosity of the nickel extraction solutions from the spent catalyst increase. At a temperature of 20 ℃, an increase in the concentration of nitric acid from 20% to 50% increases the density of nickel extraction solutions from 1.148 g/cm 3 up to 1.318 g/cm 3 . At an acid concentration of 50%, with an increase in the temperature of the solution from 20℃ to 80℃, the density decreases from 1.318 g/cm 3 to 1.261 g/cm 3 . A similar picture is observed with respect to the viscosity of nickel extraction solutions. An increase in acid concentration from 20% to 50% leads to an increase in viscosity from 0.048 cP to 0.055 cP , and an increase in temperature leads to a decrease in viscosity. Thus, at a concentration of nitric acid of 50%, when extracting nickel, an increase in temperature leads to a decrease in viscosity from 0.055 cP to 0.037 cP 3 .
The obtained results indicate acceptable rheological properties of nickel extraction solutions from the spent GIAP-8 catalyst at a nitric acid rate of 100% of stoichiometry [3] The conducted laboratory and experimental tests on the leaching of nickel from spent nickel-containing GIAP-8 catalysts with nitric acid made it possible to develop a basic technological scheme, a block diagram, a material flow diagram, and a material balance for processing spent nickel-containing catalysts into nickel nitrate [4].
On Figure 3 shows the scheme of material flows and the material balance for obtaining nickel nitrate from nickel-containing GIAP-8 catalysts . The spent nickel-containing catalyst is crushed, moistened and evaporated, decomposed with nitric acid, filtered, and nickel nitrate is separated.
The technological process consists of the following stages:  Grinding.  Decomposition.  Filtering.

Conclusion
Spent industrial catalysts are a secondary raw material for the production of metal salts. The conducted studies on the extraction of nickel from spent catalysts with nitric acid solutions showed the possibility of extracting nickel from the catalyst by steam reforming of methane GIAP-8, R -67, GIP-16. The influence of the norm, concentration of nitric acid, temperature and duration of the nickel extraction process was studied.
With an increase in the norm of 30% nitric acid from 80% to 130% of the stoichiometry for the content of nickel oxide in the liquid phase present in the spent catalysts, it decreases from 16.76÷17.14% at an acid norm of 80% to 14.56÷14 .72% at a rate of 100% and up to 12.64÷12.73% at a rate of 130%. At the same time, the degree of nickel extraction increases from 72.52-74.56% at a nitric acid rate of 80% to 81.05÷81.49% at a rate of 100% and up to 91.62÷91.68% at a rate of 130%.
An increase in the acid rate leads to an increase in the residual nickel content from 10.36% at a rate of 80% to 11.64% at a rate of 100% and a decrease to 11.04% at a rate of