Integrated recycling of catalyst waste into composite materials

The steam conversion of natural gas produces carbon monoxide and hydrogen. Hydrogen is used in the synthesis of ammonia and nitric acid. These products are used to obtain ammonium nitrate, which is used as a nitrogen fertilizer and a base substance for explosives. Natural gas is decomposed on the nickel catalyst. Due to the reactions of methane and carbon monoxide reduction to carbon, the catalyst granules are covered with a layer of carbon. Finely dispersed carbon penetrates the pores of the carrier and forms a layer on its surface that shields the catalyst granules and reduces its efficiency. The catalyst must be replaced. In Russia, the most common catalysts are nickel-based aluminum oxide catalysts. Attempts to restore the catalyst waste to its original characteristics do not yield positive result. In this regard, an urgent task is the development of technologies for the extraction and purification of components of spent catalysts. The object of the research was cylindrical granules of spent GIAP–8 catalyst, consisting of a porous carrier γ-Al2O3 with nickel oxide applied to its surface, covered with a layer of carbon. During the decomposition of GIAP–8 catalyst waste, three components were isolated: aluminum oxide, ultrafine carbon powder and nickel salts. Aluminum oxide was used to create plastic-based composites. The resulting plastic–aluminum oxide composite material has high impact strength, but is destroyed at a bending angle of 45–35 degrees. Therefore, its use can only be recommended for the manufacture of massive products. The nickel salts were used to prepare the plating electrolyte, aluminum oxide was used to obtain a coating of “nickel–aluminum oxide”. The maximum aluminum oxide content in the coating was achieved at 25 g/L dispersed phase concentration in the electrolyte. The optimal cathode current density was 2–3 A/dm2.