Recovery of Nickel from Spent Industrial Catalysts Using Chelating Agents

Abstract

The extraction of nickel from a spent primary steam reformer catalyst from an ammonia plant was carried out by chelation using ethylenediaminetetraacetic acid (EDTA) as the chelating agent. Ni recovery was optimized by varying the particle size distribution of catalyst (pretreatment of spent catalyst), stirring speed, temperature (particularly in an autoclave, where temperatures ranging from 100 to 200 °C were used), EDTA concentration, and solid-to-liquid ratio. Approximately 95% Ni recovery was achieved in the Ni extraction carried out under hydrothermal conditions in an autoclave, at temperatures of 150 °C and higher, over a 4-h period. The resulting Ni−EDTA complex was then “dechelated” using a mineral acid (H2SO4 and HNO3), resulting in the formation of a nickel nitrate or sulfate solution and the precipitation of EDTA (about 97% of the initial weight of EDTA was recovered). However, the chelation performance of Ni was shown to decrease with every successive recovery of EDTA (in the case of dechelation using H2SO4). EDX analysis of fresh and recovered EDTA established that fresh EDTA is a disodium salt whereas recovered EDTA is protonated. EDX analysis also indicated sulfur in the recovered EDTA when sulfuric acid was used for dechelation. TGA data showed a much larger weight loss in recovered EDTA in comparison to the fresh sample, probably because of a combination of two factors: the presence of sulfur species and the protonation of EDTA after recovery. It is likely that differences in recovered EDTA as evidenced by EDX analysis and TGA are responsible for the lowering the Ni chelation efficiency. This possibility is being investigated further as part of ongoing research.

Conceptual mechanism and kinetic studies of chelating agent assisted metal extraction process from spent catalyst

“…Elemental composition of the spent catalyst indicated presence of molybdenum (Mo) and cobalt (Co) as major metals, Three different values of solid to liquid ratio (S/L) were taken into consideration (1/10, 1/15 and 1/20 g/mL) for different values of reaction temperature ranging from 100 8C to 140 8C at particle size of 100-300 mm and stirring speed of 400 rpm. After chelation process, residue was separated from the complex solution and filtrate was sent for dechelation process [13]. Chelating agent EDTA was recovered during dechelation process and filtrate was treated for selective precipitation of Co/Mo on the basis of maximum solubility of metal oxides at different pH range [27].…”

“…Chelation technology has been considered a green approach for metal extraction from soil, spent catalysts and other industrial wastes due to high complexation efficiency with a wide range of metals, high thermodynamic stability in aqueous phase and recycling possibilities in further chelation cycles [11][12][13][14][15]. It has evolved over the century from being used in metal-intoxication to one based on engineering-chemistry in chemical industries, and most recently to one with increasing affinity to environmental sciences.…”

“…Spent catalysts are a major example of the industrial wastes which may cause severe environmental impact due to significant presence of nickel, molybdenum, cobalt, arsenic, zinc, cadmium, iron and other hazardous metals. Therefore, by considering the potential ecological risk associated with heavy metals, several research studies [1-10] are being carried out in recent years to develop ecofriendly methodologies for extraction of metals from industrial wastes.Chelation technology has been considered a green approach for metal extraction from soil, spent catalysts and other industrial wastes due to high complexation efficiency with a wide range of metals, high thermodynamic stability in aqueous phase and recycling possibilities in further chelation cycles [11][12][13][14][15]. It has evolved over the century from being used in metal-intoxication to one based on engineering-chemistry in chemical industries, and most recently to one with increasing affinity to environmental sciences.…”

Activity and Structural Changes of Fe‐based Catalysts during CO2 Hydrogenation towards CH4 – A Mini Review

“…[4] However, one of the drawbacks of traditional Ni catalysts is their toxicity, which necessitates special recovery techniques for spent catalysts. [5] Furthermore, the formation of highly toxic and volatile nickel carbonyls can lead to catalyst deactivation by loss of the active metal or decrease in the active surface area known as carbonyl-induced particle sintering. [6] Besides, sinter effects of the support also cause deactivation of Ni catalysts under harsh hydrothermal conditions upon methanation.…”

A small eggshell Ni/SFC3R catalyst for C5 petroleum resin hydrogenation: preparation and characterization

“…20 Oil reneries all around the world demand 300 thousand tons of FCC catalyst annually. 25 Currently, it is usually handled by means of being disposed in landlls, 26 chemical and magnetic separations, 20,25,27,28 and being used as construction material. 25 Currently, it is usually handled by means of being disposed in landlls, 26 chemical and magnetic separations, 20,25,27,28 and being used as construction material.…”