Molybdenum Extraction from Spent Catalyst Using Citric Acid: Characteristic and Kinetics Study

Abstract

Interest on the extraction of valuable metals from secondary resources has been increasing recently due to the environmental consideration. It includes the spent catalyst from hydrodesulfurization process from the natural gas purification unit in fertilizer industry to reduce sulfur content. With composition of molybdenum as one of the active elements, the spent hydrodesulfurization (HDS) catalyst is indeed interesting to study, in order to be able to recover the molybdenum which is increasing within decades in need and unit price. In this study, recovery as well as extraction kinetics of molybdenum will be observed to calculate design parameters for scaling up process. The raw material used in this work is spent catalyst from PT. Pupuk Kujang Cikampek, Karawang, Indonesia. Leaching process was conducted with particle size -200 mesh, solid ratio of 1:5 and leaching time up to 120 minutes in the atmosphere condition by variated temperature (60, 80, 90°C) and pH (1.5, 2, 2.5) of citric acid. The solid samples before leached were analyzed using Energy Dispersive X-Ray (EDX), while the leaching filtrate samples were analyzed using Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES). The result of the experiment showed the maximum recovery of molybdenum at temperature of 90°C, during 120 minutes, and acid pH 1.5, 2, 2.5 were 71.20%, 34.66%, and 19.29% respectively. The independent variables used in this study showed a significant effect of molybdenum recovery, especially the acids pH. The kinetic model was evaluated by following the Shrinking Core model which considers diffusion is suitable to predict the leaching mechanism of molybdenum using citric acid.

Review of modern scientific developments in the field of molybdenum recovery from spent catalysts

“…It was also proposed to use citric acid as an organic extractant to extract molybdenum [15], but the degree of molybdenum extraction using this technology does not exceed 72%, which is lower than that of sorption methods.…”

“…In [15], the object of study is a spent catalyst from the Indonesian PT company. Leaching was carried out using citric acid at pH (1.5, 2, 2.5) for 120 minutes at temperatures of 60, 80 and 90 o С.…”

“…The technologies for processing spent hydro-treating catalysts with production of molybdenum oxide are considered, including oxidative roasting of the feedstock, as well as such operations as: leaching by sulfuric, hydrochloric, and nitric acids, sodium carbonate [7]. Hydrometallurgical methods of decomposition of raw materials are usually combined with the subsequent extraction of molybdenum by extraction with citric acid [16], MTAA carbonate [15], or ion-exchange sorption. High purity molybdenum is characterized by a number of unique properties that are important for its use in modern technology.…”

Hydrometallurgical Molybdenum Recovery from Spent Catalyst Using Tartaric Acid Derived from Agrifood Waste

“…It is an effective leaching agent for metal extraction because of its ability to form complexes with metal ions . In this study, the recovery was carried out from agrifood waste, specifically from wine lees produced as waste from Italian wineries. , According to an estimate provided by the International Organisation of Vine and Wine (OIV), in 2014, 44.4 Mhl of wine were produced in Italy, resulting in 8 million quintals of marc, including grape seeds (equivalent to 15% of grapes vinified), and 2250000 hectolitres of lees (equivalent to 5% of wine produced) . It is evident that in regions or countries with high wine production, such as Italy, a process that involves the recovery of tartaric acid from winery waste to leach industrial waste becomes feasible.…”