A novel method for extraction of platinum from spent automotive catalyst: utilization of spent fluid catalytic cracking catalyst as flux.

A novel method of smelting of mixture of spent automotive catalyst (SAC) and spent fluid catalytic cracking catalyst (SFCC) to recover platinum and prepare glass slag was investigated. Compared to other metals collection processes for single hazardous waste solid, this method reduced the amount of fluxing materials addition and increased the processing types of hazardous solid waste simultaneously. The optimum SFCC addition, iron collector addition, Na2B2O4•10H2O addition, CaO/SiO2 mass ratio, temperature, and holding time for platinum recovery were 20, 11, 16 wt%, 0.6, 1550-1600°C, and 60 min, respectively. In this proposed combined process, more than 98% of platinum is efficiently recovered from SAC. Meanwhile, the concentration of platinum in glass slag was less than 7 g/t. The leaching characteristics of heavy metals in slag confirmed the obtained glass slag is a non-hazardous slag due to the low leaching rate of heavy metal ions. This article proposed an effective and environmentally friendly method for the recovery of platinum from SAC via a combined smelting process.

Recovery of nickel and preparation of ferronickel alloy from spent petroleum catalyst via cooperative smelting-vitrification process with coal fly ash.

Spent petroleum catalyst (SPC) is a highly toxic material since it contains heavy metals and hazardous substances. A novel recycling technology based on the cooperative smelting-vitrification process by using coal fly ash (CFA) as a fluxing material was proposed. The benefits of employing CFA in this cooperative smelting-vitrification process of SPC have been demonstrated via the results of lab-scale and scale-up experiments. The experimental results indicated that with a collector iron (Fe) addition of 26 wt%, a C/O molar ration of 1.4, and an H3BO3 addition of 14 wt%, the maximum nickel (Ni) recovery was ∼98% by controlling the CFA addition of 40-50 wt%, basicity of 0.4-0.5, smelting temperature of 1550°C, and smelting time of 60 min, respectively. In this process, a ferronickel (Ni-Fe) alloy with a high Ni grade of 10 wt% was successfully obtained, which could be directly further produced stainless steel. Meanwhile, a glass slag with a low Ni content (below 0.12 wt%) was also obtained, and its leaching characteristics further confirmed it is a non-hazardous slag because heavy metals were successfully encapsulated in glass slag, and thereby, this proposed method achieved the transformation from hazardous solid waste to general solid waste. The results of the 10 kg scale-up experiment indicated the possibility of industrialization of this new technology. Therefore, the process proposed in this study is a practical and promising process for Ni recovery from SPC and reutilization of CFA.

Influences of Pretreatment of Carbon on Performance of Carbon Supported Pd Nanocatalyst for Nitrobenzene Hydrogenation.

We in this study prepared carbon supported Pd (Pd/C) nanocatalyst using pretreated carbon by different concentrations of hydrochloric acid, nitric acid, tartaric acid and hydrogen peroxide, respectively. The nanocatalyst was used for hydrogenation of nitrobenzene. The catalytic activity and microstructure of Pd/C catalyst were characterized by High Performance Liquid Chromatography (HPLC), scanning electron microscope (SEM), High power transmission electron microscopy (HTEM) and X-ray Diffraction (XRD). Results showed that the order of catalytic activity was as follows: Pd/C (C4H6O6) < Pd/C (HCI) < Pd/C (HNO3) < Pd/C (H2O2). The values for specific surface area, pore size and pore volume all decreased after pretreatment by HCl and HNO3, and presented a slight increase after pretreatment with H2O2. The dispersion performance of particles in Pd/C catalysts obtained with 25% hydrogen peroxide pretreatment was better and these particles' mean size was 8.0 nm. Pd crystallization degree for catalysts was lower after hydrogen peroxide pretreatment, and the crystalline grains were smaller.