Synthesis of titanium-based alloys from spent SCR catalysts: A novel approach

The recovery of valuable metals from spent SCR catalysts currently centers on chromium and tungsten oxides. However, this approach demands substantial consumption of acids and bases, and due to the low vanadium and tungsten content, its economic output is minimal. In contrast, titanium dioxide, which exists in significantly higher proportions within the catalyst, is largely overlooked, aggravating environmental issues and leading to considerable resource wastage. This research proposes utilizing spent SCR catalysts as raw materials to directly synthesize titanium alloys, thereby increasing the recovery value of these discarded materials. The findings reveal that aluminum, employed as a reducing agent, efficiently reduces the majority of valuable metals in the catalyst, resulting in the formation of titanium alloys. Furthermore, the addition of calcium oxide markedly enhances the reduction process and improves slag-metal separation. When the CaO content reaches 50 wt%, titanium recovery achieves an impressive rate of 93.34 wt%. The produced alloy comprises primarily a Ti–Al alloy matrix, with a Ti–Si alloy as a dispersed reinforcing phase uniformly distributed within the matrix, demonstrating significant potential for practical applications.