Polyaniline coated Pt/CNT as highly stable and active catalyst for catalytic hydrogenation reduction of Cr(VI)

Liquid phase catalytic hydrogenation reduction is a feasible method to eliminate Cr(VI) in water, while supported noble metal catalysts are liable to deactivation. In this study, carbon nanotube supported Pt catalyst (Pt/CNT) coated by polyaniline (Pt/CNT@PANI) was prepared and applied in the liquid phase catalytic hydrogenation of Cr(VI). Characterization results disclose that after coating Pt/CNT is completely wrapped by PANI layers and active Pt particles are no longer accessible. Despite complete embedment of Pt particles by PANI layers, Pt/ CNT@PANI remains highly active for Cr(VI) reduction in liquid phase catalytic hydrogenation. The catalytic Cr (VI) reduction on Pt/CNT@PANI can be described by a PANI oxidation-reduction mechanism, by which PANI is first oxidized by Cr(VI) to form Cr(III), and oxidized PANI is reduced by catalytic hydrogenation. The Cr(VI) reduction on Pt/CNT@PANI complies with the Langmuir-Hinshelwood model, reflecting the pivotal role of Cr (VI) adsorption. Furthermore, the catalytic activity of Pt/CNT@PANI differs with PANI layer thickness and Cr (VI) reduction is positively correlated with reaction temperature. Catalyst recycling results show that after 4 cycles Pt/CNT loses 92.4% of catalytic activity, while the initial activity of Pt/CNT@PANI slightly decreases by 11.6%, demonstrating its high catalyst stability.

Automated summary

Liquid phase catalytic hydrogenation reduction is a feasible method to eliminate Cr(VI) in water. Carbon nanotube supported Pt catalyst coated by polyaniline was prepared and applied in this study. Despite being completely wrapped by PANI layers, Pt/CNT@PANI remains highly active for Cr(VI) reduction and shows high catalyst stability after multiple cycles.