Zeolite Nano-cds Photocatalytic Decomposition Of Hydrogen Sulfide, Hydrogen Research

The photocatalytic decomposition of H₂S to produce H₂ is a combinative technol-ogy of environmental treatment and cyclic utilization of resource. The key technology mainly focuses on the development of catalysts with strong visible light response, high photocatalytic efficiency and the long lifetime.In view of the disadvantages of easy photo-corrosion and low photocatalytic effi-ciency in bulk CdS semiconductor, series of nano-CdS photocatalysts supported on zeo-lites(CdS/zeolite)had been designed and prepared by ion exchange and precipitation method with three different structure zeolites of HY, Al-MCM-41 and mordenite (MOR).The effects of the preparation conditions, such as Cd2+ exchange times (n), sul-furation reaction time (τ) and calcination temperature (T) were investigated. The struc-ture and physicochemical properties were characterized by UV-Vis diffuse reflection spectra, XRD, FT-IR, N₂ adsorption, ICP-AES, SEM-EDS and HRTEM. The perform-ance of photocatalytic decomposition of H₂S to produce H₂ over the above photocata-lysts under visible light (wavelength above 400 nm) was also studied.It was known from the characteristic results that CdS nanoparticles with hexagonal structure in the CdS/HY and CdS/Al-MCM-41 photocatalysts resulted in a blue shift of the adsorption edge in UV-Vis diffuse reflection spectra. The decline of micropore volume of zeolites, the decrease of zeolite crystallinity and the changes (disappearance, shift and distortion) of characteristic peaks showed in FT-IR were all caused by the interactions between CdS and zeolites. However, the framework structure and morphology of zeolites were still maintained. The above results indicated that the CdS clusters with molecular dimension and high stabilization were formed inside the HY and Al-MCM-41 zeolite pores. It was shown from the characteristic analysis for the CdS/MOR prepared with thioacetamide that the size distribution of CdS clusters were around 3 nm, and the particle sizes of the supported CdS were confined. The application of the supported CdS with such photocatalytic properties was evidently improved in the field of photocatalysis.The zeolite-supported nano-sized CdS photocatalysts could prevent electron-hole from recombination and enhance the efficiency of H₂ evolution. The H₂ evolution rates from the decomposition of H₂S reached 24.03mmol/(h·g cat.(CdS)), 43.96 mmol/(h·g cat.(CdS)) and 16.74 mmol/(h·g cat.(CdS)) over CdS/HY, CdS/Al-MCM-41 and CdS/MOR respectively, which were 5, 9 and 3.5 times higher than that of the bulk CdS.