Properties of AC and 13X zeolite modified with CuCl2 and Cu(NO3)2 in phosphine removal and the adsorptive mechanisms

Adsorbents including CuCl2-AC, CuCl2-13X, Cu(NO3)2-AC and Cu(NO3)2-13X were prepared to remove trace phosphine from recycled hydrogen in the Siemens process of producing polysilicon, and adsorptive mechanisms were determined by X-ray diffraction and intermittent breakthrough experiments. CuCl2 could disperse better on supporters than Cu(NO3)2, and it existed in its original form. However, Cu(NO3)2 decomposed into copper oxide or basic cupric nitrate, and showed conspicuous thermal aggregation effect after calcination. Interactive effects between cupric components and supporters varied form species to species and deactivated the reactivity of CuCl2 and Cu(NO3)2 in different degree, which resulted in disparities of adsorbents' performances. CuCl2-AC and Cu(NO3)2-AC had better performances than CuCl2-13X and Cu(NO3)2-13X because cupric components were deactivated more when loaded on 13X zeolite. Chemical transformation of phosphine made adsorbents' surface renewable, and the renewed rate depended on the reactivity of cupric components. All of adsorbents showed significant recoveries of efficiencies in intermittent experiments.