Separation and Purification Technology, Vol.180, 23-35, 2017
Preparation of Cu-Fe nanocomposites loaded diatomite and their excellent performance in simultaneous adsorption/oxidation of hydrogen sulfide and phosphine at low temperature
In the study, a variety of supported metal oxide adsorbents were evaluated for simultaneous adsorption/oxidation of hydrogen sulfide (H2S) and phosphine (PH3) from crude acetylene gas at low temperature (80 degrees C), and the materials were synthesized using incipient impregnation method. Test results showed that the Cu-Fe nanocomposites/modified diatomite adsorbent (Cu-Fe/MKL) was determined to be the most promising adsorbent for simultaneous removal of H2S and PH3. The removal efficiency of H2S and PH3 may have a strong connection to the variety and amounts of functional groups and active components available as well as calcination temperatures. When the copper and iron loading amounts were 10 wt% and 6 wt% at 450 degrees C, the Cu-Fe/MKL adsorbent achieved the best removal efficiency and had the largest breakthrough adsorption capacity. It kept an impressive efficiency (100%) for 150 min and 60 min for H2S and PH3, respectively, at a relatively low reaction temperature of 80 degrees C and a GHSV of 10,000 h(-1). The adsorbents were also characterized by different methods, such as FT-IR, BET, TGA, XRD, SEM, XPS and in-situ IR. FT-IR results showed that the adsorbents modification by hydrochloric acid can provide more O-H, C-O and C=C groups, which may generate more unsaturated sites to promote the removal performance for H2S and PH3. BET results indicated that the addition of Cu-Fe composites did not change the structure of diatomite and it was optimized for simultaneous adsorption/oxidation of H2S and PH3 when the pore size distribution was approximately 7-10 nm. Moreover, XRD and TGA results revealed that metal oxides were detected after calcination, and the main active components available should be Cu-Fe nanocomposites. Furthermore, SEM images showed that iron species may play an important role to promote the dispersion of active components. In addition, in-situ IR and XPS analysis indicated that the exhaustion of sample may be determined by the loss of active components and the accumulations of products. It was considered that the excellent performance of adsorbents may be determined by the synergism of function groups, active components and dispersion capacity of them. However, because the components of diatomite were complex, the mechanism was difficult to investigate in this study. (C) 2017 Elsevier B.V. All rights reserved.
Keywords:Crude acetylene gas;Cu-Fe/MKL adsorbent;Simultaneous adsorption/oxidation;H2S and PH3;Low temperature