Hydrochloric acid modified CuAlOx catalyst for simultaneous removal of hydrogen sulfide and phosphine at low temperature

Abstract

Chemical modification was a critical method to improve the properties and structures of catalysts, which remained challenges. In this study, a series of Cu-Al catalysts were prepared by hydrothermal synthesis method for hydrogen sulphide (H2S) and phosphine (PH3) removal at 80oC, while the role of metal complexes and acid were discussed emphatically. The test results showed that the CuAlOx catalyst with HCl treatment (Cu: Al: HCl = 5: 5:1) had the highest performance of all materials tested, corresponding 37.25mgS/g sulfur capacity and 64.15mgP/g phosphorus capacity. The catalysts were characterized by X-ray diffraction, Brunauer-Emmett-Teller method, X-ray photo electron spectroscopy, scanning electron microscope images, transmission electron microscopy, inductively coupled plasma, and in situ IR. The results showed that HCl was able to expose more active sites and expand the catalyst channel by speciation generation and structural corrosion. Cu+ species was regarded as the most important constituent in the whole catalyst, which was attributed to Cu2+ species reduction due to extra electrons support of Cl ions and H2 help in the thermal treatment process. The metal coordination promoted the interaction of metal crystal faces, which had more advantages in pollutant removal than single copper or aluminum. Pollutant molecules were vertically adsorbed on Cu+ species to generate sulfur species and phosphorus species with the help of oxygen species and active sites. Subsequently, the products could be faster shifted to the surface of catalyst, and occupied active sites and vacancies, resulting in inactivation. The strategy of metal coordination and acid treatment was important, which supported more possibilities in catalytic performance enhancement for applications.