Abstract
The reduction of the ammonium nickel phosphate NiNH(4)PO(4) x H(2)O precursor into nickel phosphide (Ni(2)P), a highly active phase in hydrotreating catalysis, was studied using a combination of magnetic susceptibility and in situ X-ray diffraction and X-ray absorption spectroscopy (XAS) techniques. The transformation of NiNH(4)PO(4) x H(2)O into Ni(2)P could be divided into three distinguishable zones: (1) from room temperature to 250 degrees C, the NiNH(4)PO(4) x H(2)O structure was essentially retained; (2) from 300 to 500 degrees C, only an amorphous phase was observed; (3) above 500 degrees C, a crystallization process occurred with the formation of Ni(2)P. An in situ XAS study and magnetic susceptibility measurements clearly revealed for the first time that the amorphous region corresponds to the nickel pyrophosphate phase alpha-Ni(2)P(2)O(7). The phosphate reduction into phosphide did not start before 550 degrees C and led to the selective formation of Ni(2)P at 650 degrees C.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
