Abstract
NiWAu trimetallic nanoparticles (NPs) on the surface of support Al2O3-CeO2-TiO2 were synthesized by a three-step synthetic method in which Au NPs were incorporated into presynthesized NiW/Al2O3-CeO2-TiO2. The recharge method, also known as the redox method, was used to add 2.5 wt% gold. The Al2O3-CeO2-TiO2 support was made by a sol–gel method with two different compositions, and then two metals were simultaneously loaded (5 wt% nickel and 2.5 wt% tungsten) by two different methods, incipient wet impregnation and ultrasound impregnation method. In this paper, we study the effect of Au addition using the recharge method on NiW nanomaterials supported on mixed oxides on the physicochemical properties of synthesized nanomaterials. The prepared nanomaterials were characterized by scanning electron microscopy, BET specific surface area, X-ray diffraction, diffuse reflectance spectroscopy in the UV–visible range and temperature-programmed desorption of hydrogen. The experimental results showed that after loading of gold, the dispersion was higher (46% and 50%) with the trimetallic nanomaterials synthesized by incipient wet impregnation plus recharge method than with impregnation plus ultrasound recharge method, indicating a greater number of active trimetallic (NiWAu) sites in these materials. Small-sized Au from NiWAu/ACTU1 trimetallic nanostructures was enlarged for NiWAu/ACT1. The strong metal NPs–support interaction shown for the formation of NiAl2O4, Ni-W-O and Ni-Au-O species simultaneously present in the surface of trimetallic nanomaterial probably plays an important role in the degree of dispersion of the gold active phase.
Highlights
Supported bimetallic nanoparticles (NPs) alloys or even recently trimetallic NPs have been a strategy commonly used in nanomaterials reports [1,2,3,4,5,6,7,8]
The supported NiWAu trimetallic NPs are mesoporous amorphous solids with high Specific Surface Area (SSA) in the range of 220 to 215 m2 g−1 for the catalysts impregnated by wet impregnation plus recharge method; on the other hand, for the trimetallic catalysts impregnated by ultrasound method plus recharge method, the SSA was increased in the range of 280 to 290 m2 g−1
Four NiWAu supported trimetallic NPS nanomaterials were prepared by a three-step synthetic method in which the gold addition was the last step via the recharge method
Summary
Supported bimetallic nanoparticles (NPs) alloys or even recently trimetallic NPs have been a strategy commonly used in nanomaterials reports [1,2,3,4,5,6,7,8]. It is well known that the nanostructured nanomaterials must be designed with high stability against leaching and agglomeration or sintering. The addition of second metal in the bimetallic system significantly enhances the stability and the activity of the designed catalysts due to a synergistic interaction [9]. The addition of a third metallic component improves the stability of a second metal in a parent bimetallic system [6,10,11,12]. Jin et al [10] found the enhanced stability of trimetallic alloy material (Ni-Fe-Cu) during dry reforming of methane (DRM) and weakened leaching of Fe. The Fe was affected by the reaction conditions of this application in the bimetallic system
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